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CONTENTS.
% ‘es J oe
_ A DESCRIPTION AND CLASSIFICATION OF THE ROCKS OF THE _
_-—-« CORDILLERAS. By M. E. Wapsworru. pp. xvi, 208, and xxxiii, 8 Plates. ae

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_ October, 1884.

atlemoirs of the Museum of Comparative Zoblogy
AT HARVARD COLLEGE.
Vou. XI. Part I.

LITHOLOGICAL STUDIES.

A DESCRIPTION AND CLASSIFICATION OF THE
ROCKS OF THE CORDILLERAS.

By M. E. WADSWORTH.

WITH EIGHT PLATES.

CAMBRIDGR:
Wrinted for the fMluseum.
October, 1884.

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INTRODUCTORY NOTE.

UnpER the title of “ Lithological Studies,” a work is here presented to the public
which is, in point of fact, a continuation of the publications of the Geological Survey of
California, begun under my direction, in 1860. Had that Survey been completed, the
investigation of the rocks of the State would naturally have been one of the matters to
which our attention would, at the proper time, have been turned; and, after the stoppage
of the Survey, in planning for the elaboration of the materials in my hands, I, in 1877,
determined that the lithological collections which I had accumulated, and which repre-
sented a wide area, should be described and classified. For this purpose Dr. Wadsworth
was selected; and, a portion of his results being now ready, it is thought best that it should
be published, without waiting for the completion of the entire work. It will undoubt-
‘edly seem to the reader that what is here furnished does not exactly correspond with
or carry out the idea suggested on the title-page, namely, that this is a description and
classification of the rocks of the Cordilleras. The reason is this: Dr. Wadsworth having
been led by his investigations to place his work on a considerably different basis from
that built upon by other lithologists, has found it desirable, and indeed necessary, to
incorporate in it results obtained from the study of material not furnished by the Cor-
dilleran collections. In the portion of the work herewith offered to the public, rocks more
basic than the basalts are brought under consideration ; and in doing this, it has been
found that it was not possible to arrive at the end sought to be gained without using the
materials furnished by other regions ana by other lithologists. Should this investigation
be continued and completed —as it is hoped will be the case, a large amount of work
having been already done with that end in view — the Cordilleran collections will yield
the chief portion of the material drawn upon for the remaining portion of the volume, so
that it will be found that the work is essentially based on the collections made on the
western side of the North American continent, the study of which gave rise to the ideas

presented in this first part.
J. D. WHITNEY.

CAMBRIDGE, Mass., October 18, 1884.

a

a

5

CONTENTS.

COE A PTE Fi.

3 SECTION L

ET Wea One oo) a9 gd YS i: nh ee 1-8
The law of the Physical Universe, 1.. Definition of Lituontoey, 1, 2; of
Perrotogy, 2; and of Perrocraruy, 2. The former liquid condition of the
Earth demanded by the facts of petrography, 2. The Earth and its material in
a transition state, 2. Classification of Rocks an index of the transition, 2. The
facts of petrography demand that eruptive rocks should be derived from a portion
of the Earth beneath the sedimentary formations, 2, 3. The assumed solidity
of the Earth based on hypothetical data, 3, 4. The problem of the interior
structure of the Earth beyond the present power of mathematics, 4. The sup-
posed arrangement of materials in the Earth’s interior, 4, 5. THomson’s theory
of the solidification of the Earth, 5; his mistake, 5. Experiments on the specific
gravity relation of hot solids and liquids, 5,6. The geologist may adopt any view
of the Earth’s interior consistent with geological facts, 6. Early cessation of the
action of convection in the Earth, 6. Dissipation of the Earth’s heat through
conduction, 6. All discussions of the age of the Earth and Sun should be based
on the transmission of heat by conduction in fluids and solids of diverse specific
gravities, which would probably give a greater age than now allowed by physi-
cists, 6. Owing to the viscosity and higher specific gravity of the underlying
liquid, the Earth’s first formed crust could not sink, as held by THomson, 6, 7.
The Earth would contract as a unit, and not by the shrinking of & solid nucleus
away from the crust, 7. The dynamic agent causing the elevation of lavas, 7. The
' viscidity of the interior and the irregular thickness of the crust would prevent
the connection of volcanic vents, 7, 8. Water the accident, not the cause, of a
volcanic eruption, 8. The view that the Earth’s interior is solid, but may be
reliquefied either by increase or diminution of pressure, 8.

SECTION IL

Tur ORIGIN AND ALTERATION OF Rocks reg ae Tene me Ng” te. eee

The theory of the Origin of Rocks taught in America, 8, 9. The aqueo-igneous
origin of Crystalline Rocks, 9. Rock Structure required by these theories, 9, 10.
Actual passage of Sedimentary Rocks into Eruptive forms not proved, 10. The

Vi

CONTENTS.

origin of rocks demanded by the results of petrographical study, 10. The asso-
ciations of different rocks, and the difficulties in their separation, 10,11. The
microscopic and field evidence the only means of distinction, 10, 11. Eruptive and
Sedimentary Rocks resemble each other through the alteration of both, 11. Sedi-
mentary Rocks presenting peculiar and abnormal conditions not proper guides, 11,
12. Sedimentary Rocks found not to present the microscopic characters of Erup-
tive ones, 12. Requirements necessary to prove the passage of a Sedimentary
into an Eruptive Rock, 12. Generally positive evidence that such passage does
not exist can be obtained, 12, 13. The chemical resemblance of Sedimentary
and Eruptive Rocks owing to the derivation of the former from the latter, 13.
Minerals in Lavas of prior origin to the consolidation of the magma, 13; not de-
rived from Sedimentary Rocks and characteristic of ancient and modern Eruptives,
13, 14. Field and microscopic evidence opposed to the theory of the derivation
of Eruptive from Sedimentary Rocks, 14; the demands of that theory, 14. Vol-
canic or eruptive action began in the earliest ages of the Earth, 14; this action,
although intermitteut, is adying one, 14,15. The older Eruptives the same, origi-
nally, as the modern ones, 15; their present differences due to alteration, etc., 15.
Under like conditions alteration is proportional to the age, 15. The presence of
fragments of one rock in another is alone no proof of difference in geological age,
15, The alteration produced by internal molecular or chemical changes in the
rock mass not to be confounded with superficial weathering, 15. Metamorphism
not extended Pseudomorphism, 15. Pseudomorphism but an incidental phase in
alteration, 15. The explanation of changes in rocks, 15, 16. Metamorphism
inversely proportional to the contained silica in the original rock, when time
and other conditions are the same, 16. Eruptive Action, including Thermal
Waters, an efficient agent in Metamorphism, 16. Metamorphism dependent on
the chemical composition of the rock and the metamorphic agents, hence_litho-
logical characters no criterion for determining geological age, 16.. The constitu-
ents of rocks pass from an unstable towards a more stable condition, 16; this
passage a factor in the dissipation of energy, 16. Rocks are produced, grow old,
and decay, but are not raised again, 17. Crystalline Structure no proof of great
age or of great depth, 17. Long time not always allowed for the formation of
fine-grained and fossiliferous rocks, 17. Contraction tends to maintain a uniform
temperature in the Earth’s interior, 17, 18. Relative Progression in geological
time from abundant Acidic to abundant Basic Eruptives, 18. All Eruptives de-
rived from the Earth’s interior material which had never solidified, or which has
since been reliquefied, 18. Sorsy’s method of determining the origin of a rock
misleading, 18. Association of Rocks is alone no proof of community of origin,
18, 19. Crystalline Schists naturally occur in a region of eruptive rocks, 19.
Detinition of Lamination, 19 ; this structure common in many eruptive rocks, 19.
Joint Planes defined, 19; often mistaken in eruptive rocks for Bedding Planes,
19, 20. Cleavage defined, 20. Cleavage common both in Eruptive and Sedi-
mentary Rocks, 20. Foliation defined, 20. Foliated Limestone mistaken for
Mica Schist, 20. Foliation and Cleavage produced by the same cause at Squantum,
Mass., 20,21. Foliation common in altered eruptive rocks, 21; the planes being
at right angles to the direction of pressure, 21. Schistose or Fissile Structure, 21.
Fluidal Structure detined, 21. Schistose Structure often mistaken for Fluidal
Structure, 21; the latter mistaken for Planes of Sedimentation, 21. Lines of
chemical deposition taken for fluidal structure, 21. Arguments from analogy of
doubtful value, 22; also from one region to another, 22. Evidence not sustain-
ing the divisions of the Azoic System, 22, 23. Explanation of the structure of

CONTENTS. Vil

districts of Crystalline Rocks, 22. Application of current views in American
Geological Literature, 23. Association of Eruptive and Volcanic Rocks, 23.
Origin of Crystalline Rocks, 23. Application of current views to Vesuvius in
the time of Srraso, 24. Principles to be employed in studying regions of
Crystalline Rocks, 24. Materials of the earliest formed Lands of eruptive origin,
24. Application of the term Eruptive or Volcanic in this work, 24. The younger
Volcanic and the older Plutonic Rocks form a continuous series, 24.

SmorLoN FL
THE ORIGIN AND RELATIONS OF THE MINERAL CONSTITUENTS OF Rocks. . . 25-30

The constituents of rocks fall into three classes, 25. Two divisions of the first
class, 25 ; action of the Magma on Minerals of the first division, 25. Inclusions
in eruptive rocks, 25,26. Action of Lava on Inclusions, 26. Microscopic charac-
ters of Eruptive Rocks opposed to the theory of their derivation from Sediments,
26. Mineral products of the crystallization of a magma, 26. Mineral products
of rock alteration, 26. The chemical constitution of altered rocks not essentially
changed, 26. Cause of rock alteration, 27. Alteration a character of the rock
mass as a whole, 27. Altered eruptive rocks tend to simulate the features of
sedimentary forms, 27. The general tendency of rock alteration, 27, 28. The
concentration of ores in rocks and veins attendant upon rock alteration, 28. Ores
of mechanical and eruptive origin excepted, 28. Theory of ore deposits, 28.
Mineralogy and Economic Geology chiefly sciences of abnormal minerals, 28.
Unstable character of eruptive rocks, 28; their resemblance to chemical labora-
tories, 29; passage from unstable towards more stable chemical combinations, 29.
Induration not always an indication of exposure to heat, 29. The glassy state of
rocks is nearest their primitive condition, 29. Designations employed for the
three classes of rock-forming minerals, 29. Distinction of cases of envelopment
from alteration products, 29, 30. Application of the principles of Thermo-optics,
30. The pyrognostic characters of a mineral have little or nothing to do with its
condition before its formation, 30. The conditions under which minerals crystal-
lize from a cooling magma are different from those under which vein and altera-
tion minerals are formed, 30.

Sic, ELON. EV.

Memion ANNALS OF HOCKS 9.) faciaete .) ee Soe eg me aye. SL, 32

Chemical Analysis unable to determine the mineral constituents of rocks, 31,

_ 82. While Chemical Composition remains nearly constant, great variation exists

in the structure and mineral constituents, 31. What Chemical Analysis can do

for the lithologist, 31. Relation of Chemical Analysis of normal rocks to rock

species, 32. Analyses should be written in terms of the elements, instead of their
compounds, 32.

SECTION V.

CLASSIFICATION BASED ON MINERAL COMPOSITION . . . . . ss ee es) SOM45

Basis of the common classifications of rocks, 33; minerals used, and data re-
quired, 33.— Tue Fexpspars, 33-43. Their different modes of origin, 33.
Scnrerer’s feldspar theory, 33, 34; Detessn’s views, 34 ; HerMANN’s molecular

viii CONTENTS.

theory, 34. Waxrersnavsen’s theory, 34. Krablite a rock, and not a mineral, 34,
35. Bunsen’s view of Baulite, 35. Hunt's theory of the feldspars, 35. TscuHEr-
MAK’s theory, 35, 36; Srrene’s views, 36; PETERSEN’s objections to TscHERMAK’s
theory, 37. Dana’s method of accounting for variations in feldspars, 37.
Hunt claims to have originated TscuprMak’s theory, 37. Hunt's alteration of
his direct quotation, 37. Hunvt’s theory not original with him, and not the
same as T'SCHERMAK’S, 37. Writers who through misapprehension have acknowl-
edged Hunv’s claims, 37, 38; Stpuman charges TScHERMAK with appropriation of
Hunv's views, 38; Lreps recognizes the difference between the views of Hunt and
TscHERMAK, 38. The charges of appropriation made against TscHERMAK false, 38.
DerscLoizEaux on the optical properties of the feldspars, 38; FrRieprv’s theory
of their chemical constitution, 38; Vom Ratu’s views, 38, 39. DEscLoizEavx’s
discovery of microcline, 39. Mattarp and Livy teach that it is the same as or-
thoclase, 39. ScuustTER’s observations on the optical properties of the feldspars,
39. Feldspars not suitable to found specific distinctions upon, 39. No means
of positively determining the feldspar species in rocks, 40. DrscLoizEaux’s
method of determining feldspars, 40; Pumpetuy’s modification of, 40, 41; Pum-
PELLY anticipated by Livy, 41. The work of both independent, 41. Hawes on
the distinction of feldspars, 41. Bokicky’s micro-chemical method, 41, 42.
Szaso’s method, 42. Guo. H. Emerson’s invention of a method of distinguishing
minerals by means of crystals formed in blowpipe beads, 42°; amplified later by
Gustav Ross, W. A. Ross, and H. C. Sorsy, 42. The specific gravity method for
determination of the feldspar species, 42. Objections to the above methods, 42,
43. The twinning not constant in feldspars, 43. The chief value in lithology of
the determination of the feldspars, 43. — Tur PyrRoxeNE-AMPHIBOLE Groups, 44,
45. A variable series in them as in the feldspars, 44. Cleavage not a satisfac-
tory basis for separating Diallage from Augite, 44. Augite found in Basic and
Acid Rocks, and in the older and younger, 44. Alteration of Augite, 44. Sec-
ondary origin of some Pyroxenes, 44. Relation of Hornblende and Augite, 44,
The same hand specimen both a Diorite and Diabase, 44. The Mica Series, 45.
Secondary origin of Chlorite and Epidote, 45. — MinreratocicaL NoMENCLATURE
or Rocks. Rock Classification based on mineralogy alone, impracticable, 45,
Rock Structure valueless for specific distinctions, 45.

SHCTLION, Vi.

Naminc Rocks ACCORDING TO THE GEOLOGICAL AGE ..+*. : .... . 40-47

Such nomenclature not natural, 45. No line can be drawn at the Tertiary Age,
46. Alteration under like conditions proportionate to age, 46. The petrogra-
pher’s duty, 46. The presence of Fluid Cavities in rocks, 46. VocELsane and
JuLiEN on Fluid Cavities, 46. Fluid Cavities sometimes original and sometimes
secondary in rocks, 46. Occurrence in Tertiary Rocks, 46. The cause of the
Crystalline Structure in the older rocks, 46, 47. The Granitic Structure, 47.

SECT POR: Val

METHODS OF CLASSIFICATION=.. .. :ye ee *eaennmaeeh raw eene ee
Classification the framework of any descriptive science, 47. The mineralogical
method of studying rocks, 47. The natural method, 47. The relation of miner-
als to rocks, 47, 48. Meaning of the Natural Classification, 48. Characterization

2

Tue PRINCIPLES OF CLASSIFICATION .

CONTENTS.

of the Mineralogical Classifications of rocks, 48, 49. Compared with zotlogical
methods, 49. Question of methods, 50. Larlier publication of these principles,
50. European classifications based largely on altered rocks, 50. To express
perfectly the Natural Classification of rocks requires perfect knowledge of them,
50. The classification here introduced empirical, 50, 51. Elasticity of the classi-
fication, 51; its fundamental principles, 51.

SECTION VIIL

SECTION IX.

GENERAL CONCLUSIONS IN REGARD To SYSTEMS OF LITHOLOGICAL CLASSIFICATION

Universal law of degradation of energy, 53. Natural classification conforms to
it, 53. The demands of Petrography, 53. Expansion of materials in passing from
the liquid to the solid state, 53. Pressure tends to render the Earth’s interior
solid, 53. Sinking of the Earth’s crust, 53. The structure of the Earth indicated
by petrographical and geological facts, 54. Crystalline rocks, 54. Systems of
classification, 54, 55. Chemical analyses of rocks, 56. Alteration of rocks, 56.
Divisions of minerals and rock fragments in rocks, 56. The order of arrange-
ment of rocks, 57. Determination of a rock by means of its unaltered ground-
mass, 57. Practical application of the principles of nomenclature and classifi-
cation, 57. Specific and varietal names, 57. The use of the terms Melaphyr,
Diabase, and Diorite, 57, 58. Sub-varietal names, 58. Trivial names, 58.
Arrangement of the fragmental rocks, 58. Arrangement of rock names, 58, 59.
Varietal and sub-varietal names not essential, 59. Use of a binomial and
trinomial nomenclature, 59.

CHAPTER: I.
THE SIDEROLITES AND PALLASITES.

SHCTION FF

PmIeeOPITE: fi). 6 6s

Definition of Sripwrotite, 60. Shingle Springs, Eldorado Co., California, 60.
Stanton, Virginia, 60, 61. Coahuila, Mexico, 61. Gibbs meteorite, Texas, 61.
Butler, Missouri, 61. Toluca, Mexico, 61. General structure of meteoric sidero-
lites, 61; constituents of, 61. Widmannstiittian figures developed in, 62; also in
Greenland iron, 62. References to illustrations of Widmannstattian figures, 62.
Further divisions of the Siderolites, 62; chemical analyses of, 62, 63; specific
gravity of, 63; Iron in, 63; Nickel and Cobalt in, 63, 64; minor elements in, 64.
Terrestrial Siderolites, 64, 65. Greenland iron, 65; its origin, 65. Doubtful me-
teoric origin of many Siderolites, 65. Chemical analysis made sole test of mete-
oric origin, 65,66. Origin of masses of meteoric iron, 66 ; TscHERMAK’s views, 66 ;

53-59

60-68

x CONTENTS.

Sorpy’s conclusions, 66, 67 ; objections to their theories, 67. The organic origin
of meteoric iron and graphite, 67. MaskELyne’s use of the term Stderolite, 68.
The terms Siderite and Holosiderite, 68.

SECTION A:

PALLASITE . 0s 8 6 ee te wm

Gustav Rosr’s use of the term, 68. Definition of Pallasite, 68 ; arrangement of,
68. — Tue Meteoric Pauuasires, 69-75. ‘Tucson, Arizona, 69. Hemalga, Peru,
69. Berdjansk, Russia, 69. Deesa, Chili, 70. Atacama, Bolivia, 70. Bitburg,
Prussia, 70. Hommoney Creek, North Carolina, 71. Singhur, India, 71. For-
syth, Missouri, 71. Anderson, Ohio, 71. Krasnojarsk, Siberia, 71, 72. Potosi,
Bolivia, 72. Rittersgriin, Saxony, 72. Breitenbach, Bohemia, 73. Steinbach,
Saxony, 73. Atacama, Chili, 73. Sierra de Chaco, Chili, 73. Newton Co., Arkan-
sas, 74. Meyellones, Bolivia, 74. Hainholz, Westphalia, 74. Lodran, India,
(fees

Variety. — Cumberlandite, 75-83.

Iron Mine Hill, Rhode Island, 75-79. State of the Iron of but little impor-
tance lithologically, 76. Microscopic veins, 76. Hercynite (2), 77. Tracing
altered conditions of Cumberlandite, 77-79 ; specific gravity of, 79; diminish-
ing specific gravity with alteration, 80. First published description of Cumber-
landite, 80. Study of other iron-bearing rocks, 80, 81. Taberg, Sweden, 81.
General description of Pallasite, 81; of Cumberlandite, 81, 82. Chemical
analyses of Pallasite, 82, 83. Chemical analysis alone suggests, but does not
prove, the specific relations, 83.

CHA PTE Ry k
THE PERIDOTITES.

SECTION I.

INTRODUCTORY. 2 3 4% ew en

Rosrnsuscn’s use of the term Peridotite, 84. How employed in this work, 84.
Order of arrangement in the Peridotites, 84. The needlessness of subdivisions of
Peridotite, 84 ; yet subdivided here in conformity to general usage, 85. Defini-
tion of Dunite, 85. Proposal of the name Saxonite, 85. Definition of Lherzolite,
85. Proposal of the name Buchnerite, 85. Definition of the terms Lulysite,
Prerite, Serpentine, Porodite, and Tufa, 85.

SEC®TOR? i.
THE METEORIC: PERIDOTIPES ; > = gee. eee

Variety. — Dunite, 86.

Chassigny, France, 86; glass in, 86, 105.

.
i

CONTENTS. xi

Variety. — Saxonite, 56-94.

Iowa Co., Iowa, 86-88. Origin of the chondritic structure, 86,87. Occurrence
of a base in meteorites, 87. Dhurmsala, India, 88. Knyahinya, Hungary, 88-91 ;
organic remains in, 89. The constitution of meteorites such that they could not
have existed in conditions suitable for life, 91. Chondritic structure, 91.
Gnadenfrei, Silesia, 91, 92. Gopalpur, India, 92; feldspar in it doubtful, 92,
Butsura, India, 92, 93. Lancé, France, 93. Tourinnes-la-Grosse, Belgium, 93.
Waconda, Kansas, 93, 94. Goalpara, India, 94.

Variety. — Lherzolite, 94-101.
Pultusk, Poland, 94, 95. New Concord, Ohio, 95, 96. Mocs, Transylvania,
96. Zsadany, Banat, 96,97. Estherville, lowa, 97-101. Iron globules in, 97,
98. Peckhamite, 99, 101. Meunirr’s theory of the origin of the Estherville

meteorite, 99, 100; objections thereto, 100. Variations in structure of this
meteorite, 100, 101.

Variety. — Buchnerite, 101, 102.

Tieschitz, Moravia, 101,102. Peculiar character of its chondri, 101. Hungen,
Germany, 102. Grosnaja, Caucasus, 102. Alfianello, Italy, 102.

MIsceLLangEous, 103-105.

Bavarian Meteorites: Mauerkirschen, Eichstadt, Schonenberg, and Kriihen-
berg, 103. Cabarras Co, North Carolina, 103, 104. Mezo-Madaras, Transyl-
vania, 104. Alessandria, Piedmont, 104. Renazzo, Italy, 104; special study
should be made of this form, 104. Linn Co., Lowa, 104. Ausson, France, 104.
Nanjemoy, Maryland, 104. Drake Creek, Tennessee, 104. L’Aigle, France, 105.
Weston, Connecticut, 105. Chateau Renard, France, 105. Hessle, Sweden, 105.
Nobleboro’, Maine, 105.

Vaninty. — Tufa, 105, 106.
Orvinio, Italy, 105, 106. Chantonnay, France, 106.

SHOLLEON Tif.

THe METEORITES. — THEIR ORIGIN AND CHARACTER . ..... e. e 106-118

Masketyne’s teachings, 106, 107. Sorsy’s views, 107, 108. Forses’s micro-
scopic observations, 108. Mxrunrer’s theory and Forses’s criticism of it, 108, 109.
TscHERMAK’S idea of the tufaceous character of meteorites, and their eruptive
origin, 109, 110. Objections to the preceding views, 110-112. The Chondritic
Structure limited to a certain chemical and mineralogical type of meteorites, 110.
Continuity of the Chondri and Matrix, 110, 111. Structure of meteorites rarely
fragmental, 111, 112. Chondritic Structure produced by rapid crystallization,
111. Enclosures in meteorites, 111, 112. Meteorites derived from liquid, not
solid material, 112, 113. The Sun, or some similar body, their most probable
source, 112. Community of elements in the Sun and Meteorites, 112. Possi-
bilities of Meteorites being thrown from the Sun, 113. Probable liquid condition
of the Sun, 113. Meteoric constitution of some astronomical objects, 113. The
theory that Meteorites are thrown from the Sun is old, 113, 114. Abundance of
Metallic Meteorites in past times, 114. Meteorites not thrown from the Moon,
114 ; and not from the Earth in past times, 114. Need of further careful study

Xl CONTENTS.

of meteorites, 114,115. Objections to SorBy’s view that minerals of unlike spe-
cific gravity can intercrystallize, 115, Objections to HetmHottz’s theory that the
Earth is composed of meteoric fragments, 115,116. Boulders in Northern Drift,
fallen Meteorites, 116. Unscientific to suppose Meteorites have brought germs
of life to the Earth, 116. Destruction of germs by the cold of space, 116.
Meteorites not exposed to action of water and air, 116. Meteorites not vein for-
mations, 117. Source of metals in veins, 117. Copper in Meteoric Rocks aud
Terrestrial Basic ones, 117. Metallic Iron in Terrestrial Basic Rocks, 117.
Nickel, etc. in Meteoric and Terrestrial Masses, 118.

SEC TLON akyv;
THE TERRESTRIAL PERIDOTITES@ <<, c.5 coed ce cee scene een en

Variety. — Dunite, 118-125.

Franklin, North Carolina, 118; structure indicates eruptive origin, 118.
Webster, North Carolina, and alterations in, 119, 120. Tafjord, Norway, 120.
Dun Mountain, New Zealand, 121. Sdndmore, Norway, 121 Rébergvik, Nor-
way, 121. Bonhomme, France, 121,122. Karlstatten, Austria, 122. Tron, Nor-
way, 122. Heiersdorf, Saxony, 122, Ronda Mountains, Spain, 122,123. Serrania
de Ronda, Spain, 123. St. Paul’s Rocks, their origin and alterations, 123-125.

Variety. —Saxonite, 125-128.

Russdorf, Saxony, 125. Northern Norway, 125, 126. Thorsvig, Norway, 126.
Birkedal, Norway, 126. Hovenden, Norway, 126. Rodfjeld, Norway, 126.
Andestad See, Norway, 126, 127. Langenberg, Saxony, 127. Callenberg,
Saxony, 127. The Ziegelei, Saxony, 127. Fatu Luka, Timor, 127. Rofna, Alps,
127, 128.

Variety. — Lherzolite, 128-147.

Lake Lherz, France, 128, 129. Serranfa de Ronda, Spain, 129. Italy, 129.
Ultenthal, Tyrol, 129. Colusa Co., California, 129-132; alteration structure in,
taken for stratification, 130. Inyo Co., California, 132. Production of Magnetite
during alteration, 132. Mohsdorf, Saxony, 132, 133. Rédhaug, Norway, 133.
Baste, Harz, 133, 134. Christiania, Norway, 134. Gjorud, Norway, 135. Presque
Isle, Michigan, 136-138. Formation of dolomitic rocks, 137, 138. Eruptive
origin of this Peridotite, 138. Ishpeming, Michigan, 139. Dolomitic rocks, 139.
Transylvania, Austria, 139, 140. Fichtelgebirge, Bavaria, 140. Jaina River,
San Domingo, 140. Starkenbach, France, 140. Todtmoos, Baden, 141. Plumas
Co., California, 142. Levanto, Italy, 142. Euboea, 142. Philippine Islands,
143. Lizard District, Cornwall, 143. Troad, Asia Minor, 143-147, Dikes of
Serpentine, 144. Diallage with Cleavage of Augite, 145. Schistose Rocks and
their origin, 146, 147.

Variety. — Bulysite, 147-149.

Tunaberg, Norway, 147. Kettilsfjall, Sweden, 147,148. Varallo, Sesia Valley,
148. Lepce, Austria, 148. Fontanapass, Greece, 148. Mohsdorf, Saxony, 148.
Gillsberg, Saxony, 148, 149. ’

Variety. — Picrite, 149-152.

Austria, 149. Steierdorf, Banat, 149, 150. Inchcolm Island, Scotland, 150.
Herborn, Nassau, 150. Ellgoth, Austria, 150, 151. Anglesey, 151. Dillgend,
Nassau, 151, 152.

oe

CONTENTS. Xiil

Variety, — Serpentine, 152-161.

Fitztown, Pennsylvania, 152. Trankenstein, Silesia, 152. Leké, Norway, 152
Waldheim, Saxony, 153. Thessaly, 153. Santiago, San Domingo, 153, 154.
La Vega, San Domingo, 154. Brixlegg, Tyrol, 154. Il Piano, Elba, 154, 155
Tasmania, 155. Windisch-Matrey, Tyrol, 155. St. Sabine, France, 155, 156.
River Oisain, Timor, 156. Riviere des Plantes, Canada, 156. Melbourne, Canada,
156. Galicia, Spain, 156. High Bridge, New Jersey, 156, 157. Zoblitz, Sax-
ony, 157,158. Chip Flat, California, 158. Depot Hill, California, 158. Plumas
Co., California, 158. Finland, 158. Klopfberg, Austria, 159. Nezeros, Thes-
saly, 159. Fatu Temanu, Timor, 159. Westfield, Massachusetts, 159, 160.
Formation of Talc, 159. Lynnfield, Massachusetts, 160. River Joa, San
Domingo, 160. Newport, Vermont, 161. Celinac, Austria, 161. Texas, Penn-
sylvania, 161. Chester, Pennsylvania, 161.

Variety. — Porodite, 161, 162.
Fatu Luka, Timor, 161, 162. Strand, Timor, 162.

SECTION V.

PERIDOTITE. —ITS MACROSCOPIC CHARACTERS .......<. . . 162-165

Structure of the Meteoric Peridotites, 162. Structure of the Terrestrial
Peridotites, 163-165 ; least altered forms, 163; alteration characters, 163. Ap-
pearance of the Olivine Groundmass, 163. Alteration of the Pyroxene Minerals,
163, 164. Segregations in Serpentine, 164. Translucency of Serpentine, 164.
“Slickensides” in Serpentine, 164. Products of extended alteration in Perido-
tite, 164. Term Serpentine in Mineralogy, 164. Variability of Serpentine, 164 ;
Schistose Structure in, 164. Production of Tale and Actinolite Schists, 164, 165 ;
of Dolomitic Limestones, 165. Fragmental states of Peridotite, 165. Origin of
Ophicalcites and brecciated Serpentines, 165. Introduction of the terms JJerolite
and Merolitic for pseudo-fragmental rocks, 165.

SECTION VI.

PrRIpoTITE. — Irs: Microscopic CHARACTERS. ... ....e. « « . 165-175

General Microscopic Structure of the Meteoric Peridotites, 165-167. The Base
of, 166. The Chondri of, 166. The Olivine of, 166. The Enstatite of, 166.
The Iron and Pyrrhotite of, 166, 167. The Chromite and Picotite of, 166.
The Manbhoom Saxonite, 167. Union of Diallage and Augite Cleavage in Dial-
lage, 167. Lherzolite, 167. Minor minerals in Meteoric Peridotites, 167. Frag-
mental Meteorites, 187. Microscopic characters of the Terrestrial Peridotites,
168-175; of Dunite, 168; alteration to Serpentine, 168. Transition in the
varieties of Peridotite, 168. Characters of Enstatite, 168, 169; of Diallage, 169 ;
of Augite, 169. Alteration of the Pyroxene Minerals, 169. Description of the
alterations in the Peridotites as shown in the plates, 169-172. The Lozodn ques-

, tion, 172-174. Organic structure simulated in Felsites, 173. The supposed
Kozobn, and other organisms, the more perfect, the more the rock is altered, 173.
The inclination to unduly extend one’s line of study, 173, 174. Crucial test in
disputed problems, 174. The Zozodn in segregated or veinstone deposits, there-
fore not of organic origin, 174. Microscopic characters of Picrite, 174, 175.

XIV CONTENTS.

Obliteration of original characters in the process of the alteration of Peridotites,
175. Production of Schistose Structure in, 175. The supposed conversions of
Schists into Serpentine, 175. Absence of the Mesh Structure and Chromite or
Picotite in Serpentine due to alteration, 175. Formation of Serpentine Vein-
stones, 175. Alteration minerals in Peridotite, 175. Ground covered by the
text, 175.

SECTION VII.

CHROMITE AND Picotire.—THEIR RELATIONS . . .) 3) J) SRS ee eee

Fiscuer’s observations, 176. Datun’s studies, 176. THouvet’s observations,
176. Translucency of Chromite first remarked in 1825, by C. H. Prarr, 176. The
writer’s observations on some eighty specimens of Chromite, Picotite, and Ores of
Iron, 177-180. , Color and lustre of massive Chromite, 180. Hardness and: streak
of Chromite and Picotite, 180. Specific gravity of, 180. Coffee-brown color of,
180. Variability in color of, 180, 181. Observation of translucency, 181.
Preparation of specimens, 181. Chemical relations of Chromite and Picotite,
181-183. Views of GentH and RaMMELSBERG on, 183. Microscopic relations of,
183, 184. Conclusions regarding mineral species and their variability, 184, 185.
A natural system in mineralogy, 185. Strange history of a Chromite Analysis,
185, 186. Errors in published lists of Analyses, 186.

SECTION VIII

PERIDOTITE. — ITS CHEMICAL, “CHARACTERS Gos 4-6 < . @ 2s ea. = eee

Designation of the varieties of Peridotite, 186. Specific gravity of, 186, 187.
The Carbonaceous Meteorites, 186. As specific gravity decreases, the Iron dimin-
ishes and Magnesia increases, 187. Microscopic characters of the Cold-Bokkeveld
Meteorite, 186. Percentage of silica in Pallasite, 187; of silica in Peridotite,
187, 188. Special case of the Cabarras Meteorite, 187. Percentages of aluminia,
iron, lime, and magnesia in Peridotite, 188. The meteoric forms richest in Iron, 188.
Alteration leads to decrease in the percentage of Iron, 188. Relation of Picrite
to Basalt, 188. Minor elements in Peridotite, 188. Water proportioned to the
amount of alteration, 188, 189. General chemical characters of Peridotite, 189.

SECTION Ix.

PERIDOTITE. —ITS ORIGIN: eo (oben ee) ee we ae

Eruptive occurrence of Peridotite in the Cornwall, Troad, and Lake Superior
districts, 189. Relations of Schistose Rocks and Peridotes, 189, 190. Associa-
tion of Eruptive and Schistose Rocks, 189. The Schists produced by alteration
of Peridotite, 189, 190. Detritus of Eruptive Rocks, 190. Peridotic Volcanoes,
190. Expected occurrence of Peridotites, 190; difficulty of the study of, 190.
Production of Serpentine by alteration of Peridotite, 190. Migration of mineral
matter, 190. Chemical precipitation of Serpentine from ocean waters, 190. Con-
fusion between migrated serpentine material and that produced by alteration
én situ, 190. Serpentine question allied to tne phenomena of Eruptive Rocks and
Veinstones, 190, 191. No proof that the Canadian Serpentines are stratified
sedimentary deposits, 191. Believed inaccuracy of Dr. Hunt's writings, 191.

CONTENTS. XV

Production of Serpentine through alteration of other rocks than Peridotite, 191.
Literature of the Serpentine question, 191. ‘Talcose Rocks derived from
Peridotites, 191, 192. Steatite Rocks alteration forms of Gabbro and Diabase
(Diorite), 192. Actinolite and other schists derived from Peridotite, 192. Am-
phibole Schists, 192. Origin of Magnesian Limestones, 192. Explanation of the
alterations, 192.

BECIION X.
DOTiTm —8.btS CLANSINIGATION . . « '. «se oe wow 6 ee) 6192-194

The use of Specific and Varietal Names, 192. Definition of Peridotite, 192.
Basis of varietal distinctions, 193. Definition of the varieties, 193. Alteration
varieties subordinate to the original mineralogical ones, 193. Probable varieties
to be found by future study, 193. Most variety names not important, 193.
Limburgite of Rosensuscu, 193. Terms applied to the fragmental forms of
Peridotite, 193, 194. Tabular Classification of Siderolite, Pallasite, and Perido-
tite, 194. Essential terms in describing Peridotites, 194.

CHAPTER IV.
THE BASALTS.

SECTION -E
MEMEPEEWPRORIC. DAGAETS: © ; 5 os. tlt ll te wt Uhl hl elCUwlhUe]€6UL9D-206

Variety. — Basalt, 195, 196.

Stannern, Moravia, 195. Constantinople, Turkey, 195. Jonzac, France, 196.
Petersburg, Tennessee, 196. Frankfort, Alabama, 196.

Varigety. —Gabbro, 196-205.

Luotolaks, Finland, 196. Missing, Bavaria, 197. Juvenas, France, 197.
Shergotty, India, 197, 198. Maskelynite, 198. Pawlowka, Russia, 198. Le
Teilleul, France, 198. Bishopville, South Carolina, 199-201. Chladnite, 199.
Aqueo-igneous origin of Eruptives, 201. Manegaum, India, 201, 202. Busti,
India, 202. Shalka, India, 202. Ibbenbiihren, Westphalia, 202. Greenland,
202-205. Assuk, 203. Ovifak, 203, 204. Pfaff-Oberg, 204, 205. General
Structure of the Meteoric Basalts, 205; not fragmental, 205. Nomenclature,
205. Future changes, 206.

SECTION IL

RPE SermnpoMMVIVORIIES . <<. . . <e se ew ew ww tl tw | ( 206-208

Waterville, Maine, 206, 207. Richland, South Carolina, 207. Igast, Russia,
207, 208. Waterloo, New York, 208. Concord, New Hampshire, 208, Ande-
site type, 208.

ea CONTENTS.

EXPLANATION OF THE TABLES a TE 209

TABLES OF CHEMICAL ANALYSES 952 09.7. 90s) Stnte ee

Taste: I, Analyses of Chromite and Picotite. . . . « 2» . . » « ii-v

Tastes IL-V. — A Classified List of Complete (Bausch) Analyses of Meteoric and
Terrestrial Rocks.

TaptE II. “Siderolite 4. < 8 4°58 8 ce) vVi-—xv
Tape III. « Pallasite |<. Socsy ste) jay coe se
TasLE LV. Peridotite . . . + cs eer cuties) Lette a: Sg

Taste V. Basalt, Part I. The Meteoric Basalts oe eS Sy. Ce a

The black-faced figures in the text, e. g. 3001, refer to the numbers of specimens in the Whitney
Lithological Collection in the Museum of Comparative Zoology.

The letters A. E. prefixed, and G. and P. affixed, refer respectively to special collections, belonging
to the Whitney Collection, made by Mr. Diller in the Assos Expedition, Professor W. M. Gabb in
San Domingo, and Professor W. H. Pettee in California; e. g. A. E. 324; 250G,; 45 P.

LITHOLOGICAL STUDIES.

CuAP TER £

SEecTION I. — The Structure of the Earth.

?

Tue “natural system of rocks” ought to contain within itself a key to
the history of the earth, and to be an exponent of that history. The entire
physical universe seems to be under the government of a universal law, and
our classification ought to accord with that law, so far as it has been ex-
pressed in the rocks themselves. This law has thus far been best formulated
by Sir William Thomson as the degradation and dissipation of energy,—or, as
it may be styled, the passage from the unstable towards a more stable
condition, — the tendency towards harmony with the environment. This I
regard as the law under which the universe has moved from its beginning,
and under which it will continue its course uniformly towards the end,
believing that no turning back can occur, and that no energy once lost
can be restored except by the same Almighty Power which gave it birth.*
It is in accordance with this law that I have tried to do my work, and to
set forth the principles on which the rocks described are classified; in
other words, this is an attempt to explain the present condition of the rocks
by tracing out their past history.

The terms “lithology,” “petrography,” and “petrology” are so indefi-
nitely employed that it seems necessary to give some fixed meaning to them
here. For this purpose I define Lithology as that science which treats of
the constitution and physical structure of rocks. It corresponds somewhat
to the anatomy and histology of animals, including the study of morbid
tissues.

* Science, 1883, i. 541.
1

THE STRUCTURE OF THE EARTH.

bo

Petrology treats of the origin, history, physical features, mode of occur
rence, and relations of rock masses.

Lithology is essentially an in-door or cabinet and laboratory science ; while
petrology is exclusively a field study. The former needs for its pursuit hand
specimens only; for the latter we must have the rocks i situ.

Petrography \ define as that branch of science which embraces both
lithology and petrology. \t includes everything that pertains to the origin,
formation, occurrence, alteration, history, relations, structure, and classifica-
tion of rocks as such. It is the essential union of field and laboratory study.

So far as possible my work has been carried on according to petro-
graphical rather than ordmary lithological methods, and with the belief
that field evidence is stronger than any laboratory evidence can be in
all matters relating to the origin of rocks.

The facts developed by petrographical study seem to me to demand for
their explanation a former liquid condition of this globe, and the admission
that all rocks, not of organic origin, now forming a portion of the earth’s
crust, are the results either of that molten condition, or of the action of
atmospheric and hydrous agencies upon the formerly liquid material. The
belief in the former fluid condition is in accord with the demands of geology
and the results of physical and astronomical research ; for it seems proper to
hold, that, as is the present physical condition of the nebula, stars, sun,
planets, and satellites, so was, or is, or will be, this earth. Indeed the
various phenomena with which we are concerned seem to be but the con-
comitants and results of the passage of this earth from its active condition,
as a hot fluid mass, towards a cold, inert, and passive state. Is it not our
part to study matter in its present transitory stage, and from the facts thus
gathered to reconstruct as far as possible its past history and infer its future
course? To me the beginnings, the various transitory stages, and signs of
what the end will be, are apparent in the rocks; and the effort of the classi-
fication here employed is to give voice to these changes, or to the unstable-
ness of the rock constituents, while the classifications of others appear in
general to be based upon the assumed stability of the rock constituents, —
that is, they assume that as the rocks now are so they were, and always
will be.

I am unable to explain the facts obtained in the petrographical study of
the rocks except on the supposition that the eruptive rocks of all kinds
came from the interior part of the earth, and from below the sedimentary

eS

~~

hl, = an ee

e
j

IS THE EARTH A SOLID BODY? 3

deposits; moreover it would seem that they must come from a portion that
has either never solidified, or which through some cause has been reliquefied.
Here, then, it will be desirable that some examination should be made of
the evidence derived from physical and mathematical laws on which is based
the opinion held by many that the earth is solid.

This evidence may be considered under two divisions. 1°. That derived
from the phenomena of precession and nutation, and of the tides. 2°, That
derived from the action of matter under the combined influence of heat and
pressure.

In the first case, the conclusions which have been reached have been
obtained by assuming certain hypothetical globes with a certain definite
structure, substituting for these the name earth, and then claiming that the
conclusions applied to the aclual earth instead of to the hypothetical globes, for
which the name earth was used just as the algebraist uses 7 and y. Hop-
kins assumed for his globes: 1°, a homogeneous fluid mass enclosed in a
homogeneous solid shell; 2°,a heterogeneous fluid mass enclosed in a hetero-
geneous solid shell. The transition between the entire solidity of the shell
and the perfect fluidity of the interior mass was assumed by him as being
an abrupt one. He further assumed that the circulation would go on in
the mass until it lost its perfect fluidity in every part at nearly the same
moment.*

Sir William Thomson, in the same way, drew his conclusions from globes
assumed to have a thin shell, passing abruptly either into a homogeneous
incompressible fluid, mobile like water; or into a heterogeneous viscid
fuid interior.t :

Likewise Professor George H. Darwin has taken as the basis for his dis-
cussions, if he is not misunderstood, homogeneous spheroids which are vis-
cous and non-elastic, also those which are elastico-viscous, and those which
are either elastic, plastic, or viscous.t

The view that the phenomena of precession and nutation prove the
Newcomb and

earth to be solid was opposed by Hennessy,§ Delaunay,

* Philos. Trans., 1839, pp. 881-423; 1840, pp. 193-208 ; 1842, pp. 43-55.

+ Trans. Royal Soc. Edin., 1864, xxiii. 157-169; Phil. Mag.,1863 (4), xxv. 1-14, 149-151; Phil.
Trans., 1863, pp. 573-582; Trans. Geol. Soc. Glas., 1878, vi. 88-49; Nat. Phil. 1867, 1. 670-727 ;
Nature, 1872, v. 223-224, 257-259.

t Phil. Trans., 1880, clxx. 1-35, 447-593; 1882, clxxii. 187-280.

§ Phil. Trans., 1851, pp. 495-547; Nature, 1871, iii, 420; 1872, v. 288, 289; Geol. Mag., 1871 (1),
viii. 216-218.

| Geol. Mag. 1868 (1), v. 507-511.

4 THE STRUCTURE OF THE EARTH.

others; and although strongly supported by Thomson for some fourteen
years it was abandoned by him in 1876,* and is now generally given
up.

The view that the phenomena of the tides prove the earth to be solid
is still sustained by Thomson and Darwin, but their conclusions only apply
to the assumed globes and not to the earth itself. Their conclusions are also
opposed by Hennessy, Fisher, Airy, and many others.

The difficulty seems to be that it 1s beyond the power of any known
transcendental mathematics to grasp the problem of the earth’s structure, if
its most probable condition be assumed. This condition may be described
as being that of a globe having a density gradually increasing from the
exterior inwards towards the centre, but with its materials heterogeneously
arranged, and with the lighter crust gradually and irregularly passing into
the heavier liquid beneath.

If our attention be now turned to a consideration of the evidence derived
from the behavior of matter under the combined action of heat and pressure,
which behavior is said to prove that the interior of the earth is solid, the
important questions are: 1°. What are the materials forming the earth’s
mass? 2°. Do these expand or contract on passing from the liquid to the
solid state ?

In answer to the first question, it may be said that the results of petro-
graphical study render it probable that the portion of the interior mass
lying nearest the centre, and concerning which we have any data, is com-
posed of iron,t either with or without nickel. As we recede from this portion
we find pyrrhotite united with the nickel and iron. Then these minerals
are further joined with olivine, or olivine and enstatite, in varying propor-
tions, until a region is reached composed almost entirely of one or both of
these silicates with or without diallage. From this we pass into the common
basaltic rocks, then inte the andesites, and so on outward into the trachytic,
rhyolitic, and jaspilite forms. However true this order may have been for
the liquid earth, it is certain that in the solid portions of the crust these
materials are interlaced now with each other in every conceivable way, and
that in the chemical and sedimentary deposits they have been intimately
mingled. As to what may be the composition of the earth’s mass nearer

the centre, if there be anything there besides the iron and nickel, we have

* Report Brit. Assoc. 1876, xlvi. (sect.) 1-12.
+ Whitney’s Metallic Wealth of the United States, 1854, p. 434. Judd’s Volcanoes, 1881, pp. 307-324.

J
4
;

THEORIES OF THE EARTH’S SOLIDIFICATION. a

no clew, unless it be that very possibly some of the rarer elements now found
mixed with the iron may occur there.

It was claimed by Sir William Thomson* that the earth must have
solidified from the centre outward in accordance with the “thermo-dynamie
law” of his brother Professor James Thomson, which may be stated in these
words: Al/ materials which contract on congelation have their melting point raised hy
pressure, while bodies which expand on freezing have their melting point lowered by
pressure. Thomson, in common with nearly all physicists, held that the ex-
pansion of water and that of bismuth on freezing, were exceptional cases ;
but that contraction was the rule, and that pressure would therefore over-
come the increment of heat as the centre was approached. The mistake
made here was, that the cold solid was compared with the hot liquid; the
fact being overlooked that this law applies to the point of passage from the
liquid to the solid, and not to the relative density of the two taken at tem-
peratures differing hundreds and even thousands of degrees.

Experiments ¢ by Mallet, Centner, Millar, Whitley, Hannay, Anderson,
Nies, Winkelmann, and Wrightson show that in the case of steel, iron, tin,
copper, zinc, bismuth, antimony, etc., compared, at a temperature just below
the melting point, with the melted material at about its freezing point, the
solid is the lighter; but that these metals contract so on cooling that when
cold all, except bismuth, are then heavier. It would seem that if solids
and liquids are compared together at about the temperature of their con-
gelation the solid is the lighter; and that therefore the pressure at the
earth’s interior would cause these metals to remain liquid at a lower tem-
perature than they would on the earth’s surface.

The same law holds good for slag, and seems to do so for lava; in fact
this is probably true of almost all rocks, although the evidence is far from
being conclusive.

Experiments $ made by Hopkins, Bunsen, Moussen and others indicate
that to change the fusion point a few degrees an enormous pressure is
required, and that the law of Thomson is really capricious and variable, if
always true. Hence, so far as our knowledge extends in regard to the

* Trans. Geol. Soc. Glasgow, 1878, vi. 38-49.

+ Proc. Roy. Soc., 1874, xxii. 366-368 ; 1875, xxiii. 209-234; Nature, 1874, x. 156, 157; 1877, xv.
529, 530; xvi. 23, 24; 1878, xviii. 397, 398, 464; Proc. Roy. Soc. Edin., 1879, x. 359-362; Sitz. Akad.
Miinchen, 1881, pp. 68-112; Phil. Mag., 1881, (5), xi. 295-299.

t Report Brit. Assoc., 1854, xxiv. (sect.) 57, 58; Ann. Physik Chemie, 1850, Ixxxi. 562-567; 1858,
ev. 161-174; Everett’s Deschanel’s Nat. Phil., 1872, pp. 312, 313; 1883, pp. 331, 332.

6 THE STRUCTURE OF THE EARTH.

action of matter under pressure and heat, there is far more reason for
believing the earth to be liquid than for taking the opposite view.

From what has here been stated it would seem that there is no evidence
drawn from mathematical and physical laws which obliges the petrographer
and geologist to assume an interior structure for the earth different from
that which the facts of geology and petrography would lead them to expect.*

Starting, then, with the accepted belief that this earth was once an
intensely hot gaseous body, it follows that if the heavier gases tend to
lie nearer the centre than the lighter ones, the dissipation of heat could
only take place through the slow conductivity of gases. In like man-
ner, when the earth cooled down to a liquid mass convection would soon
cease, if it ever existed, on account of the different densities of the earth’s
materials; and here also the dissipation of heat would have to take place by
the slow conduction of liquids. In the same way, in the solid portions of the
earth the heat from the interior has to be conveyed outwards through broken,
fissured, heterogeneous material. It would seem that all these conditions
should be taken into account in all physical discussions of the age of the
earth and sun; but thus far all calculations seem to have been based upon
the laws of the relation of gases and liquids of about the same density.
There should further be considered the heat disengaged by the chemical
unions necessary to form the present mineral combinations now existent on
the earth.

As the liquid earth cooled and its materials grew viscous, all interchange
of materials would be retarded; and as the cooling continued, the lighter
exterior liquid portion would form a hot crust, which would be lighter than
the underlying liquid. On account of the viscous condition through which
the earth’s materials must pass before solidification, the crust would gradu-
ally shade into the underlying liquid, and both would be nearly in the.same
condition with each other as to temperature. It is not probable that the
crust would break up and begin to sink, because, even if its surface grew
cold, it would always have this hot solid base lighter than the underlying
viscous liquid, which, owing to the increase of specific gravity as the in-
terior is approached, would probably be more dense than any of the over-
lying cold crust. Even if the crust should become heavier, break up, and
begin to sink, this sinking would be very slow, on account of the viscosity

* Whitney, Earthquakes, Voleanoes, and Mountain Building, 1871, p. 74; Dana, Man. Geol., 1880,
p. 812.

THE PROBABLE CONDITION OF THE EARTH’S INTERIOR. 7

of the liquid, and its constantly increasing density ; while the heat imparted
to the sinking material would tend to bring it to about the same specific
gravity with the liquid portion as the sinking mass neared its melting point.
But— what is of still greater importance —the sinking material would
soon reach a liquid of different composition and greater density than the
crust; and farther than this it could not sink. That sinking of the crust
to the centre, which Sir William Thomson supposed would take place, could
only do so in case the hot solid was heavier than the liquid interior, and
that liquid homogeneous. But both these conditions appear opposed to
what we know of the properties of matter and of the heterogeneous com-
position of the earth.

The structure of the earth that would naturally follow, from what has
been above stated, would be a heterogeneous crust floating on a denser
heterogeneous liquid, and one which the interior pressure tends to keep
liquid at a lower temperature than on the surface, so far as it affects it
at all.

In an earth like this, owing to the gradual passage of the crust into the
viscous liquid interior, no shrinking of the nucleus from the exterior could
take place, but the earth would contract as a whole. A linear shortening
of the crust would occur that would crush it together, and cause its depres-
sion in some places and its elevation in others. The depression of any por-
tion of the crust into the liquid interior would naturally cause an equivalent
weight of the heavier liquid to rise, and perhaps overflow. This simple
sinking of a portion of the crust on one side with its corresponding but less
elevation on the other, with the attendant fissuring, would afford all
the dynamic agencies needed to raise lavas to the tops of our highest
mountains, and would account for the association of volcanoes with de-
pressed basins, for fissure eruptions, etc.* The contraction could hardly
be expected to be equal in every portion, while the depression of portions
of the crust with the attendant outflows would cause an unequal thickness
of the crust, with great irregularities in its base adjacent to the liquid in-
terior. The outflows, themselves, would cause this crust to be tied through
and through by the different eruptive materials.

This great irregularity in thickness, which the earth’s crust is supposed
to present, coupled with the viscosity of its interior portion next the crust,
would apparently prevent any direct or special connection between different

: * Whitney, Earthquakes, Volcanoes, and Mountain-Building, p. 90.

8 THE ORIGIN AND ALTERATION OF ROCKS.

vents, even if they were near one another. The viscidity of the cooling
liquid portion would, of itself, prevent any rapid flow of material from one
point to another. But at the same time the liquidity of the interior mass
would cause it to seek escape from pressure at any available opening, how-
ever far that vent might be from the point of pressure. Yet the more
viscous the material, the less applicable would be the ordinary law of the
transmission of pressures by liquids.

The part played by water in a volcanic eruption seems to consist mainly
of its action on the lava during its passage upwards, instead of serving as
the cause or primum mobile of the eruption. It is difficult to see how lava
in ascending to the earth’s surface could reach it without meeting water
somewhere on its way. This water with its attendant phenomena seems to
be the accident, rather than the cause of the eruption. As stated before, a
different view of the present structure of the earth’s interior can be taken,
which may not be inconsistent with the facts of petrography. This is that
the interior, or at least the portion from which our eruptive rocks come, is
solid, but in such a state that it can be readily reliquefied. This reliquefac-
tion may be brought about either from increase or diminution of pressure,
according as future experiments may show the relative densities of hot
solid and liquid matter to be. The supposition that eruptive rocks come
from these re-fused portions of the earth’s originally solidified primitive
material, would perhaps explain the origin of the minerals of the first or
foreign class, to be spoken of later, which occur in these rocks.

Sreotion IT.— The Origin and Alteration of Rocks.

Tue theory of the origin of rocks generally taught in America is the
following, with some more or less important modifications: The sedimentary
(chemical and mechanical) rocks derived from the ruins of the “ primeval
crust” form all that portion of the earth’s crust which is now known. By
ordinary denudation these rocks would be removed from one point and depo-
sited in another locality, the result being that the underlying sediments would
be still more deeply buried in one place, and exhumed in another. The por-
tions thus more deeply buried would be invaded by the earth’s central heat,
this giving rise to a more or less intense chemical action in them. The seat
of this action is known as the “ zone of aqueo-igneous fusion” (solution), and

all sediments, if sufficiently deeply buried, come within this hypothetical

THEORIES AT PRESENT IN VOGUE. 4)

zone. The different portions of the sediments would be more or less affected
and metamorphosed, according to their chemical constitution, and their prox-
imity to the hypothetical zone. If they came within the zone, their fusion
or solution would give rise to lavas and volcanic eruptions. Some authors
hold that every form of eruptive rock comes from sedimentary materials
which have been thus acted upon; while others maintain that, although the
true lavas and intrusive rocks may have been derived from non-sedimen-
tary material, yet the sedimentary rocks take upon themselves forms undis-
tinguishable from those of the volcanic rocks. Other modifications of this
theory are delegating the source of the eruptive rocks to re-fused portions
of the original solidified crust of the earth, which has been fused again on
account of relief from pressure by denudation. This last view has been
founded, so far as present evidence shows, on a misconception of the apparent
general action of matter in passing from a liquid to a solid (not cold) state ;
therefore this should be abandoned, and fusion by increase of pressure either
through the earth’s contraction or by the deposition of sediments substi-
tuted. Another theoretical view is simply a remodelling of the old Werne-
rian hypothesis, and its application to the crystalline rocks. According to
this view we are taught that all these rocks were deposited in pre-Cambrian
time, and that all eruptive rocks have been derived from these chemical ones
by aqueo-igneous solution or fusion. These crystalline rocks and their
derived eruptive forms are then divided according to their lithological
characters into distinct geological ages, and their age is said to be recogniz-
able whether the rocks themselves be seen in their original form or in that
of dikes and lava-tlows.

If the above views are correct, we should expect to find in some form-
ations rocks which had suffered every degree of alteration, the same rock
passing from an wnmetamorphosed condition into a highly metamorphosed or
even eruptive one, with every gradation between. At certain points, when
denudation has succeeded a former epoch of accumulation, the more or less
deeply buried sediments would again appear upon the surface, showing
greater or less evidence of the conditions to which they had been subjected.
By carefully selecting the localities to be studied, we naturally should ex-
pect to find every degree of change in the rocks, and various transitions by
direct passage from rocks unmistakably sedimentary into those that are
truly eruptive, in their present position, — from those rocks whose original

fragmental structure is undoubted, to those that have been in a plastic,
9

10 THE ORIGIN AND ALTERATION OF ROCKS.

semi-fluidal, or fluidal state. All these changes should exist in the same
continuous mass of rock, and we ought to be able to trace the gradations
from one place to another. That such passages have been observed, has
been repeatedly claimed, but when the localities where these facts could
be observed were sought for, they could not be found.

The results of petrographical study seem to point to the following as the
probable origin of rocks. If we start from a cooling liquid earth then all
mechanically and chemically formed rocks have come from the liquid ma-
terial originally. Furthermore, all the eruptive rocks appear to have come
from below the sedimentary ones, and are only influenced by them in their
composition, by the materials accidentally picked up during their passage
through, or flow over the latter. In the case of volcanic rocks, we should
expect to have associated with the lava, ashes, and in fact every kind of
material projected from the crater, including débris and mud.- All these
would be naturally more or less intimately mixed together according as one
was deposited on, or around the other, — or as one in its flow picked up, sur-
rounded, or overlaid another. This would associate all loose materials and
rocks of any kind that existed in the locality prior to the lava flow; while
during that time and later the atmospheric agencies would tend to still more
intimately mingle these diverse materials, and obliterate their differences.
Wherever the lava was exposed to detrital action, there would be deposited
about and around it detritus of the same material, mixed or not, as the case
might be, with that from other rocks, — especially if the eruption took place
on or near the shore line. In the case of massive or fissure eruptions and
dikes, we should expect but few or none of the common accompaniments of
an ordinary explosive volcanic eruption, but all eruptive material would be
subject to degradation, and would under proper conditions become associated
with its own detritus and that formed from other rocks. All the associated
detritus, if of one kind, would suffer the same alterations which non-frag-
mental material of the same kind has to pass through. Under conditions
otherwise identical, detrital material would doubtless be affected in a greater
degree than the solid rock, owing to the former's greater perviousness to
water. While in the unaltered condition we may be able to readily distin-
guish the fragmental from the non-fragmental forms by the unaided eye, this
is no longer possible when both have heen subject to alteration. They then
closely simulate one another, and the microscope used in connection with

the field evidence offers the only means of distinguishing the fragmental

a ae

EXAMINATION OF CURRENT THEORIES. 1]

from the non-fragmental form. When rocks of more than one kind are
mixed in the detritus, the alteration and appearance of the sedimentary rock
formed from this undergoes a corresponding modification.

We should expect to find certain very intimate relations between all
these various forms of associated rock, and it would be very difficult to dis
tinguish, in the older and more altered forms, between the material picked
up during the flow, the ashes or débris, and the solid non-fragmental rock.
The greater the amount of secondary alteration which these different rocks
have suffered, the greater the difficulty of distinguishing between them. In
no case, however, would the fragmental pass into the non-fragmental form
by insensible gradations or otherwise. It is true that they sometimes appear
to do so, but that appearance is only superficial.

In order then to decide between the different theories proposed for the
origin of eruptive rocks, it is necessary to make some examination of the
evidence offered in their support by petrographical study. For this pur-
pose the most important question is, do sedimentary rocks take upon them-
selves the characters of eruptive ones? In the writer’s studies he has found
a certain resemblance between both classes of rocks when they are of similar
composition. ‘This is, however, only in the case of rocks greatly altered, and
arises from secondary changes in each; which result in the production of
new mineral constituents, and in the obliteration of the original structure
of both to a greater or less extent. Indeed, in some cases, this obliteration
is total, the minerals and mineral characters — in fact all the characters —
of the rocks thus changed being rendered unlike those which belonged to
the original eruptive rock. These alterations are apparently more depend-
ent upon the chemical composition of the rocks, and the conditions to which
they have been subjected, than upon their having been in a fragmental or
non-fragmental state. The result is, that the eruptive rock is degraded to
the status of an altered sedimentary rock, not that the latter takes upon
itself the characters of an eruptive one. Whether the two classes thus
indicated can or cannot always be distinguished under the microscope in
cases of extreme alteration, is a problem of the future, and perhaps the
most difficult one with which the petrographer will be confronted.

Undoubtedly, a careful study of the field relations of rocks would, in the
majority of cases, suffice to settle the question of their origin.

If sedimentary rocks should be found under peculiar and abnormal con-
ditions, to present the characters regarded as typical of eruptive forms*

* Metamorphism produced by the burning of Lignite Beds in Dakota and Montana Territories. By J. A
Allen. Proce. Bost. Soc. Nat. Hist., 1874, xvi. 246-262.

12 THE ORIGIN AND ALTERATION OF ROCKS.

this would not be a basis for assuming that normally sedimentary rocks take
these characters; although this statement is one which is frequently made.

Examinations have been repeatedly made by the writer for the purpose
of ascertaining whether any rocks whose sedimentary origin was undoubted
had acquired the microscopical characters of eruptive forms, but nothing of
the kind has yet been discovered by him.

In order to prove the passage of a sedimentary rock into an eruptive one,
it is necessary to have on one side the undisputed fragmental form, and to
trace it directly by continuous passage into the non-fragmental one. Not an
inch of the parts lying between should be allowed to escape examination ;
and it must be positively known that no line of junction exists, but that the
two rocks form a continuous whole. In no case on record, however, does it
appear that passages of the kind indicated, and which have been claimed as
existing, have ever been subjected to so close an examination as is here
demanded. Eruptive and sedimentary rocks at their line of junction usually
mutually influence one another, often appearing very much alike, especially
when they have been subjected to later alterations by which both have been
affected. It is, then, to be expected that the observer who is not practically
fimiliar with these occurrences will pass directly over the lines of junction,
especially if he has been taught that direct passages of one rock into another
nay occur. His evidence is of that negative kind which, for various reasons,
can usually be obtained with ease. The evidence that the two rocks do not
pass into one another is of the positive kind, for the line of junction when
once seen can be examined and re-examined at any time; while hand speci-
mens can frequently be procured which will show both kinds of rock and their
junction in one fragment. We can then have positive field and laboratory
(including microscopic) evidence that the two rocks are not the same but
different ones. The writer has had frequent occasion to examine localities
in which the direct passage of a fragmental rock into a non-fragmental one
was said to occur, and in no case has he not been able to obtain positive
evidence that such passage did not exist, when the conditions were such that
a satisfactory examination could be made... When the evidence was lacking
it was always owing to the junction being covered, or else shattered by
jointing, frost, ete.

Practically, when the existence of these junctions had been shown, the
observers who had previously denied their existence have always said:
“That is not a typical locality; we were not quite sure about that place,

ORIGIN OF VOLCANIC ROCKS DISCUSSED. 13

but if you will go to such or such a locality, — indicating some new one, —
you will find an undoubted passage of the sedimentary rock into eruptive
forms.” When this new locality is also examined and the statements are
found to be erroneous, another one is mentioned, and so on; until one must
demand hereafter of these observers that they shall select some locality on
which they shall be willing to fully and finally stake their pet hypothesis,
and abide by the evidence.

It has been claimed that the results of chemical analysis show that vol-
eanic rocks are derived from sedimentary ones. While it is true that the
former have a composition chemically like some of the latter, this resem-
blance is easily explained by the fact that a sedimentary rock ought to
resemble chemically the massive rock from whose destruction it came. The
chief difference between them would be that resulting from the change
brought about by outside influences, the introduction of foreign material,
ete. Hence the chemical resemblance between the two classes ef rocks
ean naturally and readily be explained by the derivation of the sedimentary
from the eruptive rocks; and there is no need to resort to the unnatural and
hypothetical derivation of the volcanic from the sedimentary rocks. The
former derivation is the one seen to take place every day, while the latter
is unproved as yet, and those who hold it are apparently looking at the

- effect, and making it the cause. In other words, it seems to the writer that

these observers have taken hold of the subject at the wrong end.

In examining the products of volcanoes, certain minerals appear to be
characteristic of them, which are of prior origin to the consolidation of the
lava. These minerals show evidence that a hot magma has directly acted
upon them, and every gradation can frequently be seen between the almost
untouched mineral, and the nearly destroyed one.

I regard these minerals, unless they were caught up by the lava during
its passage from the earth’s interior to its surface, as evidences that the
material from which the lava was derived is no longer in its original con-
dition, although this condition was not like that of any of our sedimentary
rocks. Certain of these minerals are easily destroyed ; two at least, suffer-
ing alteration readily on exposure, and it seems impossible that they could
survive when the much less perishable materials of cur sedimentary rocks
have been entirely obliterated, if, as is supposed by many, they were ever
there. These minerals are unlike, either in species, variety, or form, with
possibly a few exceptions, any minerals occwrring in sedimentary rocks as a

14 THE ORIGIN AND ALTERATION OF ROCKS.

metamorphic product, 7. ¢., not derived directly from the eruptive rocks.
These minerals are characteristic not only of the modern lavas, but also
of the most ancient eruptive rocks in which secondary alteration has not
obliterated their characters; not only in the modern basalt, but also in the
ancient melaphyr; not only in the modern rhyolite, but also in the ancient
felsite. These characters are not confined to any single locality or age, but
are, so far as known, world wide, and go back to the earliest times in which
such rocks occur.*

We should then claim that the field evidence, as well as the microscopic,
is opposed ¢z ¢olo to the prevailing theory that the eruptive rocks are derived
from sedimentary ones. That theory demands immense duration of time,
unstable continents, enormous forces, a solid earth that shall be more rigid
than glass, and yet yield like a rubber ball to the slightest pressure of sedi-
ments, lava flows, or glaciers. The theory in question demands the removal
of immense masses from one place, and their deposition in another, the ele-
vation of billions of tons in order to avoid the necessity of admitting the
elevation of hundreds,—for in order to have denudation that shall bring
once deeply buried sediments to the surface, the entire mass must be lifted
bodily above the surrounding region, or from the zone of aqueo-igneous
fusion to the outer air. Which view requires the greatest foree —to elevate
and depress such enormous bulks in a solid earth, or to raise our lavas from a
liquid interior — is plainly evident. This theory requires that volcanic action
and that eruptive rocks of earlier

should be of modern birth — Tertiary
date should have been produced by ditferent forces —a view now known to
be false. To the theory that the crystalline rocks are chemical precipitates
arranged in regular succession, there arises the serious objection that the
oldest form — the so-called Laurentian — is cut by dikes of rocks which,
according to that theory, could not have existed below them; that is, they
belong lithologically to the so-called Huronian and Norian systems.

In contradistinction to the views here indicated, the writer’s petrographical
studies lead him to hold, with some others, that all voleanic or eruptive
action arises from the original igneous state of the earth — that it must have
begun in the earliest ages of this globe. This action being a manifestation
of a dying energy, must have been more active in the past than at present,
although it may have been intermittent in character as all such forces seem
to be. ‘The products of this action have been the same from the earliest to

* See also David Forbes. Nature, 1870, ii. 283-286 ; 1873, vii. 259-261.

HOW AND WHEN ALTERATION TAKES PLACE. 15

the latest geological periods; that is, a rhyolite, a trachyte, an andesite, or
a basalt of the Azoic or Palaeozoic times, was the same when erupted as is
the rhyolite, trachyte, andesite or basalt of the present day, or of the Ter-
tiary age. The difference at present existing between these ancient and
modern forms —as the writer believes —is due to the greater alteration
which the former have suffered ; although possibly, a difference in the depth,
or some peculiar condition prevailing at the time of the consolidation of the
rock, may have had some influence in causing these differences.

Under uniformly like conditions, alteration is proportional to the age, in
rocks of the same constitution and structure; but when rocks of like char-
acter are subjected to the same agencies, for the same length of time, like
results would be produced, let the age be what it will. The original crust
and the eruptive rocks must, then, have furnished the material for all the
other rocks, directly or indirectly, except such as was derived from water
and the atmosphere. To trace these changes, and to follow the rocks in all
their variations is the work of the petrographer. As did Cuvier with fossi!
bones, so may the lithologist reconstruct the original rock from the fossil
fragments of it found in other rocks. The presence of fragments of one rock
in another, however, is not to be taken as proof of difference of geological
age between them, unless it can be proved that the inclosed rock is of sedi-
mentary origin.” A lava flow on a sea-shore would have its fragments in-
cluded in any rock then forming, and this would hold true of all volcanic
ejectments. A dike, also, passing through a rock forming on the shore,
would have all materials broken from it inclosed in the rock then forming,
but both would be of the same age geologically, although differing in order
of time.

In studying the alterations in rocks we ought not to confound the great
molecular changes that go on through the rock mass as a whole, and those
changes which are due to superficial weathering. The latter reproduce to
some extent the characters of the former, but go to greater extremes, caus-
ing in the end destruction and disintegration of the rock mass itself. The
internal changes are apparently chemical or molecular changes in the whole
rock mass, instead of simple pseudomorphic changes of single minerals. In
no sense is metamorphism to be looked upon as extended pseudomorphism ;
for pseudomorphiec forms are but an accident in the process of alteration, and
they may or may not oceur, according to the amount of that alteration. All
the changes in rocks are to be explained by taking into consideration the

16 THE ORIGIN AND ALTERATION OF ROCKS.

elements of the entire rock mass, and all elements brought into it by the
percolating waters; the chemical reactions taking place between any or all
of these elements according to the special conditions, and not being confined
to simple interchanges between the constituents of two minerals, as pseudo-
morphs in mineral veins are usually explained. The failure to appreciate
the above distinctions is believed to have led to the statement of much that
is improbable in the works of many writers on pseudomorphic and metamor-
phic changes in rocks.

When we consider the petrographical structure of modern volcanic
districts and the alterations their rocks have undergone, we ought not to be
surprised at the magnitude of the changes which we find to have taken place
in rocks which have been subjected to similar conditions during countless
ages. But these changes are metamorphic, and the rocks thus altered are
metamorphic rocks. Metamorphism, however, does not appear to be lim-
ited to rocks of one kind, but affects all classes. The amount of metamor-
phism any rock undergoes under the same conditions seems to be inversely
proportional to the amount of contained silica; and this change apparently
began as soon as any of the earth’s solid material was exposed to the com-
bined action of air and water, and has continued up to the present day.
Volcanic or eruptive action, including a subsequent prolonged exposure to
hot water, accompanying the dying eruptive force, appears to have been an
efficient agent in metamorphism.

According to the above view, the metamorphic rocks produced would be
dependent upon their chemical composition and the ageney by which the
changes were effected, but would not be at all dependent upon the geolog-
ical age. Hence lithological characters would be valueless as a criterion
for determining the age of such rocks.

The writer finds that the constituents of the eruptive rocks and their
derivatives pass in their alteration from the unstable towards more stable
compounds in the conditions to which they are subjected, — that is, they
pass into forms that never can in the ordinary course of nature return to
their original condition. In this there exists a potent factor for the dissipa-
tion of energy. The potential energy of the original chemical combination
is In a greater or less degree lost, and cannot be restored except by some
foreign power, — or, in other words, the original structure and composition
cannot be normally regained. The advocates of the sedimentary origin
of igneous rocks, however, require the restoration of that lost energy, and

THEORIES OF ALTERATION DISCUSSED. 17

advocate a sort of perpetual motion. According to them these rocks are
born, grow old, and die, and their remains are raised again and again, that
the process may be repeated. The writer accepts the birth, old age, decay,
and death; but he doubts the resurrection and believes that such views
are opposed to physical laws.

A crystalline structure is indigenous in any eruptive rock, if it remains
in a condition that allows it to slowly crystallize; and this structure is not
therefore any proof of great age in a rock, or a sign that it was formed at
great depth.* |

From the above it would follow that such rocks as the felsites cannot be
taken as characteristic of certain ages (Arvonian or Huronian); but if — as
the writer, with others, holds — they are old rhyolites, they have been formed
in all ages. Again, while they may have been deeply covered with detrital
beds, there is no necessity for such a burial, or any proof that they were
once thus covered, any more than there is that the modern rhyolites have
been.

Also, the claim for long times for the formation of rocks which are fine-
grained and fossiliferous cannot always be allowed; as for instance, the
Florissant shales,t or a large deposit of fine, dust-like powder, observed in
the vicinity of the Black Hills by my colleague, Mr. Samuel Garman. This
powder is made up of minute fragments of volcanic glass, forming a bed
several feet in thickness. If it had not been for the revelations of the
microscope, would not some geologist be computing the number of thou-
sands of years it would take to form these deposits “as Nile mud,’ when
perhaps, a few weeks or even days were sufficient for this purpose. If
the deposits in question had been subjected to sufficient alteration ‘to
obliterate the original texture, who would have been able to prove the
falsity of the theory of a slow deposition of the material as an ordinary
sediment ?

Another illustration is afforded by the Lake Superior sandstone, which
shows that extreme care is required to ascertain the conditions under which
any deposit formed, before the length of time required for its formation shall
be estimated. t

To the objections offered to lavas being the sanie from all time, on
account of the difficulty of believing that the same portions of the earth's

- * Bull. Mus. Comp. Zool., 1880, vii. 111.
+ Bull. U. S. Geol. Survey, 1881, vi. 286, 287.
¢ Bull. Mus. Comp. Zool., 1880, vii. 177, 118.
S

18 THE ORIGIN AND ALTERATION OF ROCKS.

interior have been liquid since the Azoic time, it may be replied that if
contraction suffices to keep up the heat of the sun to an approximate
uniformity, so too the contraction of the earth would tend to maintain a
uniform temperature in the earth’s interior; a point that it is necessary to
consider in all discussions relating to the earth’s age. It may again be
suggested that, while basic rocks of the same character as those seen to-
day were erupted in the early ages of the earth, yet there has been on the
whole a progression from the acidic to the basic, in relative abundance, from
earlier to later times. Furthermore, owing to the irregularity in thickness
with which the earth’s crust has apparently solidified, great diversities would
be expected to exist in that part immediately below the crust in different
portions of the earth.*

Whether volcanic and all other eruptive rocks came from material that
has never cooled to a solid state since the earth began to solidify, or whether
they are derived from a portion that solidified, but has since been reliquefied,
is a problem for the future, the solution of which hinges on the origin of
the partially destroyed materials in the rocks themselves, — were they
caught up on the passage of the lava to the earth’s surface, or are they
the remains of a prior crystallization ?

If we turn to Sorby’s method for determining the origin of rocks by the
inclusions in the contained minerals, we find that it may possibly answer
in recent, surface-formed rocks; but that in the old and altered forms it
seems to carry us astray, and serves but to retard the advance of our knowl-
edge of rock formation. This is especially the case if the secondary min-
erals, like quartz, have been formed later in the rock in question by the
action of hot waters. Conclusions regarding the origin of a secondary or
foreign mineral included in a rock ought not to be transferred to the rock
itself, as those who use Sorby’s method are in a habit of doing.

The somewhat common argument that a rock associated with crystalline
schists must have the same origin as the schists, would make a dike in slate
of the same origin as the slate. Association of rocks proves nothing, for in
voleanic districts, in limited areas even, rocks of every character can be
found together. Should we then hold that because some were sedimentary,
all the others were so? Or, again, should we claim that because some were
eruptive, all the rest were eruptive? No! we ought to prove the origin of
each rock, and in every locality in which it occurs, so far as possible, and

when evidence is wanting leave the question as undetermined.

* Whitney’s Volcanoes, Earthquakes, and Mountain Building, pp. 69-107.

DEFINITIONS OF TERMS USED. 19

A region in which eruptive rocks abound is a region in which erystal-
line schists would naturally be expected to occur; for here the conditions of
metamorphism are best developed, — conditions that affect and metamor-
phose all the associated rocks, both eruptive and sedimentary, according to
their composition and physical structure. Eruptive rocks, whether in dikes
or lava flows, ashes or detritus of any kind, frequently possess the charac-
ters of crystalline schists; must they therefore be regarded as being of
sedimentary origin? The writer has seen dikes of crystalline schists cut-
ting directly across schistose conglomerates and other sedimentary rocks.
Was he to conclude that these dikes of schist were sedimentary, and had
been intruded in the form of schists; or rather that they were of eruptive
origin, — the original rock having been later metamorphosed into a schis-
tose rock? He has also seen mica schists inclosed in distinctly eruptive
granites. If the law of association is worth anything, then should it not be
claimed that these schists were eruptive? Ought not the evidence and the
facts of the origin, and not the association, to be taken as proof of what that
origin was ?

At this time, when the tendency is so strong to consider almost every-
thing the result of stratification, it seems necessary here to call attention to
some characters that for the most part are common to all rocks, whatever
may be their origin. While these characters are taken as proof positive of
sedimentation, in reality they have no bearing upon the question unless
they are exclusively confined to one class.

Lamination in a rock is one of these characters; which may be defined as
a structure, either original or superinduced in rocks of various kinds, causing
them to ¢end to split into more or less parallel layers.

This structure is very common in many eruptive rocks, especially those
of a fine-grained or glassy character, and which have become metamor-
phosed.. In many rocks an appearance of lamination is brought about by
the deposition of coloring matters in bands, and this pseudo-lamination even
has been oftentimes taken for stratification.

Joint planes may be defined as fissures traversing rocks in a regular or
irregular manner, independently of any other structural planes, induced
during the time of the consolidation of the rock or later, and dividing it
into masses of greater or less size.*

These planes are frequently mistaken for bedding planes, both in

* Faults and fissure veins are but modified joints.

20) THE ORIGIN AND ALTERATION OF ROCKS.

~

sedimentary and eruptive masses, particularly in regions of crystalline rocks.
Eruptive rocks subjected to pressure in dikes, or when they are metamor-
phosed, tend to take upon themselves a more or less parallel jointing, which
superficially resembles stratification, and which to the writer's personal
knowledge has been taken for bedding planes by some of the most promi-
nent geologists in the United States,

Cleavage is another structure, which by many is supposed to be confined
to sedimentary rocks; but this is evidently not the case. This may be
defined as a tendency in rocks to split more or less indefinitely into thin
plates, independently of any original structure in the rock masses. In the
same series, the finer the grain the more perfect is the cleavage; therefore
it is best developed in argillites, fine grained eruptive rocks, and volcanic
ashes. The presence of cleavage characters in the last two series of rocks
ought to make us careful in deciding upon the origin of any rocks from
considerations connected with their cleavage alone: further evidence should
be obtained, of a more decisive character.

Foliation is another rock structure belonging to rocks of diverse origin,
and due either to the existence of bands or layers of different minerals, or
to a more or less parallel arrangement of foliated minerals, like talc, mica,
chlorite, etc. This structure may even be taken by rocks which are not
composed of foliated minerals, as, for instance, limestone. Foliated speci-
mens of limestone destitute of mica have been brought to the writer from
Western Massachusetts, as being mica schist, and considered as supporting
the view that in that region the limestone passes directly into mica schist.

It is very difficult to give any definition of foliation that will cover all
cases of this structure, but it may in general be said to signify a structure
induced (not congenital) in rock masses by the arrangement of certain crys-
tallized minerals, or of a single mineral, in more or less parallel lines, along
which the crystals lie, flatways or lengthways. It has been found that in
sedimentary rocks the foliation may or may not correspond with the stratifi-
cation planes, and until in each case it is proved to do so it cannot be taken
as marking the origimal planes of deposition. The causes that produce
cleavage in some rocks seem to induce foliation in others. An example
of this is to be observed at the point of land south of Boston Harbor, known
as Squantum. At this locality the stratification and cleavage of the argil-
lite and sandstone are seen to differ considerably from one another, while
the conglomerate lying between has its pebbles somewhat rearranged,

"+ 1.

FOLIATION — FLUIDAL STRUCTURE. 21

giving rise to a schistose or semi-foliated structure. These foliation planes
correspond with the cleavage planes, but not with the original bedding of
the rock.

Foliation is of frequent occurrence in metamorphosed eruptive rocks,
giving rise to schistose forms which are ordinarily taken for micaceous,
chloritic, and other schists, which are usually regarded as sedimentary.
All these are cases of similar structures and similar rocks, resulting from
the alteration of rocks of diverse origin, but of similar chemical com-
position. Foliation usually corresponds to the lines of pressure, — either
from the walls or from the surface downward, and is usually brought about
by recrystallization of the rock constituents during the process of altera-
tion. Since rocks of every kind are subject to metamorphism, and none
more so than the basic eruptive ones, it is natural to suppose that highly
altered eruptive as well as sedimentary rocks would display that character
of structure which is designated by the term foliation.

Many rocks which can hardly be said to possess lamination or foliation,
show nevertheless a schistose or fissile structure, which is a property of all
more or less altered rocks, —a supermduced structure, and not a congenital
one. Hence, this structure cannot be taken as being confined to a single
class of rocks, and therefore a diagnostic for that class, as has been done by
some geologists.

Fluidal structure is a character induced in eruptive rocks through their
having moved or flowed when in a liquid or pasty condition. It is best seen
in the glassy and acidic eruptive rocks and furnace slags. This structure
belongs to, and is characteristic of eruptive rocks. It is by no means con-
fined to lava flows, but is also to be seen in dikes. The difficulty in regard
to employing it as a diagnostic character arises from the close resemblance
of it to other structures in altered rocks, and its obliteration by secondary
alteration in the rock mass. A schistose structure induced in rocks by alter-
ation is the one structure that under the microscope is most often mistaken
for fluidal structure. Fluidal structure has been.taken for bands of sedi-
mentation in a large number of instances, particularly in the older acidic
rocks like felsite and granite.

The bands of chemical deposition, as in the case of silica from hot springs,
have in some instances been confounded with the fluidal structure of erup-
tive rocks, although distinct from that both in character and cause.

In the employment of the fluidal characters in the older rocks, great

22 THE ORIGIN AND ALTERATION OF ROCKS.

care needs to be taken to prevent their being confounded with the super-
induced structures in the same rocks, for such mistakes are of very
frequent occurrence.

Arguments from analogy should only be permitted in deciding the ques-
tion of the origin of any rock when no other evidence exists; and then such
arguments should be admitted to be of a doubtful character, and not held to
be proof positive. Another prominent fallacy in petrograpby is the argument
that as the conditions are in one region, so must they be in another, — while
no effort is made to find out what the real conditions are in the latter.

The origin of the older rocks, comprising the districts regarded as Azoic
or Archean, and the principles on which they have to be subdivided into
groups, or ages, have an important bearing upon the classification of rocks,
The prevalent views regarding the constitution of these older formations
were looked upon, by the writer, as opposed to petrographical facts; hence
it became necessary to make a careful examination of the published evi-
dence in behalf of these views. This has been done and duly published,*
with the result that no real evidence has been found sustaining the current
views; and thus the petrographer is free to follow the data of his science.

The structure of the districts of crystalline rocks can in most cases be
explained in the following way. Let the reader imagine a region covered
by rock, either eruptive or sedimentary. Then suppose that here eruptive
(volcanic) action begins, and ashes, mud, lava, and the other accompaniments
of such action are mingled together. The earlier sedimentary rocks, and the
volcanic material are later cut through and through by dikes — faulted and
jointed, contorted, and if on a sea-shore, subjected to wave action before the
latter are fairly cold.

We might thus have mingled in inextricable confusion lava flows, indur-
ated and contorted sedimentary rocks, ashes, scoria, mud-flows, dikes, marine
deposits, in short, every known form of rock which can be produced by the
combined action of volcanic, pluvial, and marine agencies. After this, then
imagine the decline of the eruptive power, with the accompanying gaseous
and thermal water action. Imagine the changes in the rock structure that
these agents would produce, as previously mentioned under rock alteration,
including vein phenomena; and then consider what would be the effect upon
such a district of the action of every conceivable geological agency during
the countless years since the early geological ages. Then suppose that some

* Bull. Mus, Comp. Zodl., 1880, vii. No. 1; 1884, No. 11.

eT.

ERUPTIVE AND SEDIMENTARY AGENCIES DISCUSSED. 25

geologist be placed upon this old volcanic ground worn down to its roots,

its rocks altered or metamorphosed, its remnants of mingled lava flows, eject-
amenta, and marine deposits, and let hin be asked to give its history. If he
were educated in the prevailing views current in American geological liter-

ature, it is probable that he would declare that this was an old chemical

_or sedimentary deposit, which had been buried thousands on thousands of

feet deep under other sedimentary deposits, and in which, owing to the
inclosed moisture and the rise of the internal heat, an aqueo-igneous solu-
tion had set in, rendering the formation plastic. He would also say, that
owing to the generated gases and pressure, the lower portions of the deposit
had been forced into the upper ones, and every gradation had been produced
between the normal sedimentary rock and eruptive forms, which pass by
insensible gradations into each other. How easy and simple would this
explanation be!—nothing could be shown which the authors of such theories
could’ not explain. But how false in our supposed case such an explanation
would be. If we add to our supposed volcanoes massive eruptions, with or
without fragmental ejections (explosive action), shall we not have the same
petrographical features that now exist in regions of the elder crystalline
rocks ?—and is the explanation generally adopted for them any more
accurate ?

The intermingling of eruptive and detrital deposits here supposed is
described in almost every work on volcanic action, and it has been clearly
shown, in many of these districts of older crystalline rocks, that the series
of events here indicated has been very common.

That sedimentation has done its part the writer believes, and he has not
the slightest wish to belittle its importance ; but that it has done everything
he does not believe. Whether any of the first-cooled masses may ever be
found, is a problem for the future; but that we have to do with material
that was fluid before sedimentation began, we consider is clearly estab!ished.

To volcanic phenomena, whether explosive or massive, and to the as-
sociated water action, appear to be due the phenomena of crystalline rocks,
which occur in any and every age from the earliest times to the present.

Especial stress has here been placed upon the characters and phenomena
of eruptive rocks, in hopes of bringing about a state of geology in which
the opposing eruptive and sedimentary agencies shall both have their proper
share, — which at present they do not have, on account of the extreme to
which the advocates of sedimentation have now carried their views.

24 THE ORIGIN AND ALTERATION OF ROCKS.

The views of sedimentation have been pushed so far that one wonders if
Strabo, after he had described the volcanic characters of Vesuvius, was not
told by his cotemporaries that it was all a mistake — that the peculiar char-
acter of the rocks was owing to chemical deposition or to mechanical sedi-
ments; that all showed the slow accumulations of millions of years on a slowly
subsiding sea-floor; that the whole had been buried many miles under the
accumulating sediments, rendered plastic, causing dikes to be formed; that
all the different rocks passed by insensible gradations into one another, ete.;
and that, finally, the whole mountain was carved out by the slow process
of the removal of the sediments, and was undoubtedly, owing to the crys-
talline character of its rocks, one of the earliest formations of the globe.

In working in regions of crystalline rocks, the principles should be used
that one would employ in studying districts in which modern voleanie action
has existed, as about Naples, Mount Etna, Iceland, western North and South
America, and Japan.

If this is done, and the older districts are examined by the aid of the light
given by the modern eruptive formations, the writer believes that the pres-
ent obscurity enveloping the former would be cleared away. The greatest
difficulties in the study of such regions seem to have been in the theoretical
views of the observers themselves. The question regarding such rocks
should be, what are the facts, and not what are the theories.

It seems to the writer clear that the earlier formations of which we have
any record in the earth’s crust were not derived from the waste of earlier
lands, but rather that they are for the most part eruptive, if not portions of
the first formed crust; and that the fragmental portions were eruptive ashes,
or were derived from the waste of eruptive material.*

The burden of proof rests upon the advocate of ancient destroyed conti-
nents, te show that the materials which he supposes came from such lands
could not have been derived from the eruptive action of that early day.

The term eruptive, or volcanic, has been applied in this paper to all rocks
coming from beneath the surface, showing signs that they have been in a
fluid condition, —whether ancient or modern, — for nature has not, to my
belief, drawn any line in her rocks between the younger voleanic and the
older plutonic forms, but all form a continuous and harmonious whole.

* Geikie, Text Book of Geology, pp. 12, 13.

THE MINERAL CONSTITUENTS OF ROCKS. Zt

t
or

Section IlI.— The Origin and Relations of the Mineral Constituents of Rocks.

Taxina the consolidation of any rock as the initial point, particularly
those of an eruptive nature, the constituents fall into one of three classes:
I. Those of prior origin; II. Those formed at that time; LI. Those of later
origin.* }

The minerals of the first class naturally fall into two divisions, in the
eruptive rocks.

1. Those that are characteristic of the rock species.

2. Those that are accidental, being probably caught up in the passage
upward or during the outflow. Similar divisions are found to a greater or
less extent in the sedimentary rocks, according as they were derived from
one or more rocks, and also according to the preponderance of different
rock fragments and minerals in them.

The minerals, and fragments of minerals and rocks, occurring in rock
masses that belong to the first class, have an important bearing upon the
questions of the origin and relations of rocks—so much so that more atten-
tion will be given to them in the future than has been the case in the past.
These are in a great measure characteristic of the rock species, and should
have a very great weight in the nomenclature of sedimentary rocks ; for one
of the most important questions regarding these is, what was the original
material from which they were derived? In the volcanic rocks these minerals
are distinguished generally by the effect that the magma has produced upon
them — the blackening, breaking, tearing, and dissolving action which is so
conspicuous in the case of olivine and hornblende; while in quartz it is shown
in the fractures, the rounding of the grains, and the interpenetration of the
magma. Frequently these foreign materials, especially quartz, have radiating
rings of the groundmass surrounding them, these rings being largely composed
of crystals standing perpendicular to the surface of the inclosed piece. In all
rocks of an eruptive nature, the fragments are apparently either inclusions
caught in the passage upward, or during the surface flow of the lava, or else
derived from the remelting of the more crystalline portions of these or other
rocks at the time of, or prior to the eruption; especially when the eruption

* A. Michel Lévy, Bull. Soc. Géol. France, 1874 (3), iii. 199-236; Ann. Mines, 1875 (7), viii. 341-
346; Wadsworth, Bull. Mus. Comp. Zodl., 1879, v. 277, 278.
4

26 THE MINERAL CONSTITUENTS OF ROCKS.

~_

took place in an old vent, from which the plug of lava and ashes must be
removed before the outflow could occur.

The action of lavas upon these foreign inclusions seems to be that of a
corrosive dissolving hot magma or solution, which penetrates and gnaws its
way into the included fragments. ‘Two classes of foreign materials seem to
be characteristic of most of the eruptive rock species — simple minerals, and
rock fragments. The latter are either the same as the inclosing rock or else
they are the same as some rock known to have reached the earth’s surface
earlier in order of time. These mineral inclusions characterize the same
rock type from the earliest times to the present, when- and where-ever they
may occur. All this indicates some deep seated universal cause beyond the
influence of sedimentary rocks.

These characteristic minerals, too, are not such as occur in sedimentary
rocks; while no such admixture of material exists in the eruptive forms as
would naturally be expected to occur if they were formed from sediments.
Then too, the minerals and fragments of the more difficultly altered sedi-
mentary rocks ought to have remained side by side with these easily alter-
able foreign minerals in eruptive rocks, if the latter rocks are the re-fused
portions of the former. The microscopic characters of the eruptive rocks
are to my mind utterly opposed to any theory that they come from sedi-
ments, or anything else than the original liquid material of the earth.

The second class of rock constituents naturally occupies the most promi-
nent place in recent volcanic rocks, and a more subordinate one in the older
eruptive and sedimentary ones. In eruptive rocks, the indigenous materials
are the products of the magma when unacted upon by extraneous agencies.
It is doubtful if any minerals come under this head — direct primary pro-
ducts of crystallization of the magma— except anhydrous silicates and
oxides, a few phosphates, sulphides, and native elements, the other minerals
in the rocks belonging to the other two classes.

The third class hecomes very prominent in the older and altered rocks,
and includes the hydrous and some anhydrous oxides and silicates, carbon-
ates, and most sulphides.

These forms are the products both of alteration taking place in the rock
mass and of material brought into the rock from extraneous sources. In
one case the chemical constitution of the rock remains essentially unim-
paired, while in the other that constitution is changed to a greater or less
degree. The causes of these alterations in ancient and modern volcanic

=,

THEIR ORIGIN AND RELATIONS. 27

rocks is but imperfectly known, but the changes probably take place under
the influence of percolating waters. That these changes are slow in many
cases is rendered probable by the fact, that when rocks have been exposed
to rapid alterations by hot and mineral waters, the result is a general de-
struction of the rock mass, a disintegration of it as a whole, and not such
changes as are seen in rock masses in general. It is probable that both cold
and thermal waters have contributed to the change, as the latter are abun-
dant in volcanic regions at the present, and we have the right to infer that
they were so in past time at the localities in which ancient igneous activity
was manifested.

- These alterations are considered to be molecular, or belonging to the
rock mass as a whole, although some portions and some minerals are altered
more rapidly than others. ‘The general tendency of rock alteration seems to
be the breaking up of the original constituents, and the formation of quartz
and other minerals, that give to the rock characters closely simulating those
of sedimentary rocks.

The sediments also undergo the same changes, and in extreme cases
produce crystalline schists and gneisses. The changes in them are appar-
ently brought about by the same agencies as the changes in eruptive rocks,
and thermal waters may have been an important factor in producing crys-
talline structure in the former.

In the various alterations of the rocks of every kind the new mineral
structures come apparently from the segregation of mineral matter, either
from the rock or adjacent sources, in some place suitable for its deposition.
The place may be some fissure or cavity, or it may be in the solid rock mass
itself, by the removal of one or more chemical constituents from the immediate
point of action, and the substitution of others. So far as the rock mass goes
when no foreign material is carried into it, these changes may be defined as
the migration or aggregation of the chemical elements, produced by their
tendency to seek such unions as shall expose them under their present con-
ditions to less disturbing elements than their former relations did— a ten-
dency to pass from an unstable towards a more stable condition. The final
result of these changes is, usually, to produce clays, ochres, quartz, and car-
bonates; the latter of which while not stable in position, are apt to be so in
composition; e¢. g., calcite, while readily soluble and removed, generally
reappears as calcite — the position unstable, the union stable. The general
principle of change is the same, whether the mineral matter be reprecipitated

28 THE MINERAL CONSTITUENTS OF ROCKS.

in the rock mass itself, or is carried out and deposited in any contiguous
cavity or fissure, or borne away to be deposited from thermal or mineral
springs, or from bog, river, lake, or ocean waters.

The efforts to explain the changes in rocks and in their mineral con-
stituents by theories of pseudomorphism have generally failed, because the
changes have been attributed to the single minerals, and not to the rock
mass as a whole.

The concentration of ores in rocks, and the formation of mineral veins
seem to be brought about by the same process as the more common altera-
tion of the rock mass, or the storing up of the material in minute fissures
in the rock.* The only ditference is that the kind of material and its
amount, owing to the size of the receptacle and the extent of the ‘action,
is such as to make it commercially valuable. In this statement there would
be excepted all ores that can be proved, as some iron ores have been, to be
of eruptive origin, as well as all mechanical deposits. In this connection it
may be explicitly stated, the writer holds the view that the elements of
most of the ores were disseminated through the original and eruptive rocks,
and that when these rocks became exposed to the action of meteoric
agencies, these scattered materials were collected and deposited in the veins
and segregations in which they are now formed.t So far as now known,
the only ore of eruptive origin, in masses sufficient for exploitation, is that
of iron, which is so only in part of its occurrences. If this view is cor-
rect, it would follow that our veins and most of our ore deposits are superfi-
cial phenomena# of the earth, and that mineralogy and economic geology
as ordinarily studied relate chiefly to the secondary products of mineral
matter; or, they are the sciences of abnormal minerals.

The above described alterations in rocks and minerals, and the localiza-
tion of mineral deposits, with the consequent essential original unity of
ancient and modern rocks, naturally follow from the general law of the
passage from the unstable towards a more stable condition. This results
from the fact that the original materials of the earth, whether forming the
original crust, or appearing on the surface as eruptive rocks, are in a higher
state of energy than is adaptable to the surface conditions of this globe.
They are unstable both in temperature and in the majority of chemical
combinations formed on solidification, and heat is lost with a resulting

* Bull. Mus. Comp. Zool., 1880, vii. 123-130; Proc. Bost. Soc. Nat. Hist., 1880, xxi. 91-103.

+ Eng. Min. Jour., New York, 1884, xxvii. 364, 365.
+t Whitney, Aurif. Gravels, pp. 350-361.

THEIR CLASSIFICATION, 29

dissipation of energy ; while the chemical elements or the molecular combi-
nations tend to seek new unions better adapted to the present circumstances
of the rocks. These changes progress, going on from one form to another.
It is not uncommon to find that as steps in the progress, the ori;

ry
7)

inal miner-
als and glass are altered to other more or less well defined minerals, having
sometimes perfect crystalline form; while these in their turn yield to the act-
ing forces, and new mineral combinations are entered into, and so on down-
ward in the course of the alteration. It may be said that an eruptive rock,
when it has passed from the interior to the exterior of the earth, becomes
a chemical laboratory, in which solutions, reactions, and precipitations are
continually carried on — experiment after experiment, change after change,
succeed one another, according to the materials, reagents, and conditions.
But they always progress in one direction ; the combination last formed is
always more stable in the then conditions than the preceding combinations
were ; with any change of condition there would of course come change in
relative stability.

The induration or hardening of rocks would thus oftentimes be no index
of exposure to heat, for if the mineral formed or infiltrated into the rock
mass is one which stands high on the scale of hardness, e. gy. quartz, then
induration follows as a matter of course.

From the principle of passage or unstableness it follows that the glassy
state is nearest the primitive condition, and is to be looked upon as the
starting point of the indigenous and secondary minerals in rocks ; hence it
should come first in our study and be traced in its process of crystallization
and alteration.

The three classes of products above discussed will be mentioned hereafter
as products of the first, second, and third class, or as, Ist, foreign; 2d, indi-
genous; and 3d, alteration or secondary products.

The first two classes have been collectively and singly called by the
writer original in contradistinction to the secondary products.

Cases of envelopment occur in minerals of the second class frequently,
but they can be distinguished as easily under the microscope, in rocks not
too far altered, from the foreign or secondary minerals, as a coarse conglom-
erate can be distinguished from a granite by the naked eye, or as a piece of
wood joined to another by a mortise and tenon can be distinguished from
the natural growth of a limb.

The various changes that rocks undergo in their alterations are determined

350 THE MINERAL CONSTITUENTS OF ROCKS.

under the microscope, the same as changes are determined in objects in
botany, zodlogy, and astronomy. It 1s not necessary that one should see
an acorn grow to an oak, an apple-seed grow to an apple-tree, a lamb to a
sheep, a nebula to a star, before he can reason upon the growth of plants,
animals, and stars.* It is sufficient to be able to study these in various
stages of their growth, in order to make out their history —to examine
numerous specimens that exhibit all the various phases of existence, to make
out the general life history of the individual. So in lithology the history
of the rocks and minerals can be made out as distinctly and certainly as
the life history of the individuals in the other subjects before mentioned.

In applymg the principles of thermo-optics to the mineral constituents
of rocks, in order to determine at what temperature the rock was formed,
it should be remembered that it is only the minerals of the first class to
which they apply. These alone must have been subjected to the heat of
the liquid magma and present permanent marks of that action. Of course,
nothing can be asserted concerning the temperature to which a liquid has
been exposed, from either the thermo-optical or pyrognostic characters of
the resulting minerals arising from its cooling under various conditions ; 7 in
other words, the characters of a mineral after it is formed have little or
nothing to do with what it was before it was formed, except so far as the
relation may have been shown to exist, by experiment and by observation
of the same conditions. Investigations upon the thermo-optical properties
of minerals belonging to the first class would probably lead to interesting
results, if care were taken to select such as are typical of the lava.

It should also be kept in mind that the conditions under which minerals
are formed from the crystallization of a cooling magma are different from
those under which minerals are formed in veins, fissures, and cavities, or by
alteration of the rock mass; and that minerals truly of the second or indige-

nous class occupy a very subordinate position in our mineral cabinets.

* Peirce, Ideality in the Physical Sciences, 1881, p. 69.

+ As well predicate what was the temperature of the water glass and hydrochloric acid, from the amount of
heat it takes to fuse the chalcedonic silica which they form under suitable conditions, as to attempt to prove
the heat of a liquid magma from the fusion point of some mineral crystallizing out of its cooling solution.
The temperature at which a mineral fuses and the temperature at which it formed have no connection with
one another, except in the case of erystallization from dry fusion ; if they do, how hot corals must be!

|

VALUE OF CHEMICAL ANALYSIS IN LITHOLOGY. ol

Section 1V.— Chemical Analysis of Rocks.

At the present time the most that chemical analysis seems to be able to
do for the lithologist is to give the composition of the rock as a whole.
The many attempts that have been made to determine the mineralogical
composition of rocks by unaided chemical analysis appear to have been in
almost every case a failure. This is natural, for this method alone is unable
to take into account the three different classes of minerals in rocks, and
in its statements has to proceed as if all the minerals were the pro-
ducts of free crystallization in the rock. But while the chemical composi-
tion remains about the same, every gradation in structure and minera!
composition is known to exist, —from a pure glass to mixed glass and
crystals, to a purely crystalline rock, and to one in which all the mineral
constituents are secondary or alteration products. Since the chemical
composition of all these forms is essentially the same, the results of any
calculation of the percentage and kind of minerals inclosed, would be
nearly the same; but how different from the reality are the results of the
calculation, except when the rock is composed of crystals of the second
class alone. Even here the correctness of the result would be a matter
of doubt.

Chemical analyses of rocks, showing their ultimate constitution, if made
from specimens carefully selected and studied in the field, and further
studied microscopically, would aid greatly in lithological research. Typical
unaltered specimens are needed to establish rock species ; and for such work
the average specimens of collectors are too much affected by surface altera-
tion, or weathering, to be used. But a large proportion of rock analyses
appear to have been made from such unsuitable specimens, of whose struc-
ture, mineral composition, and field relations we know: nothing, or next to
nothing; this, too, when the chief value of such analyses is to enable us not
only to institute comparisons between the chemical composition of the rock
analyzed and that of other rocks, but also between that composition and
its origin, structure, mineral composition, and physical relations.

Chemical analyses could be made of great service in lithology by taking
a graded series of rocks, beginning with the unaltered form, and passing
gradually into the extremely altered form, comparing step by step the chem-
ical composition with the changes in structure and mineral composition.

832 CHEMICAL ANALYSIS OF ROCKS.

There is a vast amount of unconscious humbug in the constant attempts
to use chemical analyses for a purpose foreign to their nature; that is, to
determine, as before mentioned, the mineral composition by mathematical
calculations founded on rock analyses. All these efforts appear to be based
on an entire misconception of the nature of rocks. Nothing better illus-
trates the inutility of this method alone for the purpose of determining the
mineral composition, than a comparison of the speculations of chemists
regarding the minerals composing the stony meteorites and the actuality as
obtained by microscopic examination.

The writer holds, as the result of his studies, that the chemical analysis
of a normal rock corresponds with its species— that is, certain percentages
of the more prominent elements can be laid down, beyond the extremes of
which normal rocks belonging to that species will rarely if ever go, and
within which normal rocks of other species will rarely if ever come. This,
of course, applies especially to the eruptive rocks, for in the case of the
sedimentary ones, every degree of composition is to be expected according
to the sources from which the materials composing them were derived, and
the amount of sorting, chemical replacement, etc., they have undergone.

The more highly altered or weathered eruptive rocks, especially if
chemical constituents have been removed, and either replaced or not by
others, would not be normal forms. If the analyses were written in the
percentages of the elements, instead of their compounds, it is thought that
the chemical relations between the different rock species and varieties
would be more clearly apparent than at present, as Nordenskidld has
shown for the meteoric peridotites.*

From the manner in which many chemical analyses of rocks have been
made (poor work, poor specimens, and no knowledge of the rock) the
difficulties in the way of proving these relations are great; but the writer
has prepared tables which show them in an approximate manner.

' * Nature, 1878, xviii. 510, 511; Geol. Foren. Forhandl., 1878, iv. 45-61; Zeit. Deut. geol. Gesells.,
1881, xxxili. 14-30.

‘
;
}

SCHEMES OF CLASSIFICATION —THEIR RELATIVE VALUE. 30

Section V.— Classification based on Mineral COvmposilion.

Ir the artificial schemes of lithological classification are examined, it
will be found that they are generally based on the mineral composition,
the geological age, and the structure of the rocks, some rocks even being
defined by a statement of that which they are not, or that which they do
not contain.

It does not accord with the limits of this paper to enter upon any thor-
ough critical discussion of the application of such principles, but a certain
examination of them may be made, so far as they bear on the method of
classification it 1s proposed here to use. Amongst the minerals of which
the chief use is made in classification there may be mentioned the feld-
spars, including leucite and nephelite, also olivine, quartz, the micas, pyrox-
enes, and the» amphiboles; although any mineral is liable to assume in
special cases sufficient importance in these artificial schemes to found specific
distinctions upon.

Of these minerals the most important are the feldspars, and on their
presence or absence, and on the species or type of feldspar present are

founded some of the most important divisions of the rocks. In order to

successfully use any mineral in classification it is necessary that it should
be a determinate quantity — that is, it should always have in the rock one
mode of formation only —that its specific limits shall be well marked, and
that it shall be accurately determinable with fair facility.

.

The Feldspars.

That the feldspars originate in all three of the methods given previously
for the origin of rock minerals — foreign, indigenous, and secondary — the
writer thinks cannot be denied; although, for the most part, they appear
to be indigenous. In classification of this kind, the most important question
about the feldspars is, what are their divisions and the diagnostic characters
of these. A sketch of the various prominent opinions regarding their
constitution will best answer our question.

In 1846 Scheerer held that the feldspars were different grades of satura-
tion, of a radical compounded of equal atoms of R. and Al* Later he
remarked + that it was permitted to regard all known feldspars as chemical

+ Ann. Physik Chemie, 1846, Ixviii. 8337; Am. Jour. Sci. 1848 (2), vi. 61.
+ Ann. Physik Chemie, Ixxxix. 19.

5

34 CLASSIFICATION BASED ON MINERAL COMPOSITION.

combinations of either (1) anorthite and labradorite, or (2) anorthite and
albite (orthoclase), or (3) labradorite and -albite (orthoclase).

In 1850 Delesse said: “I have already had occasion to remark that we
have hitherto attached too much importance to the varieties of the feldspars
of the sixth crystalline system, and that nature has not always been limited
by the divisions established among them by chemists and geologists; the
same rock sometimes containing several varieties of these feldspars.”* In
the last reference Delesse had also pointed out that the composition of the
feldspar was not constant even in the same rock from the same locality.

In 1851 Hermann taught that in the feldspars were two molecules: one
denoted by a= (R Si, 4-/Sig),
and the other by b=(RSi + Si).

Of these molecules the species were thus compounded (giving, however,

from his list only those species of importance to-day) :—

Orthoclase = a
Albite = av
Anorthites 4 == b
Andesite: %=— = - 3
Labradorite = * = 2
Oligoclase = eel

The union in this case was regarded as a molecular union, and not a
chemical combination between the atoms. f

Sartorius von Waltershausen, in his work “ Ueber die vulkanischen
Gesteine in Sicilien und Island, und ihre submarine Umbildung,” published
in 1853, advanced the theory that there were three definite triclinic
feldspars, 7. e. anorthite, albite, and krablite, and that the other triclinic feld-
spars were formed by varying compounds of these. Krablite, or baulite, t
was then supposed to be a definite silicate, with the atomic ratio 1: 3: 24,
| but it has

since been shown to be a mineral aggregate or rock, referred at first to the

as determined by the researches of Forchhammer § and Genth ;

: * Bull. Soc. Géol. France, 1850 (2), vii. 526; see also Ann. Mines, 1847 (4), xii. 266, 267; 1849, xvi.
OAT, ODS.

t Jour. Prakt. Chemie, 1851, li. 256-258.

t Landerebe, Mineralogie der Vuleane, 1870, pp. 60, 227.
_ § Oversigt over det Kgl. danske Videnskabernes Selskabs Forhandlinger, ete., 1842, pp. 43-55 ; Jour.
Prakt. Chemie, 1843, xxx. 394.

i| Ann. Chemie Pharm., 1848, Ixvi. 271. i

COMPOSITION OF THE FELDSPARS. 35

quartz trachytes,* and later to the liparites or rhyolites,t which now
include most of the quartz trachytes of the older authors. Bunsen, indeed,
maintained both before and after 1853, that baulite was a mechanical mix-

ture —a rock, and not a mineral. t
In 1854 Dr. T. Sterry Hunt stated that the triclinic feldspars constituted
a genus, of which albite might be taken as one representative, and anor-
. thite as the other. The intermediate feldspars might be distinct species, or
they might be looked upon as variable mechanical mixtures of the two typi-
eal feldspars, albite and anorthite. A similar mixture of albite with a potash
feldspar, and anorthite with a soda or magnesian one, as well as of orthoclase
with a lime or potash feldspar, were regarded as probable. Hunt distinctly
objects to any idea that these variable feldspars were formed by chemical
unions between the different types, and makes it clear that he had in mind
the process of envelopment and variable, mechanical, contemporaneous
intererystallization, on which he founded his doctrines of the origin of
erystalline rocks, pseudomorphism, and metamorphism. In this he fol-
lowed Scheerer’s views regarding the relations of iolite and aspasiolite,
and of olivine and serpentine. The proportions of these intermixtures of
the feldspars were regarded by Hunt as entirely variable and indefinite,
; being “such mixtures of species as constantly take place in the crystalliza-
tion of homoeomorphous salts from mixed solutions,’ and he explained the
____- process in every case in the same way as he did in the case of perthite.
That this view of the mixture of the feldspars is the same as his explana-

tion of pseudomorphism can be seen from his statement that the latter has
-resulted in many jnstances from the association and crystallizing together
of homologous and isomorphous species. §

In 1864 Professor Gustav Tschermak advanced the theory that (excepting
hyalophane and danburite) there were three distinct species of feldspar:
Orthoclase, or potash feldspar; Albite, or soda feldspar; and Anorthite, or
lime feldspar. He held that soda and potash were not isomorphous, and
therefore all orthoclase crystals containing soda were mechanical mixtures

* TZirkel, Sitz. Wien. Akad., 1863, xlvii. (1) pp. 243, 244; Lehrbuch der Petrographie, 1866, i. 25 ;
ii. 154-166.

+ Zirkel Die mikroskopische Beschaffenheit der Mineralien und Gesteine, 1873, p. 541.

+ Bunsen Ann. Physik Chemie, 1851, Kxxxiii. 199, 201; Ann. Chemie Pharm. 1854, Ixxxix, 98; Preyer
und Zirkel, Reise nach Island im Sommer, 1860; pp. 317-824.

§ Proc. Am. Assoc. Adv. Sci., 1854, viii. 237-547; 1871, xx. 1-59; Am. Jour. Sci., 1855 (2), xvi. 218 ;
1854, xviii. 270, 271 ; Phil. Mag., 1855 (4), ix. 354-363; Geological Survey of Canada, Report of Progress,

1853-1856, pp. 373-383 ; 1858, p. 180; Canada in the London International Exhibition, 1862, p. 65 ; Geology
of Canada, 1863, p. 480.

36 CLASSIFICATION BASED ON MINERAL COMPOSITION.

0

(interlaminations or intercrystallizations) of orthoclase and albite. Albite
and anorthite were looked upon as two distinct species of triclinic feldspar,
and it was held that labradorite, andesite, and oligoclase were formed from
isomorphous mixtures of albite and anorthite, — that is, through the mo-
lecular union of albite and anorthite, in definite mathematical propor-
tions. These mixtures T'schermak distinctly held were not mechanical, but
molecular.

The finding of potash in the triclinic crystals formed from the molecular
union of albite and anorthite was explained by Tschermak, by the supposi-
tion that some orthoclase was mechanically interlaminated. Oligoclase,
labradorite, and andesite were united under the name of plagioclase. This
term has, however, been employed since to include both albite and anor-
thite, and in this latter sense it is generally used.*

Tschermak, indeed, does not claim this theory to be entirely original with
himself, for he remarks, ‘“ Dabei verschweige ich jedoch nicht, dass die
Grundidee dieser Vereinfachung keineswegs neu sei und ich bemerke, dass
durch die friheren Bemiihungen der Forscher, welche eine solche Vereinfa-
chung auf chemischer Basis anstrebten, also durch Sartorius von Walters-
hausen, Rammelsberg, Scheerer, der Gedanke endlich so weit entwickelt
wurde, dass Andere wie Delesse, Hunt denselben als keines speciellen
Beweises bediirftig hinsteilten.”

Tschermak’s theory was variously opposed and advocated, and on one
side or the other the most prominent chemical mineralogists arranged
themselves. It has been especially discussed by Rammelsberg, Rath, Roth,
Bunsen, Petersen, Streng, and others, with the result that it is the generally
accepted view regarding the composition of the feldspars.

Tschermak’s theory does not appear to be well understood in England
or America, and although the present writer recognises his liability to also
misinterpret it, he deems it right to point out some of these differences of
opinion, believing that in the end it will lead to a more accurate conception
of the theory than now seems to exist.

Streng later offered a theory for the feldspars, in which he held that they
were silicates, in which the Ca partly replaces the Na, and R the Si;
claiming that there were-only two principal divisions; Ist, the potash feld-
spar, and 2d, the lime soda feldspar —the latter forming a number of varie-
ties with variable composition.t

* Sitz, Wien. Akad., 1864, 1. (2) pp. 566-613.
+ Neues Jahr. Min., 1865, 411-434, 513-529; 1871, 598-618, 715-781.

THE FELDSPARS: TSCHERMAK’S THEORY. OF

Petersen objected to Tschermak’s theory on the ground that orthoclase
feldspars containing soda do not show any of the striations peculiar to tri-
clinic feldspars, which, if the theory is correct, must be mechanically mixed
with the soda-bearing orthoclase ; also, that some potash-bearing plagioclases
exhibit no trace of orthoclase.*

Professor J D. Dana, in 1867, also opposed Tschermak’s theory, holding
that the variations from the normal analyses were caused by, —

(a) Incorrect analyses.

(5) Impurities ; and often, mixtures of different feldspars through inter-
crystallization. :

(c) Alteration ; caused either (1) by the infiltration of ordinary waters,
carbonated or not — the rocks containing feldspars having been exposed to
this action through long ages past — or (2) through the same process aided
by mineral ingredients in the waters, resulting in the introduction of mag-
nesia, oxide of iron, etc., and in other changes.f

In the meanwhile Tschermak’s theory assumed great prominence, and in
1874, Dr. T. Sterry Hunt put forward the claim that he was the originator
of it. In support of this assertion he quoted from a published abstract. of
his original paper (aie, p. 35), which had given his views in an indefinite
manner, and in his direct quotation from this abstract a hypothetical state-
ment was altered to a positive one. t

As pointed out in the preceding pages, Hunt’s theory of the triclinic
feldspars is nearly the same as Dana’s (4) given above. Hunt held that
they were indefinite, variable, mechanical aggregates, or intercrystallizations;
while Tschermak held that they were formed by isomorphous molecular
unions in definite proportions. Further, Hunt’s theory does not seem to
be at all original with him.

Yet a number of writers have acknowledged Hunt’s claim, presumably
because they have never read his original papers, or else have misunderstood
Tschermak. The use of the term “mixture” with two distinct meanings
— Ist, for mechanical aggregation (Hunt), 2d, for molecular combination
(Tschermak) —has probably added to the confusion.

* Neues Jahr. Min., 1872, pp. 576-586 ; Jour. Prakt. Chemie, 1873 (2), vi. 200-212.

+ Amer. Jour. Sci., 1867 (2), xliv. 260, 399. See also System of Mineralogy, 5th ed., 1868, p. 336.
¢ Chem. Geol. Essays, pp. 438, 443-445.

38 CLASSIFICATION BASED ON MINERAL COMPOSITION.

Amongst those who have acknowledged Hunt’s claim are both Danas,*
Silliman,f Leeds, t Rutley,§ Hawes,
‘Edward Dana says that the theory “ was offered by Hunt, and has since

| and Fouqué and Lévy. §

been developed by 'Tschermak ;”’ Rutley, that Hunt’s conclusions are almost
identical with those of Tschermak ; again, James D. Dana, mistaking Hunt’s
views, stated of the latter, “In the view ... with regard to the molec-
ular relations of the feldspars, he appears to have anticipated Tschermak by

9?

ten years;”’ while Silliman goes so far as to say, “ Here will be found devel-
oped his [Hunt’s] views on the constitution of the feldspars, which were
some years later adopted without acknowledgment by Tschermak.” Leeds
appears to have been the only one who recognized the essential difference.
between the indefinite mechanical-mixture view adopted by Hunt, and the
definite molecular-union theory of Tschermak ; but he failed to see the logical
conclusion to be derived, — that Hunt** was in no sense the originator of
Tschermak’s theory, and that all the charges of appropriation made against
the latter ought to be entirely withdrawn.

In 1875, Descloizeaux, from the optical properties of the plagioclastic feld-
spars, concluded that andesite was an altered oligoclase, but that labradorite
and oligoclase are distinct species, and not isomorphous mixtures. He looked
upon their optical properties as opposed to Tschermak’s theory.j+ To explain
the chemical composition, Descloizeaux calls attention to the theory of
Friedel and others, that the several feldspars differ from one another only
in their proportions of silica, forming a series whose common difference is
SiO,: e. g., anorthite + SiO, = labradorite ; labradorite + SiO, = andesite ;
andesite + SiO, = oligoclase; and oligoclase + SiO, = albite.

While Descloizeaux admits that the composition of the feldspars may be
explained as well by Tschermak’s theory as by Friedel’s, yet he holds that
the latter accords better with the optical and crystallographic characters of
the species.

Vom Rath, on the other hand, is of the opinion that the chemical consti-
tution of the feldspars is most satisfactorily represented by Tschermak’s
theory, and holds that the formation of the intermediate triclinic feldspars

* Am. Jour. Sci., 1875 (3), ix. 102 ; Text Book of Mineralogy, 1877, p. 297.

+ Amer. Chemist, 1874, v. 106. + Amer. Chemist, 1877, vii. 335.

§ The Study of Rocks, 1879, p. 95. || Geol. New Hampshire, 1878, iii. part 4, p. 89.

{| Miner. Microg., 1879, p. 206.

** Byll. Mus. Comp. Zool., 1884, vii. 370-374, 445-454, 458, 459.

t+ Ann. Chimie Physique, 1875 (5), iv. 429-444; Comptes Rendus, 1875, Ixxx. 364-371; Neues Jahr,
Min., 1875, pp. 279-284, 395-399,

i

THE FELDSPARS: THEIR COMPOSITION. od

by the molecular union of albite and anorthite is an established law, and
not a mere hypothesis. He states that the supposition that the difference
of composition in the plagioclastic feldspars is due to the successive addi-
tion of silica molecules, takes no account of the replacement of lime and

soda, which is so intimately associated with the variation in the amount of

silica. Andesite, he holds, is distinct from oligoclase.

In 1876,* Descloizeaux described a new potash feldspar (microcline )
which is triclinic, although chemically the same as orthoclase. This dis-
covery only added to the difficulties and confusion in the feldspar question.
Mallard and Michel Lévy, however, taught later that orthoclase and micro-
cline were the same, but that the cross-twinning had become so fine that it
was no longer visible in polarized light, 7. ¢., the laminee were excessively
thin— so much so as to cause the feldspar to appear optically homo.
g@eneous.t

Extended observations were later made by Max Schuster on the optical
characters of the feldspars. He claims that these characters show a gradual
change or transition between anorthite and albite, pari passu with the varia-
tion in chemical composition ; that is, each definite proportion in the mix-

ture of anorthite and albite gives a variety whose optical properties

approach one or the other of these feldspars, according to the predomi-
nance of either. From the optical characters of any feldspar crystal,
there could be inferred its chemical composition, and the reverse. He
claims that Tschermak’s law is sustained by these observations, and such
seems to be the prevalent opinion.t These observations of Schuster are
in accordance with those of Sennamont on Rochelle salts.§ They not im-
properly may lead to very different views of mineral species from those
commonly held.

From the above, it seems clear that the feldspars are either species
with such indefinite boundaries that they (the feldspars) cannct be defined
with any accuracy, or else they form a continuous series from anorthite
to orthoclase. In either case it is improper to found definite groups and
specific divisions of rocks on a variable and indefinite group of minerals,

concerning whose nature the chemical mineralogists are not agreed.

* Comptes Rendus, 1876, Ixxxii. 885-891; Ann. Chimie Physique, 1876 (5), ix. 433-499.

+ Bull. Min. Soc. France, 1879, pp. 185-139; Neues Jahr. Min., 1880,i. pp. 174,175; Zeit. Kryst.,
1880, iv. 632, 633.

t Sitz. Wien. Akad., 1879, Ixxx. (1), 192-200; Min. Mitth., 1880 (Q), iii. 117-284.

§ Ann. Chimie Physique, 1851 (8), xxxiii. 429-437.

40 CLASSIFICATION BASED ON MINERAL COMPOSITION.

Even supposing the species were well established, have we any methods
whereby these species or divisions can be positively discriminated ?

In 1876, Descloizeaux gave a method, whereby he thought the differ-
ent plagioclastic feldspars could be distinguished from one another. This
method required a thin transparent section, either cleaved or ground par-
allel to the plane of easiest cleavage (O, OP, 001, p)—the triclinic feld-
spars being as a rule twinned, so as to show color bands parallel with the
plane of the next easier (or less perfect) cleavage. The sections are
placed on the stage of the polarizing microscope, with the color bands
parallel to any diagonal of the crossed nicols (plane of vibration or
plane of polarization) ; the section is then revolved until one set of color
bands becomes dark, or the light is extinguished in them. The angle
between this point and the former position of the section is taken. The
section is then revolved in the opposite direction until extinction of light
takes place in the alternate set of color bands. The angle between
this point and the first or original position of the section is taken. If
the section is properly cleaved, or ground, the two angles observed are
equal. By experiment on feldspars of known composition, the angles
between the nicol diagonal and the extinguished color bands, or the angle
(double the others) between the two positions in which the alternate bands
are rendered dark, have been determined; and it is assumed that all feld-
spars having the same angle of extinction as any one of these previously
determined angles belongs to the same species of feldspar. Descloizeaux
held that this supposed fixity of optical characters was opposed to Tscher-
mak’s theory.* |

Prof. R. Pumpelly endeavored to make Descloizeaux’s method practi-
cally applicable to thin sections of rocks, which he did in the following
manner: If instead of cutting sections parallel to the principal cleavage
they should be cut at any angle with that cleavage but in the zone O:
t7(p:h’; 001: 100; OP: ow P ) we should have every variation of
angle, from O° up to the maximum for that feldspar. In a thick rock sec-
tion in which the feldspars are cut at random, it is necessary first to ascer-
tain whether any feldspar section has been cut in the zone 0: i7. This is
done by ascertaining on trial if the extinction in the alternate color bands
takes place at equal angles on opposite sides of the nicol diagonal. If it

does, the section of feldspar was cut as required. A number of such sections

* Comptes Rendus, 1876, Ixxxii. 885-891; Ann. Chimie Physique, 1876 (5), ix. 438-499.

THE FELDSPARS: THEIR DETERMINATION, 41

are usually to be found in the slide, and their maximum angle is taken
as the index of the feldspar. In actual practice, Professor Pumpelly took
as oligoclase those feldspars of which several individuals in a rock section
gave angles between 32° and 36°; as labradorite, those between 36° and
62°; and as anorthite those over 62°,

When more than one feldspar is present in the slide, only that one can
be distinguished which has the highest angle; and this may be the minor
or subordinate feldspar. It is even possible for a single crystal, only, of one
feldspar, to change the conclusion as to the rest of the feldspars in the sec-
tion. Then, again, the sections examined may be so cut as to give a lower
angle than they should; therefore the observer concludes he has a different
feldspar from the one actually present. It is scarcely possible by this
method to distinguish between oligoclase and albite.*

Professor Pumpelly was, however, anticipated in order of time, in the
publication of this method, by M. Michel Lévy, who discussed the subject
mathematically, and applied the principles to many different minerals.+

That. the work of both Lévy and Pumpelly was independent and original
with both, can be inferred from the fact that the latter asked me early in
the year 1876 to undertake a mathematical discussion of this subject, in
order to aid his experimental work which he was then upon. The mathe-
matical portion the present writer had then neither time nor inclination to
perform, but the practical work of Professor Pumpelly resulted in that
method of determination which has been given before. Schuster’s results
would, however, appear to render such determinations of but little value at
present.

Dr. George W. Hawes in 1881, showed that the common method of
distinguishing triclinic from monoclinic feldspars was unreliable in certain
ceases; for labradorite from St. Paul’s Island and Canada, anorthite from
New Hampshire, and oligoclase from Bodenmais, exhibited none of these
supposed distinguishing features, 7. ¢. striation in common and _ polarized
light. +

Amongst the methods used for the determination of the feldspars, as
well as of other minerals, is the micro-chemical method of Dr. E. Boiicky,
which consists essentially in subjecting the specimen to the action of fluo-
silicic acid, hydrofluoric acid gas, chlorine gas, etc.; and microscopically

* Proc. Am. Acad. Sci., 1878, xiii. 253-309; Geol. Wisc., 1880, ii. 30.
+ Ann. Mines, 1877 (7), xii. 8392-469 ; Comptes Rendus, 1878, Ixxxvi. 846-248.
¢ Proc. Nat. Mus., 1881, pp. 1384-136.

6

4

42 CLASSIFICATION BASED ON MINERAL COMPOSITION.

examining the crystals produced, under proper conditions. This is simply a
method of making qualitative tests upon material in bulk too small to be
tested in the ordinary way.*

In 1876 Professor J. Szabé published f his method of determining feld-
spars by means of their fusion, reactions, and coloration produced in the
Bunsen flame, which gave, according to him, a means for estimating the
percentages of alkalies, etc., in the specimen examined,

Still a third method is from the crystals formed in blowpipe beads under
proper conditions. This method was invented by Mr. George H. Emerson
in 1863, and later expanded by Gustav Rose,§ W. A. Ross,|| and H. C.
Sorby.{] The results are essentially similar to Boticky’s method, qualita-
tive, but can be used with small fragments.

The last and most important method is that of separating the feldspars
by means of liquids of different specific gravities. In this way considerable
material of a certain specific gravity can be obtained for chemical analysis,
and its nature ascertained.** All these methods have their defects: as, for
instance, the feldspars which give character to the rock are of more than
one species, usually ; they contain more or less glass and mineral impurities ;
and they are subject to alteration. These factors change their specific
gravity and chemical relations, and make the determination of a few crystals
of but limited value in fixing the condition and character of the remaining
feldspars. Of all the methods the specific gravity one promises the most,
but it is not believed at present to lead to any essentially valuable results
in determining minerals like the feldspars, whose very species are so inde-
terminate. While the before-mentioned methods, and many others not
mentioned, have added greatly to the knowledge of minerals, they seem to
have blinded most observers to the general characters of the rocks they were
studying.

In the coarsely crystalline rocks crystals of feldspar, of sufficient size
for analysis, can often be obtained; but that analysis, to be of any value,
must proceed on the supposition that the crystal is pure, unaltered, and

* Archiv der naturwissenschaftlichen Landesdurchforschung Bohmens, 1877, iii. 5th Abth., pp. 1-80.

+ Ueber eine neue Methode die Feldspathe auch in Gesteinen zu bestimmen, Budapest, 1876.

+ Amer. Jour. Sci., 1864 (2), xxxvii. 414, 415; Proce. Am. Acad., 1865, vi. 476-494.

§ Monatsb. Berlin Akad., 1867, pp. 129-147.

|| Chemical News, 1868 (Amer. Reprint), ii. 74-76, 147, 148, 157-160, 196 ; Pyrology or Fire Chemis-
try, London, 1875.

{| Month. Micro. Jour., 1869, i. 349-352.

** Thoulet, Comptes Rendus, 1878, Ixxxvi. 454-456; Bull. Min. Soc. France, 1879, p. 17; Chureh, Min.
Mag., 1877, i. 237, 238; Goldschmidt, Neues Jahr. Min., 1881 (Beilage-Band), pp. 179-238.

THE FELDSPARS AS A BASIS OF CLASSIFICATION, 43

typical of the predominating feldspar in the rock; microscopic analysis
shows that the larger crystals in our rocks are generally abnormal, often
foreizn to their present surroundings, containing numerous inclusions, some-
times three fourths of the crystal being glass, microlites, ete. If a thin
section is prepared before the chemical analysis is made, it only proves
that the part examined is pure or impure, as the case may be, offering no
proof regarding the rest, only a probability ; further, the larger crystals are
usually the subordinate ones, being unlike the generality in the mass of the
rock. This method is, also, inapplicable in the cases where it is most needed ;
in the fine-grained and compact rocks, which contain few or no feldspars of
sufficient size. The larger feldspars are most subject to alteration, passing
from the basic towards the acidic,* some becoming greatly changed while
the smaller crystals are untouched; yet the analyst names the rock from
the altered, and not from the unaltered feldspar, — euphotide, for instance.t

The secondary formation of feldspars, like orthoclase in rocks, adds
greatly to the difficulty of making the classification dependent upon the
kind of feldspar present. In other cases the feldspathic material is seen
to be largely replaced by quartz and other minerals — the presence of the
first not being suspected until the crystal was examined under the micro-
scope. The twinned character of the triclinic feldspars, seen both in com-
mon and polarized light, is not a constant character, as has been pointed
out before. It has been customary to regard all unstriated feldspars in
basic rocks as plagioclase, cut parallel to the brachypinicoid, but in the
acidic rocks as orthoclase. Through the great alteration to which the
feldspars have been subject in the older rocks, all signs of twinning have
been frequently obliterated, thereby causing such crystals in granitoid
rocks to be classed as orthoclase.$ The chief value, therefore, of the
optical method for distinguishing the feldspars is apparently to deter-
mine the predominance of plagioclase, or of orthoclase ; while the chief
use of the present micro-mineralogical study of the feldspars in lithology
is the determination of the more or less acidic or basic composition of the
rocks, according to the predominance of orthoclase or plagioclase in them.
From the above it follows that a systematic classification cannot be properly

based on any such variable, indeterminate materials.

* Geo. W. Hawes, Geology of New Hampshire, iii. part. iv. 90-92.
+ T. Sterry Hunt, Am. Jour. Sci. (2), 1859, xxvii. 336-349 ; J. D. Dana, rid. (8), 1878, xvi. 340.
¢ Bull. Mus. Comp. Zodl., 1880, vii. 55, 56.

44 CLASSIFICATION BASED ON MINERAL COMPOSITION.

The Pyroxene-Anphibole Groups.

In the enstatite-hypersthene-pyroxene-amphibole group of minerals, a
similar relation seems to exist as in the feldspars, and a like variability.

In these the distinctions are founded mainly on optical, crystallographic
and cleavage characters. May there not be a similar relation between the
orthorhombic and monoclinic pyroxenes as there is between the different
feldspars? Specific distinctions between rocks have been based solely
on a difference in cleavage in minerals otherwise identical. This is the
case with augite and diallage, which thus become the means of separating
diabase from gabbro. How valid this cleavage distinction is, may be
learned from the fact, that the cleavages of augite and diallage are found
sometimes united in a single crystal of pyroxene. While augite has been
regarded as distinctive of the augite-andesites, basalts, and diabases, more
recent observations show that it is not confined to any one species of rock,
but exists in every species, from the pallasites to the rhyolites. So, too,
it was regarded as entirely characteristic of modern or younger rocks, but
this is found not to be true. This belief in the occurrence of augite in
modern rocks has arisen mainly from its ready alteration to viridite,
chlorite, hornblende, biotite, etc., which would thus cause it nearly or
entirely to disappear in the older and more altered rocks. _ Again, the
probability that pyroxene in some of its varietal forms, like sahlite, is of
secondary origin, increases the difficulty of employing pyroxene as a species
character. |

In the case of hornblende but little distinction is made in nomencla-
ture, whether the mineral is foreign, original, or secondary; but in all
these modes of occurrence it is given equal value in classification. As a
foreign product it occurs in the andesites, the augite apparently arising
from the crystallization of the dissolved hornblende material, while in the
older forms of the same andesites hornblende occurs as a secondary product,
after both the foreign hornblende and original augite. But the same rock
is given three different names, according to the predominance of augite,
foreign hornblende, or secondary hornblende. This is done, however, uncon-
sciously by lithologists, since they do not practically make these mineralog-
ical distinctions. The writer has seen two sections taken from the same
hand specimen; one of which pronounced the rock a diabase, the other a
diorite.

THE MINERALOGICAL NOMENCLATURE OF ROCKS. 45

Of other minerals, mica occurs in a series of species like the feldspars,
and in rocks is found in all three forms — foreign, indigenous, and second-
ary; while chlorite and epidote are probably always secondary. From
this it would appear that they are not suitable to designate species.

Mineralogical Nomenclature of Rocks.

As the result of my study, I have been obliged to regard classification
based on mineralogy, unless it be for some varietal subdivisions, as impracti-
cable, because it is not a natural but an artificial method; a system that
requires constant change and readaptation; and further, one that is based
too much upon theory, individual judgment, and weight of authority; a
system that admits, even requires, the “dumping” of rocks into certain
places without the slightest regard to their relations of any kind, except
it be that they hold one or at most a few minerals in common. ‘This rela-
tion is often vitiated by the observer's not taking into account whether
these minerals are natural crystallizations in the rock, foreign, or secondary
products,

When classification is based on structure it usually separates the rock
into distinct species according as it is glassy, partly glassy, crystalline, or
porphyritic. That these distinctions are valueless, the writer thinks, fol-
lows. from the fact that the same rock mass may show all these cases ;
dikes often being glassy and non-porphyritic on the edges, and crystalline
and porphyritic towards the middle. The granitic structure indicates pro-
bably a certain depth at the time of crystallization, but that this may
practically be slight has been shown by the lava flows of Keweenaw Point,
some of which are fine-grained on the surface, and coarsely crystalline

(granitic or diabasic) towards the base.

Section VI. — Naming Rocks according to the Geological Age.

Tus question has been so well discussed by Allport,* Dana f and others,
that but little needs be said upon the subject here. Chemical, microscopt-
cal, and geological evidence all point to the fact that this division is not a
natural one; and so far as my work has gone, the original characters of the

* Geological Magazine, 1871 (1). viii. 249; 1875 (2), ii. 583; Quart. Jour. Geol. Soe., 1874, xxx.

529.
+ Amer. Jour. Sci., 1878 (8), xvi. 336.

46 NAMING ROCKS ACCORDING TO THEIR GEOLOGICAL AGE.

rocks are the same from the earliest times to the present. Other things
being equal, the older rocks are more altered; but as other things are not
equal, no abrupt line can be drawn at the tertiary age, as is now generally
done; no characters exist whereby it can be done, and the line must remain
an arbitrary one. Alteration produces characters in the rocks that can be
used to indicate their greater age, or greater alteration — terms which are
not synonymous, although usually taken to be. The subject can, perhaps,
be best formulated as follows: all rocks upon the earth’s surface undergo
alteration, and when exposed to the same conditions this is proportionate
to the age. It is the unquestioned duty of the petrographer to study these
changes, and starting from the least altered rock trace the continuous series
to the most altered one of that kind. Such a system of work has been
attempted here, so far as time and means have permitted.

The presence or absence of fluidal cavities, which has been urged as a
distinction between tertiary and pre-tertiary rocks, seems to be related more
to depth, and the conditions to which the rocks have been exposed since
consolidation, than to age. The modern voleanic rocks are but the froth
of an eruption, compared with the massive eruptions that have taken place
in past time. The specimens collected are generally of a surface nature,
and would allow the very ready escape of the inclosed vapors; while at
some depth the escape could not take place as readily. Our older rocks
have in general suffered more denudation, and therefore are more likely
to contain fluid inclusions. Should it be shown that these fluid cavities are
in part, or entirely, of posterior formation to the rock, as has been urged
by Vogelsang,* and shown by Julien to be so in one case,f it would require
a new interpretation to be placed upon these and upon their occurrence.
My work would indicate that while part of the fluidal cavities are origi-
nal, some are posterior to the consolidation of the rock. A more fatal
objection to their use in separating tertiary from pre-tertiary rocks is the
finding of fluidal cavities in undoubted tertiary and post-tertiary rocks. $
Why quartz should be the mineral chosen to found this distinction upon,
and other minerals containing fluid inclusions in lavas should be ignored,
is a difficult thing to understand.

The older rocks are, as a rule, entirely crystalline, a condition arising in

* Philosophie der Geologie, p. 155.

+ Am. Quart. Microscopical Jour., 1879, i. 103-115.

¢ H. C. Sorby, Quart. Jour. Geol. Soc., 1858, xiv. 484; Franz Zirkel, Microscopical Petrography, vi.
142, 156, 157, 164, 166, 167, 170, 265; Zeit. Deut. geol. Gesell., 1868, xx. 117, 182.

METHODS OF CLASSIFICATION. 47

part from the alteration of the non-crystalline materials, and in part from
the fact of the more or less denudation which they have suffered. When
buried enough to allow of a more or less slow solidification, the tendency is
to form a completely crystalline structure, approaching more and more to
the granitic. While the chief portion of the granitic structure, like that
seen in gabbros, some diabases and diorites, true granites and syenites, is
indigenous, all does not seem to be so, and great depth does not appear to

be indispensable ; the only requirement seems to be slow solidification.

Section VII.— Methods of Classification.

THE framework of any descriptive or systematic science is its classifica-
tion, and upon it depends much of the value and suggestiveness of the work.
It hence becomes a most important and vital point that the classification
used shall be as correct as possible. The common classifications of rocks are
well known to be artificial, and the writer has found them unsatisfactory in
his work. Instead, therefore, of endeavoring to invent a new one, he has
striven to discover the laws and principles of the natural system, so far as
the rocks studied might enable him to do so.

In studying rocks by any system, two methods are open to the observer.
One is to simply describe the characters of the minerals in the rock, thus
making the minerals the principal object, and the rock the subordinate one.
In this case lithology becomes simply a mineralogical study, and the litholo-
gist a mineralogist, who looks upon his rocks as small mineral cabinets, not
realizing that the minerals are for the most part changing and changeable,
and that the true method is to trace the history and variations of the rock
as manifested in‘its mass and its constituents.

The other method is to study the rocks for the purpose of determining
their natural relations, the various changes they have undergone, and the
characters by which they may be known in all these various alterations.
In this the rock is the unit, the paramount object, and the mineral the
subordinate quantity. From this point of view the minerals in a rock
answer to the teeth and bones in an animal —very important, but not
superior in value to the animal asa whole. In a rock the mineral is the
accident, it may or may not exist; and when the rock is entirely composed
of crystallized minerals, they should be used as the teeth and bones are used

in determination, when the zodlogist has them alone in his specimen — in

48 A NATURAL CLASSIFICATION OF ROCKS.

subordination to his general knowledge of animal structure. The subor-
dinate relation of the mineral to the rock is more obscure than the same
relation of the bones to the animal as a whole, since it is true that the
mineral makes up the whole of the majority of rocks. The subordination of
the crystalline minerals to the rock unit has been above thus strongly
insisted upon since the opposite view seems to be taken by many litho-
logists, who appear to study as microscopical mineralogists, instead of work-
ing as lithologists proper.

If it is possible to find the principles of the natural classification of rocks
they ought to be applicable to any rock, whatever may be its age and condi-
tion. By the natural classification of rocks is meant that system which will
place together those forms nearest allied in their general characters, composi-
tion, structure, and origin, when the rock as a whole is considered, and not
certain of its characters only. The present artificial classifications of rocks
pick out certain mineralogical characters, and render the rock characters sub-
ordinate to them. These classifications are, to a certain extent, natural, and
afford a convenient method of arrangement, requiring on the part of the
lithologist who follows them simply skill in the determination of minerals.
The method works well in some places, in others it masses together a most
heterogeneous collection of rocks in a single species — causing some rock
names, like diorite for imstance, to remind one of the old use of the term
schorl in mineralogy. The employment of the minerals alone to determine
the rock species is like Linnzeus’s use of the stamens and pistils in botani-

cal classification — a convenient but artificial system. One in objecting to
the sexual system in botany does not reject the use of the stamens and pistils
in classification, but he does object to their over-riding all other characters.
They are to have their just and proportionate weight, but no more. So, too,
in lithology the minerals in rocks hold a similar relation to them that the
sexual organs do in plants — they may comprise all or but little of the rock
or plant. Minerals are entitled to their just and proportionate weight in
rock classification but no more; they are not to be allowed, in my judg-
ment, to become superior to the rock itself. No single character should be
allowed to over-ride all the others, that is: the presence or absence of a
single mineral ought not to remove a rock from the species to which all its
other characters assign it. In the current classifications it frequently hap-
pens that the name given to the rock depends upon the particular portion
of the hand-specimen from which the microscopic section was taken.

wer s+: “5 ~—se =

iin
"

P

MODERN METHODS OF CLASSIFICATION CHARACTERIZED. 49

The present lithological methods of classification can best be character-
ized, in a homely way, by supposing that there were placed in the hands of
a zodlogist a great number of specimens of one species of some carnivorous
animal, in every condition, from a fresh state to that ef an advanced stage
of decomposition ; also of those of the same species that had lived during
distinct periods of time, as well as of those that had lived for different
lengths of time. With these, too, let there be given to the zovlogist a
number of packages of the bones of this animal, part of the bones having
been worn and part unworn.

Now, imagine this zodlogist naming as new species every specimen more
decomposed than a preceding one; as new species, those which showed
different products of decomposition; as new species, those that gave any
variation, through that decomposition, upon chemical analysis—as for
instance, one and forty-seven one hundredths, or even nine-twentieths of
one percent. Continuing, let it be supposed that our zodlogist makes new
species, or at least varieties, out of all specimens in which he finds any teeth
or bones of other animals which have been swallowed; changing the species
or variety as often as the inclosed fragments differ; creating new species
out of all that have lived for different lengths of time; new species out of
those whose bones are fractured crosswise, as distinct from those whose bones

are broken lengthwise; new species out of the distinct packages of frag-

ments; new species according as these fragments are worn or angular;
also, above and beyond all, fixing an arbitrary date, and demanding that
all the specimens of this animal that had existed prior to that time should
be held as distinct species, and in general of different origin from those that
were of a later period. Suppose, too, that in addition, cur zodlogist should
maintain that some, or all, of the animals submitted to him were made
out of the remains of their defunct ancestors, by a species of fermen-
tation ; also, that this creative chemical action was brought about by the
deposition of the more recent remains upon the older, and that then the
older forms successively came from beneath and lay down on top, thus pro-
ducing a perpetual cycle. Let the reader suppose all this and he will gain
some idea of the principles and methods commonly employed in lithology, as
well as, in a greater or less degree, in chemistry as applied to rocks.

This is no mere fancy sketch, but, so fur as can be done by taking an
illustration from a distinct science, shows some of the principles of lithology
as taught do-day, and some of the methods upon which rocks, ever now, are

classified. :

50 REMARKS ON CLASSIFICATION.

Of course, every degree of ski]) exists in the applications of any classifi-
cation, and many men, even with erroneous principles, succeed better than
others do who work with correct ones. In this, however, it is a question of
methods and not of men; if it were the latter, then no discussion would be
possible, since the older and more experienced would always, and justly,
claim the right to have their views followed. Since it is a question of
science and methods, it is often true that some young and fresh observer
nay, starting from the ground gained by others, push on a little way beyond
them; this too, when he may not have a tithe of the ability of the others;
and it is not to be taken as presumption, if he endeavors to hold and point
out the ground he thinks he has gained.

The principles and methods employed herein were essentially enun-
ciated by me in 1879,* the chief changes being the greater extension of the
subject, owing to further investigations ; and these principles have been used
by myself and my students in papers published since. Owing to the con-
densed or abstract form of the first publication, it seems to have been but
little understood by lithologists working in the mineralogical method of rock
classification ; but it is hoped that the publications made since then, includ-
ing this, will make my meaning sufficiently clear. One thing is certain, that
unless a lithologist has had an extensive range of study of both the unal-
tered and altered forms of rocks, and seen their relations in the field, such
understanding will be difficult. Bearing upon this, it is to be poimted out.
that, outside of the rocks from a few volcanoes in Kurope, every rock that I
have seen from that country is altered, to a greater or less degree; but the
European classifications are chiefly based on such altered rocks. Hence, a
mineralogical classification would naturally be adopted there, and will be
tenaciously held to. <A lithologist who is dependent on the material that
Europe alone can furnish him, has not the means at his command of judging
accurately regarding the basis of much of my work, which has been founded
upon much fresher and less altered specimens than his. The most that I
can hope to do, however, is to call attention to, and point out, that which
seems a better way than the one at present followed. To perfectly express
the natural system of rocks requires a universal knowledge of them—a
knowledge that it is not given to any man to possess.

No definite scheme of classification can be laid down in the beginning ;
it must result from the study of all available specimens, and be the best

* Bull. Mus. Comp. Zool., 1879, v. 275-287.

THE TRUE PRINCIPLES OF CLASSIFICATION, 51

arrangement according to their natural affinities that can be ascertained
by that study. Future studies, discoveries of new rocks, and other causes
are liable, in this science as in botany and zodlogy, to change’ the particular
arrangement; but the principles and methods, so far as they are natural, will
remain the same.

The natural method is sufficiently elastic to allow of the incorporation
of whatever new divisions future investigations may require; it can never
expect to be fixed and rigid, until the sum of human knowledge shall be
complete. These changes will result simply in removing the artificial por-
tions which imperfect knowledge has incorporated with it, and bring the
classification nearer and nearer to the perfect natural system. If none of
the system here adopted is natural, then all will in time be removed.

The important principle that underlies the natural classification, as here
advocated, is the belief that the older rocks now classed as distinct species are
rocks that once were identical with their younger prototypes — the present differcnees
being due to alteration, and conditions of crystallization.

Standing next to this, is the belief in the changeableness of the mineral con-
stitution of the rocks, and the feeling that no classification should be placed
entirely on so uncertain a foundation.

As a deduction from the preceding discussion, the following statements
may be taken as guides in describing and classifying our rocks: —

Section VII.— Zhe Principles of Classification.

1. In the study of rocks, we should begin with the younger and glassy
state, and follow the gradations step by step to the most crystalline one in
the series — from the least altered to the most altered forms — tracing every
change, and studying their history in their tufaceous, poroditic, metamorphic,
or any other state in which they or their remains can exist.

2. Any rocks that can be followed in this way between certain limits,
whatever may be the changes they have undergone, form a species. In
every shape they should be retained under the specific name; the various
modifications, when of sufficient importance, being regarded as varieties,
and named as such.

3. All the petrological, lithological, and chemical characters should be
used in determining rock species; that is, the rock as a whole and in all

its relations should be considered.

THE TRUE PRINCIPLES OF CLASSIFICATION,

Or
Re
=

4, The classification should be a natural one, therefore empirical, embody-
ing all known characters of the rocks. A natural mineralogical classification
of rocks is an impossibility, as it is based on part of the characters only —
characters which are unstable. Minerals may serve for the establishment of
varieties, but not of species.

5. Geological age has no value in the classification of rocks, and is not to
be employed except incidentally in varietal forms.

6. The addition of new names in any science, unless they are absolutely
necessary for its advancement, is a detriment: the needed names should be
taken from those now in use, so far as possible, and they should be employed,
as nearly as may be, in their most approved sense ; when they belong to
varieties they should be defined as such, and placed in their natural relations
to the species of which they form a part.

7. In the classification of rocks, the original characters ought to hold
priority over any of the secondary ones; and they should give name to the
rock, and decide its relations, so long as they exist in a determinable state.
If necessary, or convenient, variety names or adjective terms can be added,
to mark the special peculiarities of secondary or other origin — but only in
especially important cases.

8. If a rock is found to have the characteristics of any species as its
prevailing characters, it should be referred to that species.

9. Chemical analysis alone, as a general rule, is insufficient to furnish
data for naming a rock, since it is to be expected that rocks originating in
different ways should have the same composition.

10. The relation of a rock to its associated rocks in the field is the
principal criterion for determining its origin, especially in the altered rocks.

11. Association alone is an insufficient guide in determining the origin
of a rock.

12. The origin of a rock should have an important bearing upon its
classification.

13. The classification should be the exponent of some general law, which
should embody all that is known at present of the rocks, and give promise
for the future.

CLASSIFICATION IN LITHOLOGY. —~— GENERAL CONCLUSIONS. 53

SecTION IX.— General Conclusions in Regard to Systems of Lithological

Classification.

Tue general results and bearing of the preceding can be briefly summa-
rized as follows : —

As is claimed for the organic world, so there is for the inorganic universe
a universal law of evolution or development expressed by the phrases:
degradation and dissipation of energy, the passage of the unstable towards the more

stable condition, —a law under which the universe has moved forward or

“run down” from the beginning, and under which its course will continue
uniformly to the end.

True and natural classification and work ought to give expression to that
law and conform to it, and the classification and arrangement herein fol-
lowed is an effort towards that end. In accordance with this, petrography
seems to demand a former liquid globe and one whose interior portions are
either now liquid, or in such a condition that they can readily become so.
If the so-called physical and mathematical demonstrations of the earth’s
solidity be examined, it will be found that they have been based on certain
hypothetical globes, of a constitution unlike that of the earth, and therefore
not applicable to it, but to the hypothetical globes only. On examining
the claim that the materials of which the earth’s interior is supposed to be
composed would tend to solidify under pressure, because they contract in
passing from the liquid to the solid state, it is found that the best and more
recent observations which compare the relation of the solid and liquid form
—both taken at a temperature near the melting point —either prove or
render it probable that iron and the various rock materials which are
believed to compose the d/ra-sedimentary portion of the earth expand on
passing from the liquid to the solid. Hence, according to Thomson's law,
pressure would tend to render the earth’s interior liquid instead of solid.

The alleged sinking of the earth’s crust to the earth’s centre could not,
according to the above, take place; since the solid would be lighter than the
liquid portion in contact with it. But if the crust were heavier it could not
sink far, unless the earth was of homogeneous material; but since we know
it to be heterogeneous —the materials varying also in specific gravity —
the crust on sinking would soon meet with material of higher specific
gravity, which would prevent any further subsidence. So, too, the heat

o4 CLASSIFICATION IN LITHOLOGY.— GENERAL CONCLUSIONS.

imparted to the sinking crust would make it lighter, while the viscosity of
the still liquid matter would retard the descent.

Since we may accept that which the facts of geology and petrography
appear to indicate — an earth with a liquid interior — we may also hold, in
accordance with observed petrographical facts, that all rocks originally came
from the cooling molten material of the globe, and that the sedimentary
and chemical rocks have resulted from the disintegration of that material,
while all eruptive or volcanic (including plutonic) forms were derived from
that material which either had never solidified or had been reliquefied ; but
they were not formed from either chemical or sedimentary deposits.

From this it would naturally follow that regions of crystalline rocks are,
as a rule, regions in which eruptive, or mixed eruptive and sedimentary
agencies have prevailed; and these rocks are of every geological age —
meaning, by eruptive agencies, the original and secondary results of a cool-
ing globe, including thermal waters. The original, including eruptive, rock
materials appear to be the same for each species, no matter from what region
they may have come. Hence the same principles should be employed in
classifying them; and the classification, to be natural, ought to express their
relationships. .

This natural classification should be based on all the characters of the
rocks, taken together. It must, of course, be an empirical one, as in zodlogy
and botany, and ascertained by studying all known forms, considering all
their relations, and arranging them according to their petrological, litho-
logical, and chemical characters. With but one exception, all classifications
in use at the present time are confessedly artificial; as can be readily seen
by examining those proposed by Naumann, Blum, Von Cotta, Zirkel, Dana,
Lang, Lasaulx, Rosenbusch, Roth, and many others. The exception is the
classification of Richthofen, which however applies only to the modern vol-
canic rocks. This, although startimg with many natural principles, has been
rendered highly artificial in its practical applications. The classifications of
rocks have usually been based on part of the characters only, to the exclu-
sion of others; as, for instance, on age, structure, mineral composition, and
upon almost every part of the rock separately, but not upon the rock as a
unit. In the schemes based on the contained minerals, but little attention
has been paid to the question whether the minerals were foreign, original,
or secondary products in the rock. So long as the same minerals existed

there, no matter how diverse their origin, all rocks containing them were

CLASSIFICATION IN LITHOLOGY. —GENERAL CONCLUSIONS. DD

called by the same name. Again, if the mineralogical classification is adopted
it is found that the species of feldspar, which form the corner stone of that
classification, and their relations, have not been definitely settled; and let
the method of determination adopted be what it will, ‘hey cannot be accu-
rately and surely distinguished from one another; therefore no system
should be placed on such an uncertain foundation. Such classifications cor-
respond to the Linnean artificial botanical classification, and hold about the
same relations to the natural classification of rocks as that does to the
natural classification of plants. The greater number of rocks separated by
these classifications into distinct species seem to be mere varietal forms oi!
certain natural species — the variation being due to alteration, or some
change in condition. Distinction should be made between superficial
weathering and the chemical and molecular changes that go on in all
eruptive rocks, after consolidation and exposure to the action of infiltrating
waters; that is, changes in the rock-mass as a whole —a change from an un-
stable to a more stable condition, a loss of energy. It is believed that to
these changes is due in general the difference now observable between the
ancient and modern eruptive rocks of the same types. In other words, to
these changes is due nearly all, if not all, those distinctions which cause the
eruptive rocks to be divided into older and younger, or into pre-Tertiary, and
Tertiary and recent. It is, then, claimed that geological age has no bearing
on classification beyond this: that the older rocks of the same type or
species are, the greater is their alteration under like conditions; and that
the greater number of the so-called rock-species of pre-Tertiary age are the
altered forms of rocks which were once identical with Tertiary and modern
rocks, The original or eruptive rocks of the universe appear to form a con-
tinuous series, from the most basic to the most acidic; but for convenience
they are to be divided into definite species, types, or groups, which on the
boundaries will naturally fade into one another. The preponderance of
characters, and not the presence or absence of any one mineral ought to
decide the place of any rock in the system, and the original characters ought
to hold priority in classification over any that are of a secondary nature
(alteration, etc.).

The natural classification, in its broader applications, can be employed in
the field as well as in the laboratory; for, as a rule, all the characters of
rocks are so related to one another that from one the others can be inferred

with a fair degree of accuracy.

f

56 CLASSIFICATION IN LITHOLOGY. —GENERAL CONCLUSIONS.

When complete (bausch) analyses are made of typical rocks, rock-species
are believed to have in their broader features’ certain limits of chemical
composition outside of which the normal forms rarely go, and inside of
which the normal forms of other species rarely come; but the mineralogical
composition is more or less unstable and variable, depending upon alteration
and other conditions to which the rock has been subjected. It is thought
that the chemical relation of rock species would be much better shown if
the percentages were expressed in terms of the elements, instead of in their
compounds — as Nordenskidld has suggested for the meteorites.

All rocks, except meteoric and recent volcanic ones appear to be more or
less altered ; and it is evidently froin these altered rocks that the classifica-
tions and principles of classification have been chiefly derived in Europe, on
the supposition that as these rocks are now found to be, so they always were,
and always will be.

Fragmental or derived rocks ought to be classed, so far as it is possible,
under the rocks from which they were derived; the object of the classifica-—
tion both of these and the massive rocks being to show their relations and
derivation so far as practicable.

The relation of one rock to its fellows in the field is the principal erite-
rion for determining its origin — particularly in the case of altered rocks.

Taking the consolidation of any rock as the datum point, the minerals
and rock fragments are found to be naturally divided into three distinct
classes of different origin : —

1. Minerals and fragments of prior origin.

(a) Those characteristic of the rock species.
(4) Those that are accidental.

2. The products of the consolidation.

3. The products of alteration and infiltration.

All may exist together in a rock, or all except those of one class may be
wanting ; and far more depends, in lithology, on being able to determine the
origin and relations of these different classes of minerals than on ability
to name the mineral species correctly. Minerals of the third class are
apparently formed through the agency of percolating waters, which may
be hot or cold.

The alterations appear in general to take place slowly ; while rapid alter-
ations, such as would be produced by hot, intensely active waters, generally,

if not always, seem to bear distinctive marks.

CLASSIFICATION IN LITHOLOGY. —GENERAL CONCLUSIONS. O7

In practically employing the principles given before, all kinds of rocks,
whether from the earth or heavens, are naturally to be described and
arranged, but only a limited portion of this work can be done here. In
the execution of this the most basic rocks known will be taken, and the
gradations between the different states traced as far as practicable.

The order will be to pass from the glassy to the most perfectly crystalline
state; from the least altered towards the most altered; from the most basic
towards the most acidic; from the non-fragmental to the fragmental or
clastic. In the case of the fragmental rocks, it is intended to proceed from
the least altered to the most altered; that is, frofn those little consolidated
towards those most indurated ; from the unaltered towards those most highly
metamorphosed. In the wide range of rocks studied, it has been found as a
rule that the macroscopic and microscopic characters could generally be
inferred one from the other; and that, likewise, from these the chemical com-
position could be declared, within certain general limits. Indeed, by the
method of classification pursued here, a bit of wnallered groundmass, not pure
glass, sufficient to fill the field of a No. 7 or 9 Hartnack objective, is enough
to enable one to tell the species to which the rock belongs, and to give some
general idea of its composition, both chemically and mineralogically.

In applying the earlier given principles of nomenclature and classifica-
tion, the following method has been practically adopted here: All the
rocks, from one end of the series to the other, are divided into species or
groups; and each of these species possesses the general characters that have
usually found voice in the generally established nomenclature. Since the
most typical forms are those of the modern eruptive rocks, their names,
when practicable, have been selected, and in them the limits of the species is
made as nearly as possible coincident with those made by the leading lithol-
ogists. Of course they are not absolutely identical, for natural boundaries
do not’ correspond entirely with the artificial fences made by man. Under
these specific or group names —such as basalt, andesite, trachyte, and
rhyolite

are placed, as varieties, the altered, as well as older (pre-Ter-
tiary) forms; which it is thought were once identical with the unaltered
or modern forms. The variety names are also used as nearly as possible in
their more general applications; but it is often found that the artificial boun-
daries of these varieties (regarded by other lithologists as distinct species)
carry them into two or more of the species, as that term is used here; ¢. /.,
melaphyr is, asa rule, a name given to the fine-grained older and altered

8

58 CLASSIFICATION IN LITHOLOGY.— GENERAL CONCLUSIONS.

rocks belonging to the species basalt, but in some cases the older forms of
andesite have been described as melaphyrs. So, too, the term diabase
includes under it, in the common artificial nomenclature, both old basaltic
and andesitic rocks —a fact which has been imperfectly recognized in the
division of the diabases into diabase and olivine-diabase. In this work
the term melaphyr and diabase will be confined to the rocks belonging
under basalt, which possess the general characters of the ordinary melaphyr
and diabase type. In the case of some names — like diorite, which has been
commonly used for a wide range of old and more highly altered rocks than
those to which the names melaphyr and diabase have been usually given —a
greater difficulty occurs in practical use. Such names are placed as sub-
varietal names, after the names of the variety or species to which they
belong, in order to indicate the line of derivation.

Many terms have been given in the past to rocks, indicating some special
stage in their alteration, which are not of sufficient importance to be used as
a variety or sub-variety form. These terms are sometimes inclosed in a
parenthesis and placed after the specific or variety name. It is necessary to
place those rocks, whose derivation is not clear, as nearly as possible in their
apparently proper situation, leaving it to the future to correct and amend
the classification.

The fragmental rocks are placed, so far as possible, under the rocks from
which they are derived ; but those whose derivation is unknown, it is in-
tended to describe and classify according to the common method of nomen-
clature, as the best now practicable.

The recent or unaltered fragmental rocks will be placed as tufas under
their proper species, while the older and altered forms will be classed as
porodites,* under their respective species and varieties.

The object is to show the natural relations of the rocks so far as possible,
and at the same time to interfere but little with the customary use of litho-
logical names.

As illustrations of my meaning, the following examples may be given,
the label of a melaphyr would be written as follows: Basalt, Melaphyr —
the following term being always subordinate to the preceding one in this
order: species, variety, sub-variety, etc., while any one of the names can
be used in speaking of the rock.

If a rock to which the name diorite would be applied in ordinary nomen-

* Bull. Mus, Comp. Zoél., 1879, v. 280.

1
=

CLASSIFICATION IN LITHOLOGY.— GENERAL CONCLUSIONS. 59

clature is found, from its structure and composition, to come under either
melaphyr or diabase, its label would be written as follows, according as it
was one or the other: —

Basalt, Melaphyr, Diorite.
Basalt, Diabase, Diorite.

But if this diorite belonged apparently to the basaltic species, but could
not be referred to either the melaphyr or diabase variety, its label would be
thus: Basalt, Diorite.

When the names are trivial, or when they are not properly variety or
sub-variety names of the species under which the specimen is placed, the
label is written as follows: Basalt, Diabase (Calc-Diabase). For the frag-
mental forms it is written, Basalt, Tufa; or Basalt, Porodite; or Basalt, Dia-
base, Porodite — as the case may be.

The variety and sub-variety names are not here considered essential, but
are employed out of deference to the common custom. However, in order
to make the work symmetrical, such names, and even new ones, have been
introduced, where it seemed necessary ; but all can be dropped or continued,
and expanded as the advance of the science may require.

The special nomenclature and its applications will be given in the descrip-
tive portion of the work, with the account of the specimens, and to that the
reader is referred. If, in course of time, a system of nomenclature like
that employed in botany and zodlogy, should be desired, the system em-
ployed here would readily furnish it, by dropping the commas between
the specific name and its variety and sub-variety, with the Latinization of
these names. The names would then be in their proper order, and aiford
us both binomial and trinomial names, as the case might be.

CHAPTER Se
THE SIDEROLITES AND PALLASITES.

Section I. — Siderolite.

In this, the first or most basic, species or group, the rock is composed
chiefly of iron—either native or in its secondary states, as magnetite,
hematite, menaccanite, etc. —and with or without nickel, schreibersite,
pyrrhotite, graphite, ete.

It includes all those masses of iron and iron ore that have fallen as
meteorites, or which formed an original, not secondary, portion of the earth,
or.are of eruptive origin, or directly derived, as fragmental deposits, from
any of these. No veins or chemical deposits of iron ore are intended to be
mecluded in this species.

The characters of the supposed meteoric siderolites have been so fully
described in numerous papers and treatises on the subject, that it is not
necessary to describe them here in any detail. A few specimens only will
be spoken of below, that the writer has seen, which will give a few of the
characteristics.

In such meteoric siderolites as that from SHINGLE Sprincs, ELDORADO
Co., CALirorniA, the iron is in a nearly homogeneous mass, since only two
small masses of pyrites have been reported to have been found in it.
The etched surface of a specimen in Professor Whitney’s collection shows
an obscure granular structure, which under the lens is seen to be formed
by some brilliant points, and small elongated ridges of like bright metallic
lustre, rising above the dull gray surface left by the acid.

Professor B. Silliman states of a specimen in his possession that the
etched surface showed under a lens “a reticulated structure with numerous
brilliant points and v-shaped lines.” * '

The meteoric siderolite from Stanton, Augusta Co., VIRGINIA, is a very

* Amer. Jour. Sci., 1873 (3), vi. 18-22.

+ wee eS Se lee _”S—“<—C:S;

i se Bo

_—

SIDEROLITE. 61

compact mass of iron, showing only a few small nodules of pyrrhotite. A
general description, with figures showing the structure of its etched surface,
has been given by Professor J. W. Mallet.*

A specimen of the Coanvuita (Mexico) siderolite in the Harvard Col-
lege Mineral Cabinet shows a compact mass of iron, with irregularly distrib-
uted elongated cells filled with pyrrhotite. The chief portion of the iron
seems to be free from these irregular masses of pyrrhotite, but some parts
are quite filled with them.

The Texas (Grpps) siderolite in the same collection shows a compact
metallic mass, holding a few rounded and irregular cells containing pyrrho-
tite. This rock has been described by Professors Silliman and Hunt, who
also give a plate representing the Widmannstiittian figures.t

The specimen of the ButLer (Bates County, Missovrt) siderolite in the
Harvard College Cabinet is very compact, but contains a few elliptical and
irregular cells filled with pyrrhotite (troilite) surrounded by rings. These
rings connect with the raised bands shown by etching. Some of the bands,
indeed, appear as offshoots from the rings. In this specimen the etching has
not brought out the Widmannstiittian figures very clearly, yet the above
relations can be distinguished. A brief description of this siderolite was
given by Professor J. Lawrence Smith, with analysis of the iron alone. The

nodules of troilite, according to him, were numerous, but free from any

schreibersite. In his specimen the Widmannstittian figures were readily
developed and found to be large and regular. t

Some siderolites like that from Totuca, Mexico, in the Harvard College
Cabinet are composed of a very coarse sponge-like mass of iron, holding
detached irregular masses of pyrrhotite, etc. In this the distance across the
iron from one cell wall to another cell wall is greater than the diameter
of the cells themselves.

The general structure of the meteoric form may then be said to be a mass

pyrrhotite, schreibersite, graphite, ete.

Associated with the meteoric iron, in intimate union with it or in com-
binations of their own, occur nickel, cobalt, magnesium, aluminum, calcium,
silicon, chromium, phosphorus, copper, carbon, arsenic, sulphur, tin, mangan-
ese, potassium, sodium, chlorine, oxygen, beryllium, ete.

* Amer. Jour. Sci., 1871 (3), ii. 10-15, 1878 ; xv. 337, 338.

+ Am. Jour. Sci., 1846 (2), ii. 870-376.
t Am. Jour. Sci. 1877 (3), xii. 213.

62 THE SIDEROLITES AND PALLASITES.

In a large number of the siderolites, etching develops in the iron those
structural planes, well known as the Widmannstattian figures, parallel to
the planes of the isometric octahedron and cube. This structure is parallel-
ized by the cleavage observed in magnetite, and by the observed structure
produced in titaniferous iron during the process of its alteration to “leuco-
xene.” Indeed, many of the altered titaniferous irons show a structure closely
resembling some of the Widmannstittian figures. These latter figures can
be taken no longer as proofs of the meteoric origin of any iron, since they
have been developed in the terrestrial iron of the Greenland basalts. The
Widmannstattian figures are so well known that it is unnecessary to repro-
duce them in the plates of this work, especially since good examples can be
found in the following papers and works : —

Schreibers’s Beitrage zur Geschichte und Kenntniss meteorischer Stein-
und Metall-Massen, Wien, 1820; Clark on Metallic Meteorites, Géttingen,
1853; Biichner, Bericht Ober. Gesell. Giessen, 1869, xiii. 99-115; Haidinger,
Sitz. Wien. Akad., 1855, xv. 554-360; 1862, xlv. (2), 65-74; xlvi. (2), 286-
297; 1863, xvi. (2), 801-308; Amer. Jour. Sci, 1846, (2), 11. 370-376,
1853, xv. 363; Brezina, Denks. Wien. Akad., 1881, xlii. 13-16; 1884, xliv.
121-158; Tschermak, Sitz. Wien. Akad., 1874, Ixx. (1), 448-458; Denks.
Wien. Akad., 1872, xxxi. 187-195; Gustav Rose, Abh. Berlin. Akad., 1863,
pp. 23-161, ete.

It is possible that could chemical analyses be made that would yield the
constitution of the siderolite masses as a whole, and thus enable their min-
eralogical and chemical constitution to be codrdinated with their structure,
that the species siderolite might be separated into several distinct, natural,
and well marked species. The most probable divisions would be into those
composed of metallic iron, and those formed from metallic iron and pyrrho-
tite. The first might possibly be separated into those bearing much nickel
and those of nearly pure iron. Of course, no such subdivision of siderolite
should be attempted unless the composition and structure both pointed
towards the separation. This would require the study of a large number of
siderolites, an opportunity for which the writer has not, even if satisfactory
chemical analyses existed. |

A list of chemical analyses has indeed been collected and will be
appended ; but it is far from being what could be desired, since it is the
custom of chemists to select the purest portion of the iron for analysis. In
fact but few analyses exist of siderolites that can be regarded as complete

SIDEROLITE.

63
when the mass contains other minerals than the iron itself. Each separate
mineral is analyzed, but the general average of the whole mass is wun-
known. Indeed, in many cases it may be difficult if not impossible,
owing to its structure, to obtain the composition of the whole, except
approximately.

Since the same mineral has nearly the same constitution, whatever may
be its associations, the native iron would be expected to yield the same

constituents whether in a large mass alone or in minute grains associated

¢
with other minerals. Consequently, the analyses of meteoric irons as now
carried on afford but little clue to their structure, for a pallasite yields the
same result as a siderolite, so far as the usual published analyses show.

The specific gravity of the siderolites varies considerably, but by far the
greater portion lie between 7.50 and 7.90. The highest number is 8.3], and
the lowest 5.75, but the average may be considered to be about 7.70. The
analyses of the siderolites have been arranged according to their percentage
of metallic iron, for in that way their relations could be best shown; but
where there are several analyses of the same rock, all are placed together
without regard to the percentage of the iron, except in the case of the first
one in the given series. The predominating percentages lie between 87.00
and 97.00, the average being about 91.00. The highest percentage of iron
is 99.81 and the lowest 37.00; but only seven analyses show a lower per-
centage than 80.00.

The percentage of nickel, as a rule, in the meteoric siderolites varies
inversely with the iron; and if it is taken in connection with its associated
cobalt and the iron— whether free, or united with sulphur or phosphorus
— it is found that with but few exceptions the three elements make over
99 per cent of the mass. The nickel varies in amount from none, in seven
analyses, and to .10 and .20 per cent, up to 12, 14, and 15 per cent. In
three extreme cases it was found to be 24.708, 56.00, and 59.69 per cent.
The percentage of nickel in the Greenland siderolites is low. One serious
difficulty in estimating the relative proportions of the iron, nickel, and cobalt
is the apparent unreliability of many of the analyses —a difference of about
four per cent existing in the nickel as determined from the same siderolite ;
and in an extreme case one chemist obtained 14.70 per cent of nickel, and
another none. Asa rule, cobalt is in amount less than one per cent, but in
a few cases reaches between two and three per cent, and in one instance is
between three and four per cent. Probably it is always present with nickel,

64 THE SIDEROLITES AND PALLASITES.

but is not found, owing to imperfect methods, which cause the cobalt to be
wanting in a large number of analyses. ;

As a rule, the other elements found in siderolites are in very small
amounts, if not entirely wanting; although m one case 15.359 per cent of
sulphur was reported. The analyses indicate that phosphorus, sulphur, cop-
per, and possibly carbon (graphite) are always present in the siderolites and
can be found when searched for with sufficient care. The greater the skill,
the greater the number of elements found, and both appear to be roughly
and inversely proportionate to the amount of iron reported.

Of course it is to be remembered that these analyses were made from
picked portions, and they do not give a fair average of the siderolite masses
as a whole.

None of the analyses of the oxidized siderolites have been given in the
tables ; for while they are quite abundant, most of them are too imperfect to
serve any useful purpose for comparison, since they have been made for
commercial purposes only. In the case of these terrestrial siderolites, it is
desirable to have them carefully selected, typical, and of known origin, and
then most carefully tested for the rare elements.

It is to be presumed that the native iron, coming to the surface of the
earth from below, would as a rule either be oxidized at that time or during
its subsequent existence; hence in but few cases is it naturally to be
expected that metallic iron would occur to any especial extent on that
surface.

In its oxidized forms, and in association with a rock belonging at the
other extreme of the lithological scale, siderolite occurs on the southern
shore of Lake Superior.

Since the author has quite fully discussed the evidence that causes him
to believe in the eruptive origin of most of the magnetite and hematite of
the Marquette district of Lake Superior, it is unnecessary to discuss the sub-
ject farther here. The other chief works relating to these ores are the
Geological Reports of Messrs. Foster and Whitney, and T. B. Brooks. A
general discussion of the various theories and of the evidence, as well as a
list of the works relating thereto, has been given by the writer in the papers
referred to below.*

From the various accounts given of the occurrence of iron ores in this
country and elsewhere, it is probable that many other eruptive iron ore

* Bull. Mus. Comp. Zo6l., 1880, vii. 1-157, 6 plates; Proc. Bost. Soc. Nat. His., 1880, xx. 470-479.

SIDEROLITE. i)

masses exist which properly should come under the species siderolite. How-
ever, it is an open question, and it will probably remain so until these
deposits can be studied with the view of ascertaining the facts bearing upon
their origin, unbiassed by any preconceived theories of that origin.

The native iron found in Greenland may properly be mentioned here,
as it is possibly a portion of the earth’s metallic core brought to the surface
by the associated basalt. The iron is in large masses associated with basaltic
rocks, as well as in fine grains intimately mixed with the basalt itself and
taking the place of the ordinary iron ores that generally occur in that rock.
It occurs with schreibersite, pyrrhotite (troilite) graphite, and magnetite, the
same as native iron commonly does in meteorites. On etching, the Wid-
mannstattian figures are produced, and thus this iron shows characters that
have usually been regarded as exclusively belonging to meteoric irons.
These figures are produced even on the little grains, six to seven millimeters
in diameter, occurring in the basalt. Whether the Greenland iron came from
the interior of the earth as metallic iron, as the writer thinks most probable,
or was produced by the reducing agency of carbon on some ores of iron, as
maintained by Steenstrup and Smith, there appears at present no doubt that
it is of terrestrial origin.

Of the large number of metallic siderolites that have been described,
but very few are known to be of meteoric origin, only some seven having
been seen to fall; while the localities in which so many occur — in moun-
tainous districts, and in regions in which eruptive action has been intense
—are such that in regard to many, doubt must exist regarding their cos-
mic origin.* Indeed, if they are truly of meteoric origin, there is a most
remarkable concurrence of localities in which telluric iron would naturally
-oceur, if at all, and the places in which iron in relatively large amounts
has fallen.

It would seem that chemical analysis should not be made the sole judge
regarding the origin of these numerous supposed meteorites. It would
appear to be necessary that a petrographical or geological study of the
localities in which these bodies are found should be made; and they ought
to be regarded as doubtful meteorites, unless the circumstances of their
occurrence preclude their terrestrial origin. That no attempt has been
made, as a rule, to ascertain the origin of these masses of iron, beyond

chemical tests, will be seen from the following :—

%* The conditions under which the Bahia siderolite was found renders it not improbable that this is of
similar origin with the Ovifak iron. See A. F. Mornay, Phil. Trans., 1816, pp. 270-259.
9

66 THE SIDEROLITES AND PALLASITES.

“Chemistry has entirely dissipated all doubts in the matter, and now an examination
in the laboratory of the chemist is entitled to more credit than evidence from any other
source in pronouncing on the meteoric origin of a body. No question need be asked as
to whether it was seen to fall, or whether this or that rock or mineral exists in the neigh-
borhood where it may have been collected. The reagents of the chemist alone are uner-
ring indications that suffice to set aside all cavilling in the matter.” *

The above statement rests upon the assumption that no terrestrial ma-
terial under any circumstances can possess the same chemical characters
that meteorites do! This basis is the one upon which most investigations
of supposed meteoric irons now proceed, and have proceeded for many
years ;t a basis that has never been carefully investigated, and which
many would probably repudiate since the Ovifak discovery. Would it not
be well if a more thorough study could be made of the conditions under
which so many siderolites have been found in the southwestern portion of
the United States, Mexico, and South America?

The origin of the meteoric masses of iron has been a question upon which
speculation has been rife. It has been suggested that they and the other
meteorites were formed in our own atmosphere; that they were thrown
from terrestrial or lunar voleanoes; or thrown from the sun; the remains
of a shattered planet; some of the spare material left over when the solar
system was made, etc. It concerns this work principally to examine the
views of those who have made microscopical studies of siderolites, and not
to discuss the general theories of others; however, it will be necessary later
to point out the probable origin of meteorites as deduced from their micro-
scopic characters. One of the most prominent of the students of meteor-
ites is Professor Gustav Tschermak, who stated in 1875 that
“the greater number of meteoric irons exhibit a structure which indicates that each has
formed part of a large mass possessing similar crystalline characters. The formation of
large masses so constituted presupposes, as Haidinger has pointed out, long intervals of
time for tranquil crystallization at a uniform temperature, and these conditions could
only prevail on one of the larger cosmical masses.” ¢

A microscopic examination of the figures observed upon the etched sur-
face of meteoric and artificial irons, led Mr. Sorby to the following con-
clusions : — ;

“These facts clearly indicate that the Widmanstatt’s figuring is the result of such a
complete separation of the constituents, and perfect crystallization, as can occur only when

* J. Lawrence Smith’s Mineralogy and Chemistry, Louisville, Ky., 18738, p. 290.

+ Newcomb’s Astronomy, 1st ed., 1878, p. 386; 4th ed. 1882, p. 397.

t Phil. Mag., 1876 (5), i. 499 ; Sitz. Wien. Akad., 1875, Ixxi. (2), 661-673. See also J. Lawrence
Smith’s Memoir on Meteorites, Ann. Rep. Smith. Inst., 1855, p. 158.

SIDEROLITE. 67

the process takes place slowly and gradually. They appear to me to show that meteoric
iron was kept for a long time at a heat just below the point of fusion, and that we
should be by no means justified in concluding that it was not previously melted. Similar
principles are applicable in the case of the iron masses found in Disco; and it by no
means follows that they are meteoric, because they show the Widmanstatt’s figuring.
Difference in the rate of cooling would serve very well to explain the difference in the
structure of some meteoric iron [s], which do not differ in chemical composition ; but as
far as the general structure is concerned, I think that we ave quite at liberty to conclude
that all may have been melted, if this will better explain other phenomena.” *

It would appear that these observers advocate the view that the sidero-
lites must have been subjected to a long and slow cooling upon some body
of sufficient size to yield the required conditions; but since the same struc-
ture can be developed in the iron of the stony meteorites, which show evi-
dence of rapid cooling, the writer is compelled reluctantly to differ from
these eminent observers, and to hold that while the Widmannstiittian figures
may have originated as they have claimed, they may occur as readily in a
small mass, cooling at a comparatively rapid rate, and therefore their origin
is to be explained in some other way. In other words, as yet, there is no
evidence that Sorby’s and Tschermak’s views are correct.

It is probable that but few will claim that the siderolites of meteoric
origin were formed by organic agencies. If they were not, it follows that
the graphite contained in them could not have been so produced. This has
a very direct and obvious bearing on the question whether the graphite in
Azoic and other rocks need have been derived from animal or plant remains,
and it negatives the supposition.7

To make graphite the evidence of life is the same kind of argument as it
is to claim that no oxides of iron and no carbonate of lime could be formed
without the intervention of life. One we knew to be oftentimes of volcanic
origin, and the other to be frequently the product of the decomposition of
rocks.. It is too much to assume, because minerals are known to form in
certain conditions, or can be formed in certain ways, that they must always
be made in that way. None of the meteorites now known appear to indi-
cate that they came from a region where life could exist as we know it;
hence, it does not seem proper to claim that life must have intervened in
their formation merely because a mineral is found in them that is ordinarily
supposed to be of organic origin.

* Nature, 1877, xv. 498.

+ J. Lawrence Smith, Mineralogy and Chemistry, 1873, pp. 284-310; Am. Jour. Sei. 1876 (3), xi. 388-
395, 433-442 ; Walter Flight, Pop. Sci. Rev., 1877, xvi. 390-401.

68 THE SIDEROLITES AND PALLASITES.

The term siderolite, or rather aero-siderolite was proposed by Professor
N. Story Maskelyne, for the meteorites to which Gustav Rose had previously
given the name pallasite. Rose afterwards divided his pallasites, retaining
the original term for all, except two specimens, which he classed as mesosi-
derites. These Maskelyne united again, but instead of using the term pal-
lasite for all, proposed the name above given. The name pallasite belongs
by prior right to these forms, while siderolite does not; therefore, I trust
Prof. Maskelyne will permit the transference of his term siderolite, as his
own, from the pallasites to the forms that I have herein classed under the
former name. It is impracticable to use the term sederife—long ago pro-
posed by Shepard—on account of the well known mineral of the same
name. The term holosiderite, proposed by Daubrée, is too inaccurate, since
the majority of the specimens are not wholly iron.

Siderolite (ovSypos, \tMos) —a stone of iron, or an iron rock — seems to
answer better than any other term for the specimens I have included under
it here, and if the transference is permitted it will save the introduction of a

new name.*

Section II. — Pallasite.

Turis name was first given by Gustav Rose to a class of meteorites, of
which he made the olivine iron rock of Krasnojarsk, Siberia, described by
Pallas in 1776, the type. Later, Rose separated this group into two divis-
ions — pallasite and mesosiderite — the latter comprising two specimens
only.f

The writer proposes to restore the term to its original use; and in addi-
tion, to place under it a few other meteorites and those terrestrial rocks that
have a similar composition and structure. As in the case of siderolite, it is
not intended to include any vein stones, but only original and eruptive
rocks of this character and their derivatives.

Of this group or species there will be given, first, descriptions of those
nearest the siderolites in structure and composition, passing then to those
nearer and nearer allied to the succeeding species — peridotite.

* Maskelyne, Phil. Mag.,1863 (4), xxv. 49; Rose.-Monatsber. Berlin Akad., 1862, pp. 551-558; 1863,

pp: 80-34; Shepard, Amer. Jour. Sci., 1867 (2), xlili. 22-28.
+ Monatsber. Berlin Akad., 1862, pp. 551-558; 1863, pp. 80-34; Abh. Berlin Akad., 1863, pp. 238-161.

PALLASITE. 69

The Meteoric Pallasites.

Tucson, Arizona.

This meteorite is represented by two forms, known respectively as the Carleton and
the Ainsa meteorites.

The Carleton pallasite is composed of quite a compact sponge of iron, containing
minute rounded grains of olivine (?) Some schreibersite in black angular grains also
oceurs.*

The Ainsa pallasite is composed of a compact metallic sponge, the minute cells of
which are filled by a white siliceous mineral in rounded grains. These grains are arranged
in rude lines, giving to the iron an appearance somewhat resembling that produced by
fluidal structure. From the torn and broken surface of a specimen in Professor Whit-
ney’s collection a number of silicate grains were removed by a needle-point, imbedded in
Canada balsam, covered and examined under the microscope. Most of the fragments
present the optical characters of olivine, and some contain bubble-bearing stone cavities,
arranged in irregular lines, the same as are the fluid cavities in quartz. A few of the
broken grains presented the polarization characters of non-striated meteoric feldspar, but
two fragments were seen which showed the polysynthetic twinning characteristic of pla-
gioclase.

Both of the above pallasites, when sawn or polished, present a more or less compact
appearance, like the common siderolites, and it is only where the Ainsa meteorite has
been forcibly torn apart, after being partially sawn, that its true structure can be seen.
Since the sawn and polished surfaces of the irons are such poor guides to their structure,
it may be that some other irons now classed with the siderolites belong here.

While the silicates + of the Ainsa pallasites are nominally clear and transparent, a
number of the fragments have been stained to a yellowish brown, owing to the oxidation
of the iron.

Hemalga, Tarapaca, Peru.

This rock, as represented by a specimen deposited in the collections of the Boston
Society of Natural History, is largely composed of iron, having irregular cavities filled
with silicates, which are considerably decomposed in places.

Mr. R. P. Greg states of a specimen in his possession, that its cavities were found to
contain pure lead, a very hard, grayish-black, semi-metallic mineral, and a yellowish-
brown one of an earthy texture, and insoluble in acids. Sometimes the lead only par-
tially filled the cavities, but at others it entirely filled them, some being large as a pea.

The specific gravity of this pallasite was found to be about 6.50.

Berdyansk, Russia.

According to Hiriakoff, this is composed of an iron sponge, with fine grains of olivine
and troilite, and on etching shows Widmannstiittian figures. Specific gravity, 6.63.§

* Whitney and Brush, Proc. Cal. Acad. Sci-, 1863, iii. 30-55 ; Haidinger, Sitz. Wien. Akad., 1863, xlviii.
(2), 301-308.
7 Whitney, Proc. Cal. Acad. Sci., 1863, iti. 48-50.
t Phil. Mag., 1855 (4), x. 12-14.
§ Geol. Foren, Férhandl., 1878, iv. 72 ; Neues Jahr. Min., 1878, pp. 653, 654.

70 THE SIDEROLITES AND PALLASITES.

Deesa, Chili.

This is composed of a compact iron sponge, containing inclosed silicates. Dr. S.
Meunier detected in it troilite, schreibersite, graphite, olivine, hypersthene, pyroxene,
enstatite, chromite, etc. Specific gravity varies from 6.10 to 6.24, but no satisfactory
analysis exists of it as a whole.*

Atacama, Bolivia.

The rock found in the Desert of Atacama, Bolivia, is described as a cellular or spongy,
metallic mass ; the cells filled with granular, greenish-white olivine. The cellular spaces
instead of being rounded, as in the other rocks of this species, are stated to be angular.
An analysis of this rock as a whole is much to be desired, although a rough approxima-
tion is given in the list of analyses. A correct chemical analysis would probably show
this to be more basic than the Pallas rock of Siberia.

A specimen in the Harvard College Mineralogical Cabinet is probably from the same
pallasite. This shows a very coarse sponge of iron, holding angular and rounded grains
of olivine. The olivine is yellowish-green in color — the yellowish tint owing in part to
a ferruginous staining. The coarseness of the iron sponge allies this more nearly than
cny of the other pallasites seen, except that from Tarapaca, to the siderolites. |

On one side it shows a surface closely resembling an ordinary slickenside, but on
another side is to be seen the remains of a fused crust — the common mark of a meteor-
ite. Some pyrrhotite was seen in this rock.

Figure 1, Plate I., is from a tracing made from the polished surface of this specimen.
Owing to the dulness of the polished face —the polishing having been done many years
ago-—it was impracticable to get the outlines exact. The general structure is well
shown for the spongy metallic iron, but the olivine grains are far more angular, as a rule,
than the figure represents them to be.

Specimens of an Atacama meteoric iron in the Mineralogical Cabinet, received from
Professor I. Domeyko, show that this formed a metallic sponge holding olivine. Only
traces of the olivine are left, and beyond it nothing can be told regarding the silicates
that might have been contained in this sponge. Some pyrrhotite was seen. This con-
tains less iron probably than the Pallas iron.

Another specimen of Atacama iron in the same Cabinet, received from a Mr. Clay, of
Philadelphia, is similar to that figured (PI. I. fig. 1), but the sponge is not so coarse,
and the olivine is more abundant. This mineral is considerably decomposed, and the
iron much oxidized.

Bitburg, Prussia.

A coarse sponge of iron, containing in its cells light-greenish-brown olivine. The
only specimen seen by the writer somewhat resembles the Atacama meteorite, but, per-
haps, contains even more iron.

* Daubrée, Comptes Rendus, 1868, lxvi. 571, 572 ; Meunier, Cosmos, 1869 (3), v. 552-556, 579-586,
612-619.
} Trans. Roy. Soc. Edin. 1831, xi, 223-228 ; Clark, Metallic Meteorites, 1851, pp. 17-19.

PALLASITE. 71

Hlommoney Creek, Buncombe Co., North Carolina.

A coarse cellular mass of nickeliferous iron, with most of the observed cells empty
but a few containing dull, yellowish-gray olivine grains. The iron exhibits, on etching,
Widmannstittian figures.*

Singhur, India.

The pallasite found at Singhur, Deccan, India, was from a basaltic hill. It is
described as a vesicular mass of iron, with the cavities either empty or else containing
“small, yellowish-white, earthy-looking bodies, about the size of peas ” — olivine (7).
No satisfactory analysis of this rock has been made.+

Its occurrence is similar to that of the iron from Disco, Greenland, and it may be of
like terrestrial origin.

Forsyth, Taney Co., Missouri.

+ we tee

A white, sponge-like mass of nickeliferous iron containing greenish olivine, the latter
being more abundant than the former.f Specific gravity, 4.46.

Anderson, Hanulton Co., Ohio.

This pallasite, which may properly be called the Little Miami meteorite, was found on
an altar in one of the earthworks now being explored in Anderson Township, in the Lit-
tle Miami Valley, Ohio. This was placed in the hands of Dr. L. P. Kinnicutt, for analy-
sis, by Mr. F. W. Putnam, the curator of the Peabody Museum of Archeology, into whose
possession it had come. The polished surface shows a coarse sponge of iron, holding,
according to Dr. Kinnicutt, olivine, bronzite, and an unknown mineral. In the section
figured in Dr. Kinnicutt’s report, the iron appears to predominate over the silicates, but
taking the mass as a whole the two form about equal bulk. In structure it closely
resembles the Pallas iron, its olivine grains being as a rule rounded, and not so angular
as the Atacama pallasite. The olivine forms the chief portion of the siliceous material.
The specific gravity of the mass is 4.72. The etched surfaces show the Widmannstiittian
figures. Analyses of the iron and of the olivine were given by Dr. Kinnicutt, and from
this a rough approximation is given of the composition of the mass as a whole, on the
supposition that the iron and olivine form about equal portions of the mass. Since
there was sufficient material it seems a pity that no complete analysis has been made.§

Krasnojarsk, Siberia.

The Pallas rock is formed by a coarse metallic sponge, whose more or less rounded
cavities are filled with olivine. This sponge-like structure, or one approaching it, is
characteristic of the pallasites, so far as known. No complete analysis of this rock has
ever been published that the writer can find, except an old one of Laugier, || in which the
iron was estimated as an oxide.

* Shepard, Am. Jour. Sci., 1847 (2), iv. 79-82.

+ Herbert Giraud, Edin. New Phil. Jour., 1849, xlvii. 56, 57.

t Shepard, Am. Jour. Sci., 1860, (2) xxx. 205, 206.

§ Ann. Rep. Peabody Mus. Am. Arch., 1884, iii. 381-384.

|| Mém. Acad. St. Peters, 1870 (7) xv., No. 6, pp. 40, 4 plates. Clark, Metallic Meteorites, 1851,

pp. 15-17.

THE SIDEROLITES AND PALLASITES.

=—T
bo

A specimen in the Harvard Mineralogical Cabinet shows the same characters as those
given in the various papers relating to this iron, including even the parallel minute tubes
in the olivine; hence this specimen is doubtless authentic. A tracing of the polished
surface of this specimen is given in figure 2, Plate I. Of course, from the method em-
ployed, the most that could be done was to show the relation of the iron to the olivine;
for the pyrrhotite could not be separated from the metallic iron in making the tracing.
This apparently has less iron than the Atacama pallasite.

A figure of a polished surface of the Pallas iron has been given by Dr. Carl V.
Schreibers, which seems to be very good, except that the olivine has been too highly

colored.*
Potosi, Bolwvia.

Of a similar character is the Potosi rock, described in 1839 as a meteoric iron,
“cavernous, filled with vacuities, most of which are irregular, but some have the form
of a rhombic dodecahedron; some of them also are filled with a greenish vitreous sub-
stance, similar to the olivine of Pallas.” f

Brahin, Russia.

This is said to contain somewhat less iron and more olivine than the Pallas rock, but
otherwise to be of similar composition and structure.

Riltersgrun, Saxony.

The Rittersgriin pallasite was regarded by Weisbach as composed of 30 per cent of
nickeliferous iron, and 70 per cent of an unmetallic brown mass. The latter was said
by Winkler to be composed of bronzite (enstatite) pyrrhotite, schreibersite, with asmanite
[tridymite].

Breithaupt had held that the silicate was olivine.t

In Fouqué and Levy’s Minéralogie Micrographique (Pl. LV. fig. 2) is given a
microscopic section of the Rittersgriin rock which shows that it is composed of iron,
diallage, olivine, and augite. The clivine contains octahedrons and grains of pleonaste.
The structure is much like that of the pallasite from Cumberland, Rhode Island
(Cumberlandite).

A specimen in the Harvard College Mineral Cabinet has been figured from the
polished surfaces. In this, while the iron in places forms a coarse sponge, in other parts
it is much less in amount and occurs in detached irregular grains. Considerable pyrrho-
tite is found in this, forming part of the sponge or in irregular grains, and in figuring
(PL. I. figs. 3, 4) has not been separated therefrom, since the design has been simply to
show the general structure. The iron where etched shows the usual Widmannstiittian
figures. The silicates cannot, of course, be separated through the examination of a
polished surface, except partially. However, this specimen appears to contain consider-
able well marked olivine.

* Stein-und Metall-Massen, 1820, Plate VIII. page 70.

+ Phil. Mag., 1839 (3), xiv. 394; Chronique Scientifique, 1839, i. 31; Ann. Physik Chemie, xlvii. 470;
Neues Jahr. Min., 1840, p. 229.

$ Nova Acta Leop. Acad. Halle, 1878, xl. 333-382; Berg. Hiitt. Zeit.,1862, pp. 321, 322.

PALLASITE. 73

Since this specimen was figured and the plate in the hands of the lithographer, A.
Weisbach’s account of it, with the accompanying beautiful plate, has been received.*

This plate, so far as the writer can judge, shows the structure exceedingly well, and,
like the two figures drawn by him, indicates the two types of structure in this meteorite.
In one it shows the sponge-like character of the iron, holding the silicates in detached
grains and masses ; in the other the iron appears to be in the detached grains lying in
the mass of silicates. The sponge-like structure shows, however, in all the detached
pieces of iron, but it is discontinuous.

A microscopic examination of this meteorite has been made by Tschermak, who
states that the asmanite is tridymite, and that the meteorite is composed of meteoric
: iron, bronzite and tridymite.t

Breitenbach, Bohemia.

. The pallasite from Breitenbach was described by Prof. N. S. Maskelyne in 1871.
This was seen to be composed of a sponge-like mass of nickeliferous iron with some
| pyrrhotite, and inclosing in its cells bronzite (enstatite), asmanite (tridymite), and chro-
}- mite. No complete analysis has been made.t
Tf this is, as has been claimed, the same as the Rittersgriin pallasite, the microscopic
| section of that rock given by Fouqué and Lévy would indicate that its composition was
considerably different from that given by Maskelyne.

| ds

Steinbach, Saxony.

The structure of this is the same as that from Rittersgriin, and these two with the
Breitenbach pallasite are supposed to be portions of the same mass.

Atacama, Chil.

To the pallasites also belongs a meteorite found on a mountain pass, in the province
of Atacama, Chili, which was described by Prof. Charles A. Joy. This rock seems to be
composed of an irregular sponge-like mass of iron holding grains of olivine and enstatite
or labradorite, most probably the former.§

The analysis given by Professor Joy is apparently the best and most complete yet
made of any of the pallasites.

74.267 lian b ie Mitiste —————————s COCO
a

Sierra de Chaco, Aiacama, Chili.

According to Tschermak, this is composed of an iron sponge, containing grains of iron
and silicate. Plagioclase, with broad twin lamelle, is quite abundant, and contains
; numerous inclusions, of bronzite, pale brownish glass, parallel layers of fine black
needles, etc. Besides the plagioclase, there were seen greenish grains of bronzite, green-
7 ish-gray rounded grains of olivine, with dust-like inclusions, brownish augite grains,
colorless particles of tridymite, some supposed cordierite, and a brownish glass. This
is considered by Tschermak to be the same pallasite as that analyzed by Joy from
Atacama.

:
; ; * Der Eisenmeteorit von Rittersgriin im siichsischen Erzgebirge, Freiberg, 1876 ; 3 pp. and plate.
+ Sitz. Wien. Akad.,.1883, Ixxxviii. (1), 348.
¢ Phil. Trans.,1871, pp. 359-365.
§ Am. Jour. Sci., 1864 (2), xxxvi. 243-248.

10

74 THE SIDEROLITES AND PALLASITES.

Newton Co., Arkansas.

A coarsely reticulated or sponge-like mass of iron, containing in its cells olivine and
enstatite (?) Chromite and pyrrhotite also occur.

The enstatite is of a greenish-gray color, and more or less stained by the iron. The
olivine is in part colorless and in part stained yellow by the iron oxide. The analysis
does not afford data to give the composition of the rock as a whole.* The specimens
seen indicate that it is closely allied to the peridotites, but probably belongs with the
pallasites, with which it is here placed.

Meyeliones, Atacama, Bolivia.

A specimen in the Harvard Mineralogical Cabinet from Meyellones, Atacama, Bolivia,
shows the iron in irregular fine semi-sponge-like masses. Occasionally, it is aggregated
into grains from one to three quarters of an inch in length, but in general the grains are
minute. ‘The iron everywhere is rough, pronged, and jagged. The silicates cannot be
distinguished. from one another, except in the case of a few rounded olivine grains.
This, with the Hainholz pallasite, lies near the peridotites bearing iron, but does not
seem sufficiently distinct to be placed in a different species from the pallasites.

Luinholz, Westphaha.

The Hainholz, Westphalia, pallasite, while much finer grained, possesses a structure
similar to those portions of the Rittersgriin pallasite that contain the least iron, and this
iron in detached masses. The former contains irregular grains and semi-spongiform
masses of iron and pyrrhotite, while the silicates form irregular masses, partly included
in the iron and partly surrounding it. The silicates apparently predominate, and show
characters much like those of the Rittersgriin pallasite. So far as can be told from a
macroscopic study of this specimen, it les near the Rittersgriin meteorite, but forms a
connecting link between it and the peridotic meteorites containing iron, like those from
Mezo-Madras, Cabarras, Iowa Co., ete. The chemical analysis, if it is a fair index of the
general composition of this meteorite, would carry it into the peridotites. This pallas-
ite has been studied microscopically by Tschermak, who states that its included silicates
are olivine and bronzite, with subordinate amounts plagioclase, augite, and a cordierite-
like mineral. The olivine grains are from 30 to 40 em. in length, and contain only few
inclusions. The bronzite grains are smaller, and contain inclusions of brown glass and
black grains. The plagioclase shows the usual twinned structure in polarized light, and
contains grains of olivine and bronzite. A few grains of augite occur, having fine dust-
like inclusions, as well as brown glass globules, and angular black grains. Only two
grains of the supposed cordierite were seen. All the larger crystals lhe in a groundmass,
composed of the same minerals, with a little interstitial brown glass.T

Lodran, India.

The meteorite from Lodran, India, is described by Tschermak as a granular mixture
of vitreous, bluish-gray, and yellowish-green grains, between which steel-gray and yel-

* J. Lawrence Smith, Mineralogy and Chemistry, Louisville, Ky., 1873, pp. 839-342.
} Sitz. Wien. Akad., 1883, Ixxxviii. 349-351.

PALLASITE. —CUMBERLANDITE. 75

lowish metallic particles are to be seen. The microscopic and chemical examination
showed that the rock was composed of nickeliferous iron, pyrrhotite, chromite, olivine,
and bronzite. The nickeliferous iron forms the cementing mass, in a fine irregular net-
work. In the finer meshes lie single crystals, and in coarser portions are inclosed aggre-
gated grains and crystals of the above mentioned minerals. This iron is of a very light
steel gray color, and, on etching its surface, shows under the microscope figures somewhat
similar to those of the Senegal iron.

The olivine forms more or less perfect crystals, which occur both in the iron and as
intergrowths with the bronzite. The olivine was determined by the crystallographic
measurements of Professor Viktor von Lang to be of the same form as basaltic olivine.
It is on the surface of a bluish-gray to a berlin-blue color, but in the thin section pale
green.

Under the microscope no well marked cleavages were seen, but undulating fissures
parallel to the basal pinacoid are common. Many of these cracks are bordered by a moss-
like black mineral, which Tschermak regards as chromite, arising from a secondary altera-
tion of the olivine. Judging from the figure given, the present writer would agree in
this particular with Tschermak.

The bronzite occurs in grains and irregular crystals. From its erystallographic char-
acters, as determined by Von Lang, it appears to be enstatite, the same as the bronzite
in the Breitenbach meteorite. The enstatite has an asparagus-green to a yellowish-
green color, and under the microscope is of a very pale green shade. It is traversed by
the usual cleavage and fissure lines, and contains inclusions of three different kinds. The
first is in the form of colorless rounded grains, which are regarded as feldspar. The next
class of inclusions are minute, round, black particles, which are referred to chromite.
The last class are fine hair-like bodies, like those commonly seen in terrestrial bronzite,
but whose nature was not determined by Tschermak.

The pyrrhotite was seen united with the iron, and often between the silicates in yel-

low grains having a metallic lustre.

The chromite occurs in black crystals and grains, possessing a strong semi-metallic
lustre. The planes of an octahedron, rhombic dodecahedron, and tetragonal triakis octa-
hedron were observed by Von Lang upon the chromite crystals. It was found in small
amounts between the silicate, and also in the iron. For a fuller description and the
figures, the reader is referred to the original paper with its accompanying plate.* It is
doubtful whether this meteorite should be placed here, or classed with the peridotites.

Variety. — Cumberlandite.

Tron Mine Hill, Cumberland, Rhode Island.

No. 998. A dark resinous, almost black, crystalline groundmass, holding, porphy-
ritically inclosed, long, striated, glassy, and milky plagioclase crystals. Powder strongly
magnetic. This rock has been exposed on one side to weathering, and shows a dark
brown mass holding grains of magnetite, and gives an earthy yellow streak. In some of
the unaltered portions, the groundmass has the oil-green color of olivine. The fracture

* Sitz. Wien. Akad., 1870. lxi. (2), 465-475.

76 THE SIDEROLITES AND PALLASITES.

is rough, splintery, and conchoidal. The rock gelatinizes with hydrochloric acid, even
in the cold, and gives a titanium reaction.

Section: A granular groundmass, composed of olivine and magnetite, holding porphy-
ritically inclosed feldspar crystals. The magnetite forms more or less connected spongi-
form irregular masses. The olivine is in crystals and grains, united directly without any
cement, and occupies the cells and interspaces between the magnetite masses. Grains of
magnetite are of frequent occurrence in the olivine. The olivine is traversed by numer-
ous fissures, and the majority of the grains show a well marked cleavage. The fissures
usually have a ferruginous staining. Besides this, the olivine is comparatively clear
and unaltered, exhibiting, however, in connection with the feldspar, a greenish alteration-
product.

The plagioclase is in grains and irregular masses, which occasionally send tongues out
into the olivine magnetite mass. It shows well marked cleavage planes, and is some-
what kaolinized along those lines, otherwise the feldspar is clear and glassy. In polar-
ized light the larger feldspar masses were seen to be made up of several polysynthetic
individuals. Some small microscopic grains of feldspar are scattered in the rock mass,
but as a rule most of it is in large crystals, clearly seen macroscopically. A few reddish-
brown biotite flakes were observed in the feldspar.

The sponge-like structure of the magnetite is the same as that of the iron in the sup-
posed meteoric pallasites, and in a similar manner contains the inclosed olivine. As
would be expected, as a rule, in any iron coming to the surface of the earth in a heated
condition (eruptive), the iron in this rock has suffered the first stage of oxidation, and is a
magnetite. The writer regards the state of the iron (its alteration) of but little conse-
quence, so long as the structure and general chemical and mineralogical composition
remain the same. This section is figured in Plate I. figure 5.

In this figure the black portions represent the magnetic iron, and the light yellow
and whitish portions the fissured olivine.

No. 999 is, both in the hand specimen and section, similar to the preceding.

No. 1000. This is weathered to a slight extent only, and shows the same characters
as the unweathered portions of Nos. 998 and 999. The sections show the same relation
of the magnetite and olivine as in the preceding. The latter mineral contains many
erains and crystals of magnetite, and is much fissured. These fissures are filled largely
with magnetite granules and air cavities. It is stained yellowish and greenish in places,
and was seen in some portions to have been changed into a greenish aggregately polariz-
ing mass.

The feldspar is clear throughout the greater portion of the mass, but in parts is
kaolinized, and contains fluid and air cavities. This mineral in one section is seen to be
in small masses, as well as large, and holding such relations to the olivine and magnetite
that it leaves no doubt that it is a later crystallization than either of the other minerals.
A small fracture extends across a portion of the section, through the feldspar and olivine
grains, forming a miniature vein. The materials deposited in this vein vary according to
its position, whether in the feldspar or in the olivine, but, at the contact of the two
minerals, contains ingredients derived from both. This might be taken on a miscroscopic
scale to illustrate the variation of veins in passing from one rock to another. In the
olivine the vein is filled with serpentinous material, but in the feldspar with silicious.

-_

PALLASITE. — CUMBERLANDITE. 77

Biotite occurs as a secondary product in connection with the magnetite. It is seen
forming a fringe about the latter, or joined on to some of its prongs, extending out into
the olivine grains. The color is dark reddish brown, and the mineral shows strong
dichroism and well marked cleavage.

In the magnetite filling some cavities and fissures, a dark green isotropic mineral, of
irregular outline and unknown characters, was observed.* This is regarded by myself
as a secondary mineral, formed like the biotite, in connection with the magnetite. In
another section considerable earthy yellowish green and green aggregately polarizing
alteration products were observed in connection with the feldspar and olivine.

In all of the preceding sections the olivine is the predominating mineral. The feld-
spar crystals are confined to one side of the hill composed of this rock, and they are

4 therefore local, and not to be regarded as characteristic of the rock as a whole.
}
| No. 1005, from the same locality as the preceding, but nearer the middle of the hill,

shows a dark granular and crystalline groundmass in which, under a lens, can be seen
olivine in yellowish green grains, magnetite, and clear greenish glassy actinolite with a
well marked cleavage. Dark green serpentinous masses occur in the rock in irregular
vein-like and nodular forms. The rock weathers to a dull brownish gray surface, while
immediately beneath the surface crust the olivine is decomposed to a yellowish brown
ferruginous earth.

Section: The general structure of the section is the same as that of No. 998, without
the feldspar; that is, like the more compact portions of the section of that specimen.
A certain amount of alteration, however, has taken place here. This specimen, like all
except those in the immediate vicinity of No. 1000, is free from feldspar. The olivine
grains are now’separated in the majority of cases from the magnetite sponge by a narrow
film of a pale greenish actinolitic alteration product, which also separates these grains

'from one another. The same product in places traverses fissures in the olivine, and
replaces some of the smaller grains. The olivine further presents in part a cloudy, smoky
appearance, arising from a dark-colored staining, extending in fine lines parallel to a
erystallographic axis. This clouding extends sometimes over part only, and at other
times over the entire crystal. A greenish yellow serpentine replaces the olivine to some
extent, and extends in vein-like forms across part of the crystals. The actinolite in the
section is in minute elongated, irregular crystals, usually forming an interlocked mass.
The olivine contains fluid, glass, and gas inclusions, as- well as detached secondary
actinolite crystals.

t

=e. So “=> a Ae oie aa. ee Ss

)

No. 1002 is macroscopically almost identical with No. 1005; but microscepically,
its olivine is less in amount, and the actinolite in better formed and larger crystals.
In many portions of the section the latter mineral appears in long-bladed crystals with
well marked longitudinal cleavage. In other cases when the crystals are cut across they
show the characteristic amphibole cleavage rhombs. They are colorless, and exhibit very-
brilliant polarization colors. Some of the altered portions of the section are of a pale
greenish hue, and formed of an interlaced mass of fibres and non-polarizing particles —
the fibres being apparently actinolite. Other portions, more coarsely crystalline, show

_ dichroism, varying from a pale green to a pale yellow.

* Dr. Geo. H. Williams thought that this might be hereynite, a mineral which he had been especially
studying. Specimens of the rock were placed in his hands, but owing to the small amount of this mineral,
together with its high specific gravity, he was unable to isolate it from the magnetite.

78 THE SIDEROLITES AND PALLASITES.

The magnetite has diminished in amount, and for the most part forms a discontinuous
sponge. This discontinuity appears to have arisen from the solution of the magnetite
along the borders of its fissures and edges, which solution in some places has removed
nearly the whole of this mineral.

The removed portions are replaced by actinolitic material. The olivine is generally
surrounded by a border of actinolitic material, whose general relation is shown in Plate IT.
figure 1, the black portion representing the magnetic sponge, the brownish parts the
smoky, fissured olivine, and the gray and white portions the secondary actinolite.

In this the actinolite band is represented by the uncolored portion surrounding the
olivine, and in its turn inclosed by the magnetite. Little granules remain in the actin-
olitic material, part of which are shown in the drawing. The olivine as before is
“smoky,” marking apparently the first stage in its alteration.

Nos. 1007 and 1008 are both in the section and hand specimen similar to the pre-
ceding number, only in some portions the alteration has not extended quite so far.

No. 1006 is somewhat more changed than No. 1002. The section is partially
crossed by greenish actinolitic material, which replaces nearly all of the original matter.
In other portions the original structure still remains, the olivine being partly replaced
by actinolite, etc. The centres of the olivine are in part only dark smoky-brown, but
in others are altered to a reddish-brown serpentinous like product. | ;

The section is stained by a greenish, yellowish, and brownish product in many places.
This section serves as the last link in the chain connecting the specimens which contain
unaltered olivine with those in which the olivine is entirely changed.

No. 1001 is from the same locality as No. 1OOO, but nearer the centre of the hill.
This is a dark greenish black rock, showing a greenish serpentinous groundmass sprinkled
with titaniferous magnetite. Rounded and irregular patches of green serpentine, com-
paratively free from the magnetite, are irregularly distributed in the groundmass. In
weathering, the magnetite is left projecting in a cellular sponge-like mass.

Section: This, hke the preceding, is composed of an irregular sponge-like mass of
magnetite, with the interspaces filled with pale greenish and grayish mineral matter.
While the structure of the section is essentially the same as that of Nos. 998, 999, and
1000, the olivine is entirely replaced by serpentine. The forms of the olivine grains
remain the same, and the fissures by which they were traversed are marked by magnetite
grains arranged in lines extending through the serpentine. With a low power in com-
mon light the section is almost undistinguishable from one containing unchanged olivine..
With a higher power, or in polarized light, the fibrous structure of the serpentine shows
itself. The polarization colors are dull, and the platy fibrous masses show some resem-
blance to tale, as well as being obscured when the fibres are parallel to a diagonal of the
crossed nicols. The original fissures of the olivine show well both in common and polar-
ized light. Magnetite is included in the serpentine, not only in original grains, as seen
in the olivine of No, 998, but also in scattered dust-like granules and irregular masses,
or in lines along the fissures. The latter magnetite is apparently a secondary product
formed during the conversion of the olivine to serpentine. The main magnetite sponge-
like mass is not quite so closely united as in No. 998, neither does it occupy so great an
extent of the section; i. e., the percentage of magnetite is somewhat smaller in this por-
tion of the hill, and continues less in all parts of the hill net immediately adjacent to

PALLASITE. — CUMBERLANDITE. 79

the porphyritic feldspar portion, so far as the writer has observed. The structure of this
section is shown in Plate I. figure 6. In this the structure of the altered fissured olivine,
closely resembling the olivine of figure 5, is clearly shown.

No. 1003 shows more serpentine characters than No. 1001, having less iron and
more of the irregular serpentine masses. In the section the characters are essentially
the same as those of No. 1001. Some talc in fine scales aggregated together was seen
towards the interior of the larger serpentinized olivines, and in the macroscopically visi-
ble serpentine masses before mentioned. The serpentine in these masses is pale-green
and isotropic. The serpentine replacing the olivine shows the same fibrous character
as No. 1001, but the structure is better marked, and the fibrous plates polarized with
brilliant colors. In portions of the section considerable actinolite was observed.

Nos. 1004, 1009, 1010, and 1011 are from the side of the hill opposite to No.
1000, and with the preceding specimens show the gradual change from one side, on
which is to be found such material as No. 1000, to those masses which have suffered
very great alteration. Part show ochery patches of ferruginous alteration. In general,
the sponge-like structure of the magnetite still remains, and besides this the interspaces
are variously filled with talc, serpentine, actinolite, etc. — the serpentinous material pre-
dominating over the others. Owing to the extreme alteration, some of these specimens
have developed an imperfect fissile or laminated structure, which might be mistaken for
bedding planes.

No. 1012. This was from an exposure near No. 1011, but separated from it by a
rivulet, and its connection with the other described masses could not be shown in the
field. This rock is much jointed, presenting an imperfect fissile structure, and is of a
dark green color, with yellowish-brown ochery spots of decomposition. On the weath-
ered surface, the magnetite shows the irregular sponge-like structure so characteristic
of all these rocks. The character of the section is like that of those last described, but
with the addition to its alteration-products of considerable dolomite. I have no hesita-
tion in declaring my opinion, from the microscopic characters of this specimen, that this
outcrop belongs to the same formation as the hill itself.

The specific gravity of the Cumberland pallasite varies according to the
state of the rock — whether altered or unaltered. Dr. Charles T. Jackson
states that it varies from 3.82 to 3.88. Mr. J. E. Wolff, Assistant in Geology
in Harvard College, kindly made some determinations for me. The specilic
gravity of No. 998 was found to be 4.06 and 4.005. The former determina-
tion was made from a fragment containing almost no feldspar, while the
latter was made from one containing considerable. Again, a specific gravity
determination of No. 1001 gave as a result 3.56, and of No. 1008, 3.59.

The two latter determinations were made from the more highly altered
portions of the rock.

Owing to the various alterations that this Cumberland rock shows, it

SO THE SIDEROLITES AND PALLASITES.

would be very interesting if chemical analyses should be made of the differ-
ent portions, in order to ascertain what changes in the ultimate chemical
composition have taken place. They should be made from material micro-
scopically examined, so that the specific gravity and chemical and miner-
alogical characters could be cojrdinated. The diminished specifie gravity of
the more highly altered portions of this rock, as above determined, would
indicate that considerable changes-had taken place in the chemical composi-
tion of the rock as a whole. Further, an examination should be made of
the least altered portions of this and all similar rocks, for the purpose of
ascertaining if they contam any of the elements so commonly found in
meteoric pallasites and siderolites. It is not impossible that, on boring, in
depth some of the iron might be found in the native state instead of being
entirely oxidized.

This rock has been used as an iron ore, for an historical account of which
the reader is referred to previous papers of the writer.*

The additions and changes made in these descriptions to those already
published, have been caused by the preparation and examination of other
sections, thus making the work more complete. At the time the former
descriptions were written, the writer assigned this rock to the peridotites —
the most basic olivine rock of terrestrial origin then known. Although its
relation to the meteorites was recognized, yet, since the present study of the
meteorites themselves was not undertaken until February, 1882, the writer
may be pardoned for not earlier perceiving its distinctness from the peri-
dotites, properly so called. It is now regarded as a pallasite in which the
iron has been oxidized — probably at the time the rock was formed. The
writer holds that the rock is eruptive, although no proof beyond its micro-
scopic characters has been obtained ; and if its relations to the country rock
should be found to be non-eruptive ones, then this view would have to be
abandoned,

If it is necessary to have a distinct name to indicate the pallasites above
described, in which the iron is oxidized, the writer would propose that of
Cumberlandite, from the locality in which it occurs in Rhode Island. He
would have preferred that of Tubergite, from the earlier described rock from
Taberg, Sweden, if that name had not already been in current use In min-
eralogy.

In this direction a vast field exists in the study of iron-bearing rocks

* Bull. Mus, Comp. Zoil., 1881, vii. 183-187; Proc. Bost. Soc. Nat. Hist., 1881, xxi. 195-197.

ae

PALLASITE.—CU MBERLANDITE. 51

containing actinolite, serpentine, etc.; and the question of the formation of
certain schistose rocks by metamorphism of these terrestrial pallasites is an
interesting one.

A similar structure to that of this Rhode Islan] pallasite has been
reported in some New York and Canada iron-bearing rocks.

Tuberg, Sweden.

Of a similar character to the Cumberland pallasite is the rock from Taberg, Sweden,
so long known and so well described by Messrs. Sjoren and Térnebohm.*

The section in the collection purchased from Richard Fuess of Berlin shows an
imperfect sponge-like mass of magnetite, holding olivine and feldspar.

The olivine is much fissured and traversed along the fissures by serpentine and mag-
netite bands, while in places it is entirely replaced by the secondary serpentine.

The feldspar is in irregular, somewhat kaolinized masses, holding olivine and mag-
netite grains. The feldspar polarizes with a polysynthetic structure.

A reddish-brown secondary biotite is associated with the magnetite, but is more
abundant than it is in the Cumberland rock.

For the full description of this rock the reader is referred to the original papers
above mentioned. This rock is figured on Plate II. figures 2 and 3. Figure 2 shows the
sponge-like magnetite with the inclosed olivine, while figure 3 shows a more highly
altered portion of the same section in which the magnetite has partly disappeared and
the silicates contain more ferruginous material. The reddish-brown portions are the
secondary mica, usually associated with or replacing the magnetite.

The pallasites may then be described in general terms as composed of a
ferrugingus sponge-like or semi-sponge-like mass, holding olivine with or
without feldspar, enstatite, diallage, augite, and chromite, or spinel min-
erals. The sponge is formed either by native iron with pyrrhotite, or by
their secondary products, like magnetite.

The alteration of these original materials gives rise to serpentine, chro-
mite (?), biotite, actinolite, ete.

The general structure of the Cumberlandite from Rhode Island may be
summed up as follows: In the least altered condition it shows a dark resi-
nous, crystalline, splintery and compact mass, holding porphyritically inclosed
feldspars, which, although characteristic of one portion of the locality, are
not essential. This rock passes into a form destitute of feldspar, but having
the same groundmass, which contains patches of a dark-green, fine-grained
alteration-product, which holds a similar relation to the groundmass as the

feldspar in the preceding. In the succeeding forms the resinous groundmass
* Geol. Foren. Forhan., 1876, iii. 42-62; 1881, v. 610-619; 1882, vi. 264-267; Neues Jahr. Min.,

1876, pp. 434, 435; 1882, ii. 66, 67.
ll

82 THE SIDEROLITES AND PALLASITES.

becomes less, and the greenish serpentinous product more abundant, until
they pass into a greenish-gray serpentinous rock spotted with secondary
ferruginous products. In many of the intermediate forms, short, brilliant
crystals of actimolite are to be seen, while the rock assumes a more or less
perfect schistose structure.

In the microscopic sections the series passes from a more or less spongi-
form mass of magnetite, holding olivine and more or less feldspar, into forms
that show in portions of the mass an alteration to a greenish serpentinous
aggregate. It then passes into a form destitute of the feldspar, in which
the partially altered smoky olivine grains aré surrounded by a band of
secondary actinolite, while the greenish serpentinous product increases in
abundance. ‘These changes go on with diminishing olivine and increasing
actinolite and greenish serpentinous material, until they have entirely
(especially the last) replaced the olivine. The structure remains the same,
but the magnetite sponge is more discontinuous and in part dissolved, while.
tale appears. In others dolomite is seen. :

In some sections the greenish secondary products, with little or no actin-
olite, replace the olivine. The figures 5, 6 (Plate I.), and 1, 2, and 3 (Plate
II.), fairly represent the general structure of these rocks, and their resem-
blance to the meteoric pallasites.

No satisfactory analyses of the pallasites exist except that of Professor C.
A. Joy of an Atacama meteorite, but the imperfect ones that have been
found have been tabulated, so as to give a rough approximation to correct-
ness. The specific gravity determinations are also not satisfactory as a
whole, since they have not been made upon characteristic specimens, but
upon selected ones. They run from a little above 7 to some below 4, but
it is probable that the majority of typical pallasites lie between 4 and 6;
although we must expect to find them graduating in specific gravity, as well
as in other characters, into both the siderolites and peridotites. The silica
ranges from 3 per cent up to 33 per cent, but the probable limits are
between 5 and 380 per cent, averaging about 20 per cent. The magnesia
ranges from 2 to over 30 per cent, but the average probably will be found,
by correct analyses, to lie somewhere between 10 and 20 per cent. The
iron in various conditions is a variable quantity, but averages about 60 per
cent; while the nickel, with one exception, is less than 10 per cent. In the
terrestrial forms (Cumberlandite) nickel is wanting, but from 6 to 15 per

cent of titanic oxide occurs. Some tin, copper, zinc, cobalt, phosphorus, sul-

PALLASITE. — CUMBERLANDITE. 83

phur, chromium, manganese, lime, and aluminum have been found in part of
the specimens analyzed. More and accurate analyses are needed before any-
thing but general conjectural statements can be made. If the analyses of
iron ores from regions of crystalline rocks be examined, like those given by
Richard Akerman in his work “On the State of the Iron Manufacture in
Sweden,” Stockholm, 1876, also from Canada and elsewhere, many can be
found whose resemblance to those of Cumberlandite is so close as to warrant
an examination of the structure and mode of occurrence of the ore analyzed.
In these we should look for from 5 to 30 per cent of silica and magnesia, but
not of necessity for any titanium. The mere analysis, without further evi-
dence, does not prove the relationship —it merely suggests it.

CHAPT Hh Et
THE PERIDOTITES.

Section 1.— Sitroductory.

Tur term peridotite is employed by Professor Rosenbusch to designate
the pre-Tertiary terrestrial rocks that are composed essentially of olivine,
with or without enstatite, diallage, augite, magnetite, chromite, picotite,
etc.* The writer would extend it so as to include all terrestrial and extra-
terrestrial rocks of similar composition and structure, and all the derivatives
of both. The state of the iron, as in the case of the preceding species, does
not appear to him to be a sufficient reason for separating the rocks herein
described into distinct species. The descriptions will be given of the me-
teoric peridotites first, and of the terrestrial ones later, as a matter of
convenience only. The order pursued in the arrangement of the meteoric
peridotites will be, so far as possible, the same as that followed with the
terrestrial ones, — those composed of olivine first, or the dunite variety ; then
those containing olivine and enstatite (olivine-enstatite rocks); then those
containing olivine, enstatite, and diallage, or the lherzolite variety; etc.
In each case those approaching nearest to the glassy condition will be
described first. Of necessity this scheme has many imperfections, owing
to the limited number of specimens studied microscopically.

While the writer does not believe in the necessity or value of dividing
the peridotite into either species or varieties— holding that they are all
essentially of one type, whatever may be the especial mineral composition —
he recognizes the fact that, excepting himself, lithologists, universally, do so
divide these rocks. He then thinks it better to conform for the present to
that method, so far as seems necessary and convenient to aid the science,
and not to retard its progress. It seems necessary, then, in deference to the
prevailing sentiment, that the olivine-enstatite-bearing rocks should be sepa-

* Mikros. Phys. ii. 524-545.

:
:
-
.
..

INTRODUCTORY. Sd

rated as a variety, the same as the olivine-enstatite-diallage ones have been
erected into the variety lherzolite. Believing, as he does, that the same
methods, rules, and principles should be employed in studying meteorites
as those used for the terrestrial rocks, and that both classes are in reality
the same, it follows that the same name should be used for both, and the
differences expressed adjectively if necessary.

In accordance with this, the variety of peridotite distinguished by olivine
should, both as meteorites and terrestrial rocks, be designated by the term
already in common use for the latter — dunile. For that variety which con-
tains olivine and enstatite, the German term enstati-olivinfels employed by
Dr. Dathe is too cumbersome for Anglo-Saxon use, or even for any general
use. It is, then, proposed here to designate all these rocks by the term
saxonite, from the country in which the terrestrial form was first so well
described by Dathe.

The term /herzolite is here applied to those rocks characterized by ensta-
tite, diallage, and olivine. The forms that are characterized by the presence
of olivine, enstatite (bronzite), and augite, are designated by the term duch-
nertte, given in honor of Dr. Otto Buchner, to whose writings on meteorites
we are so much indebted, and who gave the first description of a meteorite
having this composition.

The term eulysite is employed for the olivine-diallage forms, and picrife for
the olivine-augite variety. Of course, for all of the highly altered forms for
which the term serpentine has been already used, that name is retained ; but
in many cases, when it is known from what special variety the serpentine
has been produced by alteration, it has been described under that variety in
order to show its relations. This has particularly been the case with forms
coming from the same rock in a single locality, but showing different
stages of alteration. The fragmental forms, of which only a few have been
described, are classed under the term porodite * for the old and altered forms,
and ¢ufa for the unaltered. Thus far, in meteorites, the fragmental rocks are
all tufas, and in the terrestrial peridotites, porodites.

* Bull. Mus. Comp. Zodl., 1879, v. 280.

86 PERIDOTITE.

Section II. — The Meteorie Peridotites.

VARIETY. — Dunite.

Chassigny, Franee.

The meteorite of Chassigny * is, according to Damour, of a pale-yellow tint. Under a
lens it is seen to be formed of a multitude of little rounded grains, with a vitreous lus-

tre. In these grains occur some of a deep-black color. This description is identical —

with that which could be given of an unaltered dunite, like that from Franklin, N. C.,
for example.

According to Tschermak, microscopically, this meteorite is composed of a pale yellow-
ish olivine, traversed by fissures, and containing brownish glass inclusions. Between
the olivine grains there are to be seen here and there three-sided cavities, filled with
colorless or brownish glass, from which often radiate the fissures traversing the olivines.
In the glass can be seen with high powers colorless grains, needles, and brown crystals.
Octahedrons of chromite occur irregularly scattered through the rock.f

VARIETY. — Saxonite.

Towa County, Lowa.

The Iowa County, Iowa, meteorite in the Harvard College Cabinet presents a fine-
grained groundmass, sprinkled with pyrrhotite and iron. On the polished surface it
shows a well-marked chondritic structure.

This meteorite was described by Prof. C. W. Giimbel, in 1875, as composed of oli-
vine, an augitic material, iron, troilite, chromite, reddish garnet-like inclusions, ete. He
holds that the rock is entirely crystalline, but fragmental in character. The reader is
referred to the origmal paper for Giimbel’s figure and views.t

Specimens of this meteorite were purchased for the Whitney Lithological Collection
of the Museum of Comparative Zoology, from Ward and Howell, Rochester, N. Y., and
sections made. The sections are colored gray, with patches of brownish-yellow staining
from the iron. The gray groundmass contains irregular detached bits of metallic iron,
about which the stain extends. The groundmass is composed of crystals and grains of
olivine, enstatite, pyrrhotite, iron, and base. The section shows the usual chondritic
structure, in which granules of olivine and enstatite are cemented by the base to form
the chondri. TI can find neither in this nor in any other meteorite that I have seen any
evidence that they are fragmental in character, but rather evidence that the structure
usually observed is the result of rapid cooling upon a liquid magma of this constitution.
The crystalline structure of any mass depends upon the crystalline form its minerals
tend to assume, under the conditions to which they were exposed during that crystalliza-
tion. In the crystalline forms of olivine and enstatite, coupled with the rapid cooling,

* Comptes Rendus, 1862, lv. 591.
+ Sitz. Wien. Akad., 1883, Ixxxviii. (1), 361, 362.
t Sitz. Akad. Miinehen, 1875, v. 313-330.

—— a ae

THE METEORIC PERIDOTITES. — SAXONITE. 87

the writer believes, resides the cause of the peculiar structure of the chondritic meteor-
ites, while, if through any cause the mass cools more slowly, the result is to unite the
detached grains into larger crystals, as in the Estherville meteorite and in the ordinary
terrestrial peridotites. These structures, certainly, do not vary any more from one
another than do the glassy, the glassy and globulitic, and the ciystalline forms of basalt.

The base in this peridotite varies from a light to a dark ash-gray, and is fibrous-gran-
ular in its structure. The darker shades are generally associated with the olivine and
the lighter with the enstatite. Various gradations are seen between that state of the
base which does not affect polarized light, and that which shows feeble coloration —
properly not a base. These gradations are owing to the differentiation in it of more or
less granules of olivine or enstatite, causing the depolarization of the light. The feeble
polarization appears to be owing to a differentiation of the base so as to leave but mi-
nute portions of it in the original state, although the difference between the two states is
not noticeable in common light. The tendency of these granules is to unite into a homo-
geneous crystal, the base disappearing more and more, according to the conditions attend-
ing the solidification of the mass. Furthermore, as in other rocks, so in this, the base
should be expected to be one of the first materials, after the iron, to suffer alteration.
The writer supposes this base to be that which other writers have described as the
matrix of fine dust, formed by the comminution of the meteoric material, — flocculens,
opaque, white mineral ;* also as felspathic material, ete.

A series of grains and crystals of olivine, arranged in spherical form and cemented
by the fibrous-granular base, forms the olivine chondri. I do not regard these as rounded
forms, owing their shape to mechanical action, for no abrupt line separates them from
the surrounding material, as is the case when detached fragments are inclosed in a
matrix. In the same way the granules themselves show that they are products of crys-
tallization, and not broken fragments held in the matrix. As said before, I can see no
structure, in this or in any of the other meteorites examined, supporting the mechanical
theory of their origin; but everything observed, in my judgment, points to crystalliza-
tion in a more or less rapidly cooling body. In some instances it is, indeed, true that an
abrupt termination exists to some of the forms, but these appear to be fragments of
base, sometimes partly differentiated, caught in the liquid mass, instead of mechanical
forms torn from some previously existing rock.

This meteorite has also been described by Lasaulx, who states that it shows an evi-
dent brecciated structure, with olivine grains and rounded enstatite masses, in a fine-
grained groundmass, containing grains and fragments of crystals, as well as iron and
pyrrhotite. Plagioclase is said to be present, and the base is described as a gray, fine-
grained, aggregate, cementing mass, resembling the granular microfelsitic groundmass
of many porphyries.t

Figure 4, Plate II., shows well the finer-grained portions of this meteorite with
the native iron. The portion to the left of the centre represents one of the chondri,
composed of detached grains held in a dark base. The grains are found to be divided by
polarized light into three sets, one of which occupies the lower portion and the other two
the upper portion of the chondrus. The grains in each division act optically as a unit,
and cause the chondrus to present the appearance of a crystal composed of three
twinned portions; and it is here thought that had not the crystallization been arrested,

* Maskelyne, Phil. Mag , 1863 (4), xxvi. 138.
¢ Sitz. nieder. Gesells. Bonn, 1882, pp. 102-105.

88 PERIDOTITE.

the grains would have united from the crystallization of the base, and a three-twinned
rounded crystal resulted. The remaining portion of the figure is composed of base,
olivine, enstatite, chondri, iron, pyrrhotite, and, possibly, magnetite.

Figure 5, on the same plate, shows one of the large chondri composed of olivine and
enstatite, which blends at the lower portion of the figure with the general groundmass,
showing that they are only somewhat differently differentiated portions of the con-
tinuous mass. The grains are surrounded by a gray base, while the yellowish and red-
dish-brown tints represent the staining from the oxidation of the iron. In figure 4 the
base is darker than represented, and in figure 5 lighter. The colors of the two should be
exchanged.

Dhurmsala, Pwiyjab, India.

This meteorite is described by Professor A. von Lasaulx as having a light-gray
eroundmass, sprinkled with yellowish rusty spots. Microscopically, it was seen to
possess a chondritic structure, similar to the meteorite from Iowa County.. The chon-
dri are composed of olivine and-enstatite, with the fibrous cementing material. Besides
olivine and enstatite the rock contains iron and troilite, as well as chromite or mag-
netite.*

Kiuyahinya, Hungary.

The Knyahinya meteorite was examined microscopically by Professor Adolf Kenn-
gott in 1869. His section was of a gray color spotted with yellow, semi-transparent, but
containing opaque and dark-yellow spots. The whole appears finely grained to the
unaided vision, but spheroidally grained under a low magnifying power. The granules
are gray, and some of them more or less angular. Besides the metallic and opaque par-
ticles two crystalline minerals were seen. One is colorless and transparent, the other
gray and translucent. Some of the spherules consist essentially of one or the other of
these minerals. The opaque substances are subordinate, and are interposed between the
rounded or angular granules. Kenngott regards this spherulitic structure as the result of
a process of crystallization within the substance of the meteorite, and not from an aggre-
gation of separately formed bodies.

The opaque substances are light-gray metallic iron, grayish-yellow pyrrhotite, and a
black material. In reflected light the iron appears dark-gray and translucent, the pyr-
rhotite blackish-yellow and faintly diaphanous, and the black substance opaque. The
silicates are regarded as enstatite and olivine.

Descriptions of the granules (chondri) were given by Professor Kenngott. One is
said to possess a striped appearance, owing to alternations of a delicate transparent sub-
stance with a gray one. The bands are partly parallel and partly divergent. When
the power is 900 the structure is resolved into a mere aggregation of gray and hyaline
particles. The gray mineral (enstatite) constitutes essentially many of the round or
rounded granules, while other granules are formed from a union of the olivine and
enstatite. The two silicates crystallized simultaneously, one or the other of them, accord-
ing to circumstances, having accumulated around certain centres in a spherical form, thus
imparting to the meteorite as a whole a somewhat odlitic aspect. The original paper is
illustrated by drawings of the granules.}

* Sitz. nieder. Gesells. Bonn, 1882, pp. 105-107.
+ Sitz. Wien. Akad., 1869, lix. (2), 873-880 ; Phil. Mag., 1869 (4), xxxvilil. 424-428.

= a Se ee ee a

THE METEORIC PERIDOTITES. —SAXONITE. ‘oy

Later, Dr. Otto Hahn thought he had discovered in this meteorite a plant form com-
posed of olivine. This plant he named Urania Guiliclmi. It was regarded as lying
between alge and ferns.* Since Hahn found his plants in granite, gneiss, serpentine,
basalt, and meteorites, even in the metallic nickel-iron from Toluca, and in that of the
Pallas meteorite, the conclusion would follow that he would be able to find them almost
anywhere. His language is such that it is difficult to believe that his paper is a sober
production, and not a parody on the Eozodn literature, especially since he claims to have
found Eozoon structure in the Pallas meteorite. Perhaps this is not so remarkable, since
Carpenter found the same in graphic granite. t

Whatever may have been Hahn’s design in the publication of “ Die Urzelle,” he was
evidently in earnest in his * Die Meteorite (Chondrite) und ihre Organismen,’ Tiibingen,
1880.

This work is devoted chiefly to the structure of the chondri observed in the Knya-
hinya meteorite, and it gives very fair photographs of these. Hahn believed the
chondri were sponges, corals, crinoids, etc., while Urania was in this book placed under
the sponges.

There are some things which pass discussion, and Hahn's works belong to that class;
for the kingdom to which such forms belong must be largely a question of belief rather
than of decisive evidence. The artificial formation, by Meunier, of Halin’s sponges, corals,
and crinoids in a red-hot porcelain tube is perhaps the most decisive fact against their
organic origin. ¢

The writer believes that this is one of the very common cases in which mineral forms
have been taken to be organic ones, especially by those who were familiar with the latter
and not with the former,— cases to some of which attention has been called in the
“ Azoic System.” §

Later, Dr. D. F. Weinland continued the discovery of organic forms, principally in
the Knyahinya meteorite. He gives but two figures; that of Pectiseus Zittelui is appa-
rently an enstatite crystal, and that of “ Hahnia meteoriiica, a coral!” is evidently a series
of olivine grains. ||

These and other such forms can be found in all chondritic meteorites, while almost
every rock, especially if altered, will afford structures that can be tortured into organic
forms, if the imagination or desire be strong enough. After this has been done, who

shall say that the authors were not correct? Is not the case similar to that of the

Eozoén Canadense — dependent solely on weight of authority? Yet the Eozodn occurs in
rocks proved to be veinstones !

The specimen of the Knyahinya meteorite in the Whitney Collection shows on the
fracture a gray color and a chondritic structure.

Section: The sections show a gray chondritic mass, marked in places by a yellowish-
brown ferruginous staining ; and they are seen under the microscope to be composed of a
crystalline granular and chondritic mass, the parts often held by the dark-gray and light-
gray fibrous base and semi-base. The chondri in these sections are seen to be composed

* See Die Urzelle, Tiibingen, 1879, pp. 54-56, and Plate XVII.

7 Nature, 1876, xiv. 8, 9, 68.

+ Comptes Rendus, 1881, xciii. 737-739 ; Am. Jour. Sci., 1882 (8), xxiii. 155, 156.

§ Bull. Mus. Comp. Zodl., 1884, vii. No. 11.

|| Ueber die in Meteoriten entdeckten Thierreste. Esslingen, 1882. See also Die hypothetischen Organ-
ismen-Reste in Meteoriten, von Dr. F. Rolle, Wiesbaden, 1884; and Les Prétendus Organismes des Méte-

orites, par Carl Vogt, Geneve, 1882.
12

90 PERIDOTITE.

of enstatite, olivine, enstatite and base, olivine and base, enstatite and olivine, and of base
and minute granules of either olivine and enstatite. ;

One of the chondri is seen to possess an approximately square centre of enstatite
with some projecting points. Surrounding this, and also partially held in it, is the gray
base and semi-base, showing over much of its surface a feeble polarization, which extin-
guishes at the same time with the enstatite. The latter shows traces of zone building,
and lying parallel to the sides are other small masses of enstatite, which appear to form
constituent portions of the enstatite crystal. In polarized light, the entire chondrus
appears as a homogeneous enstatite, except that certain portions show more feeble colora-
tion. The structure seems to me to be that of a mineral crystallizing out of a magma, the
processes being arrested before it was complete. Another chondrus shows a bouquet-like
mass of the fibrous gray matter in the centre, surrounded in part by long masses of
enstatite, which hold included between and in them portions of the base. This is figured
in Plate II. figure 6, at the centre and on right of the central portion of the figure. The
lighter bars surrounding and cutting the yellowish-gray fibrous portion are enstatite,
which polarize conjointly as a single crystal. They contain portions of the base forming
the grayish parts. The central fan-shaped portion is composed of base mixed with
enstatite fibres and iron grains, and stained by oxide of iron. At the bottom of the
figure is another chondrus composed of mixed enstatite fibres and base, while towards
the left and bottom of the figure is a fissured enstatite. The rest of the figure is com-
posed of enstatite, olivine, and base, showing in places imperfect chondritic structure.

In another, the fan-like radiation of the base with the enstatite granules begins at
opposite ends of the chondri, meeting and interlocking towards the middle, but leaving
a non-differentiated oblong nebulous mass in the centre between them. The two por-
tions interlock in such a manner that they evidently form the same crystal mass — the
rudiments of a twinned crystal.

Some chondri are composed of a rude network of base— the meshes being filled
with olivine grains. This is shown in Kenngott’s figure 8. One chondrus is composed
of an enstatite crystal surrounded by a narrow border of gray matter, apparently crowded
out by the crystallization of the enstatite, as is often the case in the crystallization of the
feldspars in modern lavas.

Chondri are seen composed entirely of olivine grains, the lines bounding the grains
answering to the network of base before mentioned. One formed by an enstatite
mass with black ferruginous grains (magnetite) is found to continue across its apparent
boundary into the adjoining enstatite, the cleavage fractures and fissures extending from
one to the other, both forming in common and polarized light a continuous enstatite
crystal.

Another chondrus is composed of a sea-fan-like interior made up of base and fine
granules of olivine (?) surrounded by a coarser granular mass destitute of base, the entire
chondrus showing in common and polarized light that it was a homogeneous mass, out of
which the granules have crystallized.

In others, the base is irregularly scattered through the crystals, and held as the base
is in minerals in recent lavas. The base in this meteorite is often completely dark
during the entire revolution of the stage, and every gradation exists between this state
and that in which it affects the polarized light considerably — nearly crystallized into
the enstatite and olivine forms. While the color of the base is usually a gray, in some
cases it is of a brown to a black color in transmitted light. The descriptions of the
chondri might be greatly extended, but it would seem that enough has been given to

ae

THE METEORIC PERIDOTITES. — SAXONITE. 91

show that the olivine and enstatite crystallize out of the base, and that in the state of
incipient crystallization these minerals, coupled with the base, assume the forms that
have been taken for organic ones. The irregular distribution and relations of the base to
the crystal grains show that even apparent organic forms are wanting except in selected
cases. The mineral constitution of the meteorite is such that it could not have been
exposed to air and water without alteration of the minerals, but must have been formed
under such conditions that those agencies could not have produced their customary
effects, z.c., under the action of heat. Action that was sufficient to crystallize enstatite
and olivine out of a fossiliferous deposit, surely would have been sufficient to obliterate
every trace of such delicate microscopic organisms as these supposed corals and crinoids.
If these forms were organic, then, as Professor J. Lawrence Smith has justly observed,
carbonate of lime ought to be found in them, which is not the case. The entire mass of
the meteorite is made up of enstatite, olivine, iron, base, pyrrhotite, and apparently a
magnetite.

Its chondri appear, with possibly a few exceptions, to be secretions in the mass
formed by the tendency to crystallization, as was pointed out in the case of the preceding
meteorite, since they pass as a continuous mass into the surrounding material, and have
not the well-defined boundaries of a foreign or included mass. The possible exceptions
are of a few forms that appear as if, while in a liquid or plastic state, they might have
been inclosed in a liquid or plastic mass, and partly united with it. The supposed frag-
mental portions, or the grains, appear to me to be formed by crystallization, the same as
the grains are formed in common peridotic rocks, and not by attrition. Some of the
chondri are deformed by others, as would be natural in such a crystallizing mass.

Gnadenfret, Silesia.

This meteorite has been described by Professors J. G. Galle and A. von Lasaulx as
having a chondritic structure. The groundmass is colored light-gray, and contains
numerous spherules, colored white, gray, or dark-gray. Particles of iron of varying size
occur, while under the lens there are clearly seen little granular particles of bronze-
colored pyrrhotite and brass-yellow spangles of troilite. Rusty-brown spots occur, aris-
ing from the rapid oxidation of the iron.

Under the microscope, the thin sections were found to contain nickeliferous iron,
pyrrhotite, troilite, chromite, enstatite, and olivine. The iron is in irregular pronged
masses.

Our authors separate the troilite from pyrrhotite, the former being rare in little
yellowish grains, and the latter more abundant, in small granular aggregates having a
bronze color, also in little grains in the silicates and in the iron. The chromite is in
small octahedrons in the olivine. The enstatite appears both in the groundmass and in
the spherules. It contains inclusions of brown and colorless glass with fixed bubbles,

.and black metallic particles; also a black dust-like substance. All the inclusions are
more or less elongated in the direction of the cleavage lines.

The olivine occurs both in the groundmass and in the spherules. It is in rounded
| grains or crystal fragments of irregular contour. The grains are colorless except when
q discolored by the oxidation of the metallic iron. The olivine contains brown glass
; inclusions with one or two bubbles, also a black dust-like substance, the same as that
inclosed in the enstatite.

92 PERIDOTITE.

The chondri are composed principally of olivine and enstatite, and show the usual
variations; but for the descriptions the reader is referred to the original paper.*

Gopalpur, India.

The Gopalpur meteorite was microscopically studied by Tschermak. Its color is
erayish-brown, but in the interior whitish-gray. The groundmass is filled with numer-
ous little spherules, which are of a brownish-gray or a clear gray color. Throughout, the
groundmass glitters with yellowish points of pyrrhotite. Cellular, pronged grains of iron
could be seen in the section.

This meteorite belongs to the chondrites of Rose. The whitish groundmass is
earthy, tufaceous, containing angular fragments of anisotropic minerals of various sizes.
The larger fragments show a fibrous or stalk-like structure with an evident cleavage
parallel to their longer direction; or they are traversed only by irregular fissures. The
groundmass contains particles of pyrrhotite and iron of various sizes. Immediately
about the iron is to be seen a small amount of a dust-like, untransparent, dark-brown
material which Tschermak regards as chromite.

The larger spherules are composed principally of a radiating fibrous mineral, which is
taken to be bronzite (enstatite). Sometimes a granular mineral was observed in them.
Other spherules are made up of irregular fissured grains which are referred to olivine ;
and still others are thought to be composed of feldspar. From the figures and descrip-
tions given, the present writer thinks that the presence of feldspar is doubtful, although
‘T'schermak is one of the best authorities on that point. The author hopes that a careful
re-examination of the sections will be made.

The large, dark, opaque particles in the spherules and groundmass are iron and
pyrrhotite.

The spherules are said not to be different in composition from the groundmass. In
both can be recognized, as the essential constituents, bronzite (enstatite), olivine, iron, and
pyrrhotite. The only difference is that in the spherules the crystal grains are smaller.

Tschermak holds that the chondritic structure displayed in this meteorite was the
result of a mutual attrition of the different particles, the whole afterwards being cemented
together. He regards the whole structure as different from any terrestrial structure yet
observed. fF

Butsura, India.

The Butsura meteorite was described by Professor N.S. Maskelyne in 1863, as having
a yellowish-brown groundmass containing numerous points of metallic iron. Irregular
dark stains were observed surrounding the iron. The iron is very evenly distributed in
small, isolated, irregularly formed and sometimes crystalline looking particles. Under
the microscope the chief mass of the meteorite was regarded as olivine, associated with
a gray and an opaque white mineral. The gray mineral constitutes entire nodules in
the meteorite, and sometimes seems mingled in the apparently brecciated mass, con-
taining olivine crystals that form other nodules in it. It presents the appearance in the
former case either of a dark mottled surface spangled with dark points, or of a mineral
presenting very regular and minute parallel cleavage-planes, with dark-gray bars running

* Mon. Berlin Akad., 1879, pp. 750-771.
+ Sitz. Wien. Akad., 1872, Ixv. (1), 135-146; Min. Mitth., 1872, pp. 95-100.

a

_——— tr

a; sient ee ee

THE METEORIC PERIDOTITES. —SAXONITE. 95

along them, often in divergent rays. Another mineral was observed which was trans-
parent and presented cleavages nearly perpendicular to each other. The specific gravity
of this meteorite is 3.60.*
From the above description it is inferred that this peridotite is composed principally
of olivine and enstatite.
Lancé, Loir-el- Cher, France.

-The Lancé meteorite was examined microscopically by Dr. Richard v. Drasche. It
belongs to the chondritic type of Rose, and in the thin section showed a confused
groundmass holding a great number of rounded forms of varying structure, together with
isolated crystal fragments. The spherules were found to be composed either of olivine or
of bronzite (eustatite). Iron and pyrrhotite also were seen. .

Drasche sums up the structure of the rock as follows: The meteorite is formed by
many isolated olivine crystals, and here and there a bronzite, together with a large
number of spherules of two different kinds, lying in a tufaceous powder. The spherules
are either regularly or irregularly arranged aggregates of olivine, or they are formed. of
bronzite needles radiating eccentrically. Plates with a full description of the meteorite
were given by Drasche.t

Tourinnes-la- Grosse, Belgium.

The Tourinnes meteorite was studied microscopically by the Rev. A. Renard, S. J.

He found that upon the fractured surface the rock was of a grayish-white color, fine-
granular in structure, and with but little coherence.

Under a Jens small spherules of a grayish-brown or a pale-gray color were seen, also
yellowish points of pyrrhotite. This meteorite belongs to the chondritic type of Rose.

Under the microscope the groundmass is found to have but little coherence, and to be
formed by an agglomeration of particles, the chief of these being non-cemented grains of
olivine of irregular contour. Porphyritically inclosed in this granular groundmass were
observed iron, pyrrhotite (troilite), enstatite, and olivine.

The nickeliferous iron is in the form of indented, cellular grains. The enstatite is
gray or colorless, and possesses a fibrous structure.

The olivine shows the same characters as it does in the terrestrial peridotic rocks. It
does not appear that the irregularity of the grains was necessarily due to mechanical
action, since the same structure is to be seen in the terrestrial peridotic rocks, as for
instance that from the St. Paul’s Rocks.

The chondri were separated into two groups: those formed from prisms and fibres
of enstatite, and those formed from an agglomeration of olivine granules.

Renard held that the chondritic structure was different from any terrestrial form, and
that it was produced through the projection of incoherent volcanic matter, which through
its agglomeration formed the tufaceous-like meteorites.

Waconda, Mitchel Co., Kansas,

Some description of this meteorite has been given by C. U. Shepard and J. L. Smith.§

According to the latter it is composed of iron, pyrrhotite (troilite), olivine, and

* Phil. Mag., 1863 (4), xxv. 50-58. + Min. Mitth., 1875, pp. 1-8.
+ Mem. Soc. Belge Micros., 1879, v. 43-50.
§ Am. Jour. Sci., 1876 (8), xi. 473, 474; 1877, xiii. 211-213.

94 PERIDOTITE.

pyroxene minerals. The specimens purchased for the Whitney Collection from Ward
and Howell show an ash-gray groundmass, stained with brownish spots of rust, and con-
taining grains of grayish-brown olivine.

Section: a yellowish-brown and grayish groundmass containing iron. On one side a
black band forming the exterior (rind) of the meteorite is preserved. The groundmass
is composed of olivine grains with some enstatite. The yellowish-brown color is owing
to a ferruginous staining of the silicates, while the rind is composed of the same minerals
as the interior, but owing to the heat to which it has been exposed it has been burned
black. Clear grains of untouched silicates (olivine and enstatite) are to be seen both in
the interior and in the crust.

In one corner of the section a small amount of a fine ash-gray semi-base was
observed cementing olivine grains.

The mixed enstatite and augite with iron, and a ferruginous stained groundmass are
shown in figure 4, Plate IIT.

: Goalpara, India.

The Goalpara meteorite, according to Tschermak, is a dark-gray granular rock, having
a porphyritic structure. In the deep-gray groundmass are inclosed clear colorless and
yellowish grains.

On microscopic examination the meteorite was found to be composed of enstatite,
olivine, iron, and pyrrhotite.

The enstatite shows well-marked cleavage-planes running in two directions, forming
an angle of 92° with each other. The olivine has no cleavage, and does not occur in
distinct crystals, but in minute grains united together. The groundmass in which the
olivine and enstatite are inclosed is very fine-grained. Microscopically it is seen to be
composed of minute transparent grains, apparently olivine, and untransparent forms.
These last are of three different kinds: iron, pyrrhotite, and coal-like bodies. The iron
forms a sponge-like mass, with extremely thin cell-walls composed of cubic crystals. The
coal-like bodies are described as being in all their properties similar to soot (graphite ?).
The groundmass is said to appear in branching, leaf-like, thread-like, and dot-like forms,
winding between and around the grains forming the olivine clusters.

The student is referred to Tschermak’s paper for the complete description and figures
illustrating the microscopic structure.*

Variety. — Lherzolite.

Pultusk, Poland.

The Pultusk meteorite on the fresh fracture shows, according to Werther, as a light-
gray rock, part very fine-grained, and part of a somewhat coarser texture. This is
interspersed with numerous white and yellowish points, showing metallic lustre, also
brownish-yellow spots in the groundmass. He regards the rock as composed of nickel-
iron, olivine, enstatite (?), and chromite.

This meteorite was further described by Dr. G. vom Rath as composed of a fine

* Sitz. Wien. Akad., 1870, Ixii. (2), 855-865.
+ Schriften, Kéngsberg Gesell., 1868, ix. 35-49.

j

—_

THE METEORIC PERIDOTITES. — LHERZOLITE. 95

granular to compact groundmass, containing nickel-iron, pyrrhotite, spherules, olivine,
white crystal grains, and chromite. He states that the nickel-iron occurs in three differ-
ent forms: in large grains, in lamine, and in ramifying, pronged grains sprinkled through
the groundmass. The surrounding groundmass is sometimes stained, through the altera-
tion of the iron, to a brown color.

The pyrrhotite occurs in small irregular grains and granules of a tombac-brown color,
which, through a slight alteration, change to a dark steel-gray.

The chromite is in very small black non-magnetic grains, and only in minute
amounts. *

The specimen purchased from Ward and Howell for the Whitney Collection has an
ash-gray color and shows a chondritic structure. It contains pyrrhotite and iron.

Section: composed of a light-gray chondritic mass, containing grains of iron and
pyrrhotite. The groundmass is composed of olivine, enstatite, and some diallage. The
chondri are formed, in part, of grains and crystals of olivine and of enstatite, cemented
by a gray, fibrous base. Like those examined by the writer in other meteorites he regards
these as the product of an arrested crystallization in a rapidly cooling mass —the
solidification taking place before crystallization was complete. Part of the enstatite
chondri do not show the usual eccentric structure, but a parallel, or sometimes a very
irregular one.

The arrangement of the pyrrhotite and iron about some of the chondri reminds one
of the similar arrangement of the rejected or “ pushed out” material about the feldspars
in some andesites.

The iron is in part outside of, and in part entirely surrounded by, the pyrrhotite.

Figure 1, Plate III., shows a large chondrus at the base of the figure, composed of
enstatitic, aggregately polarizing, fibrous material. The form shows the rounded indenta-
tions seen by Tschermak in the Tieschitz meteorite, and at its upper portion blends with
the groundmass, although distinct from it elsewhere. Under the microscope its boun-
daries appear to be those of a crystallizing mass and not those of a foreign inclusion in
the groundmass. At the left of this chondrus is another radiating fibrous one, com-
posed of enstatite ribs cemented by connective tissue of gray base, holding metallic iron
grains. The remaining portions of the figure are composed of mixed chondri and the
constituents of the rock.

Figure 2, Plate III., shows the structure of a chondrus composed of olivine, enstatite,
iron, base, ete., with its blending at the bottom of the figure into the groundmass.

Figure 3, Plate IIL, shows the relations of a mass of pyrrhotite (troilite) to an
inclosed mass of metallic iron, and the whole surrounded by the chondritic groundmass.

New Concord, Guernsey Co., Ohio.

A crystalline granular rock containing pyrrhotite and iron, and showing yellowish-
brown spots of staining around the latter.

Section: a light-gray crystalline mass of olivine, pyroxene and enstatite, and con-
taining iron and pyrrhotite. The groundmass is stained a yellowish-brown in many
places.

* See further the original paper of vom Rath. Abhandlungen aus dem Gebiete der Naturwissenschaften,
Mathematik, und Medicin als Gratulationsschrift der niederrheinischen Gesellschaft fiir Natur-und Heilkunde
zur feier des fiinfzigjahrigen Jubiliums der kéniglich rheinischen Friedrich-Wilhelms-Universitat. Bonn.
Am 3 August, 1868, pp. 135-161, with plate.

96 PERIDOTITE.

The enstatite, pyroxene, and olivine are in clear grains when unstained, and are much
fissured and broken.

Some of the enstatite shows the same structure as the chondri of other meteorites
except that it wants the cementing base. That is, these grains are formed from minute
erains arranged in rod-like forms, and lying side by side. The iron and pyrrhotite is in
irregular masses and granules. Some colorless irregular patches were observed, giving
a pale color in polarized light and resembling nephelite.

Figure 1, Plate IV.,shows the general structure of the groundmass, with its inclusions
of iron, pyrrhotite, etc., and its ferruginous staining. This groundmass is fine-granular,
with some traces of chondritic structure.

Moes, Transylvania.

This meteorite has been described by Koch, Tschermak, and Brezina, and the follow-
ing is condensed from Tschermak’s description. On the fresh fracture the rock appears
as a gray and white, rough, friable mass, flecked with little brown and yellow spots, and
traversed by fine black veins. The grayish-white groundmass contains small spherules
of varying size, small grains of iron and pyrrhotite, and occasionally larger grains of iron.
Those chondri which are granular and vary from a white to a yellowish color are com-
posed of olivine, but those of a white color and of a fine rod-like or fibrous texture are
composed of enstatite. Under the microscope the stone was found to contain olivine,
enstatite, diallage, plagioclase, iron, pyrrhotite, rarely chromite, and a black undetermined
mineral. The olivine is pale-yellowish green, and contains irregular inclusions of a fine
black dust, angular black grains, and glass. The enstatite has a pale-greenish color, and
contains brownish, rounded glass inclusions, spherical and lens-shaped vapor cavities, and
small black spheres. The diallage contains inclusions of abundant black dust and grains,
and glass, with some microlites. Part of the diallage presents the characters of diopside.
The plagioclase appears in colorless rounded grains, containing many irregular, brownish,
glass inclusions. In polarized light many of the feldspars show well-marked character-
istic twinning. The iron is in small spheres in the groundmass and in the chondri, as
well as in rounded and elongated rough grains, sometimes showing a cubic cleavage.
The pyrrhotite occurs in minute grains.*

Zsadany, Temesvar Conutat, Banat.

Dr. E. Cohen made a microscopic study of the Zsadany meteorite in 1878. Macro-
scopicaliy, the following constituents were observed: —

1. A fine-crystalline, light-gray groundmass, in which appeared scattered grains with
a conchoidal fracture and a vitreous lustre. These were mostly water-clear or else of
a pale honey-yellow color.

2. Grains of the color of pyrrhotite, and grains or leaves of nickeliferous iron.

3. Numerous dark gray crystalline spherules, with a rough surface, and a faint
resinous lustre on the surface of fracture. On the polished surface they show an
elliptical form.

In the thin section two classes of these spherules were seen. One is composed of
small columns of an enstatite-like mineral. This contains a few small pores, and

* Koch, Min. Mitth., 1883, v. 234-244; Sitz. Wien. Akad., 1882, Ixxxv. 1, pp. 116-132; Tschermak,
ibid., pp. 195-209 ; Brezina, ibid., pp. 335-348.

|
.

ee ae

se

THE METEORIC PERIDOTITES. — LHERZOLITE. 97

between the columns a cloudy substance was observed. Cohen is in doubt whether this
substance is an alteration-product or has intruded.

The second is formed from aggregations of round or angular olivine grains and a
cloudy substance. The olivine and enstatite also occur in the groundmass. The enstatite
incloses some opaque grains and colorless microlites. The olivine contains some pores
which are for the most part empty, but some of them appear to hold a little fluid.

_Cohen thought that an accessory mineral observed was hypersthene. Pyrrhotite and
nickeliferous iron were also seen. Between all these constituents lies a cloudy, very
rarely feebly transparent substance which appears to be identical with that observed in
the spherules.

Cohen seems to adopt the mechanical theory for the origin of chondritic structure,
but, following Giimbel, holds that the eccentric radiated structure of many of the
spherules is owing to a secondary formation.*

Cohen’s cloudy substance is doubtless the gray, fibrous, base and semi-base observed
by the present writer in other meteorites — like the Iowa one, for instance.

Estherville, Eminet Co., Iowa.

The Estherville meteorite has a grayish granular groundmass, holding irregular graias
of olivine and diallage. The olivine grains are of various sizes, from minute ones to
those two inches in diameter. Scattered through the mass, in irregular nodular jagged
forms, occurs the iron. Some bluish-gray fragments were seen inclosed, but of an
unknown nature, although they may be olivine. The groundmass is identical in appear-
ance with that of the finer-grained peridotites, and, excepting the iron, the rock is strik-
ingly similar to some from North Carolina.

Two or three patches composed of yellowish-green olivine, and a glassy white mineral
were seen. The latter resembles feldspar or quartz, but it would probably not be found
in the section, or by chemical analysis, unless especial portions were taken for examina-
tion. The iron shows imperfect dodecahedral forms with striated faces. One imperfect

‘form resembled a cube face modified by two pentagonal dodecahedral planes. A few small

black grains were seen resembling picotite or chromite. The crust in some places shows
that it was derived from the fused olivine; hence if the fusion point of this olivine could
be ascertained, it would give the minimum temperature of the surface during its passage
through the air. The specimen above described, in the Harvard College Cabinet, is said
to weigh twenty-eight pounds, and it affords, on account of the large extent of its frae-
tured surface, a good opportunity to study the macroscopic characters of this peridotite.
This specimen, in some places, shows the remains of an internal cavernous structure, its
cell-walls being lined with minute crystals.

Section: a grayish groundmass, holding grains of enstatite, olivine, and diallage, with
iron and pyrrhotite. The groundmass is composed of a crystalline, granular aggregate of
these minerals.

The olivine is in clear, rounded grains, of irregular outline. Lying in the olivine
are numerous grains and irregular masses of iron, which are usually confined to certain
portions of the mineral, and are wanting in some crystals. Besides the larger, easily
recognizable, irregular, semi-sponge-like masses of iron surrounding, projecting into, or
included in the olivine, drop-like forms are seen extending in irregular lines from

* Verh. Natur. Med. Verein, Heidelberg, 1878, ii. (2), 154-163.
es 13

YZ ‘

9§ PERIDOTITE.

points on the larger iron masses through the silicate. These globules are of every size,
from those whose metallic lustre and character can be readily recognized with low
powers to those remaining a fine dust when magnified one-thousand diameters. It cannot
be said that the finer dust-like portions, resembling the globules in the basaltic base, are
the same as the larger globules of iron; but the gradual transition in size between the
grains of different sizes, and, with the increase in power, the increase in number of
globules that can be recognized as metallic iron leads one to suspect that all these gran-
ules, whatever may be their size, are of the same origin and material—iron. These forms,
in the minute state, are similar to some of the inclusions in the olivine of the Cumber-
land pallasite, but in the latter case the iron, if occurring, would be oxidized. Some of
the olivine grains show a fine cleavage adjacent to the cross fissures.

The enstatite is in irregular and oval masses, with a perfect longitudinal cleavage and
a cross fracture. The extinction takes place in polarized light parallel to the cleavage.
The enstatite contains inclusions of olivine and of iron, the same as previously described
in the olivine.

The diallage has an irregular longitudinal cleavage, its forms being the same as those
of the enstatite. The cleavage lines of the diallage are either cut by irregular cross-
fractures, or connect by oblique fissures, so as to give an irregular network over the face,
rendering it more obscure and cloudy. The extinction is oblique to the principal
cleavage planes. It contains the same inclusions as the enstatite. While the olivine,
enstatite, and diallage are all clear, transparent, and colorless in the thin section, yet
their cleavage characters are so distinct that in general they can readily be distinguished
from one another without the use of polarized light.

The iron and pyrrhotite are in detached granules, droplets, irregular jagged masses,
and in imperfect sponge-like forms. In some cases they form an irregular net-work in
the groundmass, and in an imperfect ring surround the larger grains of olivine, enstatite,
and diallage. The material for the above described sections was purchased from W. J.
Knowlton of Boston.

Figure 5, Plate III., represents a central crystal of diallage with the surrounding
groundmass of olivine, enstatite, diallage, iron, pyrrhotite, and the ferruginous staining.

Figure 6, Plate III., shows the semi-sponge-like mass of.iron and pyrrhotite with
their inclosed silicates, forming a groundmass holding two porphyritic crystals of dial-
lage and enstatite, showing their characteristic cleavages and inclusions, although the
latter are imperfectly represented.

Attention was originally called to this very interesting meteorite by Prof. 8. F. Peck-
ham, who stated that a preliminary examination showed that the metallic portion was
an alloy of iron, nickel, and tin. “Full half the mass consists of stony matter which
appears in dark-green crystalline masses embedded in a light-gray matrix. .. . Some
of the crystalline masses are two inches in thickness, and exhibit distinct monoclinic
cleavage. Under the microscope, in thin sections, olivine, and a triclinic feldspar appear
to be imbedded in a matrix of pyroxene. ... A small piece of the metal polished
and etched exhibited the Widmanstiittian figures very finely.”* Prof. C. U. Shepard, in
the same volume (pp. 186-188), gives a further description of this meteorite. He writes:
“Tt is marked by the unusual prevalence of chrysolite and meteoric iron, the former
probably constituting two-thirds its bulk; also by the size and distinctness of the
chrysolitic individuals, together with their pretty uniform, yellowish-gray or greenish-

* Am. Jour. Sci., 1879 (8), xviii. 77, 78.

THE METEORIC PERIDOTITES. — LHERZOLITE. 99

black color; and by the ramose or branching structure of the meteoric iron. Nearly
one-half of the chrysolite, however, is more massive, approaching fine-granular, or com-
pact. Yet in this condition it is still highly crystalline, and difficultly frangible. This
portion is of an ash-gray, flecked with specks of a dull greenish-yellow color. The
lustre is feebly shining. . . . Especially is it observable that tle stony portions nowhere
present traces of the oolitic, or semi-porphyritic structure, so common in meteoric
stones. ..

-“The meteoric iron, besides being in ramose branches, is also in enveloping coatings
around the chrysolite, somewhat as in the Pallas and Atacama irons.... The
presence of schreibersite in the metal is apparent to the naked eye.” The minerals that
Shepard supposed that he found were chrysolite, schreibersite, chromite, troilite, a “ felds-

_ pathic mineral, presumably anorthite,” and an “opal-like mineral of a yellowish-brown

color, which I take to be chassignite.”

Later, J. Lawrence Smith made a further examination of the Estherville meteorite.*
He found olivine, bronzite, nickeliferous iron, troilite, chromite, and an opalescent silicate.
The last has a light, greenish-yellow color, and cleaves readily. It was regarded as
formed from one atom of bronzite plus one atom of olivine. Smith further says: “I
examined carefully for feldspar and schreibersite, but the absence of both lime and alu-
mina (except as a trace) clearly proved the absence of anorthite; and the small particles
of the mineral that might have been taken for schreibersite, were found on examination

" in all instances to be troilite.”

Dr. Smith’s chemical analysis was made in such a manner that it is impossible from
it to draw any conclusions as to the relative proportion of the elements in the mass as
a whole.

Later,t Smith named the “opalescent silicate” peckhamite, and thought from his
farther analyses that it was probably composed of two atoms of bronzite to one of oli-
vine

In 1882 Dr. Stanislas Meunier described the microscopic characters of the Estherville
peridotite, which he referred to the logronite type of meteorites —one of the 43 types
proposed by him in 1870. He found the following minerals: olivine, bronzite, pech-
hamite ? pyrrohotite, schreibersite, magnetite, and nickeliferous iron.

The olivine is in very large crystalline fragments, yielding in polarized light a most
brilliant colored mosaic. In common light they are colorless, often cleaved and filled
with crystalline inclusions. Liquid bubbles in spheroidal cavities, remarkable for their
large size, were seen. In converging light the crystals show two systems of brilliant
rings, whose axes show strong dispersion.

The bronzite is in poorly formed crystals, clearly dichroic, and showing a well-marked
parallel rectilinear cleavage.

The peckhamite is in large, feebly colored crystals, composed of alternations of lamine,
inversely affecting polarized light. The action of acids upon them causes one to regard
this mineral as composed of extremely thin interlaminated layers of bronzite and olivine.
The magnetite is in perfect octahedrons.

M. Meunier concludes as follows: “In presence of these different characters of com-
position and structure, it is seen that the identity is complete with the logronite already

* Am. Jour. Sci., 1880 (3), xix. 459-463, 495, 496.
+ Am. Jour. Sci., 1880 (3), xx. 186, 137.
+ Cosmos, 1870 (3), vi. 70-73, 95-98, 152-155, 186-188, 210-215.

100 PERIDOTITE.

described. We must believe with respect to the Estherville form, that the primitive
mass in the condition of debris, in part stony, in part metallic, accumulated in some
crevice, has been subjected to metalliferous emanations, of which the product, under the
form of a fine network, has soldered together the components previously disconnected.
The spaces — so remarkable — existing sometimes between the modules of iron and their
rocky matrix, are artificially reproduced in the process of metallic cementation of the
dust of peridot, by a method which I have already described.” *

The present writer finds himself obliged to dissent from M. Meunier's views regarding
the origin of this meteorite, for the following reasons: He (the writer) can nowhere
in the sections find any evidence that its materials ever held any different relation than
the present, and no sign of a former fragmental state is observable to him; but he does
see evidence that is convincing to him that the entire mass has been formed by cotem-
poraneous crystallization, i. e., it has the same structure that a terrestrial lava of the
same composition, cooling under conditions that would allow the entire mass to crystal-
lize, would have. The inclusion of the iron in the silicates, indicating their later solidifi-
cation, would show that the iron was not a posterior emanation. Such a formation as
M. Meunier supposes could not take place without leaving a record behind of its action.

It has been hoped that a complete microscopic description would have been pub-
lished by Professor C. W. Hall, of the University of Minnesota (see Professor Peckham’s
paper before referred to, page 98); but thus far he has been unable to get time for the
work. Professor Hall has very kindly sent me some of his sections for examination,
and the additional information obtained from them is given below.

The sections sent by Professor Hall are, in their general and mineralogical char-
acters, so unlike those already described, that were it not for the source from which
they were obtained, it would be very difficult to believe that they came from the same
meteorite.

They have a confused light-greenish-yellow groundmass, holding irregular masses of
olivine, enstatite, and feldspar. The groundmass appears to be composed of olivine,
enstatite, feldspar, pyrrhotite, and magnetite. But little native iron is to be found in the
sections. The groundmass is stained a ferruginous yellow in many places, and the com-
mencement of a serpentinous alteration was seen in some of the olivines.

The feldspar is in irregular glassy masses, and in imperfect crystals, showing stria-
tion and extinction oblique to the nicol diagonal. They contain inclusions apparently of
olivine, enstatite, magnetite, bubble-bearing glass cavities, etc.

The olivine and enstatite contain also glass inclusions, magnetite, etc. The enstatite
in some places is dichroic along its cleavage planes, owing to its slight greenish altera-
tion.

These sections, having been prepared by a student, are of such thickness, and ground
with so uneven a surface, that the study of them is very difficult. A few grains resem-
ble quartz, but they are probably unstriated glassy feldspars. My thanks are due Pro-
fessor Hall, and I regret that I cannot profit more by his kindness. These sections are
so much unlike those previously described, that I trust he will have further and thinner
sections made, and publish a complete description of them himself. +

From the various descriptions given it is to be concluded that the Estherville perido-
tite varies considerably in its mass, in different portions — from those parts entirely iron,

* Comptes Rendus, 1882, xciv. 1659-1661.
+ It is probable from their alteration that the material from which these sections were made had b2en
exposed to atmospheric agencies for some time.

_—_——

THE METEORIC PERIDOTITES. — BUCHNERITE. 101

those of a sponge-like iron mass holding silicates, those of but little iron with the sili-
cates, and those that are pure or nearly pure silicates. If detached portions should be
taken and analyzed chemically and microscopically, it could be claimed that this meteorite
is a siderolite — a pallasite — a peridotite, and all be equally correct so far as the portion
examined would show; but studying this meteorite as a whole, its proper place both
chemically and microscopically appears to be with the peridotites. The variations in the
descriptions given by the different observers who have examined this meteorite, are
doubtless owing, in many cases, to the actual variation in the rock itself. It offers a
striking illustration of the need of some more general method than a purely mineralogi-
cal one in naming rocks.

Since the preceding was written, specimens of this meteorite, containing peckhamite,
have been received from Professor Peckham. The sections present for the mass of the
meteorite the same composition and structure as those obtained from Professor Hall.
The peckhamite presents the optical characters and cleavage of enstatite, but is filled
entirely full of vapor cavities, iron, glass, brown grains, etc. To these inclusions is appar-
ently owing the coloid appearance of peckhamite, and the variation in its analysis; while
Meunier probably mistook plagioclase for this mineral.

VARIETY. — Buchnerite.

Tieschitz, Moravia.

A microscopic study of the Tieschitz meteorite has been made by A. Makowsky and
G. Tschermak. The color of the meteorite on its inner surface is ash-gray, and it has
a chondritic structure. It shows many minute deep-eray, or dark-colored globules and

_ splinters, and occasionally larger spherules of the same color ; also, little white globules

and fragments, which are subordinate in amount to the former. Lying between them
were seen an ash-gray earthy groundmass, and a very few yellowish particles showing
metallic lustre. Certain characters of some of these spherules had never been described
previously in any other meteorite. Some show a concave impression upon them, indi-
eating plasticity during their formation. Some of these latter spherules also show out-
side of these concavities an excrescence having a round or pointed termination. These
characters not harmonizing well with Tschermak’s friction theory of the formation of
the globules, which will be later given in this work, (pp. 109, 110), he adopted a new
theory, that while these grains are the result of volcanic eruption and explosion, their
form could be derived from their plastic condition, instead of from the friction of solid
particles as he had held before.

The general characters of the meteorite were much the same as those of the preced-
ing. Olivine, bronzite, enstatite, augite, pyrrhotite, and nickeliferous iron were the min-
eral constituents observed.

The olivine was found in the groundmass, and in some of the spherules. Inclusions
of black angular grains, and of brownish glass with fixed bubbles, were seen.

The bronzite is principally in stalk-like and fibrous forms. It contains also inclus-
ions of brown glass, with immovable bubbles.

The enstatite has about the same form as the bronzite, contains the same inclusions,
and is white or of a pale color. It occurs in chondri and fragments. Augite was found
in small amounts in globules, having the same inclusions as the olivines.

102 PERIDOTITE.

The pyrrhotite occurred in small grains, not only in inclusions in the globules and

fragments, but also in the groundmass.
The iron is mostly in irregular pronged particles in the groundmass. *

Lungen, Germany.

The Hungen meteorite has been described both by Buchner and Tschermak. Tscher-
mak stated that the section showed quite large particles of iron, a few small grains of
magnetite, with fragments of minerals and spherules in the groundmass. Some small
untransparent grains without metallic lustre were thought to be chromite or picotite.

The other minerals were olivine and bronzite, besides brown angular grains that
were supposed to be augite. This, like nearly all the meteoric peridotites, is chondritic.
Needles and grains of a water-clear mineral, and fine grains of chromite were seen in
the olivine. The enstatite contained brown needles and grains, as well as the chromic
iron dust.f

Grosnyja, Caucasus.

The color of the interior of the Grosnaja meteorite, according to Tschermak, is a
blackish-gray, sprinkled with clear to whitish-colored points. In the section the
eroundmass is black and opaque, while many of the inclusions were either opaque or
transparent only in spots. Other inclusions were transparent, and showed mostly a
spheroidal structure, although a few pieces were angular.

Tschermak distinguished five different minerals: a clear-green olivine, bronzite,
augite, pyrrhotite, and a carbonaceous mineral. Iron in very small amounts was also
found.

This meteorite showed chondritic structure, as seems to be usual with the olivine-
enstatite ones.{

Alfianello, Brescia, Italy.

This meteorite has been microscopically studied by Baron von Foullon. It has a
chondritic structure and is composed of nickeliferous iron, olivine, bronzite, an augitic
mineral, pyrrhotite, and maskelynite. The fresh fracture shows a pale-grayish white
finely crystalline surface sprinkled with pyrrhotite. The olivine is of a light color and
generally in grains. The bronzite is somewhat of a light-yellowish to brownish-yellow
color, and shows cleavage lines. The maskelynite was found as an intergrowth with the
bronzite, occurring as a colorless, water-clear substance.

The chondri are irregular and show about the usual structural varieties. §

* Denks. Wien. Akad., 1879, xxxix. (2), 187-202, 5 plates; Sitz. Wien. Akad., 1878, Ixxviil. (1),
440-443, 580-582; Verh. Nat. Verein, Briinn, 1879, xviii. 40, 41.

+ Min. Mitth., 1877, pp. 318-316.

{ Min. Mitth., 1878 (2), i. 153-164.

§ Sitz. Wien. Akad., 1883, Ixxxviii. (1), 433-443.

THE METEORIC PERIDOTITES. 103

MISCELLANEOUS.

Bavarian Meteorites.

In 1878 Prof. C. W. Giimbel gave an account of his microscopic examination of five
meteorites that had fallen in Bavaria at different dates during the 18th and 19th
centuries. Four of these are described below, and one later under 7he Pasalts.

1. The Mauerkirschen Meteorite.

_ This rock is of a light-gray color, with black spots of metallic iron, which in places
show oxidation. It has a very fine-grained groundmass, which incloses blackish and
yellowish grains. The stone shows the chondritic structure, and has the usual charac-
ters. The groundmass contains fragments and grains of the various minerals.

Giimbel holds that this meteorite contains olivine, a feldspathic and an augitic
mineral, pyrrhotite, chromite, and iron.

2. The KEichstadt Meteorite.

This rock also belongs to the chondritic meteorites, and was thought by Giimbel to
contain an augitic and two feldspathic minerals, as well as olivine, iron, pyrrhotite, and
chromite.

3. The Schénenberg Meteorite.

This, like the preceding, belongs to the chondritic type, and was thought by Giimbel
to contain the following minerals: olivine, iron, pyrrhotite, chromite, schreibersite, a
feldspathic, a scapolitic, and an augitic mineral.

4. The Krédhenberg Meteorite.

According to Giimbel this chondritic rock contained olivine, pyrrhotite, iron, chromite,
an augitic mineral (bronzite ?) and a feldspathic mineral (labrador ?).*

It is not probable that the meteorites above described by Giimbel in reality differ
much in mineralogical characters from the common forms, the determinations being here
thought to be imperfect. It is therefore to be hoped that in the light of the advances
made in the knowledge of the microscopic characters of minerals, a reéxamination will
be made to these meteorites.

Charlottetown, Cabarras Co., North Carolina.

This stone is described as having, on the fresh fracture, a dark, bluish-gray ground-
mass, holding porphyritically inclosed crystals and grains of a grayish-white mineral,
with a tinge of lavender-blue.t

The specimen in the Harvard College Cabinet shows the usual chondritic structure,
and contains considerable iron. The grayish-white minerals, with a tinge of lavender-
blue, are the chondri, which are well marked in this meteorite. It possesses a striking

* Sitz. Miinchen Akad., 1878, viii. 14-72.
+ C. U. Shepard, Proc. Am. Assoc. Ady. Sci., 1850, ii. 149-152.

104 PERIDOTITE.

similarity to the Iowa Co. meteorite, although the chondri are somewhat smaller.
Judging from the general characters of the Cabarras meteorite, it is probable that
Shepard’s analysis is incorrect, and it is hoped a new one will be made.

Other specimens of meteoric peridotites in the Harvard College Mineral
Cabinet, macroscopically examined by the writer, are : —

Mezo-Madaras, Transylvania.

This shows a somewhat coarse chondritic structure, and contains grains of iron and
pyrrhotite.
Alessandria, Piedmont.

This has a grayish groundmass showing an imperfect chondritic structure, and con-
tains considerable iron in grains and in films running through it.

Renazzo, Ferrara, Italy.

This has a dark surface or groundmass, holding grayish-white rounded grains or
chondri. Since this specimen shows no fresh fracture, but little can be said about its
characters. It resembles closely, in external appearance, some of the Cordilleran
andesites, possessing a dark, glassy groundmass holding rounded, glassy feldspars.

This meteorite has been described before as similar to an obsidian-porphyry and
possessing a compact, black, enamel-like groundmass, holding numerous _light-gray
spherules.*

This meteorite ought to be studied microscopically, for it promises to be one of the
most interesting specimens examined by that method, and will probably throw much
light upon the origin of meteorites, especially if it should prove to be, as it appears, less
devitrified than other meteorites microscopically examined.

Hartford, Linn Co., Iowa.
This has a light-gray granular groundmass showing chondritic structure, and is
sprinkled with metallic particles.
Ausson, Haute Garonne, France.

The specimen shows a gray groundmass, and possesses a well-marked chondritic
structure.

Naiyemoy, Maryland.

This is the same as the Ausson rock, except that its structure is of a finer character.

Drake Creek, Sumner Co., Tennessee.

This has a light-gray, fine-eranular groundmass, sprinkled with iron in various forms.
This stone closely resembles that from Hartford, Linn Co., Iowa.

* Buchner, Meteoriten in Sammlungen, 1863, pp. 46, 47.

]

THE METEORIC PERIDOTITES. — TUFA. 105

LP? Aigle, Orne, France.

This possesses a gray groundmass, holding chondri. One of the chondri shows a
concave depression, the same as those described by Tschermak as occurring in the
Tieschitz meteorite. (See ante, page 101.)

Weston, Connecticut.

This shows the same gray groundmass as the preceding, and an excellently developed
chondritic structure.

Chiteau Renard, France.

This has a light-gray groundmass, sprinkled with metallic points.

Hessle, Sweden.

This has a grayish chondritic groundmass.

Nobleboro’, Maine.

This specimen is apparently fragmental in character, and closely resembles a trachytic
or rhyolitic ash. The specific gravity, according to Webster, is 2.08, but, according to
Rumler, 3.092. It is probable that Webster’s chemical analysis is not correct, the speci-
men, if authentic, not bearing out any such analysis as that published by him.*

This meteorite ought to be reéxamined chemically, and studied microscopically.

Variety. — Tufa.
Orvino, Italy.

The structure of the Orvinio meteorite is described by Tschermak as uncommon and
remarkable. The rock is composed of clear-colored fragments, surrounded by a compact,
dark, cementing mass.

The fragments are yellowish-gray, and contain spherules and particles of iron and
pyrrhotite. The cementing material is blackish, compact, and splintry, holding nearly
uniformly-distributed particles; and near its contact with the fragments shows an
evident fluidal structure. This makes it in the highest degree probable that the cement-
ing material was once in a plastic condition and in motion. The fragments are darker,
harder, and more brittle at the junction with the inclosing mass than they are in the
middle. From this it would seem that the matrix had been at a very high temperature
when plastic.

The fragments and matrix both have almost the same composition, density, and
mineral characters.

This meteorite resembles a voleanic rock in which a fine matrix holds fragments of
rock of the same character. The structure is the same as it is when a younger compact
lava breaks through an older and more crystalline one.

The fragments have the usual chondritic structure. They contain, besides iron and
pyrrhotite, olivine, bronzite (enstatite), and possibly some feldspar. For the further

* Bost. Jour. Phil., 1824, i. 386-389; Buchner, Meteoriten in Sammlungen, 1863, p. 46.
14

106 THE METEORITES. —THEIR ORIGIN AND CHARACTER.

description and figures the reader is referred to the original paper.* If Tschermak is
correct this meteorite must have come from a body either partly solid and partly liquid,
or one in which cooler fragments fell into the liquid mass.

Chantonnay, Vendée, France.

This is described by Tschermak as composed of olivine, bronzite, a finely-fibrous
translucent mineral, nickeliferous iron, and pyrrhotite. Its structure is similar to the
Orvinio meteorite ; that is, is composed of chondritic fragments cemented together by a
black, glassy and semi-glassy material. f

Section III.— The Meteorites. — Ther Origin and Character.

Ir is thought most convenient to enter upon these questions here in con-
nection with the largest class of authenticated meteorites. And in doing
this the views of those persons who have studied them microscopically will
be especially referred to.

Professor N.S. Maskelyne taught, in 1863, regarding the chondritic meteo-
rites : —

“that there have been stages in the progress of the slag-like mass from the first origin of
the spherule — in perhaps a seething lake of mixed and molten metals on which a rare
oxygenous atmosphere was acting and fermenting out as it were the more oxidizable ele-

ments — to the final state of compact continuity in which the spherules are found agglu-
tinated together or imbedded in a magma of mineral.” ¢

The previous year he had said: — -

“The spherules which characterize this structure are often composed of a single crys-
tallme and homogeneous mineral, with a radiating structure; often they are breccias
made up of several crystals of the same or of different minerals united by a granular
network of mineral. These spherules are often surrounded by a shell of meteoric pyrites

or iron, and are set in a mixed mass, often highly porphyritic, composed of similar ingre-—

dients with the spherules. The solidification of this ground-mass marks, probably, a
second stage in the history, the former indicating the very gradual separation by cooling
of some of the ingredients of the aérolite, and the latter the result of the further gradual
cooling of the residuary mass. There is no glass or uncrystallized matter apparent in
any aérolite yet examined.” §

Professor Maskelyne’s views were set forth again in 1875, but with great
caution and indefiniteness. The following extract gives the chief additional
point bearing on the chondritiec structure : —

“We may, perhaps, go so far as to suppose that if groups of the individual particular
units of a meteor cloud once should approach each other to a distance small enough to

* Sitz. Wien. Akad., 1874, Ixx. (1), 459-465. + Sitz. Wien. Akad., 1874, Ixx. (1), 465-472.
+ Phil. Mag., 1868 (4), xxv. 440. § Proc. Brit. Assoc., 1862, xxxii. (sect.) 188-191.

4

a.

4 SORBY’S VIEWS. 107

give their mutual gravitation a sensible influence, they might gradually collect into
masses, and acquire a cohesion more or less compact according to the conditions imposed
on such masses during their subsequent history. .. . We may, indeed, assert that the
meteorites we know have, probably all of them, been originally formed under conditions
from which the presence of water, or of free oxygen, to the amount requisite to oxidize
entirely the elements present were excluded; for this is proved by the nature of the
minerals constituting the meteorites, and by the way in which the metallic iron is dis-
tributed through them.” *

In 1864, Mr. H. C. Sorby announced the presence of glass and gas cav-
ities in the olivine of meteorites. He stated that

“the vitreous substance found in the cavities is also met with outside and amongst the
erystals, in such a manner as to show that it is the uncrystalline residue of the material
in which they were formed. . . . It is of a claret or brownish color, and possesses the
characteristic structure and optical properties of artificial glasses.”

Of the chondritic structure Mr. Sorby says, it appears that

“after the material of the meteorites was melted, a considerable portion was broken uy
into small fragments, subsequently collected together, and more or less consolidated by
mechanical and chemical actions. ... Apparently this breaking up occurred in some
cases when the melted matter had become crystalline, but in others the forms of the
particles lead me to conclude that it was broken up into detached globules whilst still

~ melted.” F

The same year Mr. Sorby remarked that the earliest condition of meteo-
rites was that of igneous fusion, but he thought that the Pallas iron afforded

“physical evidence of having been formed where the force of gravitation was much
smaller than on our globe, either near the surface of a very small planetary body, or
towards the centre of a larger, which has since been broken into fragments.” t

In 1865, Mr. Sorby developed his views still further, stating : —

“The character of the constituent particles of meteorites and their general microscopi-
eal structure differ so much from what is seen in terrestrial volcanic rocks, that it
appears to me extremely improbable that they were ever portions of the moon, or of a
planet, which differed from a large meteorite in having been the seat of a more or less
modified volcanic action. A most careful study of their microscopical structure leads me
to conclude that their constituents were originally at such a high temperature that they
were in a state of vapour, like that in which many now occur in the atmosphere of the
sun. . . . On cooling, this vapour condensed into a sort of cometary cloud, formed of small
erystals and minute drops of melted stony matter, which afterwards became more or less
devitrified and crystalline. This cloud was in a state of great commotion, and the parti-
cles moving with great velocity were often broken by collision. After collecting together
to form larger masses, heat, generated by mutual impact, or that existing in other parts

* Nature, 1875, xii. 485-487, 504-507, 520-523.

+ Proc. Roy. Soc., 1863-64, xiii. 333, 334; Phil. Mag., 1864 (4), xxviii. 157-159 ; Report Brit. Assoc,
1865, xxxv. 139, 140.

$ Geol. Mag., 1864 (1), i. 240, 241; Report Brit. Assoc., 1864, xxxiv. (sect.) 70.

108 THE METEORITES. — THEIR ORIGIN AND- CHARACTER.

of space through which they moved, gave rise to a variable amount of metamorphism.
In some few cases, when the whole mass was fused, all evidence of a previous history has
been obliterated ; and on solidification a structure has been produced quite similar to that
of terrestrial voleanic rocks. Such metamorphosed or fused masses were sometimes
more or less completely broken up by violent collision, and the fragments again collected
together and solidified. Whilst these changes were taking place, various metallic com-
pounds of iron were so introduced as to indicate that they still existed in free space in the
shape of vapour, and condensed amongst the previously formed particles of the meteorites.
At all events, the relative amount of the metallic constituents appears to have increased
with the lapse of time, and they often crystallized under conditions differing entirely from
those which occurred when mixed metallic and stony materials were metamorphosed, or
solidified from a state of igneous fusion in such small masses that the force of. gravita-
tion was too weak to separate the constituents, although they differ so much in specific
gravity. . . . I therefore conclude provisionally that meteorites are records of the exist-
ence in planetary space of physical conditions more or less similar to those now confined
to the immediate neighborhood of the sun, at a period indefinitely more remote than
that of the occurrence of any of the facts revealed to us by the study of Geology —
at a period which might, in fact, be called pre-terrestrial.” *

These views of Mr. Sorby were again given to the public, with additional
matter, in 1877. He then stated that

“it is very probable, if not absolutely certain, that the crystalline minerals were chiefly _

formed by an igneous process, like those in lava, and analogous volcanic rocks... .
Some [of the spherules] are almost spherical drops of trwe glass in the midst of which
crystals have been formed, sometimes scattered promiscuously, and sometimes deposited
on the external surface, radiating inwardly; they are, in fact, partially devitrified glob-
ules of glass, exactly similar to some artificial blow-pipe beads....I1.. . argue that
some at least of the constituent particles of meteorites were originally detached glassy
globules, like drops of fiery rain... . We cannot help wondering whether, after all,
meteorites may not be portions of the sun recently detached from it by the violent dis-
turbances which do most certainly now occur, or were carried off from it at some earlier
period, when these disturbances were more intense.” f

David Forbes stated that meteoritic stones are seen under the microscope

“to be an aggregation of fragmentary matter resembling a volcanic ash or breccia, in
which, whilst some of the particles have been in a molten state (the presence of both
glass and air cavities in them indicating that they were in the molten state when gases
or vapours were being given off), others show no signs of fusion; so that the structure of
meteorites confirms the views that they have been formed out of the débris of some pre-
viously existing larger mass, or even out of the ruins of some planetary body.” ¢

Dr. Stanislas Meunier has done much work in the study of meteorites,
published a large number of papers, and holds some decidedly original views
regarding their origin. He maintains that all have a common origin, and

* Geol. Mag., 1865 (1) ii. 447, 448. + Nature, 1876-77, xv. 495-498.
t Geol. Mag., 1872 (1), ix. 222-935.

OO ee

THEORIES OF MEUNIER AND TSCHERMAK. 109

possess types corresponding to rocks and structures of terrestrial origin,
i. e. to lavas, dunite, lherzolite, serpentine, breccias, pumice, metallic veins,
metamorphic rocks, etc. David Forbes thus concisely gives the views of
the former :—

“Meunier, who has of late written more copiously than concisely on the subject of
meteorites, whilst believing them to be fragments of broken-up planets, regards these
bodies as but the last stage in the evolution of planetary bodies, and suggests that the
moon is rapidly coming to this stage from the irregularities and incipient fissures visible
on its surface, its dissolution not having taken place before, owing to its greater magni-
tude; arguing still further, that once broken up into fragments, these would arrange
themselves concentrically according to their densities, those which before formed the cen-
tral part of the planet, which he regards as most heavy and metallic, on the outside;
and the others, according to their weight, in the interior. This arrangement he considers
accounts for siderites or meteoric irons having first fallen in the earliest ages of the
world, then the siderolites [pallasites], and afterwards the stone or aérolites proper; and
owing to the meteorites of some recent falls, particularly that of Hessle in Sweden, hav-
ing contained considerable carbon, he predicts the fall of a totally different class cf
meteorites in future. These hypotheses seem, however, to be but mere assumptions inca-
pable of proof, for although only some very few instances of siderites [siderolites] hav-
ing fallen in historic times are recorded, as compared to the much larger number of
aérolites ; still there is no proof that the proportion was different in prehistoric times,
especially as it is well known that the latter would be infinitely more likely to escape
observation than the former.” *

Prof. Gustav Tschermak, in 1875, taught that meteorites were the result
of the disruption of cosmical bodies by explosive agencies. He stated that

“the constitution of many of the meteorites shows that they are the result of a grad-
ual tranquil crystallization ; while others, on the contrary, are composed of fragments,
and are the product of disintegrating forces. The majority are made up of minute flakes
and splinters and of rounded granules.”

Following Haidinger, he regarded the chondritic meteorites as tufas, and

states that the spherules have the following characters : —

“1. They are imbedded in a matrix consisting of fine or coarse spiinter-like par-
ticles.

“2. They are invariably larger than these particles.

«3. They are always distinct individuals, never merging into each other or joined
together.

“4, They are quite spherular when composed of a tough mineral, and in other cases
merely rounded in form.

“5. They consist sometimes of one mineral, sometimes of several minerals, but
always of the same material as the matrix.

“6. The structure of the interior of a spherule is in no way related to its external
form. They are either fragments of a crystal, or have fibrous structure (the fibres

* Geol. Mag., 1872 (1), ix. 234.

110 THE METEORITES. — THEIR ORIGIN AND CHARACTER.

taking an oblique direction towards the surface), or have irregularly barred structure, or
are granular.

“These chondra bear no indications of having obtained their spherular form by crys-
tallization. . . . They resemble rather the spherules which are frequently met with in
our volcanic tuffs. . . . As regards the last mentioned chondra, we know them to be the
result of volcanic trituration, and to owe their form to a prolonged explosive activity in
a volcanic ‘ throat, where the older rocks have been broken up, and the tougher particles
have been rounded by continued attrition. The characters of the meteoric chondra indi-
cate throughout a similar mode of formation. . . . It is certain, in short, that the spher-
ules are the result of trituration.

“The [meteoric tuffs] are peculiarly characterized as containing no trace of a slag-like
or vitreous rock, nor enclosing distinct crystals in the matrix; in short they exhibit
nothing which their formation from lava would lead us to look for. All that is to be
seen in them is the triturated product of a crystalline rock. Some of the tufaceous
meteorites bear evidence of a later modification wrought by heat. . . . Others, again,
exhibit phenomena which can only be explained on the theory of their having under-
gone a chemical change subsequent to their formation. . . . Still, with the many proofs
which we possess of the action of heat, we have not yet met with a meteorite which
resembles a volcanic slag or a lava. Although the meteorites are comparable to vol-
canic tuffs and breccias, this comparison cannot be extended beyond a certain point.
The volcanic activity, of which the meteorites furnish evidence, consisted in the disinte-
gration of solid rock, in the modification, by heat and otherwise, of already solidified
masses. . . . It is, then, by explosive activity, and that alone, that the breccias and tuffs
which we find in meteorites have been formed. . .. The volcanic activity of which
those mysterious masses of stone and metal are evidence, may be compared to the violent
movements on the solar surface, the more feeble action of our terrestrial volcanoes, or the
stupendous eruptive phenomena of which the lunar craters tell the history. . .. Vol-
canic activity is a cosmical phenomenon in the sense that all star-masses at a stage of
their development exhibit a phase of volcanic activity.” *

The objections to the theoretical views of ''schermak, Sorby, Forbes, and
Maskelyne, can be briefly stated as follows: —

The chondritic structure appears to be limited to meteorites of a peculiar
chemical and mineralogical character, while all, even of this special kind, do
not possess such structure. Hence, if it was purely mechanical, one can
hardly see how this structure could be so localized, not even being universal
for this special class. Again, if the spherules are the broken-up, and rounded
fragments of prior existing rock, they should have the composition of that
rock as a whole, instead of generally being composed either of olivine and
base, or of enstatite and base. Also, they ought to show in their interior
the structure of the rock from which they were derived; while distinct
lines of demarkation, and a want of continuity, ought to exist between

* Phil. Mag., 1876 (5), i. 497-507; Sitz. Wien. Akad., 1875, Ixxi. 661-673.

y

THE CHONDRITIC STRUCTURE, 11]

each spherule and the adjacent matrix, as is the case with terrestrial rocks
so organized. Such a relation does not appear to exist, except rarely in
meteorites, but the chondri usually pass into the adjacent matrix the same
as the secretions formed by a cooled lava do into the surrounding magma.
So, too, we find different materials mixed in terrestrial tufas; and since dif-
ferent kinds of rock fall in meteorites, these supposed meteoric tufas, if of
mechanical origin, ought to contain all these different forms, instead of only
the same material as the groundmass.

As stated previously, it seems to me, from microscopic study of these

structures, that they do not show any evidence of fragmental origin, but
they show rather that they have been produced by rapid and arrested crys-
tallization in a molten mass; the result being in part due to the forms
which the olivine and enstatite tend to assume on crystallization. If time
enough had been given, an entire crystallization of the material would
have taken place, as in the Estherville peridotite, and in the common ter-
restrial peridotites. Of the latter, the crystallization is either complete,
or else the original structure has been obliterated by alteration. If we
could find rapidly cooled, unaltered terrestrial peridotic rocks, I should
expect to find in them the chondritic structure, the same as the Esther-
ville meteorite possesses the structure of an unaltered terrestrial peridotite,
and the meteoric pallasites possess that of the terrestrial ones.

A similar method of crystallization, with the production of a similar struc-
ture, has been observed by me in the crystallization of watery vapor on the
windows of horse-cars during extremely cold weather. When the window is
untouched the crystallization is after the usual manner, familiar to all as
occurring in our houses; but when the car-window has had this first deposit
removed, as is frequently done by passengers, for the purpose of looking
out, the abundant vapor of the crowded car is rapidly deposited on this cold
surface, and in such abundance as to give rise to similar elliptical and spheru-
litic figures, which in form and appearance resemble the chondritic forms the
more closely the more they interfere with the development of one another.
They also possess the eccentric-fan and ribbed structure so commonly seen
in the enstatite chondri — the radiation starting from one side. Again, on
interfering with one another, they tend to take a rounded, instead of an
angular or irregular form.

That rounded, drop-like masses should be inclosed in meteorites is natu-
rally to be expected, in case they came from the sun or any similar body, for

112 THE METEORITES. —THEIR ORIGIN AND CHARACTER.

material is continually being thrown up from their surfaces and falling back
again; and it is to be expected that some of these drops would be inclosed
and thrown up in other masses before they had been entirely liquefied,
although they were probably viscous.

So far as meteorites have been examined by me, they do not appear to be
fragmental in the sense of consolidated cold masses joined together. It is
possible that ‘they may be composed in part at least, of molten globules —
originally united in a pasty condition; but the uniformity of composition of
each spherule is a remarkable circumstance, if they are formed from drops.
One would suppose that each chondrus would possess all the elements of the
meteorite as a whole.

So fur as can be learned from the structure of most meteorites, it appears
to the writer that they must have come from a liquid mass, and that in the
majority of cases the length of time in which they passed from the liquid to
the solid condition was not great. The silicates held in the interstices of
metallic masses, like the pallasites, would have time to crystallize through
the effect of the heat of the surrounding iron, and the chondritic structure

would not be developed in this class as a rule, if at all; while Professor Ball’s*.

claim that meteorites must have been torn from a solid rock does not seem
to be borne out by the structure of the meteorites themselves. Starting
with the hypothesis that all cosmical matter was originally in a gaseous state,
and that this gas, through condensation or otherwise, was intensely hot, the
writer believes that the meteoric material, reaching the earth, was thrown
from some one or more of these condensing bodies, formed from this cosmi-
cal matter during its liquid or partially solid state. He holds that of these
bodies, the most probable one serving as the source of meteorites is the sun,
as suggested by Sorby — they either being thrown from it now, or in past
time, through eruptive agencies, whose action can now be seen upon its sur-
face. It is of course possible that any of the celestial bodies, when in the
incandescent condition, while eruptive forces were sufficiently active, might
be the originator of meteorites; but before any meteorites are attributed to
them, it is necessary that it should be shown that their probable constitu-
tion corresponds to that of the meteorites in question.

The number of elements common both to the sun and meteorites lends
some support to their relation as advocated here. These elements are iron,
titanium, calcium, manganese, nickel, cobalt, chromium, sodium, magnesium,

* Science for All, iv. 31.

——

THE ERUPTIVE ENERGY OF THE SUN. 113

copper, hydrogen, vanadium, strontium, aluminum, sulphur (?), oxygen,
lithium, tin, and carbon.

The question whether it would be possible for meteorites to be derived
from the sun by their being thrown off from it by eruptive agencies, is a
problem for physicists ; if it can be shown that the sun’s constitution is such
as to render it not improbable that meteorites could have this origin. The
immense velocities of the eruptive prominences— from 100 to 200 miles
per second, or, according to Proctor, 500 miles — indicates, with their great
height of sometimes from 150,000 to 550,000 miles, a violence of eruption
tending to hurl solid materials far away from the sun into space. The ele-
ments seen in the spectrum of these prominences, iron, sodium, magnesium,
titanium, calcium, chromium, manganese, and probably sulphur, are with
one exception, common ingredients in meteorites.*

If the above-mentioned velocity may, on investigation, be deemed suffi-
cient to project matter into space, the prevailing view of astronomers that
the sun as a whole is gaseous, and neither liquid nor solid, would certainly
be opposed to the solar origin of meteorites. As before stated, their con-
stitution would, so far as we are acquainted with the action of gaseous
substances, demand that the meteorites should be derived from a hot liquid.
The body from which they came might be for the most part solid, or
gaseous, or both, but that the portion from which they came should be
liquid seems a necessity. The liquid condition of the sun is also the best
explanation of the eruptive phenomena now observed upon it.f

Should it be shown that meteorites might come from the sun, its eruptive
energy being sufficient, it would be rendered probable then that meteorites
might have been thrown from the sun when larger, as well as from the
planets and their satellites during their condensation —if the nebular hypo-
thesis is accepted. It would certainly seem that the present view of the
partial or entire meteoric constitution of the corona, the zodiacal light, the
Gegenschein, of Saturn’s rings, and of comets, bears directly on this question.
If our sun may do this, is it not consistent to suppose that other suns may do
the same, and thus account for the comets, their varied orbits, as well as for
the supposed diverse constitution of the August and November meteors.

The theory that meteorites come from the sun is by no means a new one,

* Young, The Sun, 1881, pp. 202, 207-212.
+ Young, 7. c., p. 211.
15

114 THE METEORITES. — THEIR ORIGIN AND CHARACTER.

being as old as the days of Diogenes Laertius, and in recent times has been
advocated by Hackley,* Wilcocks,t Williams,$ Sorby, and others.

If, in the process of condensation of the sun from a gaseous to a liquid
state, the metallic portion liquefied before the silicates, would it not in some
measure account for the metallic meteorites being so common in the past and
rare at the present time, and for the peridotic ones being the common type
now? -On account of their specific gravity, meteorites, as a rule, could not
be derived from the moon; unless it should be held that its interior is now
much hotter than the earth’s interior, and its density made less through
that means. This is an improbable supposition on account of its small size,
compared with that of the earth, which would lead to its more rapid cooling.
Since the specific gravity of the moon, as a whole, is about that of the more
common meteorites, and if the law of the increase of density from the sur-
face to the centre is the same as that observed upon the earth, it follows
that the moon’s surface formations must have far less density as a whole than
those belonging to the earth. The law of eruption as observed upon the
earth is, that the lighter eruptive material as a whole is most abundant,
while the rocks approaching the mean density of the earth are compara-
tively rare, so much so that their presence is generally denied. This law
ought also to hold good on the moon, and eruptive material from it, forming
meteorites, ought to have less specific gravity as a whole than our granites.
The astronomical reasons have usually been regarded as sufficient to show
that meteorites could not come from the moon, and that theory is not now
especially urged by any one.

Such a view as advocated by Messrs. Ball and Rodwell,§ that meteorites
were thrown from the earth in past times, is negatived by their general
composition, which, as a rule, is different from the exterior portions of the
earth. If they were originally terrestrial, these meteorites ought to more
commonly possess the characters of basalts, andesites, trachytes, ete.

Whether the view that meteorites came from the sun demands too great
i loss to his mass, since accurate records have been kept, is a problem for
the physical astronomer. |

Since it is possible that careful examinations of meteorites by chemical
and spectral methods will throw light on the constitution of the celestial

* Proc. Am. Assoc. Adv. Sci., 1860, xiv. 4-6.

+ Proc. Am. Phil. Soc., 1864, ix. 8384-387.

t The Fuel of the Sun, London, 1870, pp. 131-142.

§ Scicnee for All, iv. 82; Nature, 1879, xix. 493-495.

CONTEMPORANEOUS CRYSTALLIZATION OF IRON AND SILICATES. 115

bodies — especially concerning the strange lines in the sun’s spectrum — it
would appear that meteorites ought to be studied more critically than ever
for the rarer elements, as well as for some at present unknown.

Careful examinations ought also to be made on microszopic sections of
recently fallen meteorites, in order to ascertain if any changes have taken
place in the rock since it was first formed, but before it reached this earth,
since all changes now seen in them are referred to the action of our atmos-
phere after the fall of the meteorite. It is not to be expected that in
any way can any clue be obtained as to how recently or how long ago the
meteorite left its parent mass, since no alteration in its substance can be
expected to have taken place in inter-solar space.

Mr. H. C. Sorby’s view* that it is impossible for minerals of so diverse
specific gravity as iron and olivine to crystallize together in the pallasites
and other metallic meteorites on the surface of the earth or any large body,
but that they came from the metallic centre of small bodies, or else formed
small planets by themselves, does not seem to be well founded. The same
method of reasoning would prove that magnetite could not be formed with
leucite, or feldspar, or augite in any lava-flow on the earth’s surface; yet
they are minerals of common occurrence together in lavas. Hence it is
claimed here that the crystallization of silicates with metallic iron might, so
far as gravity is concerned, take place on the surface of the earth as it has
been proved to have done in Greenland. So too, if such a structure and
arrangement of iron and olivine could not take place on the surface of a body
like the earth, then the rocks of Cumberland, Rhode Island, and of Taberg,
Sweden, ought not to exist since they have this structure and are at the
surface of the earth. The difference between the magnetite and olivine is
not so great as that between the native iron and olivine, but yet it is sufhi-
cient to cause a separation, if Sorby’s view is correct.

Helmholtz’s theory that the earth is built out of meteorites is negatived
by the following facts: the geological formations in and of themselves are
not composed of detached fragments like meteorites; meteorites, so far as
known, are not found in the geological formations; and the chemical com-
position of the latter is different from that of the meteorites. His view
seems to be a pure theory without any regard being paid to the actual
known structure and composition of the earth and meteorites. As well

* Quart. Jour. Sci., 1864, i. 747.

116 THE METEORITES. —THEIR ORIGIN AND CHARACTER.

might the physicist explain the dispersion of boulders in the northern drift,*
or the origin of the large nuggets in the gold placers by supposing that they
were meteorites, as to explain the earth’s structure by the meteoric theory.

The further supposition that the earth has been formed from meteoric
matter that became entirely fused from the impact of the falling masses is
one that makes an assumption and then deprives us of every means of dis-
proving or proving it.

Everything relating to the state of the earth prior to its fluid condition
is of course a matter of conjecture, and theories relating to it are beyond
scientific discussion, as belonging to the unknown and unknowable.

The origin of meteorites, as shown by their structure, yields but little
assistance to the theory of the introduction of life upon this planet through
their agency; since the conditions under which they were formed, and those,
so far as can be ascertained, to which they have been since subjected are not
compatible with life as understood upon this globe.f

In other words it may be said that meteorites show in their structure
that they have been formed from molten liquid material, while their chemical
composition is such as to show that they could not have been exposed to air
and water upon any globe in conditions compatible with life as we under-
stand it. If their structure points to an igneous origin, and their composition
shows that they could not have been exposed to conditions such as earth-life
demands, then Sir William Thomson was not right in claiming that it was
scientific to suppose that life was brought to this earth by meteorites. It
certainly only pushes the question of life a little farther off; it begs the
question but does not solve it, even could it have been shown that life might
have been thus brought here. Zollner was indeed right in opposing this
theory and regarding it as unscientific. Assuredly, the germs inclosed in
crevices would be destroyed by the cold of space, as much as the exterior
ones would be by the heat generated by the passage of the meteorite
through the air. It is not intended to state that water or air could not be
present on the body from which meteorites come, but that the meteorites
could not have been exposed any length of time to such agencies, or their
constitution would have been changed.

* Since the above was written such an explanation has been published, entitled: ‘‘ Ragnarok — the Age
of Fire and Gravel,” — by Ignatius Donnelly.

+ W. Thomson, Proc. British Assoc., 1871, pp. civ., ev. ; 1877 (Sect.), p. 43; A. Thomson, ibid., 1877,
p. 75; Helmholtz, Popular Scientific Lectures (Sec.-Ser.), 1881, pp. 193, 196, 197; Nature, 1875, xi. 212;
J.C. F. Zéllner, “Ueber die Natur der Cometen, Leipzig,” 1872, p. 24; Walter Flight, Pop. Sei. Rev.,
1877, xvi. 890-401; David Forbes, Geol. Mag., 1872 (1), ix. 234, 235.

O°

THE SOURCE OF VEIN MATERIALS. 117

Again since mineral veins appear to have been formed on the earth by
the action of percolating waters, none of the meteorites can be of such vein
formation, as has been claimed by M. Meunier, since they show by their coin-
position that they have not been exposed to or formed in the presence of
water; and so far as the present writer is concerned, he sees nothing in their
structure supporting such a theory, even if, as Meunier seems to think, these
veins were formed by sublimation.

The finding of many of the metals, in larger or smaller amounts, in
meteorites points to a relation between them and terrestrial eruptive rocks.
The association of metallic veins with eruptive or metamorphosed rocks,
coupled with other characters, indicates that our metals, as concentrated in
veins, have generally been derived by aqueous and chemical agencies from
eruptive rocks and their débris. This deposition may be direct or indirect,
but primarily the starting point is believed to have been the original molten
material of the earth.*

The more common association of metalliferous veins with basic rather
than acidic rocks points towards the deeper-seated origin of the former, as
has been claimed by many.t

The occurrence of copper in so many of the meteoric forms has, it seems
to the writer, an important bearing on the question of the origin of the
native copper of Lake Superior. He holds that it was derived from the
associated basaltic rocks as he has set forth in another paper.t

If copper is an almost constant associate of meteorites, ought it not to
naturally be associated with eruptive rocks which are held to be part of the
original materials of which the solar system is composed? The basic
rocks are naturally, then, the ones with which the copper should be associ-
ated, and it is with basaltic rocks—diabases and melaphyrs— that it is
commonly found, as, for instance, on Lake Superior, Bay of Fundy, and in
Newfoundland.

The metallic iron in the basalt of Greenland, the native iron found in
basalts by Dr. Andrews, that found in gabbros from New Hampshire, by Dr.
George W. Hawes, and in gabbros from the west of Scotland, by Mr. J. Y.
Buchanan, all serve to connect the meteorites with the terrestrial rocks. §

* Whitney, Aurif. Gravels, pp. 310, 311].

+ Whitney, Earthquakes, Volcanoes and Mountain Building, p. 85.

+ Bull. Mus. Comp. Zodl., 1880, vii. 180.

§ Report Brit. Assoc., 1852, xxii. (Sect.) 34, 35; Geikie’s Text Book of Geology, 1882, p. 64; Geol.
New Hampshire, 1879, iii. part 4, p. 24.

118 PERIDOTITE.

In the same way the presence of nickel, chromium, tin, copper, and cobalt

in the group of terrestrial olivine minerals, serves to connect the earth
‘2 .

and meteoric bodies; as also does the presence of nickel in the terrestrial

pyrrhotite and magnetite.

Section IV. — The Terrestrial Peridotites.

Variety. — Dunite.
Franklin, North Carolina,

5134. An oil-green, crystalline-granular rock, weathering from a yellowish-green to a
reddish-brown. Composed of a granular mass of olivine, holding irregular grains and
crystals of chromite and long needles of tremolite. It contains some tale and dark-green
chlorite.

Section: a clear, pale-yellowish, fissured mass, composed of olivine, with some talc,
chromite, and tremolite. The olivine is in clear transparent grains, tinged slightly yellow
along the fissures. It contains some chromite and glass inclusions, — the two often being
associated. The tale is in clear irregular plates, showing a longitudinal cleavage. The
polarization is generally simple, but sometimes aggregate. An earthy, white substance
was observed in some cases lying between the lamine.

The chromite is generally in octahedral crystals, although a few minute grains of j irreg-
ular form were seen. The chromite was opaque in every instance. A few minute
rounded grains were observed, that may possibly be picotite.

The section, to my mind, presents the characters of a granular rock, resulting from a
cooling igneous magma —an eruptive rock. The olivine is in grains which are separated
only by fine cracks, every irregularity in one being matched by corresponding irregular-
ities in its neighbors. If these grains were olivine sands aggregated by wind or water,
such uniformity would not exist. The grains would be irregularly massed together, with
interstitial portions filled with binding material. The cracks which separate the different
individual grains are the same as those which separate different portions of the same
grain. The absence of any signs of wearing to the grains, and their matching one another
as they would in this substance when completely crystallized, point towards an eruptive
origin for the rock. In addition, long, lenticular, much broken grains are seen, whose parts
show in polarized light that they belong to the same individual. They are arranged at
every angle with one another; but if these grains had been deposited as a shore sand, it is
difficult to see how they could have retained their sharp thin cutting edges. Again, these
grains and the general structure of the rock are like those observed in the Estherville
meteorite, which I think no one would be inclined to regard as a beach deposit. The
granular structure appears to me to be due to the crystallization of a mineral inclined to
take such a rounded form as olivine usually has. The same structure and arrangement
of the grains from a cooling eruptive rock had been previously seen by the writer in quartz
in some granitoid rocks frem Lake Superior, part of which are known to be in dikes, while
the others are probably also eruptive.*

Many of the larger olivine grains show a faint banded polarization, the bands being
nearly parallel with a crystallographic axis. The structure of this section is shown in
Plate IV. figure 2; the darker bands indicating the fissures in the grains.

* Bull. Mus. Comp. Zodl., 1880, vii. 52-55.

THE TERRESTRIAL PERIDOTITES. — DUNITE. 119

Webster, North Carolina.

5135. A crystalline-granular rock, of a yellowish-brown color on the fresh fracture.
Lustre resinous and greasy, fracture uneven-conchoidal. Weathered to a granular pale-
yellow mass, on the exterior portions. Contains grains and crystals of picotite.

Section: of a pale-yellow color; composed of olivine, enstatite, diallage, picotite, and
serpentine. The olivine forms the chief portion of the rock, and is in irregular fissured
erains. It is clear-transparent, and holds grains of picotite, some of which are in minute
lenticular forms. The picotite is very abundant, but mostly in minute microscopic
grains of a coffee-brown color. The macroscopic picotites are opaque, except in the thin-
nest portions.

The enstatite and diallage are in small, transparent, irregular masses, lying between the
olivine grains. Both are traversed by longitudinal fissures, but in general the enstatite
cleavage is better marked and more finely fibrous than that of the diallage. The latter
mineral was observed sometimes to have the uregular, approximately right-angled cleay-
age of augite. Although the enstatite could sometimes be separated from the diallage by
its cleavage, in general the distinction was made solely by optical methods.

The serpentine is mainly of a pale-yellowish color, although in some places a darker
or brownish color was observed. It follows the fissures, making a network, envelop-
ing the fragments of olivine, enstatite, and diallage. Many of the olivine grains now
separated by serpentine are seen by their optical characters to be parts of the same
original crystallographic mass. The serpentine is plainly a secondary product, formed
from the alteration of part of the original minerals, comprising this peridotite. In some
parts of the section in which the mineral fragments were small, the minerals have been
changed entirely to serpentine, forming ganglion-like masses in this plexus of serpentine.
The serpentine shows the common fibrous polarization, the fibres standing perpendicular
to the walls of the channel.

Plate LV., figure 3, shows well the yellowish and greenish serpentine alteration along
the fissures, and surrounding the clear olivine grains. The brown spots are picotite
grains.

Dr. F. A. Genth, in 1862, made an examination of some Webster (Jackson Co., N. C.)
peridotite, and stated that they gave “evidence that chrysolite is probably the mineral
from which tale slate and many of the serpentines have been formed.” *

Dr. Alexis A. Julien regards the North Carolina peridotite as formed by consolidated
olivine sand —a detrital deposit derived from the wearing down of older eruptive rocks.
He describes the rock as occurring in long lenticular masses, that show a laminate’) struc-
ture; giving his reasons why he regards this lamination as due to the sorting of sediments
deposited in water. His reasons for holding that the dunite is a sedimentary rock are
good so far as they go, but they do not appear to be conclusive; since the same condition
of things could readily exist in an eruptive rock. The rock, when altered near the surface

of disintegration, is, according to Julien, bound together by a network of quartz or actino-

lite fibres.

The alterations in the rock-mass, as traced out by Dr. Julien, are very interesting.
Briefly, they are as follows: 1. Chalcedonic; 2. Hornblendic; 3. Talcose ; 4. Ophiolitic ;
5. Dioritic.

In the first, the silicates are decomposed, the silica forming chalcedony or chert, while
the bases remain as soft ochreous grains, or are entirely removed.

* Am. Jour. Sci., 1862 (2), xxxili. 199-203.

120 PERIDOTITE.

In the second case, the alteration consists in the formation of a few crystals, and in
every oradation from that to a state in which the dunite has been transformed into a more
or ieee schistose rock, largely composed of hornblende, and actinolite or tremolite. A few
erains of olivine usually remain unchanged even in these extreme alterations.

The third change is brought about either by the direct alteration of the olivine, or by
the conversion of the secondary actinolite itself into tale. Through this alteration talcose
rocks are formed, like tale-schists ; as well as amphibolitic or olivine ones bearing tale.

The fourth alteration has been described by me in the preceding account of the Web-
ster peridotite, and hence I will not here quote from Dr. Julien, farther than to say that
according to him tale is frequently associated with the serpentine, thus forming a talcose
serpentine.

The fifth and last alteration is “confined to a single locality, and consists of an inter-
nal conversion of the olivine into amphibole —a bright grass-green variety which Dr.
Genth has identified as smaragdite or kokscharoffite — and albite, sometimes with abun-
dantly disseminated particles of ruby red corundum, producing a peculiar variety of
diorite or gabbro. Again, this very rock has been subsequently attacked by a secondary
process of alteration, the albite grains being enveloped by an alteration-crust of margarite,
and the condition of hornblende modified. The result of this action is a coarse margaritic
gabbro.”

Dr. Julien believes that many of the amphibole and talc-bearing schists and serpen-
tines along the Appalachian belt are the equivalents of the North Carolina dunite.

The North Carolina peridotites have been described in previous papers by Genth,
Jenks, Kerr, C. D. Smith, Shepard, J. L. Smith, Raymond, and others.*

In most of the above papers, corundum is especially treated of, since it has been
largely found associated with the peridotites of the Southern States. This mineral Genth
regards as original, but Julien as a secondary product of alteration. Various opinions
have been advanced concerning the North Carolina peridotite— that it is of chemical,
sedimentary, and eruptive origin. Messrs. Kerr and C. D. Smith who have, except Julien,
studied the rock most in the field, regard it as eruptive, but the published evidence given by
them is, like Julien’s, not conclusive. The reasons that the present writer has for believing
this rock to be of eruptive origin have already been given. It hardly seems possible that
the olivine could have been deposited as a loose sand, exposed to water and air, consoli-
dated, and remained until the present time unchanged.

Tafjord, Norway.

The rock from Tafjord, Norway, as seen in a section purchased from Richard Fuess,
Berlin, is composed principally of rounded grains of olivine, with some enstatite, cof-
fee-brown picotite or chromite, and a little magnetite. The structure is essentially the
same as that of the peridotite from Franklin, North Carolina. The form and arrangement
of the enstatite are very similar to those of the tale in No. 5184.

Méhl describes this rock as being similar to the one from Rédfjeld, but with less
enstatite, and some magnetite. +

* Am. Phil. Soe. Proc., 1873, xiii. 361-406 ; 1874, xiv.; 1882, 216-218, 381-404; Quart. Jour. Geol.
Soc., 1874, xxx. 303-306 3 Geol. of North Carolina, 1875, vol. i. 129-130; Appendix D, pp. 91-97, 102-
107 ; 1881, vol. ii. 42, 43; Am. Jour. Sci., 1872 (8), iii. 301, 302; iv. 109-115, 175-180; 1873, vi. 180-
186; Pop. Sci. Monthly, 1874, iv. 452-456; Trans. Am. Inst. Min. Eng., 1878, vii. 83-90.

+ Proc. Bost. Soc. Nat. Hist., 1882, xxii. 141-149. See also Science, 1884, iii. 486, 487.

t Nyt Mag., 1877, xxiii. 115, 116.

THE TERRESTRIAL PERIDOTITES. — DUNITE. 121

Din Mountain, New Zealand.

The peridotite (dunite) of New Zealand is described by Hochstetter as a Mesozoic
eruptive mass, associated with serpentine and hyperite, also of eruptive origin. This
dunite is a crystalline-granular rock, of light yellowish-green to a grayish-green color on
the fresh fracture, and weathering to a dirty, rusty, sometimes yellowish, sometimes red-
dish-brown color. Fracture uneven, granular, angular, and coarse-splintery. It was
found to be composed of granular olivine, holding octahedrons of chromite, with rounded
edges. The serpentine was formed by the alteration of the peridotite in situ.*

M. Renard has given a brief description of the microscopic characters of this rock.
The section is composed of irregular grains of olivine, but of larger size than those in
the St. Paul’s peridotite, to be described later. “With this exception, the other micro-
scopical characters are the same in both rocks: the fissures, more or less regular, marked
by black lines, intense chromatic polarization of the olivine, roughness of the surface,
etc., etc. The sections of chromic iron in dunite are larger than those in the specimens
from St. Paul, but in other respects they present the same features.” T

Sondmire, Norway.

The thin sections of this rock, according to Brogger, contain predominating olivine, with
(very sparingly) beautiful green smaragdite, here and there a grain of brownish-yellow
enstatite, and chromite in little grains. The olivine is fresh, clear-green, and in the sec-
tion colorless, and fine-granular. Some grains show one cleavage parallel to the longer
direction of the crystals, and another perpendicular to the same. Only a trace of altera-
tion to serpentine was observed. The smaragdite is of a green color, fresh, and shows
pleochroism. The only two grains in the section were elongated in the direction of the
vertical axis, and show cleavage lines running in the same direction. The enstatite
occurs in a few scattered grains. They are fresh, brownish-yellow, finely striated, and
crossed by cleavage-planes. The chromite appears in little, irregular, rounded grains.

This peridotite is associated with and lying in schists, and is called by Brogger an
olivine-schist. ¢

Robergvik, Skrenakken, Norway.

This rock was described by H. von Mohl as composed principally of olivine grains,
containing octahedrons of picotite and deep hair-brown, transparent, chromite crystals.
Magnetite was present, and some of the olivine grains showed a change to fibrous cbry-
sotile. Lamelle of fibrous enstatite were seen. §

Bonhomme, Bluttenberg, Vosges, France.

A blackish-green rock, with a rough, splintery fracture, showing a brilliant shimmer
from numberless minute points, and traversed in part by many blackish veins. In thin
splinters it is clear-green and translucent. In the section the olivine grains are seen to

* Zeit. Deut. geol. Gesell., 1864, xvi. 341-344; Reise der Novara, Geologie von Neu-Seeland, pp. 217-
220.
+ Report Challenger Expedition, Narrative ii. Appendix B. pp. 22, 23.
¢ Neues Jahr. Min., 1880, ii. 187-192.
§ Nyt Mag., 1877, xxiii. 114.
16

122 PERIDOTITE.

be clear and fresh, but in some points a change to serpentine has taken place. Picotite
and a reddish garnet (?) were observed.
The other accessories were a few plates of amphibole minerals and iron ores.*

Karlstitten, Austria.

Tschermak describes a grayish-green, fine-grained rock from this locality, as com-
posed of olivine, united with serpentine, grass-green smaragdite, and little, black, pitch-
like, or semimetallic grains of picotite.T :

Tron, Ocsterthal, Norway.

This is similar to the serpentine from the Andestad See to be later described. The
olivine grains are changed, along their boundaries and fissures, into a chrysotile. This is
in part of a platy-granular structure, and part composed of parallel fibres. In some por-
tions grains of olivine with unaltered centres are to be seen. Considerable magnetite
was observed.

Enstatite is comparatively rare, and when present contains some picotite grains and
crystals, a few of which were seen in the olivine.

A section of this rock obtained from R. Fuess is entirely altered to serpentine. The
gray, serpentine groundmass is traversed by bands of ferruginous and gray material,
resembling closely those represented in figures 1, 2, and 4 of Plate V. Dark-brown, trans-
lucent picotites were observed scattered through the serpentine, their borders jagged and
opaque, probably as a result of alteration. The serpentine is filled with minute black
grains of some iron ore.

Heiersdorf, Saxony.

According to Dathe, the Heiersdorf rock is medium grained, containing pale-red gar-
nets, and showing under a lens quartz and feldspar, with light-greenish and brownish
olivine, as well as black, lustrous crystals. The principal portion of the section is olivine.
This is seldom fresh, but generally cloudy or altered to serpentine, forming the usual net-
work, and containing some dust-like ore. The olivine contains some picotite or chromite
grains.

Plates of magnesian mica occur in the neighborhood of the garnet and ore particles.
The garnets are of the size of a pin’s head, and are somewhat altered. The majority are
entirely changed from the singly-refracting garnet substance to a doubly-refracting, radi-
ately-fibrous material. This has a pale-blue ageregate polarization color, but in common
light is greenish and feebly dichroic. The minority of the garnets have a small alteration
zone surrounding them, of colorless fibres, probably asbestus, arranged perpendicular to
the garnet boundary. Light-brownish zircon grains also occur. §

Ronda Mountains, Spain.

The serpentine of the Ronda Mountains, covering an area of nearly 600 square miles
has been described as eruptive by Joseph Macpherson.|| With the serpentine were

* Bruno Weigand. Min. Mitth., 1875, pp. 186-192.

t Sitz. Wien. Akad., 1867, lvi. 275-279.

t{ Nyt Mag., 1877, xxiii. 120, 191.

§ Neues Jahr. Min., 1876, pp. 227-229.

| On the Origin of the serpentine of the Ronda Mountains, J. Macpherson, Madrid, 1876, 20 pp. 2 plates.

THE TERRESTRIAL PERIDOTITES. — DUNITE. 125

found imbedded large masses of peridotite. The peridotite is irregularly disseminated
through the serpentine, showing an intimate connection of the two. The peridotite is
found to be composed of olivine grains, traversed by numerous fissures, and containing
irregular fragments aud octahedrons of picotite. The rock itself usually varied from a
greenish-gray to various shades of green.

The serpentine is generally of a dark-green color, traversed frequently by veins of
chrysotile, and not uncommonly charged with crystals of diallage. It is said that in some
places the serpentine “is traversed by great parallel planes of fracture, which at first sight
might be mistaken for stratification.”

The alteration of the olivine takes place along the fissures, the iron separating in thie
serpentine as magnetite and chromite. This serpentinization gradually extends until
only small grains of olivine are left, and then on until the entire rock is altered to serpen-
tine. A perfect and gradual transition was traced from the beginning of the process to
the complete transformation. The alterations are shown very well in the figures accom-
panying Macpherson’s paper.

Serrania de Ronda, Spain.

This rock, according to Macpherson, is of a clear, greenish-gray color, with a lustre
between a greasy and vitreous. ‘The section is composed of a crystalline-granular aggre-
gate of olivine fragments, containing numerous picotite grains. The olivine shows brilliant
polarization colors, and sometimes a striation parallel to the plane of extinction, while it
is traversed by irregular fissures.*

St. Paul’s Rocks.

These rocks were described by Darwin as unlike any rock he had met. He states:
“The simplest, and one of the most abundant kinds, is a very compact, heavy, greenish-

black rock, having an angular, irregular fracture. . . . This variety passes into others of
paler-ereen tints, less hard, but with a more crystalline fracture. . . . Several other varie-

ties are chiefly characterized by containing innumerable threads of dark-green serpentine,
and by having calcareous matter in their interstices. These rocks have an obscure, con-
cretionary structure, and are full of variously colored angular pseudo-fragments. .
There are other vesicular, calcareo-ferruginous, soft stones. There is no distinct strati-
fication, but parts are imperfectly laminated, and the whole abounds with innumerable
veins, and vein-like masses, both small and large.” Darwin states that the rock is not
of volcanic origin —not necessarily meaning by this anything more than that it was
not a modern eruptive formation like that of the other islands visited.f

These rocks being the haunts of birds, a phospatic incrustation had been formed on
part of the surface, and Professor Wyville Thomson states “that they look more like the
serpentinous rocks of Cornwall or Ayrshire, but from these even they differ greatly in
character. . . . Mr. Buchanan is inclined to regard all the rocks as referable to the ser-
pentine group. So peculiar, however, is the appearance which it presents, and so com-
pletely and uniformly does the phosphatic crust pass into the substance of the stone that

I felt it difficult to dismiss the idea that the whole of the crust of rock now above water

might be nothing more than the result of the accumulation, through untold ages, of the

* Anal. Soc. Esp., Hist Nat., 1879, viii. 251, 252.
+ Voleanic Islands, 1851, pp. 31-33, 125.

124 PERIDOTITE.
insoluble matter of the ejecta of sea-fowl, altered by exposure to the air and sun, and to
the action of salt and fresh water.” *

According to Rey. A. Renard, the rock is composed essentially of very small olivine
grains similar to those of the New Zealand dunite. Fluid cavities were also observed.
Chromite (picotite) is abundant in irregular, generally lenticular grains, of a brownish-
yellow color. Renard further described a pale green mineral of irregular outline, and a
cleavage forming an angle of 124°, which he assigned to an amphibole mineral. Ensta-
tite in colorless or clear greenish-yellow sections was observed, possessing an evident
lamellar structure. A structure seen in the sections by Renard was regarded by him
as a fluidal structure.

In a later publication, M. Renard seems to have abandoned his idea of the eruptive
origin of these rocks, and inclines to the view that they are formed from crystalline
schists, the supposed fluidal structure being really schistose structure instead. He
regards this peridotite as remarkably fresh and unaltered. Color, “ blackish-gray, bordering
green, which when deep looks perfectly black.” Its component minerals, as determined
by M. Renard, are olivine, chromite, actinolite, enstatite, and a pyroxenic mineral. For a
fuller description the reader is referred to the original papers. $

M. Renard thinks that the association of olivine rocks with schists proves their similar
origin, and therefore much peridotite is sedimentary ; overlooking the fact that a region of
eruptive rocks is one in which the sedimentary rocks are most likely to become schistose.
Furthermore, many eruptive rocks are schistose, through secondary changes in them after
eruption. Again, many eruptive rocks have associated with them ashes and other frag-
mental material of eruptive character, as well as sedimentary deposits, all of which brings
into intimate relations metamorphosed eruptive rocks and schists. This is a case to
which the principles earlier given in this volume apply. It is especially difficult to see
how denudation could take place to the great depth in the ocean required when, as
M. Renard admits, there is no evidence of depression.

Two specimens of this rock were kindly sent me by Mr. John Murray, of the Chal-
lenger Expedition. One shows on the fracture a dark grayish-green color, and as M.
Renard remarks, closely resembles a quartzite. Weathers to a yellowish and brownish-
gray. The section is seen to be composed of olivine, enstatite, diallage, picotite, chromite
or magnetite, pyrite, actinolite, and serpentine.

M. Renard remarks that the minerals have their longer axes placed parallel with the
supposed schistose or fluidal structure. In this section the larger grains stand in every
direction, some of the olivine grains having their longer axes exactly at right angles to
one another. No structure has been observed by me that I should regard as schistose.
A slight schistose appearance has been produced in my judgment by the secondary altera-
tion of the rock. Fortunately, one of the specimens sent me is of the rock said by M.
Renard to be entirely fresh and unaltered. He also states that the structure of this rock
is peculiar, and unlike that of other olivine rocks. In one section a portion of the rock is
only slightly altered, and this portion shows the common structure of peridotites. The
main mass of the rock, described by M. Renard as the groundmass, is in my opinion
greatly altered, and contains only the remnants of the original minerals, surrounded by
their alteration products. M. Renard regards this groundmass as composed entirely of

* Voyage of the Challenger, ii. 100-108. t Neues Jahr. Min., 1879, pp. 389-394.

{ Report of the Scientific Results of the exploring Voyage of H. M. S. Challenger, 1873-76. Narrative,
vol. ii. Appendix B., 29 pp., 1 plate; Description Lithologique des Récifs des St. Paul. extrait des Annales
de la Société belge Microscopie, 1882, 58 pp.

THE TERRESTRIAL PERIDOTITES. — SAXONITE. 125

olivine grains, but of this I have grave doubts. The characters as seen microscopically
do not appear to me to be those of ordinary olivine, but rather those of one or more min-
erals of secondary origin. That this groundmass is of secondary origin, for the most part,
is shown by its occurrence along the fissures in the unaltered olivines, by its relations to
the minerals which it surrounds, which are the same as those existing in other rocks
between the original minerals and their secondary products, and by the secondary schis-
tose structure. In such cases as these much depends upon the experience and especial
kind of work that the observer has done, and unfortunately such evidence cannot be
placed in words so as to enable others to judge of its correctness.

It is contrary to the laws of physics and chemistry that a mineral in altering should
produce itself again —there is rather a passage from an unstable compound in the condi-
tions in which it then is, to one more stable in the same conditions. If I am right regard-
ing this alteration of the olivine the resulting mineral or minerals must belong either to
another variety of olivine or to a distinct species.

The actinolite, chromite, picotite, magnetite, pyrite, and serpentine, I regard in this
case as secondary products in the rock, and not original ones.

As said before, in places the section shows the olivine unaltered, and having the same
relation between the grains that exists in other rocks when the granular structure is due
to crystallization from an igneous magina, and not from detrital action. M. Renard hes
pointed out that the actinolite is more abundant in the fine groundmass than elsewhere in
the sections, which is in accord with my view of their origin. One section shows at one
end that it is composed chiefly of a confused mass of pale-greenish mouoclinic crystals,
showing cross fracture, and which are here referred to actinolite.

An examination of sections from the more highly altered rock shows that on further
alteration the fine groundmass becomes changed from a clear to a dirty-yellowish one, but
slightly polarizing. The hand specimens sent me bear evidence that they are surface and
weathered specimens—to which probably much of the difficulty in their study is due;
for, judging from M. Renard’s descriptions, he had similar specimens to mine. In this I
would by no means judge of what M. Renard saw, but only of the sections that I have
myself studied. |

It is to be hoped that should these rocks ever be visited again great pains would be
taken to procure specimens as deep in the solid rock as it is possible to obtain them.*

Variety. — Saxonite.

Russdorf, Saxony.

Dathe described a peridotite from Russdorf, Saxony, as fine-grained, and of a light-
ereen color. Olivine formed the essential portion of the rock-mass. This mineral was
slightly altered on its edges to a granular substance of a light-yellowish to brownish color ;
also, along the fissures the olivine grains are changed to a light-yellowish, almost homoge-
neous mass. Inclosed in the olivine are black octahedral crystals of picotite or chromite.
The enstatite shows in colorless, finely-striated sections. Olivine in small grains and
small black needles was observed inclosed in the enstatite.t

Northern Norway.

Helland describes some of the peridotites from Northern Norway as composed of fresh
olivine, containing picotite, together with enstatite and grains of iron ore. Serpentine

* Science, 1883, i 590-592. + Neues Jahr. Min., 1876, pp. 233-235.

126 PERIDOTITE.

from this region was found composed of serpentine, with olivine fragments, and magne-
tite. Another serpentine rock contained only serpentine, diallage, and magnetite.*

Thorsvig, Norway.

This rock is stated by Mohl to contain 60 per cent of olivine, 30 per cent of enstatite,
and 10 per cent of anorthite and magnetite. The olivine and anorthite were in grains,
and the enstatite in table-like forms, without crystalline contour.f

Lirkedal, Norway.

From Birkedal, Norway, according to Mohl, was obtained a peridotite composed of
olivine and enstatite, with some magnetite, chromite, mica, and anorthite —the latter
mineral composing about 10 per cent of the rock-mass.t

Hovden, Horningdal, Norway.

This peridotite, according to Mohl, is composed of olivine grains and enstatite plates,
with magnetite and brown mica. The enstatite is in part of a light yellowish-eray, and
in part a very strong nacarat color. It is cut through by parallel fissures, is fibrous, and
contains many loose aggregates of brown needles and laminz.§

Rodfjeld, Norway.

Dr. H. von Mohl described a rock from Rodfjeld, Murusjé, Norway, as made up of
olivine grains, enstatite, and a little ledge-formed feldspar. The olivine in places is
described as suffering a total change to chrysotile. ||

Andestad See, Aure, Norway.

This stone, according to Mohl, is composed of 75 per cent of olivine in angular grains,
20 per cent of enstatite and tabular-formed aggregates, and 5 per cent of chromite in
granular aggregations.

Only a small portion of the olivine remains clear and fresh. Around the contour of
the freshest grains wind strings of a dirty greenish-yellow chrysotile. The grains them-
selves are sometimes of a dirty grayish-yellow color or cloudy, and show aggregate polar-
ization. Here and there a grain is entirely changed to a nearly opaque liver-brown
serpentine.

The enstatite is nearly colorless, beautifully cleaved, and here and there is finely
fibrous — the fibres being parallel. 4]

In part, this rock is so far changed to serpentine, that only here and there do the
olivine grains show any clear central portions remaining. The enstatite remains in part
as fresh as in the preceding, except in its cross fractures, which are filled with chrysotile.
In part, the enstatite is completely serpentinized, but recognizable on account of its
platy pores and its parallel fibrous structure. The chromite remains unchanged. **

A section of the Andestad-See peridotite, purchased from Richard Fuess, of Berlin,

* Neues Jahr. Min., 1879, p. 422. t Nyt Mag., 1877, xxii. 115.
t Nyt Mag., 1877, xxiii. 116. § Nyt Mag., 1877, xxii. 116.
|| Nyt Mag., 1877, xxiii. 113, 114. q| Nyt Mag., 1877, xxiii 118, 119.

** Nyt Mag., 1877, xxiii. 119, 120.

¢ a
4

THE TERRESTRIAL PERIDOTITES. — SAXONITE. 127
has the following characters: A yellowish-green groundinass, holding several crystals of
enstatite. Under the microscope the section is seen to be formed by a serpentine plexus
holding olivine, enstatite, and chromite. The olivine remains only in small grains, sur-
rounded by the serpentine, to which the remainder of the olivine mass has been changed.
The olivine is generally very pure and clear, but its fissures are traversed by the serpen-
tine; grains, even some little distance apart, showing in polarized light that they are por-
tions of the same crystal.

Figure 4, Plate 1V., shows the structure of this section. The greenish portion repre-
sents the serpentine, the grayish-white portion at the upper part of the section is the
partly altered enstatite, the white grains inclosed in the greenish serpentine mass are oli-
vine, and the dark grains are chromite.

Langenberg, Saxony.

A dull, black, serpentine mass, hoiding numerous brownish-black bronzite (enstatite)
crystals. In the thin section the bronzite crystals show an extraordinarily fine, wavy,
fibrous structure, parallel with the extinction plane. It contains arranged along the
planes of the fibres little opaque needles, and pellicles of hydrous oxide of iron, and is par-
tially altered to a feebly doubly-refracting substance — serpentine. Sometimes the crys-
tals are cloudy and altered — bastite. The olivine has been altered to serpentine, having
the usual maschen texture. Magnetite (?), and little crystals of chromite (?) were also
observed.*

Callenberg, Saxony.

This rock has a blackish-green to brown color, and contains little bronzite crystals.
In the section the olivine is seen to have been replaced by serpentine, with the usual
network structure. The bronzite is also more or less altered, and chromite, hematite, and
other iron ores were observed.}

The Ziegelei, between Russdorf and Meusdorf, Saxony.

A leek-ereen serpentine, containing bastite (enstatite) crystals. The section shows
the mesh structure of serpentine divided from olivine, and fibrous-bastite (enstatite) with
chromite and other iron ores. t

Fatu Inka and Fatu Termanu, Timor.

This rock, according to Wichmann, is of an oil-green to blackish-green color, and
holds bronzite and chromite. Under the microscope the serpentine shows the mesh struc-
ture, indicating its alteration from olivine. The meshes are light-green to colorless, and
the interstitial spaces of a brownish-green color. The bronzite (enstatite) in the section is
colorless, and free from all inclusions, except secondary products. §

Rofna, Alps.

A compact, dark, purplish-green rock, containing folia of enstatite, having a jointed,
crushed structure, with the sides coated with greenish serpentine, and presenting a schis-

* Dathe, Neues Jahr. Min., 1876, pp. 338, 339. + Dathe, Neues Jahr. Min., 1876, pp. 339-341.
+ Dathe, Neues Jahr. Min., 1876, p. 339.
§ Jaarboek van het Mijnwezen in Nederlandsch Oost-Indié, 1882, pp. 211-213.

128 PERIDOTITE.

tose aspect. The section shows a reticulated network of opacite, with interspaces having
a fibrous border and a granular centre of serpentine. ‘The section further contains some
enstatite altered to serpentine, magnetite, and a little picotite, or chromite, and hematite.
This is regarded as an altered olivine-enstatite rock. Further examination of these Alpine
serpentines showed that they were either derived from rocks of this character, or else
from olivine-augite-enstatite rocks.*

Variety. — Lherzolite.

Lake Lherz, France.

The famous lherzolite occurring about Lake Lherz, and at various localities between
that lake and Vicdessos and Sem, in the department of Ariége, in the Pyreneean region of
Southern France, has been described by Professor T. G. Bonney as a crystalline aggregate
of olivine, enstatite, and diallage (diopside), with some picotite; the texture varying from
a finely to a coarsely granular. Color on the fresh fracture, a dark greenish-gray or olive-
green. The rock on close inspection shows specks of emerald-green diallage, waxy look-
ing, dull-green serpentine, resinous, pale-brown enstatite, and minute grains of picotite,
inclosed in the predominant dull-colored, or glassy, olivine mass.

The sections are grayish to water-clear aggregates of olivine, enstatite, and diallage,
holding picotite. The section is traversed by a network of fissures, and is thus coarse or
fine-granular in different portions. The olivine is in rounded, water-clear, more or less
irregular grains, and is the predominant mineral, forming, according to Zirkel and Bonney
two-thirds of the whole mass of the rock. ‘The enstatite is clear, colorless, and sometimes
shows a slight, silky texture. The diallage, like the enstatite, is in irregular fragments,
sometimes clear and transparent, and at others shows a faint tinge of green. Both it and
the enstatite are often feebly dichroic, varying from colorless to various pale shades of
green. Sometimes the diallage varies simply in the depth of the green tint. These min-
erals are not to be certainly distinguished one from the other, except by their optical
characters.

The picotite occurs in coffee-brown, irregular masses and grains, the latter often
grouped together in little masses, scattered along from the ends of some larger mass.
The color is sometimes a yellowish-green, and Professor Bonney describes some as being
of a deep olive-green. I should regard the picotite as being the first formed mineral,
instead of the last, as he regards it. In some portions of the sections serpentine has been
formed along the fissures, showing fibrous polarization, the fibres sometimes lying parallel,
sometimes perpendicular to the walls. Near these serpentine veins the olivine is dark-
ened along its fissures, apparently from the separation of magnetite or chromite in a fine
powder. In some cases these black grains are united into irregular, branching, spiney
masses. Masses of these black aggregations are seen arranged in the centre of the vein-
lets of the serpentine, like islets in a stream. Professor Bonney, in his sections, was able
to trace the alteration of the olivine to serpentine, one of his sections showing a network
of serpentine veins surrounding and penetrating the other minerals. In the sections
before me, the olivine is in some cases changed to a pale-greenish serpentine, holding
minute aggregations of the ferruginous grains, These serpentine masses are generally iso-
tropic, although showing in a few points the fibrous aggregate polarization of serpentine.

* Bonney, Geol. Mag., 1880 (2), vil. 538-542.

THE TERRESTRIAL PERIDOTITES. — LHERZOLITE. 129

This isotropic character of the early stages of the alteration-products of minerals, has
been frequently observed by the present writer in the case of many, other minerals.

The sections herein described are of two slides, from Voigt and Hochgesang, purport-
ing to come from Vicdessos (European Collection, Nos. 71 and 165). Some additions
have also been made from the excellent description of Professor Bonney, to which the
student is referred.*

-This lherzolite was regarded by Bonney as undoubtedly eruptive, on account of its
observed relations to the adjacent rock.

Serrania de Ronda, Spain.

This rock, according to Macpherson, has a greenish groundmass of olivine, holding
emerald-green diopside. Under the microscope it is seen to be composed of olivine,
enstatite, and diallage (diopside).

_ The diallage is of a clear green color, dichroic, and has a fibrous structure. The
olivine is clear and fissured, but shows in places a partial change to serpentine. The
enstatite resembles the diallage in its general characters, but has a yellowish color.
Picotite is common.t

Italy.

Numerous peridotites — lherzolites and serpentines — have been described from Italy
by the Italian lithologists, particularly by Professors Alfonso Cossa and Torquato Tara-
melli. These appear to be composed principally of olivine, enstatite, diallage, and picotite,
and their secondary products. Most of the serpentines seemed to have been formed by
the alteration of the lherzolite variety of peridotite. Cossa’s work contains many valu-
able chemical analyses of the olivine rocks which have been tabulated, and for the general
descriptions and plates the student is referred to Cossa’s Ricerche Chimiche e Microsco-
piche su Roccie e Minerali d’ Italia, Turin, 1881; and to the publications of the “ Accade-
mia dei Lincei” of Rome.

Ultenthal, Tyrol.

A coarse, granular, greenish-white rock, according to Sandberger, holding bronzite,
chromdiopside, and picotite, in grains and rounded octahedrons. A fine-grained variety
shows a schistose structure, and holds rose-red and deep blood-red pyrope. This rock is
altered in part to serpentine.§

Ridge between Indian and Bear Valleys, Colusa Co., Cal.

3001. A yellowish and grayish-brown groundmass, containing porphyritically
enclosed somewhat bronze-like crystals of enstatite and diallage. Under the lens the
groundinass shows @ greenish network, holding a yellowish or gray substance between the
meshes. Section: a greenish-white crystalline mixture of olivine, enstatite, and diallage.

* Geol. Mag., 1877 (2), iv. 59-64.

+ See also Charpentier, Journal des Mines, 1812, xxxii. 321-340; Essai sur la Constitution Géogno-
stique des Pyrénées, 1823, pp. 245-264. Ann. Physik, 1814, lvii. 201-208; Delamétherie, Théorie de la
Terre, 1797 (2d ed.), ii. 281, 282; Lecons de Minéralogie, 1812, ii. 206, 207; Picot de Lapeyrouse, Mém.
Acad. Toulouse, iii. 410; Lelievre, Journal de Physique, 1787, xxx. 397, 398; Vogel, Journal des Mines,
1813, xxxiv. 71-74; Zirkel, Zeit. Deut. geol. Gesell., 1867, xix. 188-148 ; Damour, Bull. Soc. Géol. France,
1862 (2), xix. 413-416; J. Kiithn, Zeit. Dent. geol. Gesell., 1881, xxxiii. 398,

+ Anal. Soc. Esp. Hist. Nat., 1879, viii. 253-258.

§ Neues Jahr. Min., 1865, pp. 449, 450.
17

130 PERIDOTITE.

The whole is traversed by a reticulated series of fissures, which in each mineral partakes
of its usual mode of fracturing.

The olivine is the predominating mineral. It forms rounded irregular grains traversed
by numerous fissures. Larger fissures surround the main olivine masses, these veins being
marked by a yellowish-brown central line of earthy ferruginous and serpentinous mate-
rial, on each side of which extend borders of pale-green serpentine. The borders are of
various widths, and usually ramify in little veinlets of serpentine through the fissures
intersecting the olivine individual. In places, the entire olivine is altered to serpentine.
he serpentine in polarized light usually shows fibrous polarization, the fibres being
arranged perpendicular to the sides of the fissures. The yellowish-brown earthy mate-
rial that marks the medial line of the main veins has entirely replaced the olivine in
some portions of the section, giving rise to brownish patches. The serpentine is filled,
along various planes and especially alone the central line of the veins, with innu-
merable minute fluid cavities, so minute that even magnified over nine hundred diame-
ters they remain as fine black globulitic specks, totally reflecting the transmitted light.
Occasionally one larger than the rest shows the narrow outline of the common full fluid
cavity.

The enstatite is in elongated crystals and irregular grains, traversed by the usual fine,
fibrous cleavage. The surface of the crystals is somewhat smooth and silky, and the
principal cleavage is broken occasionally by fractures running obliquely across the ecrys-
tals. The larger enstatites frequently show a greenish fibrous alteration extending along
the fissures.and sometimes reaching the main body of the crystal.

The diallage is, like the enstatite in most of the sections, clear and colorless. It can
generally be distinguished from the latter mineral by the roughness and irregularity of
its cleavage, owing to the acute angle at which two of the cleavages meet in most of the
grains. Like the smaller enstatites, the diallage is in irregular grains and masses, and both
occasionally contain rounded grains of olivine, and crystals and grains of picotite. In one or
two cases grains were observed showing the cleavage of augite. Some of the diallage plates
have an earthy-white or cloudy appearance, marking a certain amount of alteration.
Sometimes both the enstatite and diallage are traversed by serpentine veins, and the
smaller grains surrounded by that mineral.

Picotite occurs in yellowish-brown octahedrons, as well as in irregular masses, opaque
for the most part, but translucent and of a yellowish-brown color in places. How much
of this might properly come under the head of chromite can not be told. In the yellow-
ish-brown serpentine veins are arranged grains showing the lustre of magnetite, which
mineral is also seen in some portions of the before-mentioned opaque irregular masses of
picotite (?).

The microscopic structure of the rock is shown in figure 1, Plate V., which indicates
the grayish, fissured, partly altered olivine and enstatite grains, the dark picotite grains,
and the brownish veins traversing the rock-mass.

This rock was described by the collector, Mr. W. A. Goodyear, as metamorphic, but
with the stratification generally almost obliterated. Mr. Goodyear probably took a some-
what banded arrangement of the minerals, as observed in No. 8002, and a tendency to
split into platy masses, for stratification. Since both of these are common in eruptive rocks,
the latter showing especially on alteration and weathering, further evidence is required
upon the subject. Microscopically and lithologically they belong to rocks which the best
evidence pronounces to be eruptive. It is to be hoped that future geologists, in visiting
the locality, will endeavor to settle the question of the origin of these most interesting

THE TERRESTRIAL PERIDOTITES. — LHERZOLITE. 151

rocks by an examination of their relations to the associated rocks. Of the occurrence
Mr. Goodyear states: “ The great mass of the rock throughout the whole ridge consists
of, apparently, a serpentinoid matrix, filled with foliated crystals of a hard, green mineral,
which I suspect to be pyroxene, forming a rock similar to that of which large quantities
occur near Guenoc and Coyote Valley. But there are also immense quantities of serpen-
tine without these crystals.” *

The associated rocks, according to Mr. Goodyear, were some hard metamorphic sand-
stones, and a few shales.

No. 3002 is from the same locality.

This has a reddish-brown groundmass, holding crystals of enstatite and diallage. The
same reticulated network is observed in the groundmass as in the preceding, but the-in-
closed portions are of a yellowish- or reddish-brown color. A roughly banded appearance is
produced by a somewhat linear arrangement of the enclosed crystals. Both this and the
preceding are surface specimens. Some of the crystals in No. 83002 show the well-
marked characters of bronzite. Section: this is composed of a reticulated network of
serpentine veins, holding rounded and iregular grains of olivine, enstatite, and diallage ;
while larger enstatite crystals are porphyritically enclosed. This rock was evidently once
a crystalline-granular mass of olivine, enstatite, and diallage, but now it exhibits a stage
of alteration somewhat in advance of that shown in No. 8001. The same reticulated
network of serpentine, with the same reddish-brown medial line, is to be observed as in
the preceding; in fact, the structure of the two rocks is identical. The serpentine ex-
tends from the medial line of the veins inward along the fissures, until only portions
of the original minerals are left surrounded by it. In many cases the serpentine has re-
placed the entire mass of the rock, but still retains the marks of the fissures along
which the alteration took place. The serpentine extending out from the reddish-brown
portion of the veins is of a pale greenish-yellow color, and shows fibrous and aggregate
polarization — the fibres, as usual, being perpendicular to the sides of the vein. While
part of the olivine lying inclosed in this network is unchanged, much of it has been
altered to a reddish-brown serpentinous mass like that forming the centre of the veins.
In many cases this last extends only partly through the olivine grain leaving a central
portion of unchanged olivine, but in others the alteration is complete. This reddish-
brown alteration shows a tendency to extend in fibres parallel to the crystallographic axis,
or along the latent cleavage planes. The general characters given in describing the minerals
in No, 83001 hold good here. The enstatite is more highly altered to the greenish fibrous
product, while it is frequently crossed by fissures at right angles to the principal cleavage.
The serpentine veins in this and in the diallage are more abundant and pronounced than
in No. 8001; but these minerals evidently are more slowly altered than the olivine. Of
the enstatite and diallage, the former is the more readily changed. Picotite or chromite
occur as before, but in somewhat larger masses.

Figure 2, Plate V., shows the general microscopic structure of this rock, the dark to
black portions representing the iron-ore grains; the white portions are the unchanged oli-
vine, the orange-brown and yellow colors mark the differently altered portions of the
olivine (serpentine), while the dark-brown bands are serpentine veins like those which
are shown to some extent in figure 1 of this plate.

Figure 3, Plate V., is from the same rock, and shows the structure of the partly
altered enstatite. The main portion of the figure is that mineral with its cleavage lines

* Unpublished Report made to Professor J. D. Whitney.

132 PERIDOTITE.

and alteration-products represented by the gray and brown lines running from top to
bottom. The enstatite crystal is crossed from right to left by a yellowish serpentine vein
connecting two portions of the altered olivine mass represented by the mixed brown,
yellow, and white. The dark grains are the iron ores, or picotite.

Figure 1, Plate VII. represents an enstatite crystal from the same rock,in a more
highly altered condition. The primary cleavage runs from right to left, and the secondary
from top to bottom. The greenish color shows the earlier stages of the alteration, and
the yellow color the following or serpentine stage, although part of the serpentine mate-
rial may have been brought in from the surrounding olivine mass not shown in the

figure.

Foot of divide between Round Valley and Bullfrog Creek, Inyo Co., Cal.

3003. A compact oil-green groundmass, holding bluish-black and bronze-like crys-
tals of enstatite. The rock is traversed by a few veins of pale-green serpentine, while
a chrysotile vein occurs at one end.

Section: a yellowish-green groundmass, holding porphyritically enclosed some dark
enstatite plates. The groundmass shows under the microscope the same reticulated net-
work of veins as that seen in 8001 and 8002, the veins being readily distinguishable
both in common and polarized light. While the structure remains in general the same as
in 8001 and 83002 the entire groundmass is changed to serpentine: that is, it is a dis-
tinct pseudomorphous replacement by serpentine of all the essential structural character-
istics of the preceding rocks. Even black opaque masses are seen having all the structural
features of the picotite of Nos. 3001 and 3002.

Much magnetite or chromite is seen scattered throughout the groundmass, or collected
into open aggregations. The enstatite in some cases retains its usual polarization charac-
ters, with the well-marked cleavage. In others it has been so highly altered that only
traces of the cleavage and the orthorhombic extinction in polarized light remain of its
usual diagnostic features. All the enstatites are filled with grains of magnetite, which in
some crystals are arranged along the cleavage lines. The powder of the enstatite crystals is
magnetic, and it is to the magnetite that their bluish-black color is due. The magnetite
is regarded as a product formed during the conversion of the rock into serpentine. The
evidence afforded by the microscopic structure of this rock, it seems to me, is proof posi-
tive that this serpentine was formed from the metamorphism of a peridotite, the beginning
of which change is to be seen in No. 8001, and still further advanced in No. 83002.

The general structure of this section is shown in figure 4, Plate VI., which displays
an altered enstatite crystal with its secondary magnetite, surrounded by the serpentine
replacing the olivine.

Mohsdorf, Saxony.

This rock, according to Dr. E. Dathe, is compact, blackish-green, and contains crystals
of diallage and enstatite, which show a mother-of-pearl to silky lustre, and a light-yel-
lowish color, while they are finely striated. The principal material of the section is
olivine, part of which is in large rounded erains with few fissures, and part in smaller
grains, traversed by cracks, and more or less altered to a greenish-fibrous serpentine.
The olivine contains little octahedral crystals of chromite or picotite, with rounded angles.
The enstatite is in light-greenish, elongated sections, sometimes holding olivine grains, and
traversed by cleavage lines parallel to 010. JDiallage also occurs, recognized by its opti-

THE TERRESTRIAL PERIDOTITES. — LHERZOLITE. 133

cal relations and cleavage. Greenish, crumpled chloritic plates and fibres, forming rosette-
like aggregates, are associated with the garnet as an alteration-product. Also, brownish
plates, with the strong dichroism of biotite, were seen. Besides the secondary chlorite
and biotite, magnetite and hydrous oxide of iron have been produced by the alteration of
the garnet. The latter mineral is next in abundance to the olivine, and in its fresh state
is traversed by fissures.*

Rodhaug, Gusdals See, Norway.

This peridotite is stated by Mohl to be formed of a regular mixture of olivine grains,
enstatite plates with some grass-green diopside, and chromite grains and octahedrons.
The olivine is in part changed to serpentine, but in general it is water-clear and free from
pores and inclusions. The grains often show a grayish-yellow ferruginous tint, and the
serpentinized portions are composed of short fibres, causing the fissures to appear broader,
impellucid, and of a grayish-yellow color.

The enstatite is in single scales, which are numerous and of a nacarat color.

The very pellucid, leek-green chromdiopside is in feebly dichroic, ledge-formed pieces,
filled with round and pipe-formed glass pores.

The chromite forms rounded grains or octahedrons with rounded edges. Portions of
these grains are of a dark hair-brown color when viewed by transmitted light.

Baste, Harz.

5062. A erayish-black rock, with grayish-white spots. It shows the characteristic
schiller of the enstatite (bastite), with its enclosed olivine grains. Considerable brown
biotite can also be seen.

Section: dark greenish-gray, and composed of an irregular sponge-like mass of ensta-
tite, diallage, and feldspar, with their alteration-products, holding rounded, partially
| altered olivines. The least altered olivines are traversed by numerous fissures, most of
which extend through the adjoining pyroxene. These serve as channels for the percolat-
ing waters, and more or less black ferruginous material exists in them. In those olivines
that are further changed the ferruginous bands increase, and a greenish serpentine is
observed bordering the sides of the fissures, while the amount of clear, unaltered olivine
between the meshes made by the fissures grows less. Every gradation of alteration can be
observed in this section, from that above mentioned to those olivines in which an entire
alteration has taken place, a serpentine mass remaining, which shows by its structure and
ferruginous bands the former fissure lines of the olivine. In some highly altered portions
a few grains of olivine can be found, a mere remnant of the larger grain once there. The
enstatite and diallage are traversed by numerous cleavage lines and fracture planes, which
are bordered by a greenish serpentine. The pyroxene minerals are of a pale-yellowish
tinge, slightly dichroic, and in places much altered to the serpentine. The feldspar in
part retains the characteristic polysynthetic twinning of plagioclase, which here has the
same broad banding as that commonly observed in the feldspar of gabbros. For the most
part it is altered to a clear or gray fibrous mass, with brilliant aggregate polarization
similar to that of liebenerite. In some places it has been changed to a dirty-green
viriditic mass.
Picotite and iron ores occur in the mass of the rock, the former mineral being found

;
:
.

* Neues Jahr. Min., 1876, pp. 230-282. + Nyt Mag., 1877, xxiii. 117, 118.

134 PERIDOTITE.

even in the feldspar. A little brownish-biotite was observed as a secondary product,
The structure of a portion of this section is shown in figure 2, Plate VIII.

Another section, purchased from Voigt and Hochgesang, shows similar characters, but
part of the olivine and enstatite is not so much altered as in the preceding. While in
the former the diallage largely predominated, in this only enstatite was observed.

A section of so-called serpentinfels of Baste, purchased from R. Fuess of Berlin,
shows a gray and greenish-brown sponge-like mass holding serpentinized olivines. The
general structure is like the preceding ones described from Baste, as well as those to be
later given from Christiania and Gjdrud, Norway, but the alteration has progressed con-
siderably further. Tale and amphibole occur as secondary products, as does a pale bluish-
green mineral associated with a mineral of pale pinkish or grayish color. From their
association and relations the bluish-green form seems to be a better developed state of
the gray mineral. Since both are isotropic, and have the usual structure and relations
observed belonging to garnet, I am inclined to refer them to that mineral. Associated
with these are coffee-brown picotite or chromite grains, which also appear to be of second-
ary origin, and closely resemble those found in the St. Paul’s peridotite.

No. 5041 is another specimen of the so-called schillerfels from Baste, Harz, obtained
from Voigt and Hochgesang. This is a greenish-black rock, showing the schiller of the
altered pyroxenes, and holding rounded grains of serpentinized olivine. Weathered on
one side to a rusty-brown. ‘The section of this is very similar to the one last de-
cribed, but contains more picotite, and none of the pale bluish-green mineral has been so
far observed.

Streng states that the schillerfels of the Harz is a mixture of anorthite, protobastite,
diaclasite, compact schillerstein, schillerspath, serpentine, and chrome-bearing magnetite.*

Figure 1, Plate VIII., shows a portion of the structure of an enstatite mass with its
enclosed olivines — the characteristic fissuring of both minerals being shown. The dark
grains in the olivine are picotite and the greenish portion indicates the beginning of
change in the enstatite.

Figure 2 of the same plate indicates a change in the rock still further advanced, and
shows the olivine discolored by secondary iron ores bordering the fissures, and more or less
changed to serpentine, while the enstatite is considerably altered. Figure 5 on the same
plate exhibits a phase of extreme alteration, the rock, while retaining its structure, having
its olivine entirely, and its enstatite and diallage nearly, if not entirely, replaced by ser-
pentine and various secondary products.

Christiana, Norway.

5063. <A dark, nearly black rock, showing in places the schiller of the pyroxene
minerals, and occasionally exhibiting grayish-white spots. At one end it presents an
appearance similar to that of the forellenstein of Volpersdorf. One side is coated with
serpentine and dolomite.

Section: a grayish-white spongiform mass, enclosing greenish, serpentinized olivines.
The olivine is much altered, showing the usual reticulated network of magnetite with the
later greenish and yellowish serpentine. Part of the olivine enclosed between the meshes
remains intact, or only slightly smoky. In some of these elongated tubes of minute size

* Neues Jahr. Min., 1862, p. 521.

a ae ee ee

~ ea es,

THE TERRESTRIAL PERIDOTITES. ~ LHERZOLITE. 135

occur similar to those observed in the olivine of the Siberian pallasite (ante, p. 72).
These tubes lie parallel to the plane of extinction in the olivine.

The grayish-white groundmass is composed of enstatite, a little diallage, and various
secondary products. The enstatite varies from a clear transparent mineral to a_pale-
brown and a reddish-brown. The last is so associated with the first as to indicate that it
is a partially altered state of the first. This reddish-brown portion owes its color to the
same included plates as those commonly seen in bronzite and hypersthene ; and it could
be well called the former, or, because the mineral is feebly dichroic, the latter. Whether
the altered portions of the groundinass are derived in part from the alteration of feldspar
or entirely from the pyroxene minerals, is not known. No distinguishable feldspar was
seen. The pyroxene minerals are in part changed to serpentine, and in part to an indefi-
nite aggreyately polarizing mass, usually surrounded by one or two bands of secondary
minerals standing perpendicular to the bounding surface. The outer band possesses a
polarization similar to that of enstatite, while the inner resembles an amphibole mineral.
In some cases on the olivine side, another band composed of serpentine was observed. A
similar structure frequently exists in altered gabbros, but in this case the products are
not sufficiently well defined to be determined. Considerable dolomite was seen in the
more highly altered portions of the rock. Altered picotite or chromite (slightly translu-
cent and reddish-brown in spots), as well as iron ore produced during the conversion
of the olivine into serpentine, was found. Only a small portion of this ore remains in
the parts where the conversion of the entire olivine mass is most complete.

Figure 3, Plate VIII., shows the general structure of this rock. The white portions
have the granules still unchanged in the greenish secondary serpentine material, which in
part replaces the original olivine. The brownish portions forming a matrix for the altered
olivine are the enstatite and diallage, which for the most part are changed. The bluish
band on the right is one of the alteration-borders between the olivine and enstatite.

Gjérud, Norway.

This, according to Méhl, is principally composed of rounded and obtuse-angled olivine
grains, which form from sixty per cent to seveuty per cent of the mass.

Along the contours and fissures the olivine is changed to a bright leek-green, gray-green,
and grass-green chrysotile, whose fine fibres are arranged partly across, and partly
parallel to, the direction of the veins. The centre of these chrysotile veins is generally
filled with a fine black line of magnetite or by aggregations of magnetite grains.

Some hypersthene or an augitic mineral occurs in the section. This is dichroic, of a
chocolate-brown color, but altered in part to a cloudy-grayish and yellowish-white sub-
stance, supposed to be a magnesium carbonate.*

In a section of Gj¢rud serpentine purchased from R. Fuess, a gray, sponge-like mass is
seen holding the greenish, serpentinized olivine. Excepting that the alteration has pro-
gressed some further, the description of the Christiania peridotite would apply to this
section. If the dichroism of the rhombic pyroxene arises from alteration, as I suspect it
does, there seems to be no reason for calling it hypersthene, instead of enstatite.

Its structure and alteration are shown in figure 4, Plate VIII.

* Nyt Mag., 1877, xxiii. 122, 123.

136 PERIDOTITE.

Presque Isle, Michigan.

65. <A dark grayish-black to black rock, showing in places the irregular shimmer of
enstatite holding olivine. ;

Section: grayish-green, and composed of an irregular mass of enstatite, olivine,
diallage, magnetite, and various secondary products like feldspar, viridite, dolomite, ser-
pentine, etc. The olivine with its secondary products forms in places the principal
portion of the section; in other parts the enstatite and diallage are the chief minerals ;
while the olivine and magnetite are held in grains in the interior. The olivine crystals
are comparatively large, but much fissured and altered along the fissures and exterior.
The interior portions are clear or smoky, except where the olivine material has been
completely changed. The alteration shows. in the form of cloudy bands of magnetite
traversing the crystal along the fissure lines, while a further change is shown by the for-
mation of greenish and yellowish serpentine along the same lines. The change continues
until the olivine is entirely altered. The magnetite usually assumes an irregular grating
form or network extending through the serpentine, as well as being arranged in lines
which show the former position of the olivine fissures.

The enstatite and diallage have a slight tinge of green, and are slightly pleochroic.
They are traversed by longitudinal, transverse, and irregular fissures, the latter being more
abundant in part of the diallage. They form together an irregular sponge-like mass
holding olivine, and thus present a structure not unlike that of the Atacama and Siberian
pallasites, in which they play the réle of the iron. They seem to form the same identical
continuous mass, but with a high power the line of union can be faintly seen. It
probably would have never been discovered if polarized light had not directed attention
to it.

The enstatite polarizes with a pale greenish tint differimg but little from the natural
color, while the diallage shows brilliant hues of mixed yellow, red, and violet. Both are
more or less altered along the fissures to a greenish or a yellowish-green serpentinous
product, which is dichroic, varying from a green to a yellowish-brown shade. Similar
dichroism, but less marked, was observed in the serpentine of the olivine. In the highly
altered portions of the section are lath-shaped crystals, branching from a centre in a fan-
shaped mass. These appear to be feldspars, some of which possess plagioclastic characters.
Associated with these occur brown biotite, a little apatite, and some augitic material. The
structure of these patches closely resembles that of some diabases. The entire section is
traversed in places by a pale greenish serpentine in veins holding dolomite, the latter
mineral occurring elsewhere in the section. Some actinolite was observed. The mag-
netite is in octahedrons and irregular grains, as well as in the secondary forms before
mentioned. The cloudiness of the olivine seems to be due to magnetite granules.

Besides the serpentine, a bluish-green fibrous viriditie product occurs, associated with
brown biotite plates in such a manner as to lead to the belief that this product is an
earlier stage in the formation of biotite, which is evidently an alteration product here.
The structure of the enstatite portion is shown in figure 3, Plate VII.

73, from the same locality, is a dark grayish-black to black rock, mottled with
minute specks of grayish-white, as well as with pyrite. Weathers to a rusty brown.
Section: of a dirty green color, and composed principally of olivine grains and crystals,
with magnetite held by a light green mass of enstatite, diallage, and various secondary
products. The alteration of the olivine is greater here, as a rule, than in No. 65. The
magnetite bands along the fissures are wider, and fewer portions are left showing the

THE TERRESTRIAL PERIDOTITES. — LHERZOLITE. 137

olivine polarization. The secondary products are as in the preceding, but more abundant
and well marked. Much less enstatite and diallage exist here than in No. 65, and they
are more highly altered. The interspaces between the olivines more commonly contain
pale greenish serpentine, bluish-green and yellowish biotite (?) material, dolomite, mag-
netite, etc. Much of the serpentine shows the coarse fibrous laminze so commonly
observed in the serpentines described in this volume. In portions of this section and
in another slide from the same hand specimen the change of the rock mass to serpen-
tine is nearly, and sometimes quite complete, the forms of the olivines being distin-
guishable through the arrangement of the magnetite and the serpentine.

The general structure of section.is shown in figure 4, Plate VII.

67, from the same locality, is composed of the same dark grayish-black rock, which
here presents a brecciated appearance on account of its being traversed by rambling veins
of light-yellowish serpentine. In the section the rock appears as a dirty greenish mass
traversed by greenish-white veins. It is composed of serpentine pseudomorphs of
olivine, filled with beautiful dendritic growths of magnetite, as well as with irregular
masses of the same mineral, The interspaces contain the various secondary products
before described : micaceous (viriditic) material, serpentine, magnetite, feldspar, dolomite,
etc. The veins are composed principally of dolomite grains and serpentine, the former
predominating.

74, from the same locality, is much like No. 65, but the grayish spots are more
abundant. Under the microscope it is seen to be composed of a coarsely fibrous lamellar
serpentine traversed by the irregular network of magnetite so common in the serpen-
__ tinized peridotites. It contains a little dolomite and one plate of a micaceous mineral
& was observed. This was feebly dichroic, greenish and yellowish, extinguished parallel

to the nicol diagonal, and polarized with a beautiful purplish-blue tint. It presents a

fine micaceous cleavage parallel to the line of extinction, and it is probably partially
} _ formed biotite.
71, irom the same locality, is a grayish-green rock traversed by grayish-white veins of
dolomite, which give to it a rude appearance of foliation. The rock contains a number
of reddish-brown patches formed from a breccia of the decomposed rock held by minute
reticulated veins of dolomite. The section is composed of yellowish and bluish green,
and reddish-brown pseudomorphs of olivine held in a granular mass of dolomite.
Crystals and grains of magnetite are scattered throughout the rock. The olivine in the
greenish pseudomorphs has been entirely replaced by serpentinous and ferruginous
material with dolomite, the first predominating. The reddish-brown pseudomorphs have
the ferruginous material the most prominent, and it is these pseudomorphs which form
the reddish-brown patches before referred to. The fissures of the olivine are represented
by ferruginous and sometimes by dolomitic bands, and these bands can sometimes be
seen in the dolomite, showing the form of the pseudomorph when the latter has been
almost entirely replaced by dolomite. A portion of the structure of the section is shown
| in figure 5, Plate VII., the gray groundmass being dolomite and the greenish patches the
| pseudomorphs after olivine.

69, from the same locality, is a pale oil-green serpentine, banded and spotted with
_ dark and light brown. The section is composed of a granular and fibrous mass of
serpentine and dolomite, with ferruginous and earthy material, all holding brownish-
yellow earthy pseudomorphs after olivine, which are traversed by the ferruginous bands
representing the olivine fissures. These pseudomorphs are wanting in portions of the
section. Much of the serpentine shows the fine fibrous polarization of chrysotile.
18

|
?
:

138 PERIDOTITE.

66, from the same locality, is a dark greenish-brown rock traversed by a network of
oil-green serpentine veins, giving it a roughly foliated appearance. The section is very
similar in character to that of the preceding.

70 is a dirty green rock coming from the upper portion of the mass at Presque Isle.
Section grayish, and composed principally of a granular mixture of dolomite and serpen-
tine with some ferruginous and micaceous materials, ete.

72, is from a portion of the Presque Isle peridotite which has been so filled by
dolomitic material as to form a vein. The rock is brownish-gray with a slight pinkish
tinge, and composed of granular dolomite holding masses and grains of the decomposed
peridotite. It presents the usual structure observable in veins formed by the decom-
position and the partial removal of the original rock, and its replacement by vein
material. This more properly comes later, in the portion of this work in which the vein-
stones are described ; but on account of its connection with the previously described peri-
dotite it is given here. The sections are composed of a dirty gray granular dolomite,
holding patches of ferruginous material, both dark and light yellowish-brown. In places
the darker portions show the cherry-red color of hematite, and appear in part at least to
replace olivine.

The Presque Isle peridotite was microscopically studied by Dr. A. Wichmann, who
gave a short description of it under the name serpentine, stating that it consisted only of
olivine, serpentine, and magnetite.* No chromite was found, on making proper tests,
in the Presque Isle rock, either by Professor Whitney — or myself ;{ but Dr. Rominger
states § that it contains two per cent of chromic iron in small octahedrons readily attracted
by the magnet, although he does not remark whether this iron was tested to prove the
presence of chromium or not.

This peridotite is confidently believed to be eruptive from the following observed evi-
dence. On the southeastern side the overlying Potsdam sandstone dips quite irregularly
from twenty to thirty degrees southerly. Its strata follow continuously the curve of the
underlying peridotite, and even in places form anticlinals. The surface of the peridotite
is an irregular knobby one, while it forms as a whole an immense knob. To this knobby
structure the layers of the sandstone conform continuously, as layers of blankets would,
and they show no signs of deposition against or around the knobs, but rather a structure
as if the sandstone layers had themselves been indented and bent by the peridotite itself.
The sandstone with its conglomeritic portion for some two or three feet above the perido-
tite has been greatly indurated and changed, showing heat action, particularly that of
thermal waters. It is filled with vein and chaleedonic quartz; and indurated and red-
dened as such rocks are known to be when in contact with eruptives of later date than
themselves. These indurated portions show, on examination under the microscope, that
much of the quartz is a secondary water deposit formed’ since the deposition of the frag-
ments composing the rock. Above this indurated portion comes the ordinary unaltered
sandstone. No fragments of the peridotite could be found macroscopically in the field or
microscopically in the laboratory in the sandstone. Now the sandstone does not hold
such relations to the Azoic rocks of the district when in contact with them, and it seems
right to maintain that this peridotite is younger and an eruptive rock, intruded in the
form of a laccolite since the Potsdam sandstone was laid down.||

* Geol. Wisc., 1880, i. 618. + Am. Jour. Sci., 1859, xxviii. 18.

¢ Bull. Mus. Comp. Zodl., 1880, vii. 61. § Geol. Mich., 1881, iv. 136.

|| See Foster and Whitney, Geology of Lake Superior, 1851, ii. 17, 18, 92, 121, 122; Bull. Mus. Comp.
Zool., 1880, vii. 2, 3, 6, 9, 10, 23, 60-66.

ee ee en eee

J
;

THE TERRESTRIAL PERIDOTITES. — LHERZOLITE. 139

See. 29, T. 48, R. 27. Three and one-half miles northwest of Ishpeming,
Michigan.

242, A gray, somewhat fibrous rock. Section: a gray mass traversed by a network
of magnetite. It is composed of a light gray and colorless transparent mass of serpentine
with some dolomite, aud has the usual reticulated arrangement of the magnetite so char-
acteristic of the serpentines produced from the alteration of olivine rocks.

241, from the same locality, is a greenish- and reddish-brown rock traversed by green-
ish-gray serpentine veins. Weathers light yellowish-green. The reddish-brown color is
owing apparently to a ferruginous staining of the serpentine folie. Section is brownish-
gray and composed of a pale greenish-yellow serpentine traversed by irregular reticulated
magnetite bands, and spotted by irregular ferruginous stains of reddish- and brownish-yellow.
While in the hand specimen these stains present the appearance of distinct micaceous
foliz, Iam unable by the microscope, either in common or polarized light, to find any
structure peculiar to them and distinct from the serpentine, beyond that belonging to
ordinary ferruginous stains. The serpentine shows an irregular fibrous and lamellar
structure in polarized and common light.

245, from the same locality, is similar to the preceding. Its staining is deeper, and
the rock is coated on one side with a chrysotile and dolomite vein. In the section the
fibrous structure, the magnetite network, and the ferruginous staining are all more
strongly marked than in the preceding.

243, from the same locality, is a greenish-gray rock with the ferruginous staining
showing in a few spots only, — principally along fissures. The section is gray, and under
the microscope is seen to be composed of pale greenish-yellow serpentine with cloudy
spots. These appear to be occasioned by a fine magnetite dust, which is generally associ-
ated with an approach to crystallization on the part of the surrounding material, which
somewhat affects polarized light. Numerous pale greenish scales occur in abundance in
the serpentine, and have the polarization characters of tale. Crystals and grains of mag-
netite are scattered throughout the section.

235, from the same locality, is a clear translucent green serpentine containing magne-
tite grains. It weathers light-colored, even to a chalky-white. The section forms a clear
almost colorless mass spotted with crystals and grains of magnetite. The same mineral
also traverses the section in the form of a vein. In common light the clear serpentine
mass shows fibrous structure, which is beautifully brought out in polarized light. The
magnetite appears as a secondary product.

Associated with these are other specimens of greenish- and reddish-brown serpentine
often traversed by dolomite veins. In large masses this dolomitic material with tale
seems to have replaced nearly all of the serpentine, giving rise to a rock called locally
limestone. Much chrysotile also occurs.*

Transylvania, Austria.

Tschermak describes a schillerfels + from this region as a dark-green rock with white
spots composed of olivine, bronzite, diallage, magnetite or chromite, and a little anorthite.

* See further, Bull. Mus. Comp. Zodl., 1880, vii. 65, 66; Wright, Mineral Statisties of Michigan, 1879,
pp- 204-206; Rominger, Geol. Michigan, 1881, iv. 137-143. ‘

t Herbich appears to class this with eruptive rocks. Verh. Mitth. Natur, Hermannstadt, 1865, xvi.
172-183.

140 PERIDOTITE.

The olivine is traversed by a network of dark-green serpentine fibres, and the diallage and
bronzite are both somewhat altered. Associated is a compact dark-green serpentine hold-
ing some chysolite and chromite. Another rock from the same district is of a dark olive-
green color, flecked with white spots ; and contains a platy greenish-brown shining diallage,
a deep green finely granular mass of olivine, and small white grains of anorthite. The
olivine is here traversed by a network of dark-green serpentine.*

Fitchtelgebirge, Bavaria.

These rocks are composed principally of olivine with enstatite, chromdiopside, augite,
and magnetite. The olivine is more or less altered into a serpentine, showing the usual
network structure. The enstatite is in elongated, fibrous, brilliant clear wine-green
needles, and the chromdiopside in roundish, compact, somewhat fissured particles. The
groundmass consists of a mixture of chlorite, serpentine, ete.T

A Pebble from the Jaina River, ten to twelve miles N. W. of Mt. Mariana, Chico,
Prov. San Domingo, San Domingo.

252 G. A compact dark-green groundmass holding crystals of brownish pyroxene
and traversed by veins of chromite. .

Section: a gray groundmass holding iron ore and crystals of enstatite and diallage.
The groundmass is composed almost entirely of clear beautifully polarizing serpentine,
which shows in its structure traces of the bounding planes of the minerals from whose
alteration it was derived. A little white plagioclase, traversed by cleavage planes, was
observed, portions of which had been rendered gray and nearly opaque by kaolinization.
Only a few small fissured olivine grains were observed. The enstatite and diallage can
here as a rule be distinguished by their cleavage, the latter being much less regular than
the former, and closely like that of augite. Both are in irregular grains, more or less
altered to a greenish- and yellowish-brown product. Where the change has progressed
far, the ordinary serpentine of the groundmass is the result. Sometimes the serpentine
resulting is filled with minute black globules, or with minute microlitic forms, ar-
ranged in lines forming definite angles with one another. The iron ore is in part in
crystals and part in irregular grains and masses. The structure is shown in figure 6,
Plate IV.

This rock was collected by Professor W. M. Gabb.

Starkenbach, Bluttenberg, Vosges, France.

According to Weigand this is soft black rock containing brownish-yellow and brass-
yellow crystals. In the thin section the rock is seen to be composed of bronzite (ensta-
tite), diallage, olivine, magnetite, hornblende (smaragdite ?), and picotite, with more or
less serpentine. The enstatite and olivine are more or less traversed by fissures filled
with serpentine. The hornblende is in minute plates, while the bronzite is the predomi-
nating mineral.t

* Sitz. Wien. Akad., 1867, lvi. 261-274.
+ C. W. Giimbel, Die palaolithischen Eruptivgesteine des Fichtelgebirges, 1874, pp. 38-41.
+t Min. Mitth., 1875, pp. 192-196.

~~

THE TERRESTRIAL PERIDOTITES. — LHERZOLITE. 14]

Todimoos, Baden,

5000. The specimen from this locality in the collection is a blackish-green compact
one, containing a few enstatite and diallage crystals, It weathers to an earthy rusty-
brown, showing the network method of decomposition frequently observed in the perido-
tites. This with the sections was purchased from Voigt and Hochgesang, Gottingen.

One section has a greenish groundmass holding crystals and grains of enstatite, dial-
lage, olivine, and picotite. The enstatite is in part clear and unaltered, holding picotite
grains, and in part it has suffered a greenish and yellowish serpentinous alteration. The
same can be stated of thé diallage. Both are in rounded crystals and irregular masses,
and show the usual cleavage lines.

The olivine when unchanged is in clear grains, the remnants of the original larger
erystals and grains. That a series of these grains now separated by the serpentine bands
once formed the same crystalline mass, is shown conclusively by their possessing the same
optical orientation. The major portion of the original olivine has been changed to ser-
pentine, the structure showing the successive stages of alteration. The serpentine formed
first along the fissures has a dividing line indicating the fissure, and on both sides the ser-
pentine fibres stand at right angles to that line. The color of this serpentine is generally
a light yellowish-green. The interior portion occupying the interspaces left between the
network lines above described, is occupied by serpentine of a different shade of green,
sometimes lighter, sometimes darker. This serpentine, which replaces the olivine grains
before described, shows not only by its color, but also by its structure, both in common
and in polarized light, that it possesses a distinct organization from that of the network,
and is distinctively a later product. The serpentine forms the chief portion of the
groundmass and is feebly dichroic. While it is usually of some shade of yellowish-green
to pale-egreen, in some cases, especially about the ferruginous products, it is of a bluish-
green color, doubtless owing to the ferrous oxide. Some secondary actinolite and tale
exist associated with the pyroxene minerals. The picotite is in coffee-brown and pale-
greenish irregular grains scattered throughout the section in the different minerals. Tlie
larger grains along their fissures and edges are altered to a black ferruginous product,
probably chromite. This alteration sometimes extends nearly, aud sometimes quite,
through the entire picotite grain. Considerable secondary iron ore exists, which is either
chromite or magnetite.

Another section has a yellowish-green groundmass containing grains of enstatite,
diallage, and picotite, and traversed by veins of tale. The groundmass is a network of
serpentine of a pale yellowish-green color, surrounding portions of a deeper green repre-
senting the unfissured parts of the olivine, while the meshes follow the fissures. The
enstatite and diallage are in places only slightly altered; but for the most part they are

traversed by threads of the serpentine web, and possess a fibrous alteration-structure

showing a more or less aggregate polarization; yet in the majority of cases they retain
their relative extinction. This serpentine is very beautiful in polarized light. The pico-
tite is in irregular fissured grains, sometimes opaque, but more commonly with dark
brown to black edges, and with a light brown to dark reddish-brown interior. Much
ferruginous material in grains and irregular patches is distributed through the section.
This serpentine has been referred by Rosenbusch to the lherzolites.

142 PERIDOTITE.

From Spur between Deadwood and Poker Flat, Cal.

111 P. A dark-yellowish and brownish-green rock containing enstatite grains and
tale scales; and traversed by lght-greenish serpentine veins. Section: a greenish-eray
mass flecked with magnetite grains and traversed by a grayish-yellow serpentine vein.
The chief portion of the section is serpentinous material, in which besides the magne-
tite are scattered the remains of enstatite crystals and a few grains of olivine and diallage.
The serpentine varies in color from white to yellowish and green. In places clear white
leaves of tale associated with magnetite occur ; while some hematite is to be seen. Along
the sides of the serpentine vein before mentioned the section is black with the rejected
magnetite. Much of the enstatite contains the same inclusions that the bronzite variety
is accustomed to hold. -

The structure is shown in figures 3 and 6, Plate VI.

Levanto, Italy.

One specimen described by Prof. T. G. Bonney from this locality is a purplish-
or brownish-black rock veined occasionally with dull green, and flecked with crystal-
line folia of glittering bronzite, while another specimen is of a more granular texture,
greener color, and rougher fracture than the preceding, but otherwise similar. The
second rock, in the thin section, is seen to consist chiefly of olivine grains separated by
threads of serpentine. It contains opacite, enstatite, augite, and perhaps a little diallage.
Opacite [magnetite] occurs in the enstatite and a little picotite was observed.

The first specimen was seen under the microscope to have been completely altered, no
olivine remaining intact. Much opacite was found, which often forms continuous strings,
and is present to a greater or less extent in the grains that were formerly olivine. It
forms bands towards the exterior of the grains, or is disseminated throughout them.
Diallage and enstatite are both present, the latter being surrounded by a border of a ser-
pentinous mineral, into which are continued the principal cleavage planes, often marked
by opacite lines. Thin bands of serpentine indicate the prismatic cleavage.*

Near Limni, Eubcea.

A black splintery rock, which, as described by Becke, contains lustrous bronze-colored
grains of enstatite. Under the microscope it shows the evident maschenstruktur of the
serpentine which holds lens-formed masses of fresh olivine. This groundmass porphy-
ritically contains fresh enstatite of a pale brownish color and a marked fibrous texture.
This mineral is sometimes altered to a feeble bluish polarizing product. This alteration
extends from the exterior along the fissures towards the interior. Diallage, reddish-
brown octahedrons of picotite, and secondary magnetite also occur. ;

Similar to this is a rock from Mantoudi, in the northern portion of Eubcea. This is
brownish, and contains numerous plates of enstatite in a fine-grained groundmass. No
diallage was observed, but the brownish color of the rock is due to brown hydrated
oxide of iron.

Sunilar to this isa rock from the district of middle Eubcea, between Chalcis and
Gides, which has a reddish-brown groundmass holding tombac-brown enstatite (bastite).
No olivine remains unaltered to serpentine.

* Geol. Mag., 1879 (2), vi. 362-371.

SS ee

THE TERRESTRIAL PERIDOTITES, — LHERZOLITE. 143

A rock of similar character was obtained between Kumi and Kastrovolo, in middle
Eubcea, possessing diallage instead of enstatite. The diallage is partly altered intoa
greenish substance and partly into tale plates.

A serpentine from Kumi was found to contain much chromite, magnetite, and some
green ouvarovite.*

Oberlauf, Luzon, Philippine Islands.

A dark blackish-green serpentine-like compact rock, with crystals of clear green dial-
lage and brownish enstatite. The principal cleavage planes show a mother-of-pearl
lustre. Microscopically the rock possessed the usual mesh structure, and contained mag-
netite and picotite.t

Lizard District, Cornwall.

The serpentines of this district were found to present intrusive relations to the
adjoining rocks by Prof. T. G. Bonney. They send tongues and dikes into the latter and
hold included fragments of them, while the adjacent rocks at their junction with the
serpentine were often altered and contorted. The microscopic examination indicated that
the serpentine resulted from the alteration of lherzolite. The following is condensed
from Professor Bonney’s description of the rocks and sections. The rock from Coverack
Cove is a dull mottled, red and green rock with flakes of a silky bronzitic mineral in the
green portion. Under the microscope the serpentine forms golden-colored and reddish-
and greenish-brown reticulated veins, which enclose colorless olivine, as well as auyite,
enstatite, and diallage. Original and secondary iron ores occur. <A rock from Mullion
Cove has a similar composition and structure, but the alteration of the olivine has pro-
eressed further, with a differentiation of the common black ferruginous dust. A few
small grains resemble picotite.

At Gue Graze a similar but more decomposed rock was obtained, which appeared to
contain a pseudomorphic product after feldspar. From the Lower Pradanach and the Nill
quarries similar rocks to that from Mullion Cove were obtained, but in one from Helston
Road a little hornblende was observed.

The rock from Goomhilly Downs is a banded dull-colored light-greenish serpentine,
containing in the section, besides the serpentine, olivine, hornblende, magnetite, and some
picotite. A number of other sections were examined, but they are mainly similar to the
above, or else have been more highly altered, so that the olivine was entirely changed ;
but the reader is referred to the original paper for the particulars.t

Two other areas of serpentine were later examined in the Lizard district, one of which
shows excellent junctions and is clearly intrusive in the associated schist. Bonney also
re-examined the other portions of the district previously studied by him, and found the
strongest evidence of the intrusion of the serpentine into the associated sedimentary
rock. §

From the Troad, Asia Minor.

Owing to certain arrangements, and for a consideration, the lithological collection of
the Assos expedition has become the property of Professor Whitney, and passed over to

* Min. Mitth., 1878 (1), i. 477-485.

+ Konrad Oebbeke, Neues Jahr. Min., Beilage Band, 1882, 1. 499.

+ Quart. Jour. Geol. Soc., 1877, xxxiii. 884-928 ; 1883, xxxix. 21-23.

§ Phil. Mag., 1882 (3), xiv. 478; Quart. Jour. Geol. Soc., 1883, xxxix. 21-28.

144 PERIDOTITE.

my charge. Mr. Diller (who collected the specimens) has kindly consented that I should
use his written description of the Assos serpentine rocks, not yet published except in ab-
stract,* and it is given below, with a few verbal changes to adapt it to the present work.

“Serpentine occurs in the Troad at Qara-dagh . . . derived from the alteration of
eruptive rocks; also about the summit of Mt. Ida in small lenticular masses in talcose
schist, and belongs to the stratified rocks; also . . . forming low rounded conical hills
near the base of Qara-dagh. The rock is usually of a deep green color, but varies,
becoming bluish or reddish, often presenting smooth fibrous surfaces like slickensides,
and occasionally an imperfect columnar structure. Although locally uniform, it is gen-
erally made porphyritic by a fibrous or lamellar mineral, whose cleavage plates between
crossed nicols show an acute bisectrix with the plane of the optic axes at right angles
to the fibrous structure. The mineral is bastite, and in all probability has been produced
by the alteration of enstatite.

“Under the microscope the composition of the rock is seen to vary greatly. Sometimes
it is composed almost wholly of a network of serpentine containing a few grains of unal-
tered olivine, bastite, and much iron ore. In other cases the serpentine is a subordinate
constituent, and olivine forms the chief mass, in which are imbedded enstatite, for the
most part changed to bastite, and also very rarely a colorless mineral, with prismatic and
pinacoidal cleavage. It appears to belong to the pyroxene group, but with the few sec-
tions present its optical relations could not be determined. It is evident that the
serpentine of Qara-dagh is derived from an olivine enstatite rock.

“Jn the Kemar Valley, a short distance east of where it opens into the Trojan Plain,
loose blocks of serpentine containing numerous very bright silvery crystals of bastite have
been observed. In the thin section, besides serpentine, olivine, enstatite, bastite, and
irregular dark grains, there occur numerous small black crystals whose square rhombic
and hexagonal sections indicate that they may belong either to spinel or magnetite ; but
as they are not translucent, they are most likely magnetite.

“Further up the valley the serpentine is indistinctly porphyritic, and occurs inti-
mately associated with schists and crystalline limestone, through which it appears to pene-
trate in the form of irregular dikes. Its specific gravity is 2.593. The microscopical
structure of these rocks is strongly contrasted with that of the serpentine from Qara-
dagh. Between crossed nicols they appear rather coarsely microcrystalline, and through-
out the greater portion of the section are not only uniform, but show no trace of the
characteristic reticulated structure of serpentine derived from the alteration of olivine.>
However, here and there a few meshes of the old net are still preserved, and there
appears to be a passage from this portion into the other, in which the same structure can-
not be traced. The porphyritic crystals, as in the other cases, are bastite, with considerable
quantities of carbonates. According to Mr. Frank Calvert the serpentines in the vicinity
of the Kemar Valley occur as distinct dikes cutting the crystalline limestones, so there
can be no doubt concerning their eruptive nature, and they are in all probability derived
from olivine enstatite rocks. }

“Near the centre of Mt. Ida the oldest rocks crop out, and among them are talcose
schists, which by the addition of olivine pass into small lens-shaped masses composed

* Papers of the Archeological Institute of America, Classical Series, i. 201, 203; Science, 1883, ii.
255-258.
} Hussak, after studying microscopically a number of Alpine serpentines, concluded that in the ser-

pentines derived from schistose rocks the characteristic reticulated structure, chromite, and picotite are
wanting.
to)

THE TERRESTRIAL PERIDOTITES. — LHERZOLITE. 145

almost exclusively of the latter mineral. According to the nomenclature of Brogger, the
rock of these patches should be called olivine schist. By alteration it gives rise to ser-
pentine with the characteristic reticulated structure which ever marks the serpentine de-
rived from olivine.* Occasionally the fibrous serpentine forms veins of considerable size
in the adjacent rocks. The olivine schist when purest has no schistose structure. The
passage from pure tale schist in which no olivine occurs to that composed almost completely
of olivine, takes place sometimes within a short distance. The chief mass of the rock, how-
ever, is a middle stage between the two extremes, having a distinct schistose structure and
composed for the most part of olivine and talc, besides considerable quantities of pyroxene
as well as other minerals not yet determined.”

Differing in some points from Mr. Diller, although agreeing with him in the main, it
has seemed best to add more special descriptions of the individual rocks and sections in
question. It is further necessary to do this in order to point to the gradations and altera-
tions which are conspicuous in them. Part appear to belong to the lherzolite variety,
while others are so far altered that it cannot be predicated what was their original com-
position as a whole.

A. E. 824, from Mitylene, is a greenish-black compact rock containing lighter green
erystals of enstatite. The section shows a grayish-brown groundmass, holding crystals
of enstatite and diallage. This groundmass is formed by a network of grayish-brown
serpentine, holding olivine, enstatite, diallage, and iron ore. Much of the enstatite is
altered to a grayish-brown fibrous serpentine, but some portions remain intact in part
of the crystals, while other crystals are entirely unaffected. The diallage is abundant,
but in small irregular grains and imperfect crystals. Part of this appears to be an
augite-diallage, for it has well developed both the prismatic cleavage of augite and
the orthopinacoidal cleavage of diallage, as well as traces of a clinopinacoidal cleavage.
Elongated dashes of iron ore are occasionally arranged parallel to 010, forming with
the well-developed cleavage parallel to 100 a rectangular grating. Part of the iron
ore is secondary, occurring in grains arranged in the centre of the serpentine veins,
but part appears to be the product of alteration of picotite, since the interior portion
still is of a translucent reddish-brown color. From its general characters the ore is
probably chromite with some magnetite.

A. E. 208, from Qarai-dagh, is of a similar character, but has less enstatite and diallage,
and more olivine. In some places the olivine has suffered almost no alteration, while in
others the change is complete. The rock is compact, greenish-black, containing light-
greenish enstatite crystals, and coated with a greenish “slickenside ” of serpentine.

A. E. 209, from near Mt. Daydah by the Plain of Troy, is a grayish-green rock hold-
ing enstatite crystals altered into a talcose-like material (bastite) and presenting a
greenish to silvery-white appearance. The section is similar to the preceding, but more
highly altered, the serpentine predominating. The diallage is abundant, and in its
structure closely resembles that of the meteorites, being composed of a series of granules
ageregated together into larger masses, and separated by little patches of different
material.

A. FE. 481, from the southeast part of the Chiplak, Mt. Ida, is a dark-green rock
weathering brown and containing tale scales and grains, and bands of chromite. The
section is grayish, and presents a schistose appearance, owing to the arrangement of
its iron ore, ete. It is composed principally of a serpentine network enclosing olivine.
A little enstatite and diallage were observed, also iron ore and secondary tale.

* With this statement of Mr. Diller the present writer is unable to agree.
19

146 PERIDOTITE.

A. k. 207, four miles northwest of Eanedeh, is a compact greenish-brown rock, weath-
ering rusty-brown, and contains enstatite crystals. Section: ereenish-gray and composed
principally of secondary serpentine, with its network structure holding later altered oli-
vine grains, and altered enstatite crystals containing much iron ore, and traversed and
stained by ferruginous material. Many of the olivine grains between the meshes appear
in common light as unchanged olivine, but in polarized light the change to serpentine is
seen to be complete. Some dolomite occurs, while portions of the ‘section present a
similar structure to that given in figure 4, Plate VI.

A. E. 482, from the central part of the Chiplak, Mt. Ida, is a greenish-gray schistose
rock closely resembling some mica schists owing to its contained tale scales. It holds
actinolite and yellowish-brown altered olivine. Section: greenish-gray and composed of
olivine, iron ore, secondary serpentine, talc, and actinolite. JI am inclined to regard this
rock as an altered massive rock, instead of a metamorphosed sedimentary one.

A. E. 265, from the summit of Mt. Ida, is a similar schistose rock, composed of
olivine and actinolite, with tale scales lying between the lamination planes. The section
is composed partially of olivine, which is somewhat altered to a dirty-green serpen-
tine, and partially of actinolite crystals. Iron ore and tale also occur. Mr, Diller
has called this a tale schist; but I am unable to agree with him, for it appears to
me to be a metamorphosed peridotite, in which the actinolite and tale are alteration-
products. The foliation appears to me to have been produced during the metamorphosis,
and not to be congenital.

A. E. 485, from the northwest summit of Mt. Ida, is a schistose rock of a grayish-
green color. The schistose structure appears to be due to alteration and to the production
of tale scales. Section: composed of a network of greenish serpentine containing olivine
and secondary actinolite and tale. The form of the olivine grains, and their relation to one
another and to the other minerals, are such that I am unable to look upon them as either
of mechanical or of metamorphic origin. The actinolite is clearly an alteration-product,
and frequently separates portions of the same olivine individual.

There are two rocks numbered A. E. 488. One, coming from the central part of the
Chiplak, Mt. Ida, is a compact greenish-black rock containing tale scales and weathered
brown. The section is composed of serpentine, olivine, actinolite, tale, and iron ore.
The alteration of the olivine has been quite extended in this. The second A E. 488 is
from the northwest summit of Mt. Ida, and is a dark compact rock with little trace of a
schistose structure. The section is composed chiefly of serpentine, talc, iron ore, actino-
lite, and a little olivine.

A. E. 478, from the summit of a ridge east of Mt. Ida, is a dark greenish and grayish
rock weathering brown. Itisa surface specimen. Section composed of a network of green-
ish serpentine holding olivine grains, and associated with actinolite, tale, iron ore, ete.

A. KE. 217, from the Kemar Valley, is a compact dark grayish-green rock with green-
ish and grayish porphyritically enclosed enstatite crystals. The section is composed
principally of a clear pale greenish and yellowish serpentine, holding diallage, enstatite,
some tale, and iron ore. The serpentine shows traces of the structure of the minerals
from which it was formed.

A. E. 216, from the same valley, is a similar rock, and in the hand specimen pre-
sents considerable resemblance to that described from High Bridge, N. J. The section
is much like that of A. E. 217. The altered enstatite and diallage have ferruginous
material so arranged in their fissures as to give them a close resemblance to bronzite and
hypersthene,

THE TERRESTRIAL PERIDOTITES. — EULYSITE. 147

A. E. 214, from the same locality, is a similar, but more highly altered rock, which
contains talecose material.

The greenish talcose schists from Mt. Ida are stated by Mr. Diller to be associated
with and to pass into the olivine-bearing rocks above described from that locality. Ac-
cepting the accuracy of his statement, it is proper to touch upon their microscopic charac-
ters so far as they bear upon this relation.

A. E. 484 is a greenish talcose schist containing grains and crystals of magnetite.
Stained slightly with yellowish-brown ferruginous material from the decomposition of the
magnetite. The section is composed principally of tale holding magnetite and patches
of partly altered olivine and enstatite, traversed by a peculiar eozo6dn-like network of iron
ore, with the longest and best marked portions approximately parallel with an optic axis.

A. E. 274 is a coarser greenish-gray tale schist, composed of tale and actimolite
(Diller’s pyroxene) with iron ore and the remains of partially altered olivine.

A. E. 270 is a beautiful green tale schist, containing crystals of actinolite and grains
and crystals of iron ore. Only a few olivine grains were seen.

It seems to me from the study of these rocks, coupled with similar evidence obtained
from the examination of other rocks, like cumberlandite, that these schists and sclistose
forms are the results of the alteration of peridotites: that is, the schists are derived from
the olivine rock, and not that from the schists. This view is, of course, opposed to that
of Mr. Diller and the majority of lithologists and geologists.

Variety. — Eulysite.

Tunaberg, Norway.

The rock from which this variety is named was first so called and described by Axel
Erdmann, in 1849, as a granular mixture of diallage, garnet, and altered olivine.*

According to the later studies of H. von Mohl, it contains fresh clear angular grains
of olivine cut by numerous fissures and holding much magnetite in powdery vrains, while
the olivine is here and there altered into serpentine. A pale sea-green diallage occurs,
forming large grains in the rock. This diallage shows a fine fibrous parallel structure
(cleavage), which is often crumpled. This mineral often contains layers of very minute
lamin, which make with the cleavage planes angles varying from 20° to as much as 60°
or 70°. They are arranged in parallel lines. Pale almandine-red garnet in drop-like
rounded grains, and magnetite also, form constituents of the rock. Mohl estimates the
percentages of the minerals as olivine (fayalite) 60 per cent, diallage 35 per cent, mague-
tite 3 per cent, and garnet 2 per cent.

The above description by Moéhl answers very well for the section in this collection
purchased from Richard Fuess. The general structure and relations of the crystals
indicate that the diallage and garnet, if not all of the minerals, are the results of a
recrystallization of the rock materials; i. e. it appears to be a rock whose structure has
been produced by alteration and secondary crystallization, with but little if any of the
original structure and minerals remaining.

veltidsfjall, Sweden.

According to Tornebohm, this rock is a fine granular one, greenish on the fresh
fracture, and weathering yellowish. Microscopically it is composed of irregular olivine

* Neues Jahr. Min., 1849, pp. 837, 838. + Nyt Mag., 1877, xxiii. 119.

148 PERIDOTITE.

grains, colorless pyroxene (diopside), colorless mica, and chromite. The olivine is fresh,
and with the pyroxene is almost free from inclusions. The chromite is brownish on the
edges, and is often surrounded or accompanied by the mica.*

This rock is said to be associated with schists, and to be a concordant part of
them.

Varallo, Sesia Valley.

Prof. A. Stelzner described a fine-grained greenish-black rock from Varallo, in Sesia
Valley, as composed of olivine, hornblende, and bronzite in nearly equal amounts. Green
grains were observed which were isotropic and regarded as probably chlorospinel. +

Lepce, Austria.

A blackish fine-grained olivine mass with light greenish-gray foliated diallage having
a metallic lustre.

The section is composed of predominating somewhat serpentinized olivine, whose
fissures are filled with a black powder; as well as a light reddish-colored diallage, which
is fibrous and shows a feeble dichroism between light red and light green.f

Fontanapass, Locris, Greece.

According to Becke the rock from this locality is a light-colored fresh olivinfels,
holding porphyritic crystals of diallage.

In the thin section it is seen to contain the following minerals: olivine in irregular
colorless fresh grains, traversed by numerous irregular fissures ; serpentine in thin plates
along these fissures; diallage, very fresh, and traversed by cleavage planes, but sometimes
this mineral is changed to a rhombic fibrous alteration-product ; and picotite, in little
reddish-brown, translucent quadratic or hexagonal sections.

A somewhat similar rock comes from Pyrgos, at the foot of Hymettus, in Attica.
This has a black and green spotted groundmass holding large crystals of enstatite which
are much altered (bastite).

In the section the rock shows the ordinary network of serpentine, to which the
olivine has been entirely changed. Picotite and magnetite occur.§

Mohsdorf, Saxony.

This rock, Dathe states, contains as its most prominent mineral diallage. Sometimes
along the fissures are alteration-products of calcic carbonate and iron. The olivine
which is held by the diallage is generally altered to serpentine, which is filled with a
powder of iron ore. Some garnet occurs.||

Gillsberg, Saxony.

According to Dathe, this is a dark green rock composed of dark brown to black
elongated crystals, which in the thin section are dichroic from light brown to dark brown,

* Geol. Foren. Férh., 1877, iii. 250; Neues Jahr. Min., 1880, ii. 197.
+ Zeit. Deut. geol. Gesell., 1876, xxviii. 623-625.

¢ C. v. Jolm, Jahr. Geol. Reichs., 1880, xxx. 447.

§ Min. Mitth., 1878 (1), i. 475-477.

|| Neues Jahr. Min., 1876, pp. 233.

THE TERRESTRIAL PERIDOTITES. — PICRITE. 149

and have the cleavage of hornblende, garnet, olivine altered to serpentine in part, biotite
strongly dichroic and containing little opaque needles, diallage, and iron ore.”

A similar serpentine was described by Dathe from Crossen, near Mittweida, in
Saxony; but it appears to be a somewhat more altered rock (J. ¢., p. 245).

VARIETY. — Picrite.

Austria.

Picrite, according to Tschermak, when in a fresh or little changed state, has a dark
green color, and varies from a finely crystalline to a plainly crystalline character.

That from Sdh/e has a blackish groundmass containing a large number of olivine
crystals. Microscopically the groundmass holds granular feldspar, grains of magnetite,
scales of black mica, and little hornblende crystals.

The Freiberg and Giimbelberg picrite shows a dark groundmass holding olivine
crystals traversed by numerous fissures filled by a serpentinous mineral; also blackish-
sreen grains of diallage. The groundmass is similar to that of the Sohle picrite: granu-
lar feldspar, biotite scales, magnetite grains, and a few hornblende crystals, with here and
there thin strings of serpentine.

The picrite from Schénaw has a blackish-green groundmass holding olivine and dark-
green mica. The mica forms aggregations of scales. Much serpentine also occurs in the
rock. The groundmass consists of a granular feldspathic mass, grains and octahedrons
of magnetite, blackish-green augite crystals, rarely some needles of apatite, also calcite
grains, and some serpentine.

An altered picrite from Sdhle is a dark greenish-gray rock flecked with pistacite
green spots. It contains altered diallage and olivine crystals, hornblende prisms, dark-
green mica plates, magnetite grains, and silicates like gymnite and palagonite.

Another altered picrite from Bystryc, has a clear gray very fine-grained groundmass,
holding inclusions of bluish-gray to apple-green and blackish-green colors. Pseudo-
morphs after diallage and olivine occur, while the rock further contains magnetite and
fine fissures filled with calcite.

The above picrites are stated to be eruptive in the Cretaceons.

Steierdorf, Banat.

A blackish rock resembling basalt, and containing porphyritically enclosed olivine and
quartz. It is somewhat porous, and holds calcite amygdules. The section shows that
the principal minerals are olivine, augite, and hornblende. Calcite occurs as an alteration-
product, and quartz as an inclusion, while an isotropic base was seen. The olivine is in
large, well-defined crystals, and in smaller rounded forms. It is for the most part fresh,
but it shows here and there along its edges and the borders of its fissures an alteration to
a dark brown radiated fibrous aggregate. The olivine contains inclusions of glass, augite,
hornblende, and picotite. The latter is in large brown isotropic sharply defined octahe-
drons. The augite is of a light-reddish color, and the crystals are fresh with a feeble
pleochroism. It contains inclusions of glass and picotite. The hornblende is of a dark
brown color, with strong pleochroism, and contains glass particles. The hornblende is

* Neues Jahr. Min., 1876, pp. 244, 245.

150 PERIDOTITE.

often associated with the augite. The quartz is in water-clear, beautifully polarizing fis-
sured grains containing fluid and glass inclusions, as well as apatite needles.*

Incheoln Island, Scotland.

An apparent intrusive mass is described by Dr. A. Geikie as composed of a serpenti-
nous base holding honey-yellow grains of olivine, dark lustrous augites, and a few plates
of brown biotite. In the section the olivine is in a great measure undecomposed, though
presenting the usual exterior band and transverse threads of serpentine. The augite is
of a pale yellow color, and in large and well-defined prisms, often enclosing olivine. A
little milky plagioclase full of fissures and decomposition products was observed. Long
scales of rich brown biotite occur here and there; also a few plates and grains of probable
titaniferous iron. One of the most conspicuous constituents is a rich emerald-green to
grass-green decomposition product, filling up the interstices and running in veins and
irregular streaks or tufts through the rock. Other pale or colorless aggregates, which are
sometimes distinctly fibrous, also occur. These various decomposition products some-
times show the polarization of serpentine, and sometimes that of chlorite. Some zeolitic
fibrous tufts were seen.f

Herborn, Nassau.

The section purchased from Richard Fuess is composed of pale brownish-yellow augite
and clear fissured olivine surrounded and held by the secondary serpentinous products.
The augite in places is changed to a pleochroic green fibrous mineral, whose extinction,
being parallel to the nicol diagonal, presents a strong contrast in polarized light to the mono-
clinic augite. The augite holds numerous rounded grains of olivine, the same as enstatite
commonly does in other rocks. The olivine is in rounded fissured forms, surrounded and
traversed by the plexus of alteration material. Part of the latter is dichroic, varying from
a green to brownish-yellow, and from its relations to the secondary brownish-yellow biotite
it is regarded as a transition stage in the formation of the biotite. It is in irregular fibrous
forms, the fibres being crumpled and aggregated together. In other portions some whitish
fibrous material occurs, which affects polarized light in the same manner as part of the ac-
tinolite does in the cwmberlandite. However, the chief portion of the alteration material
is serpentine. The olivine is in part very clear, and in part changed to a pale-yellowish
serpentine filled with globulites and margarites of iron ore. They are seen in the serpen-
tine veins ramifying through the olivine, and projecting like pseudopodia from the sur-
rounding material into the partially or entirely altered olivine. The ore also forms
black grains and crystals (some of which are octahedrons) in the olivine, and in the
network of alteration material. It frequently forms black bands, rows of grains, or fine
powder, along the fissures or centres and sides of the serpentine veins. The biotite
is in irregular yellowish-brown scales and grains, some of which are surrounded by the
black ore grains. It is strongly dichroic, and shows oftentimes a wavy, fibrous polar
ization. (Plate VIII. figure 6.) |

Elligoth, Austria.

This rock is described by Dr. H. y. Méhl as having a black to blackish-green serpen-
tinous groundmass holding many mica and hornblende particles.
The section is in part a very fine tufted serpentine, and in part a scaly fibrous one, of

* KE. Hussak, Verhandl. Geol. Reichs., 1881, pp. 258-262.
+ Trans. Roy. Soe. Edin., 1879, xxix. 506-508.

a
:

THE TERRESTRIAL PERIDOTITES. — PICRITE. 151

all possible colors from a pale apple-green to a brilliant grass-green, bright ochre-yellow,
siskin-green, and reddish-brown, one color running into the others. Further, there occur
remnants of the olivine grains having a light or ochre-yellow tinge, and also magnetite
and gothite. The olivine remnants when untouched by alteration are colorless, very
pellucid, beautifully polarizing, but extraordinarily rich in fissures, whose edges are cloudy
with minute magnetite grains. Some show a light blue color, owing to exceedingly
minute powder-like grains. Vapor, glass, and fluid cavities, as well as spinel inclusions,
occur sparingly.

The serpentine mass includes fiery reddish-brown mica; very light grayish-brown,
finely fibrous, or step-like, rough, feebly dichroic enstatite; a little clear light-brown,
feebly dichroic angite, traversed by irregular fissures; and strongly dichroic fissured horn-
blende, varying from clear ochre-yellow to a deep blackish-brown. A little apatite and
plagioclase were also observed. This is a cretaceous or tertiary eruptive rock.*

Pen-y-cariusiog, Anglesey.

According to Bonney this rock in the section is seen to be composed of augite, horn-
blende, actinolite, magnetite, opacite, serpentinous material, ete.

Augite occurs in colorless grains and crystals, some of which show a characteristic
cleavage. The hornblende, including actinolite, is in (1st) innumerable small acicular or
blade-like crystals, in irregular tufted groups, which are pale greenish or colorless, and
feebly, if at all, dichroic; (2d) small crystals often exhibiting characteristic cleavages and
even crystallographic planes, green-colored and strongly dichroic; and large brown crys-
tals, supposed to be pseudomorphs after augite. These minerals occur in a serpentinous
or chloritic groundmass containing no unchanged olivines, but pseudomorphs after that
mineral were thought to be observed. Some talc (?) was seen, as well as other micaceous
secondary products.

Later Professor Bonney found a number of boulders of this rock on the western coast
of Anglesey. In general these were similar to the one just described, although in one
some decomposed feldspar and some diallage were observed. A little apatite, mica, ete.

were seen in some of the sections.t

Near the River Dill (“ Diligegend”’\, Nassau.

This rock in the fresh condition has a blackish-green color, and contains copper-col-
ored mica, green chromdiopside, hypersthene, picotite, and magnetite.

The olivine is in water-clear to pale yellowish-green grains, traversed by fissures
along which occurs a fibrous greenish or yellowish-green serpentine containing mag-
netite grains, ete. The chromdiopside appears as a rule in irregular leek-green grains
showing cleavage, and is sometimes altered to a leek or smaragdite-green serpentinous
aggregate.

The hypersthene is pale-brownish, and shows an evident brachypinicoidal cleavage.
It contains the usual violet-brown lamine, and olivine grains.

The mica shows a reddish-brown color darker than the hypersthene, is dichroic, and
associated with the magnetite. The picotite is in deep black octahedral crystals, which
are dark brown, and feebly translucent on the thin edges.

* Neues Jahr. Min., 1875, pp. 700-703. + Quart. Jour. Geol. Soc., 1881, xxxvii. 137-140.
£ Quart. Jour. Geol. Soc., 1883, xxxix. 254-260.

153 PERIDOTITE.

Beside the magnetite, there occurs a whitish opaque mineral substance, which is con-
sidered to be magnesite.

A similar rock, which comes from the nickel mine Mii//e Gottes in the Weyherhecke,
Nassau, is described as a granular to compact serpentine of a dark-green color. In the
dark groundmass lie many minerals; as, for instance, calcite, magnesite, chrysotile, schiller-
spar, pyrite, chalcopyrite, and millerite. The olivine is much changed to serpentine, as
also is the hypersthene. The chief difference between this and the preceding appears
to be mainly in the greater amount of alteration.*

Variety. — Serpentine.

Fritztown, Berks Co., Pennsylvama.

1562. Section: a greenish-yellow serpentine holding crystals of grayish-white dolo-
mite. Under the microscope in part of the section the serpentine is seen to form a net-
work following the fissures in the clear, unaltered olivine, and enclosing grains of it, the
fibres being generally parallel to the direction of the serpentine veins. In other portions
only traces of the olivine remain, while in still others only the structure of the serpentine
shows its origin. The direct conversion of olivine into serpentine is well illustrated in
this section. The dolomite is in rhombohedrons, and irregular, sometimes geniculated
grains. The larger forms mostly contain an irregular central portion of a clear, fissured
mineral, closely resembling olivine in its clearness; but it is isotropic, and belongs to
spinel. One grain, however, showed a pale grayish color in polarized light. The dolo-
mite is surrounded by a white border of ageregately polarizing fibrous serpentine, which
in places occupies considerable of the section. The serpentine about the olivine is in
the middle of the fissures of a clear greenish-yellow color, but next the olivine frequently
passes into a clear nearly white serpentine. (Plate VII. figure 6.)

The rock is composed of a mixture of greenish and yellowish serpentine and grayish-
white dolomite. Many colorless and pale bluish octahedrons of spinel were observed in
the dolomite. Three of the sides of the specimen show a “slickensided” surface coated
with serpentine, dolomite, and white mica (phlogopite ?). This rock is an “ ophicalcite.”

Frankenstein, Silesia.

Prot. T. Liebisch describes this rock as a siskin-green to oil-green serpentine mass
holding chromite. In the section it shows the usual network of serpentine enclosing
colorless olivine grains, minute crystals of actinolite, and whitish talc-like plates.

Leki, Norway.

The section shows portions in which the olivine is still unaltered, but it is rendered
cloudy by a magnetite dust scattered through it.

In other portions the magnetite is very abundant, and in polarized light the rock is
seen to contain numerous plates and fibres, having a similarity to sericite, or to tale and
chlorite. It contains grains of a magnesium carbonate.

* Konrad Oebbeke, Inaug. Diss., Wurzburg, 1877, 38 pp.
+ Zeit. Deut. geol. Gesell., 1877, xxix. 732. + Mohl, Nyt Mag., 1877, xxiii. 121.

THE TERRESTRIAL PERIDOTITES. — SERPENTINE. 153

Waldheim, Saxony.

5002. A dark grayish-green rock, purchased from Voigt and Hochgesang, mottled
with spots of lighter grayish-green, and containing chromite.

Section: greenish-gray with a reticulated network of iron ore. Chiefly composed of
clear colorless or pale yellow and pale green serpentine. This retains in part the structure
of the fissured olivine, and in part that of the enstatite crystals which it has replaced.
In the latter, the plane of extinction is the same as that of the enstatite, while in the
serpentine replacing the olivine we have the reticulated network following the fissures,
with the polarization of the serpentine first formed along the fissures differing from that
later replacing the central portions of the grains. This difference is to some extent
observable in common light, so that one is able to trace out the forms of the original en-
statites, and then those of the olivine grains which were enclosed in them. The structure
of the rock thus revealed shows that it was originally composed principally of olivine
with comparatively small amounts of enstatite.

The Waldheim serpentines have been studied by Dathe, who describes that from the
Tunnel as a blackish-green stone holding sinall garnets and many clear vitreous points.
The section is composed of well-marked olivine grains, with the secondary serpentine,
magnetite, garnet, picotite or chromite, and diallage. That from the Quarry on the Gebere-
bach is a dark-green serpentine showing olivine grains. In the section the olivine shows
various degrees of alteration to an ore-bearing serpentine, forming the usual reticulated
network. It also contains diallage and garnet, the latter of which is sometimes altered
into chlorite. The serpentine from the Breitenberg is of two kinds: one a dark green
serpentine, hard and brittle, and carrying garnet, and the other softer, tougher, and
wanting garnets. The former answers in character to the Tunnel and Quarry serpen-
tines, while the latter shows the network structure of serpentine, and holds iron ore and
enstatite (bastite).*

f

Kokkino-Nero, Thessaly.

Dark, nearly black compact rock, traversed by strings of yellowish-green fibrous ser-
pentine. In the section it shows the usual network of serpentine associated with altered
diallage or enstatite crystals.

Similar to this is a rock from Polydendri which contains both altered diallage and
enstatite, as well as garnet and picotite grains.

A similar rock from MNeokhort shows comparatively fresh diallage traversed by fine
parallel fissures along which are arranged small needles and plates.

Between the Rivers Dajao and Cenoli, Province of Santiago, San Domingo.

120 G. A dark-brown rock flecked with greenish spots. Contains a little tale, and
is traversed by serpentine veins having greenish borders and a dark central line owing
to the iron ore in it. (W. M. Gabb, Collector.)

Section: banded greenish-yellow and black. The greenish-yellow portions are seen to
be composed of yellowish pseudomorphs of serpentine after olivine, traversed by fissures
and surrounded by a network of whitish fibrous serpentine with the fibres arranged per-
pendicular to the course of the veinlets. In other portions the remains of some apparent
pyroxenic mineral occurs, while elsewhere the serpentinous material is quite compact, but

* Neues Jahr. Min., 1876, pp. 239-243. + Becke, Min. Mitth., 1878 (1), i. 472, 473.
. 20

154 PERIDOTITE.

shows to some extent the characters of serpentine replacing olivine. The dark band is
formed of irregular masses and grains of iron ore, arranged in the serpentine in a vein-like
form. Some of the serpentinous material is isotropic. The structure of a portion of the
section is shown in figure 1, Plate VI.

At the foot of the first rise on the ridge, edge of the river on the road from. La Vega
to Jurabacoa, Province of La Vega, San Donungo.

142 G. <A dark reddish-brown compact rock, breaking with a conchoidal fracture.
Traversed by some veins of a greenish-white serpentine. Contains many bronze-like
crystals of altered enstatite (?). (W. M. Gabb, Collector.)

Section: a brownish and greenish mass composed of serpentine, dolomite, picotite or
chromite, and ferrite products. The usual arrangement of the serpentine, in a network
following the outlines and fissures of the original olivine grains, is seen; this is marked
by veins formed by brown and black dust and grains of ferruginous material mixed with
serpentines, having a similar arrangement to that observed in the California peridotites.
ordering these veins is a band of whitish serpentine, which sometimes occupies the
entire interspace. In the majority of cases the portions between the veinlets are com-
posed of a greenish-yellow serpentine having the form and outline of the fractured
olivine grains.

Lying in the sections are a number of white, greenish, and grayish patches, of the same
outline as the pyroxene minerals usually occurring in the peridotites. They enclose
rounded portions of the serpentinized olivine ; and in part have the fibrous cleavage of
enstatite, while in part their structure is irregular. They show aggregate and fibrous
polarization as a rule, but occasionally the optical characters of altered enstatite. Pico-
tite or chromite occurs in irregular masses of a black and translucent deep coffee-brown
color. Its grains are traversed by fissures and black bands, part of which, in reflected
light, show metallic lustre with numerous crystalline facets.

Some dolomite with well-marked cleavage occupies a portion of one section, in the
form of irregular somewhat rounded patches. A few veins traverse the mass, having been
formed after the main serpentinous alteration of the rock. The whole section is sprinkled
with black-brown and yellowish-brown grains, dust, and aggregations of ferruginous
material. The structure of this rock is shown in Plate V. figure 4.

Brixlegg, Tyrol.

According to Von Drasche this shows a compact network of magnetic iron grains, with
a fibrous serpentine mass, which encloses some remaining grains of olivine and diallage.
The serpentine is said beyond question to have resulted from the alteration of olivine and
diallage.*

i Piano, Elba.

A greenish-brown mass traversed by talcose (?) veins, and containing altered enstatite
crystals.

Under the microscope it is seen to be composed of brownish, greenish, and yellowish
serpentine largely filled with black dust-like granules, having a network structure and

* Min. Mitth., 1871, i. 2. See also B. Hussak, Ibid., 1882 (2), v. 76, 77, who found angite in this
rock, and throws some doubt on the correctness of Drasche’s work.

THE TERRESTRIAL PERIDOTITES. — SERPENTINE. 155

cut by talcose (?) veins which are crossed by later chrysotile ones. The enstatite is
in part altered to the talc-like material, and in part to serpentine. It is probable that
olivine predominated over the enstatite when the rock was unaltered. This was pur-
chased from Voigt and Hochgesang.

Launceston, Tasmania.

5170. A dark green rock, purchased of Ward and Howell, sprinkled with chromite
and tale scales. Weathers greenish-white.

Section: greenish-gray with cloudy blotches. Composed of a pale yellowish fibrous
serpentine showing brilliant polarization, and altered enstatite crystals, tale scales, and
chromite. The tale is grayish-white, of feeble polarization, and usually associated with
the iron ore. In some cases it is dichroic, varying from a gray or yellowish-gray to a
pale bluish tint. The enstatite in some cases retains its original plane of extinction,
although altered to a pale yellowish serpentine mass. The cloudy spots are caused by
innumerable grains of iron ore locally concentrated.

Windisch-Matrey, Tyrol.

According to Von Drasche this serpentine is interbedded in a calcareous mica schist
The color varies from a light green to a deep green or brown, and the rock is sprinkled
with calcite, asbestos, and chrysotile grains and fibres. Drasche placed the specimens in
two divisions.

1. This is an olive-green rock flecked with yellowish-brown spots, and contains
diallage, ankerite, and a white scaly mineral with irregular outlines. The section under
the microscope shows a groundmass formed from a compact network of a rhombic
mineral, which occupies the principal portion of the section. In addition grains of
magnetite and diallage were seen. Some tale was also observed.

2. The other variety is a dark-green very fine-grained rock sprinkled with light-green
diallage crystals and white tale plates. The section under the microscope is seen to
contain the network formed by the rhombic mineral, magnetite arranged in bands,
diallage, etc.*

The section in the Whitney collection from Voigt and Hochgesang, from this locality,
has- the following characters. Color pale green, but broken by veins and spots of black
iron ore. In polarized light the section shows the usual structure of a serpentinous rock
produced by the alteration of a peridotic one. It contains scales of tale and granular
masses of pyrite. Some of the iron ore is in forms resembling the picotite grains in the
Lake Lherz rock. These forms are traversed by fissures, and in reflected light it is seen
that the ore bordering them is crystalline showing metallic lustre, while the remaining
portions do not present these characters. The talc is so arranged that it appears to have
arisen from the conversion of enstatite material. The rock apparently contained originally
olivine, enstatite, and picotite at least. The section is traversed by veins of serpentine
and talcose material.

St. Sabine, Vosges, France.

5169. <A greenish-black compact rock, weathering grayish-brown.
Section: pale green, and composed of serpentine in which a few altered enstatite
graius were observed. A few nodules occur which are formed in the interior of grayish

* Min. Mitth., 1871, i. 3-8. See also E. Hussak, Ibid., 1882 (2), v. 78-80.

156 PERIDOTITE.

fibrous material having a feeble polarization and containing irregular brownish-yellow
spots, which affect polarized light more than the enclosing material does, The exterior
portion of these nodules is formed of pyroxene granules (diallage) somewhat serpentinized
with irregular grains of a deep-green color and isotropic, — pleonaste.

River Oisain, Timor.

Dr. A. Wichmann describes from the River Oisain a serpentine of a dark bluish-gray
color, porphyritically holding bronzite crystals and small grains of calcite. ;

Microscopically the serpentine has the usual mesh structure, and contains within its
interstices colorless patches showing aggregate polarization. Opaque grains of iron ore
are common. The bronzite is altered, and contains along the cleavage lines a blackish-
brown aggregate of minute plates as well as black needles. Chromite in brown trans-
lucent grains, and calcite also, were seen.*

Range 11, Riviere des Plantes, Canada.

According to Mr. Frank D. Adams, this serpentine contains a few remains of a
rhombic pyroxene (enstatite), which are slightly pleochroic and have numerous black
needles arranged parallel to the cleavage and rhombic axis.

Melbourne, Canada.

According to the preceding observer, this rock is of a dark-green color, and composed
of a serpentine mass containing some irregular fragments of a rhombic pyroxene (en-
statite). These show pleochroisra varying from green to a reddish color, and have a
well-marked cleavage or fibrous structure.+

Galicia, Spain.
The serpentines of this country are composed, according to Macpherson, principally of
serpentine produced from the alteration of olivine, and holding the remains of enstatite or
diallage crystals, ete.t

High Bridge, Hunterdon Co., New Jersey.

1403. A mottled rock of black and oil-green, having a reticulated and somewhat
banded structure. The powder of the rock is attracted by the magnet, and tests show
the presence of chromium.

Section: greenish-white with black and dirty-brown spots. The least altered portions
are the dark spots, with their included crystal forms. The spots show the structure in
common and polarized light of serpentinized olivine, while the crystal forms present a
cleavage similar to that of some enstatite, but more like that of diallage. Both spots and
crystals are now completely changed to serpentinous material. The main mass of the
section is white, slightly tinged in places with a pale yellowish-green color. It is
traversed by fissures, and contains much disseminated iron ore in dust, grains, and irreg-
ular aggregations. In common light this groundmass shows but little evidence of its
origin, but in polarized light there is distinctly revealed the usual network of serpentine
fibres when formed from the alteration of au olivine rock. The story of the change can

* Samml. Geol. Mus. Leiden, 1884, ii. 105-110. ¢ Anal. Soc. Esp. Hist. Nat., 1881, x. 50-53.
+ Report of Progress ; Geol. Survey of Canada, 1880, -81,-82, p. 19 A.

a

THE TERRESTRIAL PERIDOTITES. — SERPENTINE. 17

be read as clearly as in those rocks which are only partially altered. The picture was
there; the polarized light served as the developer only. Figures 5 and 6, Plate V., show
the structure of this rock.

1404, from the same locality as the preceding, is a greenish- and brownish-black rock,
with lighter greenish spots, and coated with light greenish serpentine on “slickenside ”
surfaces.

Section: a yellowish and gray mass sprinkled with black spots of iron ore and in
places traversed by a reticulated network of the same. It is composed principally of
serpentine containing crystals and granules of iron ore, besides being traversed in much
of its mass by the network of the same. It is also stained brownish-yellow by oxide of
iron. In portions of the section are grayish spots, which sometimes show in their
interior greenish grains. These interior grains are remnants of the original olivine,
while the gray portions are formed of the serpentinized olivine traversed by numerous
fissures filled with innumerable dust-like granules. The iron ore in a few points is feebly
translucent, and in part shows no metallic reflection, but it is traversed by bands that do
show the metallic lustre. Therefore it is probably a mixture of chromite and magnetite,
which appear to be commonly associated in the majority of serpentines. The general
structure is represented in figure 5, Plate IV.

1567 is a rock that in the hand specimens appears to be the same as No. 1404, but no
sections of it have been prepared.

1563, from the same locality,* is very similar to No. 1408, but is more altered and
weathered. It contains chromite and talc. It has a yellowish-green groundmass of ser-
pentine traversed by innumerable reticulated veinlets of a dark green to black serpentine.
These veinlets give a structure to the rock that might be taken by some for stratification

Section : a grayish-green mass formed of translucent, feebly polarizing, grayish, finely
granular serpentinous material, traversed by a network of innumerable veins of clear,
more or less brilliantly polarizing serpentine. Much chromite occurs in regular
pronged masses, grains, and heaps of grains, principally arranged along the serpentine
veins. While some may be original or else picotite altered i situ, the chief portion
appears to be of secondary origin in the serpentine.

1564, from the same locality, is a dark-greenish rock filled with tale scales and
weathering to a yellowish rust-like product, with the tale masses protruding from the
surface. This talc forms crystalline masses similar to those formed by chlorite.

The section is an irregular mixture of pale yellowish serpentine and grayish-white
tale with iron ore. The ore is principally associated with the tale, forming bands along
the cleavage planes. The talc plates are partly isotropic and partly feebly polarizing,
and are colorless or gray. The structure and relations of the serpentine and tale are such
as to indicate that the serpentine has replaced the olivine, and the tale the pyroxene

minerals.
4 Zoblitz, Saxony.
5001. A mixed reticulated greenish and brownish-red rock, containing roundish
} reddish-black to black spots.

Section: greenish- and brownish-red with grayish-black spots. The principal portion
of the section is serpentine. This shows the reticulated structure in common and
polarized light, frequently having between the colorless meshes greenish patches repre-

* All the High Bridge, New Jersey, serpentines were the gift of Mr. 8. H. Dean.

158 PERIDOTITE.

senting the portions of the olivine last altered. In some portions the section is filled
with reticulated veins of brown and cherry-red hematite. The dark spots are owing to
portions being filled with innumerable granules of iron ore, arranged about some central
lines, much like iron filings about the poles of a magnet. Tale fibres are common.
Chrysotile veins cut the section in various directions.

From tral below Chip Flat, Sierra Co., Cal.

45 P. The specimens are green and more or less rubbed or “slickensided,” as are the

great majority of serpentine rocks. The only section is of a pale yellowish-green color
traversed by black bands of iron ore. The serpentine shows a coarsely aggregate and
fibrous polarization, and appears from its structure to replace, in part at least, olivine and
enstatite. The ore crystals are octahedrons, some of which are translucent either as a
whole or on the edges. The translucent portions are reddish-brown, and the opacity
does not seem to depend upon the size, since some comparatively large crystals are
translucent, while very minute ones are often opaque.

40 P. Similar to the preceding. This rock occurs apparently in two bands, enclosing
slate, according to the collector, Professor W. H. Pettee.*

119 P. is of similar character. In the interior it is compact, massive, and dark, but
on the exterior smoothed and coated with greenish and light greenish-yellow serpentine.

Depot Hill, near Camptonville, Sierra Co., Califorma.

35 P. A compact greenish-gray rock with irregular bluish-black spots, and traversed
by chrysotile veins.

Section: a compact grayish and greenish-yellow mass, composed principally of ser-
pentine with iron ore, and dolomite. From the structure of the serpentine and the
arrangement of the iron ore, it is probable that olivine and enstatite were former con-
stituents of this rock, which was only found in a boulder.

From a belt four hundred feet wide, between Whiskey Diggings and Hepsidam,
Plumas Co., Califorma.

89 P. A bluish-black and greenish mottled: rock, showing a reticulated structure.
It is traversed by yellowish-green serpentine veins.

Section: a gray groundmass spotted by magnetite and traversed by veins of magne-
tite and yellow serpentine. The groundmass has been so entirely changed to serpentine,
showing the usual network structure, that none of the original silicates were observed.
So far as can be judged from the structure, the rock originally contained olivine and
enstatite, at least. Figure 5 of Plate VI. shows its present structure and the serpentine
veins which traverse it.

Finland.

According to Lagorio, the Finland serpentine forms a fibrous mass of yellowish-gray
to green color, showing the usual network (Maschenstructur). It contains no olivine
grains, but some fissured ones of dolomite or calcite. The microscopic structure is very
finely fibrous, and it forms masses in a limestone.§

* Aurif. Gravels, p. 434. + Ibid., p. 429. t Ibid., p. 451.
§ Micro. Analyse Ostbaltischer Gebirgsarten, 1876, p. 48.

ee

§
4
F

THE TERRESTRIAL PERIDOTITES. — SERPENTINE. 159

Klopfberg, Austria.

This rock, according to Dr. F. Becke, is a light green to dark porous soft stone, bearing
long, colorless tremolite crystals, chrome-bearing magnetic ore, and numerous soft silver-
white tale scales. The rock is greatly altered, and in the section shows the usual net-
work, arising from the alteration of olivine, which in the darker stone still exists in single
grains, but in the light green specimens the olivine has disappeared, and grains of a
rhombic carbonate appear in its place.*

Nezeros, Thessaly.

A dark, nearly black rock, rich in chromite, has been described by Dr. F. Becke as
showing in the thin section the usual mesh structure formed by the serpentine and iron

ores. It also contains a little colorless actinolite, possessing the prismatic cleavage of
hornblende.t

Fatu Temanu, Timor.

A dark bluish-green rock with light green spots and magnetite grains. Microscopi-
cally this serpentine evidently was derived from olivine, and it shows a characteristic
network especially marked through the arrangement of the ore particles which form the
medial lines. Bordering them are light green bands enclosing the darker-colored inter-
stitial portion. Much chrysotile occurs, and a whitish-green picrolite, forming in the
section a finely fibrous cloudy mass. f

Four miles from Westfield Centre, Westfield, Massachusetts.

1073. Section: greenish-yellow with grayish-white spots, and traversed by an irreg-
ular network formed from dust, grains, and crystals of black iron ore. The serpentine in
polarized light shows aggregate and fibrous characters, while dolomite occurs sprinkled
through much of the section’s mass. The grayish spots seem to be formed of dolomite
mixed with serpentine and tale.

The hand specimen is a dark grayish-black rock, with light greenish irregular patches
of serpentine, talc, and dolomite. This structure is similar to that of the other specimens,
1074, 1075, 1076, 1077, 1078, and 1079. In the weathered surface forms the tale is
better crystallized, showing its normal structure, while the dolomite is more abundant and
better marked. In these specimens every gradation can be traced between the light-
greenish serpentinous colloid-like masses to the well-differentiated aggregations of tale
plates. These specimens show clearly the production of talc, dolomite, and serpentine
from the metamorphosis of peridotites.

This rock (1078) weathers to a rough deep-pitted surface, colored grayish and coated
with lichens. Here the difference is strongly marked between the internal molecular
alterations and the superficial surface weathering.

I have been greatly indebted to the kindness of Mr. S. H. Dean, of High Bridge, N. J.,
for this and many others of the serpentines of Eastern North America described here.

1074. This section is similar to that of No. 1078. The iron ore forms in places

* Min. Mitth., 1882 (2), iv. 341-343. + Min. Miith., 1878 (1), i. 470-472.
+ Wichmann, Jaarb. Mijnw. N. O. L., 1832, pp. 214-216.

160 PERIDOTITE.

quite a rectangular grating, and much tale is present in curved and bent fibrous masses.
The veneral structure of this section is shown in figure 2, Plate VIT.

1081, also from Mr. 8. H. Dean, was obtained by him from the bed of the West-
field River in Russell, Massachusetts. This is a leek-green serpentine, containing
grains of chromite and closely resembling that from Chester and Texas, Pennsylvania.
No section.

Lynnfield, Massachusetts.

1087. Section: pale yellowish-green, mottled with spots of clear grayish-white and
with dust and grains of iron ore. In common light under the microscope, the greenish
portion shows the dirty green spots commonly seen, formed from the alteration of the
unfissured central portion of the olivine grains. In polarized light it shows the common
reticulated meshwork of most alteration serpentine. The clear grayish-white portions are
formed of interlacing and divergent fibres and plates, optically orthorhombic, and polar-
izing with clear, beautiful tints, varying from yellowish-white to yellow and red. The
iron ore is crystalline granular, opaque, has but little lustre, and resembles chromite.
The forms of the larger grains resemble those of picotite when only partially altered.
The general structure is shown in Plate VI. figure 2.

The hand specimen is a dark grayish-green compact rock, mottled with black iron ore
and tale scales. This specimen was kindly presented to the collection by Professor N. S.
Shaler. Later the locality has been visited by Professor J. D. Whitney and myself, and
other specimens answering in general characters to the above were obtained. While this
serpentine is much jointed, no evidence of stratification was seen, and it was apparent
that the approximately parallel jointing had been taken for stratification by previous
observers. No contacts with the adjacent rock could be found. In a pit near the quarry
the rock is a mottled dark grayish-black one, which in thin splinters is dark green.

A serpentine of much finer quality and of a dark green color, was found outcropping
by the side of the road to the northwest. A dark green much broken and fissured ser-
pentine outcrops opposite C. W. Hersey’s blacksinith’s shop, in Peabody, on the road
near the line between that town and Lynnfield. While no definite field evidence regard-
ing its origin could be obtained, the general appearance of the outcrops was that of an
eruptive mass metamorphosed, nothing being observed that indicated either chemical or
mechanical sedimentation.*

The Lynnfield serpentine shows when tested the presence of chromium, and the rock
powder is magnetic.

From the road between La Vega and Jarabacoa, at the first crossing of the River Joa
going from the former town, Province of La Vega, San Domingo.

141 G. This is a much altered foliated rock, composed essentially of light greenish-
white and yellowish darker green serpentine. The foliated structure appears to be
entirely due to the alteration and pressure to which the rock has been subjected. No
section was made of this rock. Collected by W. M. Gabb.

* Sce also Crosby, Occas. Papers, Bost. Soc. Nat. Hist., 1880, iii. 115; Hitchcock, Final Report,
Geol. Mass., 1841, p. 159.

THE TERRESTRIAL PERIDOTITES. — PORODITE. 161

Newport, Vermout.

95. This rock was collected by Mr. J. H. Huntington, near Mr. C. Gilpin’s residence.
It is a grayish-green rock having a greenish serpentine groundmass, holding grayish and
brownish masses and crystals of a ferruginous carbonate, showing well-marked rhombohe-
dral cleavage.

Section: a gray mass traversed and sprinkled with black iron ore. Composed of a
coarsely fibrous’serpentine, a dirty gray, feebly polarizing carbonate showing well-marked
rhombohedral cleavage, and iron ore. The serpentine forms the principal portion of the
section.

Celinac, Austria.

A light-green rock containing dark particles of amorphous silica. The section shows
the usual network of serpentine with isotropic silica and picotite.*

Texas, Pennsylvania.

A clear leek-green serpentine, obtained from W. J. Knowlton, 169 Tremont Street,
Boston, containing chromic iron in veins and crystals, or scattered granules.

Section: clear and grayish-white, with black spots of chromic iron. The clear portions
show the fibrous polarization of serpentine, some of the fibres being distinctly optically
orthorhombic in character. In the grayish portion he plates and fibres of tremolite ;
while the chromite is opaque in transmitted light, except in the thinnest portions, which
are translucent and reddish-brown. By reflected light the grains are dull, and without
lustre. The larger grains are traversed by fissures filled with serpentine. A grain of
pyrite was observed.

Chester, Pennsylvania.

1487. A clear leek-green compact rock containing grains of chromite. Weathers
yellowish and greenish-gray. Section: clear grayish-white fibrous mass showing the
usual aggregate fibrous polarization.

This and the preceding one show the extreme change in rocks to pure serpentine.

Variety. — Porodite.

Fatu Luka, Timor.

Large, rounded pieces of serpentine cemented by pale-whitish and finely spherulitic
opal and a greenish paste. The serpentine is yellowish and grass-green, and shows the
mesh structure. The history of these altered fragments is summed up by Wichmann
as follows: —1. The formation of the peridotite. 2. The formation of the serpen-
tine, including the separation of the iron ore and the beginning of the Maschenstructur.
3. The decomposition of the iron ore and the formation of the yellow network. 4. The
impregnation of the interstitial portion with the alteration-product,— chromite. 5. The
alteration of the exterior into a finely fibrous compact gray substance.

The cement is mostly serpentine with a fine scaly material.f

* C. v. John. Jahr. Geol. Reichs., 1880, xxx. 448. + Jaarb. Mijnw. N. O. T., 1882, pp. 216-222.
21

162 PERIDOTITE.

Strand, Timor.
>)

Another porodite of similar character was described by Wichmann as a greatly decom-
posed fragmental rock, composed of rounded and angular fragments of dirty-brown and
brownish-green serpentine, cemented by a sometimes lighter, sometimes darker, dirty-
brown and greenish-brown mass. Microscopically this serpentine is similar to the pre-
ceding, but is more altered. The interior portion of some of the grains is filled with a

a

dirty-brown hydrated oxide of iron.

Another porodite from Fatu Luka, Timor, was described by the same author as a dirty
light-brown and brownish-green tufaceous rock with numerous serpentine and pheestine
(enstatite) fragments. The rock effervesces feebly with acid. The serpentine shows
under the microscope a network structure especially of the iron ore, while the interior
orains are greenish. A somewhat altered bronzite containing ore grains occurs, The
cement is of a brownish shade, homogeneous and isotropic. *

Srction V.— Peridotite. — Ils Macroscopie Characters.

THE meteoric forms show in general a fine, more or less granular ground-
mass of some shade of gray — varying from a light gray or grayish-white to
a bluish or dark gray. Often they are porphyritic from enclosed chondri,
pyrrhotite, and metallic iron. Again they are apt to show brownish-yellow
spots of ferruginous staining, owing to the oxidation of the iron ores. The
grayish color appears to be mainly due to the finely divided state of the
component silicates, as well as to the natural color of the base and the en-
statite. The olivine is in too minute grains to show its characteristic
color, except in rare cases. The chondri frequently appear as gray, brown,
bluish, and white grains in the groundmass, giving the appearance of a
fragmental structure to the rock.

The completely or coarsely crystalline forms, like those from Estherville
and Chassigny, present a gray to pale yellow crystalline mass closely
resembling that of the least altered terrestrial peridotites if not identical
with it.

The iron ores occur as irregular masses, sometimes of a semi-sponge-like
structure, and in the form of metallic iron, pyrrhotite, chromite, and
magnetite.

While the silicates are not usually sufficiently distinct to be determined
macroscopically, yet they sometimes are, and olivine in such cases shows in
pale green or yellowish grains, having a conchoidal fracture and the
same general characters this mineral has when it is of terrestrial origin.

* Jaarb. Mijuw. N. O. I., 1882, pp. 216-222.

ITS MACROSCOPIC CHARACTERS. 163

It has been above stated that the least altered of the terrestrial peri-
dotites present an appearance and structure essentially similar to the
meterorite of Chassigny and the portions of that from Estherville which
are comparatively free from iron. They are of a grayish-green or green
color, crystalline granular in structure, and usually contain more or less
dark grains of picotite or some iron ore, disseminated throughout the mass.
The first traces of change are in coloration, passing from a green to a
yellowish-green, yellowish, and to a yellowish- or rusty-brown. The rocks
are more or less vitreous or greasy in lustre. With increasing altera-
tion, a reddish-brown to grayish-brown color predominates ; and _ this
finally passes into a dark greenish-black to black compact rock, somewhat
resembling the basalts, but of a duller color, more resinous lustre,
and more compact, as well as of a higher specific gravity and _ less
hardness.

The crystalline granular groundmass of olivine or serpentine may or may
not porphyritically enclose crystals and grains of enstatite, diallage, and
augite. These minerals usually appear as greenish, grayish, or bronze-like
crystals and grains scattered in the rock. They commonly weather to
bronze-like, more or less cleavable and platy forms; and even cn the fresh
fracture of some specimens show in certain lights ‘as an irregular network,
brightly reflecting the light, and holding in its meshes the dark-greenish
altered olivine.

The olivine groundmass when altered presents under the lens the appear-
ance of yellowish or grayish granules cut and surrounded by a fine reticu-
lated network of a darker material (serpentine); but when the change
has progressed further, the groundmass becomes compact and apparently
homogeneous.

As the more highly altered states are reached, the variations in the
macroscopic appearance become exceedingly numerous; so much so, that
only a few of them can be mentioned here. The color generally is some
shade of green, varying from a dark green or greenish-black to a yellowish-
green. Sometimes it is reddish (brownish- or cherry-red), owing to the state
of its ferruginous contents. The pyroxene minerals, when occurring, vary
in amount of alteration from the porphyritically sprinkled bronze- or copper-
like crystals to silvery-white, and to grayish and greenish forms, which in
turn pass into patches of serpentine of a deeper green color and more
compact texture than the groundmass, but which finally become completely

164 PERIDOTITE.

blended with, and entirely lost in, the serpentine groundmass. Oftentimes
the pyroxene minerals are replaced by greenish to whitish talcose material
and tale scales. In the process of alteration, segregations of serpentine,
dolomite, magnetite, chromite, ete., occur, giving rise to veins of serpentine
(chrysotile) and to veins and nodular masses of dolomite and iron ores lying
in or traversing the serpentinous groundmass.

However dark the altered peridotites may be in color, the thin splinters,
as a rule, are translucent and transmit a greenish or yellowish light. The
more or less serpentinized peridotites are traversed by fissures, which are
most abundant in those entirely changed to serpentine. The sides of
these fissures usually are polished or coated with serpentine, talc, etc.,

b

forming “slickensides” ; which, it is conceived, may have some connection
with the chemical alteration of the rock itself.

Amongst the various forms produced by the extreme changes are a
yellowish, more or less gummy-looking substance, and a grayish, yellowish,
to chrome-green translucent serpentine. While these are oftentimes pro-
duced from the alteration of the rock i su, they also appear to be formed
by migrated serpentinous material, and in such cases to belong to the vein-
stones. These secondary massive products contain more or less iron ore
in the form of chromite or magnetite. It is to these nearly pure serpen-
tines, which result from the complete change or migration of the material,
that the term serpentine, as it is used in works on mineralogy, properly applies,
But from the general and microscopic characters of the material known as
serpentine in lithology, it would appear that under that name is placed a
mineral of variable composition, forming a series like feldspar or pyroxene,
or else several distinct minerals are now so placed.

Further, in the process of alteration there often results a fissile or schis-
tose structure, giving rise to a pseudo-lamination. In part this seems to be
owing to the segregation of chrysotile, serpentine, iron ores, dolomite, etc.,
in approximately parallel lines; and in this case the fissility is often only
apparent and not real. Sometimes the schistosity seems to be due to pres-
sure during the time of alteration. Occasionally the rock has a brecciated or
conglomerate structure, owing to the vein serpentine or dolomite surround-
ing less altered portions of the rock. With the formation of tale or actinolite
in these altered peridotites, the transition to a true schist is evinced by
various gradations, until a true tale schist or actinolite schist results. These
schists are greenish in their normal condition, but often through decom-

ee ee an

|

ITS MICROSCOPIC CHARACTERS. 165

position of the iron, become stained and present a rusty brown and gray
aspect closely simulating many mica schists.

Owing to the production of dolomite, there results, in part at least,
ophicalcites and dolomitic limestones — the purity depending on the amount
of alteration, and on the materials both carried into and removed from the
reck during the process of alteration. These dolomitic limestones are usually
gray, green, or yellow, but sometimes of quite a clear grayish-white color,
and crystalline in structure. In the above, only a portion of the various
forms produced in the process of alteration so common in peridotic rocks
could be mentioned; but it is hoped that enough has been given to afford
some idea of the general appearance of these rocks macroscopically.

Of necessity, from the mode of origin of the peridotites and their ex-
posure to detrital agencies, various detrital or poroditic forms must result.
Undoubtedly, when they are re-consolidated, it is exceedingly difficult to
distinguish these true breccias, conglomerates, and sandstones from the
pseudo-fragmental forms of similar structure that are produced in this rock
species, as in every other, by the filling of fissures, or by the dissolving of
portions of the rock and their replacement by other material, while intersti-
tial portions of the rock remain i sifu. The poroditic forms of the peridotites,
so far as now known, are all of a serpentinous character, having been
greatly altered; but it is suspected, and in many cases claimed, that other
forms are of like detrital origin; however, conclusive proof of this is still
wanting.

It is probable that part of our ophicalcites and brecciated serpentines are
of a poroditic origin, while others appear to have been produced by changes
in the massive rock 7x siw; that is, they do not properly belong to the
fragmental rocks to which they are generally assigned. It is proposed here
to distinguish these falsely appearing detrital forms by the terms pseudo-
breccias, conglomerates, and sandstones; or, collectively, as pseudo-frag-
mental or detrital rocks; or, better still, by the introduction of the term
merolite (wépos, MMos), and its adjective form merolitic, for them, since they

are composed of detached portions of the same rock.

Section VI.— Peridotite. — Its Microscopie Characters.

BEGINNING with the meteoric peridotites, the first variety is composed
of rounded fissured olivine grains with brownish glass inclusions, brown-

166 PERIDOTITE.

ish interstitial glass, and scattered crystals of chromite. In the next type
enstatite enters as a constituent, and the chondritic structure appears. The
groundmass is of a grayish color sprinkled with iron, pyrrhotite, and
brownish ferruginous spots; and is composed of grains and crystals of
olivine, enstatite, chromite, iron, and base, enclosing larger masses of these
minerals and chondri. The base is fibrous-granular in structure, and varies
from a light to a dark ash-gray, while it occurs with every gradation, from
that not affecting polarized light to that in which the differentiation has
been carried to such an extent that it shows a feeble coloration in this light,
and at best is only a semi-base. The chondri are composed of olivine and
base, enstatite and base, and enstatite, olivine, and base; all being more
or less associated with iron ores, and. generally passing gradually into
the adjoining groundmass. The olivine chondri usually contain a darker
base than the enstatite chondri, and are composed of grains and crystals of
olivine cemented by the base, which in some cases produces forms some-
what resembling organized structures (Plate II. figure 4). The enstatite
chondri show, like the olivine ones, a more or less spherical form. The
enstatite chondri are usually composed of fan-like, eccentrically radiating
ribs of enstatite cemented by the lighter gray fibrous base, and they
sometimes simulate superficially certain organized structures (Plate IL fig-
ure 6; Plate III. figure 1). The olivine and enstatite chondri are composed
of granules and crystals of enstatite and olivine cemented by the base
(Plate II. figure 5).

The olivine of the meteorites is usually clear or pale greenish, although
often stained by ferruginous material along its fissures. It is more or
less fissured, contains inclusions of glass and iron ores, and generally is
in rounded grains, and but rarely in well-defined crystals.

The enstatite is in grains and crystals, which are clear and transparent,
but which sometimes display a faint green tinge, and contain glass inclu-
sions. ‘The mineral shows as a rule one longitudinal approximately parallel
cleavage, with sometimes another —or a cross fracture — at right angles
to the first cleavage (Plate HI. figure 6). The iron is in irregular grains,
having in the section in reflected light an appearance nearly like ground
steel (Plate II. figures 4, 5, 6; Plate III. figure 3). Sometimes the iron is
quite dark, and is united with pyrrhotite and possibly magnetite (Plate III.
figures 2, 3,4, 5,6; Plate IV. figure 1). The pyrrhotite shows a dark bronze

color and a rough granulated surface in reflected light, and frequently sur-

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ITS MICROSCOPIC CHARACTERS. 167

rounds grains of metallic iron (Plate III. figure 3). The common ferrugi-
nous staining and the granular structure of the groundmass is shown to a
greater or less extent in all the figures of meteoric peridotites given in the
plates.

The chromite or picotite occurs in dark-brown to black, opaque to trans-
lucent grains and octahedrons.

An entirely crystalline form of saxonite occurs in the Manbhoom (India)
meteorite, which T'schermak has described as composed of a greenish-yellow
granular mixture, in which bronzite and olivine have a nearly equal color.
Besides these, there are numerous grains of pyrrhotite and little grains of
iron. In the thin section granular olivine is seen to be the principal consti-
tuent. This is traversed by fissures, and has few inclusions. Bronzite occurs
in rounded or elongated grains, with a fibrous structure, and both it and the
olivine have a pale-green color. Further, the rock contains colorless grains
of plagioclase (?) and roundish opaque pyrrhotite and iron grains.*

The next variety is formed by the addition of diallage, but otherwise the
structure remains the same. The diallage shows not only the common lon-
gitudinal cleavage, but it is also much cut by an irregular augitic cleavage,
thus enabling its ready separation from enstatite in some cases. It other-
wise is closely like the enstatite in its general characters and in its inclu-
sions (Plate III. figures 5, 6).

Sometimes the lherzolite variety of the meteoric peridotites is found to be
entirely crystalline, and in this case the chondri and base are wanting, and
the rock is composed of a crystalline granular aggregate of olivine, enstatite,
diallage, iron, pyrrhotite, and chromite. In this the olivine contains irreg-
ular masses and globules of iron; while the enstatite and diallage have the
same inclusions, not only of iron, but also of olivine grains.

In the next type augite is added, but it makes no essential change in the
general characters of the rock. In some of the peridotic meteorites, plagio-
clastic and possibly orthoclastic feldspar, peckhamite, schreibersite, graphite,
etc., occur in subordinate quantities.

The microscopic study of meteorites is yet so incomplete that it is pos-
sible that other types and characters may be later added.

In two cases a fragmental or brecciated structure has been seen, giving
us tufaceous meteorites, which, otherwise than this, show the common chon-

dritic characters.

* Die mikros. Besch. meteoriten, 1883, i. 10; Sitz. Wien. Akad., 1883, Ixxxviii. (1), 362, 363.

168 PERIDOTITE.

In the terrestrial peridotites we commence with dunite — a clear granular
inass of fissured olivine grains, which are either colorless or slightly tinged
yellow or green. Sprinkled through the olivine mass are dark to brownish,
opaque to translucent, grains and crystals of chromite or picotite, and mag-
netite, as well as sometimes a few enstatite plates, either colorless or of a
greenish tinge (Plate IV. figure 2).

In these a gradual change to serpentine begins by its production along
the fissures of the olivine, forming a yellowish or greenish network, and this
change goes on until the olivine is completely altered, and only the network
structure remains (Plate IV. figures 3, 4; Plate V. figures 1, 2, 4; Plate
VI. figure 2). Again the change extends so far that not even this trace
of the original structure remains (Plate VI. figures 5, 6; Plate VII. figure 2).
In the process of alteration to serpentine, that formed first along the fissures
generally takes a different structure and color from that later produced by
the alteration of the interior portion of the olivine grains — thus showing
two, and sometimes three, stages in the progress of alteration. While the
mode of alteration is thus conspicuous in the earlier stages, the final result
is to produce a pure, clear, homogeneous serpentine, of a uniform yellowish
or greenish tint, or even colorless; in which no trace remains of the original
structure, to tell its derivation. The proof of these changes is found in fol-
lowing out the various gradations in the different peridotites, particularly
in different portions of the same rock-mass.

By the gradual increase in the amount of enstatite present, we pass into
the succeeding variety — saxonite, and this again, by the addition of diallage,
gradually passes into the /herzolite variety, and this into the succeeding form
(buchnerite) by the addition of augite. Again, we pass gradually to those
forms in which the enstatite has disappeared, and only diallage (eulysite) or
augite (picrife) remains with the olivine to form the rock. Every gradation
exists between these forms, and they are closely allied in physical and
chemical characters.

The enstatite appears as a clear, colorless mineral, or else as one slightly
tinged with green. Sometimes it oceupies a subordinate portion of the rock,
then again it forms the chief part, holding the olivine inclosed in and
subordinate to it. The enstatite is sometimes feebly pleochroic, and shows
a well-marked longitudinal cleavage; the development of which, instead of
forming a smooth fracture, usually occasions the tearing of a rough line,

with stringy fibres extending from one side to the other. Besides the longi

Sree SS eS er ee

“

ITS MICROSCOPIC CHARACTERS. 169

tudinal cleavage, a cross fracture, at right angles to the principal cleavage,
is often present.

The diallage possesses similar characters to the enstatite, and generally is
undistinguishable from the latter except optically, but sometimes it shows two
cleavages approaching those of augite, breaking the surface into rough, irregu-
lar rhombs, which serve to distinguish the diallage in question from enstatite.
Again, diallage has not only its proper longitudinal cleavage, but also the
well-marked cleavage of augite. This fact indicates that there is no real dis-
tinction between diallage and augite, but both form a continuous series.

The augite is pale-yellow or brown, shows its characteristic cleavage, and
is sometimes feebly pleochroic. It occurs in grains and crystals, and some-
times encloses olivine grains.

Since the olivine, octahedral oxides, and their alteration-products in the
varieties of peridotite are like those in the first-described variety, it remains
simply to trace the alterations in these varieties as they are modified by
the addition of other minerals than olivine. The pyroxene minerals, as
a rule, are Jess liable to alteration than olivine, and are frequently deter-
minable after the olivine has been entirely changed. This is indicated in
Plate IV. figure 6, and in Plate VI. figures 3 and 4. The enstatite usually
shows its alteration by the formation of a greenish product along its cleavage
planes (Plate V. figure 3; Plate VII. figure 1). As the alteration progresses,
the pyroxene minerals are transformed into a yellowish or grayish serpen-
tinous mass, which may show aggregate polarization, or may retain that of
the mineral from which it has been derived.

The various changes in the peridotites can perhaps be best followed from
the plates. In Plate IV., figure 1 indicates a typical dunite composed of
unchanged olivine grains, with only a cloudiness produced by the fissures by
which the mass is traversed. Figure 3 shows another dunite containing
brown picotites and exhibiting the formation of greenish and yellowish ser-
pentine along the fissures of the olivine, with sometimes a complete serpen-
tinization of the interstitial olivine grains. Figure 4 shows a saxonite in
which the alteration to greenish serpentine has progressed so far as to leave
only a subordinate portion of clear olivine grains untouched. Part of the
enstatite has been changed to serpentine, while part is only partially altered,
as shown in the upper left-hand portion of the figure.

In Plate V. figure 1, is shown the commencement of alteration in a lher-

zolite, in which the olivine and pyroxene minerals assume a gray tinge, and
22

170 PERIDOTITE.

the whole mass is traversed by brown veins bearing iron dust along the
medial line. Figure 2 shows further progress in the change; the brown
veins increase in number and strength, and the ferrugimous medial line
becomes more strongly marked. Bordering these veins are bands of yellow
serpentine, which in their turn are fringed on the inner side by orange,
yellow, and brown serpentine, which again encloses grains of the still un-
altered olivine. In figure 4 the change has progressed still further. The
same brown veins with their ferruginous backbone are to be seen, but the
yellow serpentine has engrossed the remainder, cutting out the orange-yel-
low serpentine and the still unchanged olivine grains seen in figure 2.
Towards the base of figure 4 and on the right and left are to be seen the
remains of two partly-altered grayish pyroxenes. Plate VI. figure 4 shows
a still further change; in which the brown veins and the interstitial por-

tions are only distinguished by slight shades of color. Inclosed in this is an.

enstatite, which retains its characteristic optical characters, but still it is
altered and filled in by magnetite grains, which have separated out during
the process of alteration. Figure 2 shows still farther change, in which
the brown veins are only represented by their intermedial line of magnetite
dust, which is bordered by a pale-yellowish or nearly colorless serpentine,
holding interstitial rounded patches of serpentine, representing the last-
altered olivine cores.

Plate V. figure 3 shows the mode of alteration in the enstatite, taken
from the same section as figure 2. At the left and right of the upper por-
tion of the figure are to be observed portions of the altered olivine mass as
shown in figure 2, while a yellowish serpentine vein joins the two parts,
and cuts the enstatite. Along the cleavage-planes of the enstatite the
greenish and yellowish secondary product extends, while the interme-
diary portions are unchanged. Plate VII. figure 1 represents a still greater
change in a crystal of enstatite from the same section. The colors are
deeper, and fewer unchanged, intermediary portions exist, while the cross
cleavage is well shown by the yellowish-green serpentine bands following
its planes.

In Plate V. figure 5, we see the remains of serpentinized diallage erys-
tals, showing optically the characters of serpentine surrounded by brown
bands and all inclosed in pale-yellow and colorless serpentine. In figure 6 is
shown another portion of the same section, in which the change has proceeded

to a greater extent, leaving only the brown serpentinous masses to represent

ag Cee, . <<

ITS MICROSCOPIC CHARACTERS. 171

the altered minerals. Figure 1, Plate VI., shows a similar change. The
figure at its base possesses a character similar to that of figure 4, but in the
remaining portion is composed of clear, colorless serpentine, holding iron ores
and yellowish serpentine pseudomorphs after olivine grains.

Figure 3 represents a serpentinized peridotite containing rejected iron ores
and in the central portion the remains of enstatite crystals. In figure 5 we
have an entire alteration of the rock to a light or colorless serpentine, filled
with the precipitated iron ores, and traversed by yellow veins of serpentine.
In figure 6 is to be seen a portion of the same section as that shown in
figure 3. This is traversed by a yellowish, obliquely-banded, serpentine
vein, while the adjacent bordering serpentine is filled with the ferruginous
products rejected during the process of the formation of the serpentine vein.
Plate VII. figure 2 shows a peridotite in which the change has gone so far
that no trace remains of the original structure, while the precipitated ferru-
ginous products largely assume the form of a rectangular grating in the
yellow serpentine.

In figure 3 of the same plate, is shown an altered lherzolite in which
enstatite forms the groundwork, inclosing the olivine. The enstatite shows
the usual greenish alteration along the cleavage planes and throughout much
of the interstitial portions. The olivine is chiefly distinguished by the

rrains

rejection of large quantities of magnetite dust on the borders of the g

and their fissures. Sometimes the separation of the ferruginous material
in this form has been carried so far as to render the olivine grains nearly
or quite opaque. Figure 4 shows a further change in this lherzolite, in
which the enstatite is partly replaced by greenish serpentinous material, and
partly by dolomite and other secondary products. The olivine is altered
and in part replaced by serpentine, magnetite, ete., although portions yet
remain unchanged. Figure 5 indicates a still further alteration in this
lherzolite, and one in which the enstatite and part of the olivine have been
replaced by a groundmass of granular dolomite. The olivine grains now
appear only in the greenish and brownish pseudomorphs after that mineral,
inclosed in the dolomite groundmass. Figure 6 shows a yellowish secondary
serpentine mass with inclosed colorless grains of unaltered olivine, and, so
far as this portion of the section is concerned, is closely like that shown in
Plate IV. figure 4, except in the former the serpentine is yellow, and in the
latter it is green. But in addition, there occur in the serpentine, in the

above-mentioned figure 6, gray and brownish particles and grains of secon-

172 PERIDOTITE.

dary dolomite that evidently have replaced a portion of the groundmass, and
in other parts of the section have produced an ophicalcite.

An interesting series of lherzolites is shown in the first five figures of
Plate VIII. In figure 1 is represented a groundmass of enstatite enclosing
fissured and unaltered olivine grains holding picotite. The pyroxene mineral
is but slightly changed, showing this in one greenish band — extending a
little distance from one of the upper olivines — also in the yellowish-brown
tinge of the whole mass. We next pass into a form (fig. 2) in which the
pyroxene minerals are more changed and of a deeper brownish color, while
the boundaries between them and the olivine are less distinct. Again, the
separation of the iron ore-dust aiong the fissures and borders of the olivines
becomes strongly marked, and a series of black ore-bands extends across the
lower portion of the section. In figure 3 the alteration is seen to be still
greater, the color of the pyroxenes higher, and their cleavage planes nearly
obliterated ; while in some cases a bluish border extends between them and
the olivine grains. The olivines are much altered to a greenish serpentine,
showing its network formation along the fissures, and with the iron ores
holding in the interstices some still unaltered portions of olivine. However,
in some of the grains the whole mass has been replaced by serpentine.
Here, as elsewhere, it can be seen that while iron ores are the first pro-
ducts formed during the progress of the chemical changes which lead to
the production of serpentine, these ores either disappear during the sub-
sequent changes, or else are aggregated together in collections of greater
or less size.

Figure 4 shows a still further progress in the alteration, the pyroxenes
being greatly changed and in some parts replaced by a grayish mineral, as
shown on the left of the centre. Only a very few portions of the olivine
have escaped the general alteration to a yellowish serpentine, while the
original fissures of the olivine are shown by the arrangement of the
remnants of the ore bands. In figure 5 the alteration of the rock has
progressed still further, the pyroxenes being entirely changed or nearly so ;
and the olivine completely altered to a pale yellowish serpentine, in which
only portions of the ore-bands are still visible.

This series of sections possesses an additional interest from its bearings
on the cozodén question, for they were examined by Dr. Wm. B. Carpenter, in
the presence of Mr. Alexander Agassiz and myself, regarding the occurrence
of eozodn in them. They belong to the variety of peridotite commonly

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——

_

ITS MICROSCOPIC CHARACTERS 173

called schillerfels, and are usually looked upon as being of eruptive origin.
It can be readily seen that the present writer regards the series as forming
a progressive set of changes, coming down in regular order from the first to
the fifth; but Dr. Carpenter took a different view. He found the remains
of eozodn in every one, but the fossil was best preserved in the last section
(fig. 5), and it was more and more illy defined in regular order, through
metamorphic action, following the retrograde arrangement, going from
figure 5 back to figure 1.

The same ground was also taken by Dr. Carpenter in reference to the
sections shown in figures 5, 4, and 3, of Plate VII., although field evidence
has shown this rock to be of eruptive origin.* Lozoén in various stages
of preservation was found by him in other sections, even including some
made from dolomitic veinstones. Sections of the felsite pebbles forming the
Calumet and Hecla conglomerate, and other bands of conglomerate on
Keweenaw Point, were shown Dr. Carpenter. The present writer in 1880 f+
called attention to the simulative appearance of organic structure assumed
by their groundmass during the alteration of the rocks. On examining these
sections, Dr. Carpenter thought that the rocks must be of organic origin, and
these forms the remains of sponges and other protozoa. Now it is to be
remembered that the original source of these pebbles has been found by
Foster and Whitney, + and later by Irving,§ in eruptive felsites breaking
through the copper-bearing rocks.

In the examinations made by Dr. Carpenter of the various sections laid
before him, it was noticed that the more the rock was altered, or the nearer
it approached a veinstone in character — or better, when it was a veinstone
— the more perfect and the better preserved were the fossils.

Dr. Carpenter was frankly told the writer’s views about the eozodn, the
origm of the rocks in question so far as known, the supposed mode of
production of these forms, and the object of their presentation to him;
and he as frankly and unreservedly gave his opinions. Of course, since Dr.
Carpenter’s views have not been published over his own name, and were not
the fruits of long-continued critical study on the specimens in question,
they are not proper subjects for criticism — as his published views would be.
The object for presenting them here, is simply to call attention to the fact

_* Ante, pp. 136-139; also Bull. Mus. Comp. Zodl., 1880, VIL. 60-66.
+ Bull. Mus. Comp. Zodl., 1880, VIT. 113-120.

t Geology of Lake Superior, Copper Lands, 1850, pp. 70, 71.
§ Sec. Ann. Rep. Director U. 8. Geol. Survey, 1881, p. 33.

1 hy fe: PERIDOTITE.

that zotlogists and paleontologists, however skilled they may be in the
study of organized remains, tend to extend that kingdom in which they
have most experience over every form .of the mineral world simulating
organic forms. So, too, it is not to be denied, on the other hand, that
mineralogists and lithologists are likewise prone to unduly extend their
kingdom. In all such cases of dispute, between the biologists on one hand
and the petrographers on the other, every effort should be made to show
that the conditions under which the rock containing the supposed organic
remains was formed, were incompatible with one or the other view, instead
of leaving the question to the weight of authority. For example, while the
lithologist might insist for ail time that these forms were produced by
alteration, and that he could trace every step from the beginning to the end,
the biologist might also insist that the forms were organic, and that he could
trace every step from the most perfect form to those whose structure had
been almost entirely obliterated by subsequent metamorphism. Both follow
the same series, but each one traces it out in the reverse way from the other.
Who shall decide between them? Plainly this can only be done satisfactorily
by independent evidence which will disprove one side or the other, For
example, the mode of occurrence of some of the rocks in which Dr.
Carpenter found fossils, is that of eruptive bodies and veinstones; therefore,
the proof of their origin decides the question, in these cases, adversely to
the biologist.

The case of the eozodn affords another example of the successful appli-
cation of the above method of determining the nature of a disputed form.
It has been found by Professor Whitney and myself that limestone contain-
ing eozodn, acknowledged to be such by Carpenter, Dawson, and Hunt, cuts
off dikes running through the country rock; thereby proving this eozodnal
limestone to be a later deposit than the country rock, or a veinstone. This
decides the case completely against the biologist, and removes from the
decision every element of ambiguity or theoretical reasoning; since a vein-
stone formation of later date than the country rock is entirely incompatible
with the growth of an organism such as the eozodn is claimed to be.*

In figure 6, Plate VIIL, is shown one of the picrites in which the augite
appears on the right hand of the section. This mineral exhibits in places,
particularly at its base, a greenish alteration-product, and it incloses grains

of olivine fissured and partly altered to serpentine. The remaining portion

* Bull. Mus. Comp. Zodl., 1884, vii. 528-538.

IT’S MICROSCOPIC CHARACTERS. 175

of the section is composed of serpentine, olivine, biotite plates, iron
ores, etc.

In the course of the conversion of peridotites into serpentine, it has been
seen that the original characters of the rock were gradually obliterated,
giving a texture to the serpentine that showed its mode of formation. But
it was found that on further change, patches appeared which showed no trace
of the mode of formation, and that these gradually occupied the entire rock-
mass, yielding specimens whose microscopic characters gave no clue to their
origin. In these extreme alterations a more or less schistose structure is
often produced in the rock, and from this, the writer conceives, has arisen
the view already referred to, that serpentine rocks are derived from
schists as well as from massive rocks (ane, pp. 144-147). The absence of
the reticulated or mesh structure in the serpentine, and the supposed want
of chromite and picotite appear to be entirely due to the great alteration
which produces a structure in the rock almost if not quite identical with thet
of serpentine veinstones. ‘The only apparent difference between the mode of
formation of these serpentines that are homogeneous and the serpentine
veinstones, appears to be that in one the molecular or chemical changes have
taken place in the body of the rock, while in the other a transference to a
new locality has been superadded. There may be mentioned amongst the
various products of alteration found in the peridotites — besides serpentine,

dolomite, and iron ores — the following: actinolite, hornblende, smaragdite,

quartz, zircon, spinel, garnet, feldspar, talc, chlorite, biotite, and various
other micaceous minerals and carbonates.

For the special variations and further details, the reader is referred to the
descriptions of the specimens from different localities. The points that
seemed to the writer most important, in the case of nearly every peri-
dotite or group of peridotites which has been microscopically studied, have
been presented in the preceding pages. This was necessitated by the small
number of Cordilleras peridotites at hand, and our still imperfect knowl-
edge of the group, which seemed to demand somewhere a tolerably complete
summary of the observed cases and their combination into a connected
series.

176 PERIDOTITE.

Srction VII. — Chromite and Picotite. — Their Relations.

AN interesting question is the relation of chromite to picotite. Professor
H. Fischer described the former as opaque, yet sometimes magnetic from the
contained magnetite ;* but m a later paper he stated that chromite, in the
finest dust and under a high power, was translucent and of a red-brown to
red color.t

Dr. E. Dathe found that the chromite from Baltimore was, in thin splinters,
translucent and of a brown color much like brown obsidian glass, and that
this phenomenon could be observed with a low power. The same was also
found by him to be true of the chromite from Waldheim.t From this, Dathe
concluded that the ordinary microscopic distinction between picotite and
chromite, based on the translucence of the one and the opaqueness of the
other, was incorrect. M.J. Thoulet also found that the chromite from Réraas
in Norway, and that from Negropont, were translucent, showing in trans-
mitted light a color mixed with yellow and red. The grains were traversed
by fissures which were impregnated with the surrounding rock material, —
serpentine in the first case, calcite in the second. In reflected light the
chromite shows a violet-rose color or a gray, and in the portions impregnated
by magnetite the characteristic metallic-blue reflection of the latter mineral
was observed.§

Although the translucency of chromite is considered by lithologists to
have been first noticed by Fischer, it would appear to have been earlier
remarked by C. H. Pfaff, who stated in 1825, in describing a compact mass
of chromic iron from Massachusetts, that it was characterized by a thin violet
rim on the plane of fracture.||

In order to ascertain, so far as possible, the microscopic relations of
picotite to chromite and the other iron ores, a number of sections have
been re-examined with special reference to these points; and the powder of
picotite and chromite from a number of different localities has also been

microscopically studied.

* Kuitische mikroskopisch-mineralogische Studien, 1869, pp. 5, 6, 20-22.

+ Ibid. 1873, pp. 44, 77.

{ Neues Jahr. Min., 1876, pp. 247-249.

§ Bull. Soc. Min. France, 1879, ii. 84-37.

|| “‘ Charakteristisch fiir dieses Chromeisen ist eine diinne violette Rinde auf den Ablésungsflichen. Die
Masse war derb.” Jour. Chemie Physik, 1825, xlv. 101-103.

Se

—- oo.

CHROMITE AND PICOTITE. 177

The picotite from Vicdessos is coffee-brown to yellowish-brown, translu-
cent, and shows a smooth surface in reflected light. The chromite or picotite
of St. Paul’s Rocks is greenish-brown to brownish-yellow in color, translucent,
and contains in association with it and in its interior, grains of pyrite and
other iron ores of secondary origin. The chromite itself is here thought to
also be an alteration-product.

The mineral in the Todtmoos peridotite shows in part a pale yellowish
central portion surrounded and traversed by portions of a coffee-brown color
which fade into a surrounding black opaque exterior. Number 142 G., from
San Domingo, has its mineral in part colored deep coffee-brown, translucent,
and traversed by dark opaque bands, part of which are magnetite. The
mineral is in part entirely opaque. In numbers 3001 and 3002 froin Colusa
Co., California, the picotite or chromite is yellowish-brown in part, but most
is opaque and gives a dull, grayish reflection. Some grains were found to be
partly filled with pyrite, and some are traversed by black opaque bands along
the fissures, while others again show a brownish surface in reflected light,
traversed by bluish magnetite veins. One grain had a translucent centre,
with a brown opaque border cut by magnetite veins.

The mineral in the Baste schillerfels is in part coffee-brown and in
part opaque. The translucent grains contain opaque portions. In this,
as in many of the others examined, the opacity appears to arise from,
and to be proportionate to, the amount of alteration in the picotite or
chromite.

In the Webster (N. C.) peridotite the smaller grains are coffee-brown and
translucent, but the thicker interior portions are of a much darker color than
the edges. The larger grains are coffee-brown and translucent on their
edges, but opaque in the interior, and show a rough surface with a dull
reflection. A few of the smaller grains have the same characters. The
powder is coffee-brown and translucent on the thin edges. The mineral in
the Andestad-See rock is of a coffee-brown color in the thinnest portions, and
in minute grains, but the remaining portions are opaque, and give the usual
dull reflection. Some of the grains are cut by fissures filled with serpentine.
Part of the grains in the Tafjord rock are entirely translucent and have
a yellowish-brown to a reddish-brown color; part are entirely opaque, and
have a rough surface with a dull lustre; while part have the exteriors and
some of the central portions translucent, and their remaining portions

opaque, The Tron (Norway) rock has the centres of the grains translucent
23

178 PERIDOTITE.

and of a deep reddish-brown color. The remaining portions are crystalline-
granular, with a dull lustre. The Texas (Pa.) chromite in the sections is
mainly opaque and traversed by fissures filled with serpentine. The surface
of the chromite is rough, crystalline-granular, and the lustre dull; but in the
thinnest portions the mineral is translucent and of a brown color. The
powder in the thin portions is translucent and of a greenish and reddish-
brown color. The color of the massive chromite is velvety black, and it has
a resinous to vitreous lustre, like the chromite from North Carolina. The
mineral in the serpentine from Windisch-Matrey (Tyrol) is mostly opaque
and filled with magnetite, but a little of it was seen to be translucent and of
a brownish color. The mineral in the Franklin (N. C.) peridotite is entirely
opaque in the thin section, and its surface shows a dull lustre, is black, rough,
and granulated ; but its powder is translucent and of a deep yellowish-brown
color on the thin edges.

The ores in the Herborn (Nassau) picrite are all opaque. Part have a
bluish reflection, and part a dull one. The grains are in part mixed with
pyrite. A brownish translucence seen at the borders of the ores in a few
cases, is here considered to be owing to the coloration of the adjacent
silicates by the iron oxides.

In the peridotites (mostly serpentines) from Gjdrud and Christiania,
Norway; Elba; Presque Isle and Ishpeming, Michigan; Westfield and
Lynnfield, Massachusetts ; High Bridge, New Jersey ; Newport, Vermont;
Deadwood, Hepsidam, Chip Flat, and Depot Hill, California; numbers 120
G. and 252 G., San Domingo; and Tasmania, the ores seen are all opaque,
while part are undoubtedly magnetite.

The general characters of the chromites or picotites and other iron ores
in the peridotites of the “ Assos Expedition” are as follows: A. E.324 has
the centre of one grain of a yellowish-brown color with a velvety reflection.
The border is granular, opaque, and traversed by fissures filled with serpen-
tine. Some of the other grains are reddish-brown, and translucent in spots;
the remaining portions of these grains, and the entire mass of the remaining
grains are opaque.

A. E. 265 has its chromic ores in grains and octahedrons, which are trans-
lucent and of a deep brown color. They show a brilliant bluish lustre in
reflected light.

A. E. 207 has part of its grains translucent on the thin edges, and of an

orange-brown to a deep cherry-red color; while the remaining grains are

*
;
|

¢

CHROMITE AND PICOTITE. 179

opaque. Of part of the grains the reflection is dull; but of others, even of
the translucent parts, it is bluish metallic; structure, granular.
Most of the isometric oxides in A. BE. 209 are opaque and in irregular gran-
ules and crystals. Some of the larger grains are traversed by an irregular
network of crystalline grains, giving a bluish metallic reflection, and holding
interstitial portions of a dull lustre. Part of these interior portions are
opaque, and part are translucent and of a deep reddish-brown color.
In A. E. 217, 473, and 216 two different kinds of ore were observed.
One is granular, opaque, and bluish-black in reflected light. The other is a
dull, earthy-brown, amorphous mass in reflected light, but translucent and of
a pale grayish-brown color by transmitted light. The two are frequently
united in the same grain, and the first is here considered to be magnetite,
while the second is a limonitic product of decomposition of iron ores.
A. E. 481 has its mineral in irregular opaque grains of a dull lustre, and
traversed by cracks filled with serpentine.
A. E, 214, 270, 274, 482, 483, 488 (bis), 484, 485 have their ores all
9paque and granular, giving a bluish reflection.
Through the kindness of Professors F. A. Genth and Edward S$. Dana, a
number of chromites were obtained for examination.
The following twenty-four were sent by Dr. Genth. All were found to
be translucent, most showing this with a low power, but some required a
high power. The color is a yellowish-brown in transmitted light, in the
specimens from Westfield, Vermont ; Chester, Massachusetts; Walter Green's
mine, Delaware Co., Pennsylvania; Moro Phillip’s mine in Marple Township,
Delaware Co., Pennsylvania; Webster, Jackson Co., North Carolina; and
Western North Carolina.*
The chromite from the Phillips mine, Nottingham, Chester Co., Pennsyl-
vania, is of a yellowish-brown color tinged variously with green and reddish-
brown. That from Media, Delaware Co., Pennsylvania, is in crystals, the
. powder of one of which is perfectly opaque, and that of another a deep
2 yellowish-brown. In the following the color is a deep yellowish-brown and

a reddish-brown: Davis Moore’s mine, Middletown Township, Delaware Co.,
| Pennsylvania ; Wood’s mine, Texas, Lancaster Co., Pennsylvania; the Red
5 Pit, and Low’s mine from same county; Soldier’s Delight, Maryland; Culs-
agee,t Macon Co., North Carolina; Hampton’s, Yancy Co., North Carolina ;

* This last is from the specimen analyzed by Dr. Genth as being from Franklin, Macon Co., North
Carolina, and containing 44.15 per cent. of chromic oxide. (See table of analyses.)
+ There were two specimens from this locality, one in octahedral erystals, the other massive.

180 PERIDOTITE.

Troup Co., Georgia; Dudleyville, Alabama; California; near New Idria,
Monterey Co., California; Ural Mountains; and Euboea, Greece. Another
specimen from California had a yellowish and greenish-brown color, while
one from Sweden, when very thin, was of a deep-brown coffee-color.

The seven following chromites were sent by Dr. Dana. Those from
Lancaster Co., Pennsylvania; Cecil Co., Maryland; Franklin, North Carolina;
and Bisersk, Ural Mountains, have a yellowish-brown color. Two specimens
from Texas, Pennsylvania, require to be very thin to become translucent,
and are of a yellowish-brown to reddish-brown color. One from Jamaica,
West Indies, is greenish-yellow in its apparently freshest state, but in the
partially changed condition it is reddish-brown.

A chromite obtained from Mr. Kerr, Commissioner from North Carolina
at the New England Fair of 1885, in thin splinters is of a clear coffee-brown
color with a greenish tinge. Its fracture is smooth, and presents a surface
closely resembling a hardened black gum or pitch — for example, albertite —
and has a lustre varying from resinous to vitreous. This was chipped from
a large block sent to that exhibition. Most of the chromites examined have
a pitchy or resinous look, with a velvet-black color closely resembling solid
coal tar; but some are dull. While it may be said that in general more or
less translucency exists in the powder of chromite, this apparently resides
only in certain portions of the mineral, which is not translucent as a
whole.

So far as the writer is aware, no tests have been made to compare the
relative hardness of picotite and chromite, but the former has been assumed
to have that of the normal spinel. In the same way the color of the streak
of picotite does not appear to -be known for itself; while that of chromite
would seem to be due to its translucency.

In specific gravity the two minerals bear close relations. Chromite varies
in its specific gravity as follows: 4.031, 4.0639, 4.11, 4.115, 4.1647, 4.319,
4.422, 4.439, 4.49, 4.50, 4.534, 4.56, 4.566, and 4.568; while the only deter-
mination of picotite found, places it at 4.08.

Both minerals have the same crystallographic form, the same color to their
thin sections, and the same color and lustre in the massive state.

The term cofee-brown as used in this text and in the writings of others
partakes of the same variability in shade that the infusion of coffee itself does,
running from a yellowish or greenish-brown through a reddish-brown to a
deep dirty- or muddy-brown, The depth of color, even in the same specimen,

CHROMITE AND PICOTITE. 18]

appears to be due in part to the thickness, and in part to alteration. For
example, in some the yellowish-brown and reddish-brown shades are mingled
in such a manner that it is evident that the latter shade is due to change in
the state of the iron, and marks a stage in the progression towards opacity.
In other cases the two tints are so related that the shade is seen to be due
to the wedge-shaped form of the fragment examined.

The translucency is better observed in the powder than in the thin sec-
tion, if the mineral tends to be at all opaque, since thinner edges are obtained
by the process of fracture. The writer has found the quickest and simplest
way to prepare the powder for microscopic examination, — to place a minute
fragment, less than a pin’s head in size, on a glass slide,* and then crush it on
this slide under a clean knife-blade. The scattering of the powder can be pre-
vented by placing a finger over the blade at the point under which the grain
lies. In this way, by using a small blade, the finger projects over both sides
and serves as a cushion to prevent the broken particles from flying off, gives
a more uniform pressure, and saves the production of so much fine dust as to
obscure our observations. ‘Thus the powder can be directly examined on the
slide on which it was crushed.

It does not appear practicable at the present time to enter upon any
satisfactory discussion of the chemical relations existing between picotite and
chromite ; yet, as a contribution towards that desired end, a list of analyses
of the two minerals has been arranged in order of the relative percentage
of chromic oxide, and it will appear in the list of tables as Table I. One of
the difficulties in the way of a satisfactory determination of the relations
of chromite and picotite is the absence of analyses made from material care-
fully studied microscopically, as well as a like absence of analyses made from
material of intermediate grades between the typical picotite and the typical
chromite. For it will not escape the observer’s attention that the analyses
naturally group about these two poles, since typical specimens are selected
for analysis, Another difficulty is the fact that only five analyses of picotite
and one of chrompicotite are known, out of the one hundred and twenty
analyses here collected.. Hence it is that the series of analyses is far from
being so continuous as it would probably be found to be if more attention
had been paid to the question of the relations of these two minerals.

The percentage of chromic oxide begins as low as 4.74 per cent in one
chromite, and in the picotites does not rise higher than 8 per cent, while the

* Any window-glass, if cut of proper size for the stage of the microscope, will do.

182 PERIDOTITE.

chromites next in order contain 9.80, 16.80, three between 17 and 18 per cent,
then 21.16 and 31.20. The chrompicotite, however, contains 56.54 per cent
of chromic oxide. The highest percentage is 77.00, in a doubtful analysis
by C. H. Pfaff; while the next lower has 64.17 per cent.

The highest percentages of alumina in the chromites are 30.17, 27.83, and
24.71, but in general it diminishes in amount as the chromium increases.
In picotite the alumina is high, being 50.34, 52 47, 53.93, 55.34, and 56.00
per cent, and in this occurs the only real chemical difference between pico-
tite and chromite. In the chrompicotite the alumina is 12.13. The percent-
age of magnesia is about the same in both the chromites and picotites, and
does not bear any observable proportion to any other element. The highest
percentages are, in picotite 23.59, and in chromite 28.71 and 25.40.

The oxides of iron irregularly increase as the chromic oxide does, rising
as high as 45.22, 48.46, and 62.02, while the lowest percentages are 2.30,
5.60, and 9.00; but picotite contains the following: 22.27, 21.42, 15.25,
24.60, and 24.90, and the chrompicotite 18.01. The silica and lime diminish
irregularly as the chromic oxide increases. The highest percentages of silica
are 26.01, 26.70, and 14.211; and of lime 24.36, 13.26, and 10.55.

The minor and rare elements are the oxides of nickel, manganese, and
carbon.

The more general relations are perhaps best shown in the tables inserted
here in the text.

TABLE L

No. of Analyses. 23. 25. 27. 28. | Lv.

pers Ze 4.74-38.12, 39.05-44.91, 45,00-52.12. | 52.12-57.20. || 58.00-77.00.
Pereentage tim-| 3 |e |3|¢|3|e|le|slslslelsielellglsiale ¢lsigiaislale |eislale ¢
weotminens. 5/3214 12/3/38 |2|2]s lala |s(alalie (2 |sia a|s le |s (a (ale ele la,s
Me iQ a Macc 4c TAY Bele eee Ae eA es ee pee ee SAINTE Pe Soi Ge Aion ens (teal eee Ac |1O} Bile. dees
ATO pcs. Neeel contol alr Ont BTL is | OES fea oe ee pea a FESS 35 Wo | (oa PA NST Bese ae TPG MNGH Ese mae
Fe, 0, & FeO}.../10)11| 8} 3]...1... - al Dest eLO Ge BW eee) fal) Com LES 1591253 5|4/1916 LS ee
Sl Os aes 7d || al Vc oer QBs Oi cell ace eee eee | ee V2.0 ale ee ee AMC Sa eel ees 3 LS lease
GaOz eat 19) Sako Hi at el ae (LZ) Sil 51S eal aaah Wale)» tua & _ ee Cy is ee ee (114) 3 lj

Table I. has placed in its upper line the number of analyses in each set ;
in the second line, the percentage limits of the chromic oxide in these
analyses; while on the third line is placed the percentage limits of the
magnesium, aluminum, ferric, ferrous, silicon, and calcium oxides. Below are

given the number of analyses found in the above limits. Thus, for instance,

CHROMITE AND PICOTITE. 183

in looking at the table it can be seen that in the first 23 analyses the limits
of Cr, 0, are 4.74 and 58.12; while in these 23 analyses, there are to be
found of analyses of Mg O, one having no Mg O; four having less than 10 per
cent; fourteen carrying between 10 and 20 per cent; four carrying between
20 and 30 per cent; and none having any higher percentage. But in these
same 23 analyses we see that there are five (picotites) which carry between

50 and 60 per cent of Al, Os.

TABLE fI.
Percentage Limits. g = a % 5 3 3 & E = z
Peo a | Ss oe) Spe” | & bee
CrsO ea Ys 7 | 4) 2) 16} 36 | 43 |-12} 14
| eS Peer ae Gi 19-13 | 6.) 10 1 |
BS OV ACK, Site 18 4 | 28 | 49 | 13 5 3
AG Sete 8) 53 | 36) 12] 1 5 | 4
I ULECS (Oe os ine te 15 |} 42 | 55 8
STi See Teoh bag :b” 9 l
re ae 19 | 27] 2] 1 el ee
= dsreb J aie

In Table II. there is given in the upper line the percentage limits for the
different constituents, and below, the number of analyses whose constituents
fall between those limits. Thus it will be seen that out of the 120 analyses,
there are seven containing less than 10 per cent of Cr, O,, four between 10
and 20 per cent, etc.; while there are 81 analyses in which no Fe, OQ, is re-
ported and one which has between 60 and 70 per cent of it. From the above
illustrations, the use of the tables will doubtless be readily understood.

In reply to a question of the present writer as to his views concerning
the chemical relations of chromite and picotite, Dr. Genth states that, in
common with many others, he thinks “ that all the aluminates, ferrates, ete.
of Mg, Zn, Mn, and Fe, which are isometric, are only varieties of the species
R R, O, — which so gradually change from one into the other, that it is often
difficult to say where one begins and the other ends. Of typical forms we have
only spinel (Mg Al, O,), magnetite (Fe Fe, O,), and magnoferrite (Mg Fe, Q,).
All the rest are mixtures. As for chromite, ] have never seen a specimen
which did not contain magnesia and alumina, although some of the analyses
do not give any; but there are a great many poor analyses.”

In the same manner, Rammelsberg classes together chromite and picotite,
not even placing the latter under spinel.*

In the microscopic study of chromites and picotites we see a reason for
the variability in their chemical analyses, and the nearly constant presence

* Handbuch der Mineralchemie, 1875, pp. 141-144.

184 PERIDOTITE.

of silica and other impurities. We further find various gradations in
different specimens, and even partly in the same grain, between the yel-
lowish- to reddish-brown mineral, and that which is opaque and crystalline-
granular, with or without magnetite or some of the other iron ores, like
limonite or hematite.

The above investigations apparently point to the following conclu-
sions : —

That picotite in its freshest state is, in the thin sections, a yellowish- or
ereenish-brown, clear mineral which is subject to alterations, causing the
color to deepen to a darker brown or muddy coffee-color, and even to a
black and opaque mass. The changed forms vary from a dull, earthy mass
to a crystalline-granular one which frequently contains more or less magne-
tite. Commonly, the more the rock is altered or changed to a serpentine,
the less apt is one to find any of the translucent grains, and the greater is
the amount of magnetite.

It is probable that picotite and chromite belong to the same mineral
series, the term picotite being more commonly applied to the freshest states,
and that of chromite to those forms more altered, and to the local aggrega-
tions arising from the migration of the chromic oxide during the alteration
of the associated peridotic rock.

The results deduced from the microscopic study of minerals, lead to the
conclusion that most of our mineral species are not definite compounds
corresponding to a special chemical formula, but rather are varying and
variable compounds. They are seen to contain inclusions of various kinds,
and to exist in various stages of alteration and decomposition. This we see
in the case of micaceous products which occur in certain greenish, fibrous,
and scaly forms, produced from the alteration of various minerals. Now,
while these forms are microscopically undistinguishable from one another in
their earlier stages, they are seen to result in their further change, in the
production of biotite, hornblende, chlorite, hydrous micas, etc. Now shall we
give a distinct name to each of these variable and interminable micaceous
forms, whenever from its analysis we can torture a chemical formula into
being; or shall we recognize the variability, and use our mineral names
simply as type-names about which the related products in their various
stages are grouped? The latter is the method employed in this work. The
variability of mineral species not only occurs in the micaceous minerals above
mentioned, but it is seen in picotite and the ores of iron, the feldspars, serpen-

eS

ee SS

CHROMITE AND PICOTITE. 185

tine, pyroxenes, amphiboles, and in almost every mineral or group of minerals
that has been studied to a sufficient extent to afford us much information
about its composition. Our minerals in Nature’s laboratory appear to be
produced and grow, to change and decay, to pass away and be succeeded by
others, ever passing onward from the unstable towards the more stable; re-
action after reaction, replacement after replacement, following one another
according to the varying conditions, as they do in the chemist’s laboratory.
When we can learn the order of succession by alteration, and the various
relations minerals thus hold to one another, we may hope for a natural sys-
tem of mineralogy, which will display to us their origin and line of descent,
with their relationships. In the establishment of such a system, the micro-
scope and chemical reagents must go hand in hand, and the work is yet
hardly begun.

An analysis of a chromite from Riraas, Norway, given in Table I., has had
a strange history. It was attributed to Laugier by Rammelsberg in his
Handworterbuch des chemischen Theils der Mineralogie, 1841, pp. 163, 164,
and in his Handbuch der Mineralchemie, 1860, pp. 171-174; and from these
works of Rammelsberg it has been copied in the third, fourth, and fifth
editions of Dana’s System of Mineralogy, and elsewhere. The work from
which the analysis is said to have been taken is the sixth volume of the Ann.
Mus. d’Hist. Nat. It was proved by the present writer not to occur there,
and after a long search, its history has been found to be as follows : —

The analysis was published in the Annales des Mines, 1829 (2), V. 516,
as taken from the “ An. du Bureau des mines de Suéde, t. 9, 1825,” but the
name of the analyst was not given. Since the writer is unable to see, for
the present at least, the Swedish journal referred to, the analysis has not
been traced any further backwards. It was then copied by Beudant,*
together with an analysis of Seybert, but in both cases without mention of
the analyst or the source. Before this, however, it had been republished by
Franz von Kobell,} without being attributed to any analyst, and without
reference to the original source, but placed after a reference to an analysis
by Laugier. This then evidently gave rise to Rammelsberg’s mistake ; while
it also led Hausmann ¢ and Brooke-and-Miller§ to attribute the analysis to Von
Kobell himself, as they have done in their mineralogies. Thus this analysis

* Traité élémentaire de Minéralogie, 1832, 11. 667, 668.
+ Charakteristik der Mineralien, 1831, ii. 255.

+t Handbuch der Mineralogie, 1847, ii. 420.
§ An Elementary Introduction to Mineralogy, by the late William Phillips, 1852, p. 263.

24

186 PERIDOTITE.

has been credited over forty years to a chemist by whom it showed on its face
it could not have been made, since Laugier was not in the habit of carrying
his percentages into the decimals, at most, beyond one place,

This, and numerous other mistakes which have been found in the process
of looking up the analyses for this work, are obviously due to the neglect of
authors to verify the analyses which they take at second hand. The present
writer has no doubt that he has contributed his quota of errors also, although
he has endeavored to go to the fountain-head when possible; but with the
accidents of twice copying and of passing the work through the press, the
chance for errors to creep in are great; and they could only be entirely
eliminated by again searching out the scattered literature, and comparing
the originals with the tables in type —a labor which is impracticable at the

present time.

Section VIII. — Peridotite. — Its Chemical Characters.

In the appended table of chemical analyses (Table FV.), when the variety
to which the meteorite belongs is known, the name of the variety is given,
with an asterisk prefixed to indicate that it isa meteorite. When the variety
is unknown, the simple designation, meteorite, is employed. The varieties of
the terrestrial peridotites are given so far as possible; but when not known,
the term used by the analyst to designate the rock is placed in the column
of varieties.

The specific gravity of the unaltered peridotites is generally between
3.00 and 5.80, with the meteorites standing, as a whole, somewhat higher
than the terrestrial forms, since they are less altered. As the alteration
proceeds, the percentages in general fall, as was observed in the case of
cumberlandite. Two of the carbonaceous meteorites fall very low on the
scale, being 1.7025 and 1.94. These meteorites are thought to belong to
this group in all respects except their carbonaceous matter, for sections of
the Cold-Bokkeveld meteorite are seen as dense black masses, with brownish-
gray spots of silicates and carbonaceous grains. The whole mass is very
friable, and the silicates are in minute grains; but they appear to be chiefly,
if not entirely, olivine and enstatite. The resemblance to a mass of mixed
soot and olivine grains is striking — the latter being seen scattered here and
there through the dark mass.

To return: the specific gravity of the altered forms, particularly of

ITS CHEMICAL CHARACTERS, 187

serpentine, lie almost entirely between 2.50 and 3.00. This decrease in
specific gravity is generally accompanied with a diminution of the relative
ferruginous contents, and an increase in that of the magnesia.

It was observed in the pallasites that only one contained over 30 per cent
of silica, while it may be seen here that only three of the lherzolites fall
below that percentage, and one of these is a carbonaceous meteorite which
contains considerable organic matter and water. Another of these analyses
is considered to be worthless. In the mention of the chemical analyses,
reference, as a rule, is had to the first one when more than one is given fora
single locality ; for when several analyses are available, that one is placed
first which is thought to be the more nearly correct, judging by the analyses
and the analyst, when any especial difference exists. Of course, no such

differences in composition occur in the same specimen, as some of the given
analyses display, and many of these are poor and unreliable.

Only two of the analyses show for peridotite a higher percentage than
47 per cent — St. Paul’s Rocks 47.15, and the Cabarras meteorite 56.168.
This meteorite has in general been assigned to the basaltic division of the
meteorites ; but since, macroscopically, it has the characters of the peridotites,
it has here been placed with them, in the belief that some error exists in the
published analysis. It is to be hoped that a microscopic examination and
further chemical analyses will be made of the Cabarras stone.

Only two meteoric and three terrestrial peridotites have a percentage of
silica above 45, and below 47, per cent. One of the meteorites has two
analyses in which the silica is respectively 46 and 48.25 per cent, made by
Higgins in 1811. Had the second analysis been placed first, then the above
statements would have varied accordingly.

From the above it can be seen that out of 193 different peridotites
analyzed, all but 11 have their percentage of silica lying between 30 and 45,
while the vast majority are included between 35 and 43 per cent. The
meteorites preponderate in the lower percentages — the terrestrial rocks in
the higher ones.

Except in the case of the picrites there cannot at present be said to be
any gradation in the percentages of silica, according to the variety, from
dunite up to picrite, although a tendency towards some arrangement has
been observed. Of course, the more nearly the rock approaches to a purely
olivine one or to a pure serpentine, the more nearly the percentage of silica
will correspond to the typical analyses of those minerals.

188 PERIDOTITE.

The vast majority of analyses show a percentage of alimina less than 5,
but the picrites tend to have more (mostly between 10 and 20), as also some
of the others, thus approaching the basalts. The highest percentage is in the
Muddor stone analyzed by Frank Crook — 26 per cent —a doubtful analysis.

The amount of iron in various states distinctly varies in the meteoric and
terrestrial peridotites; so much so, that from the sum of the percentages the
class can readily be inferred in most cases. In the meteorites the iron in
every condition varies somewhere about the mean of 30 per cent — those
forms having the lower percentages of silica, usually more than 30, and
those having the higher percentages of silica, contain generally less than 30
per cent.

In the terrestrial peridotites the iron percentages are commonly below 10,
and universally below 20 per cent. The more highly altered the rock, the
less is the percentage of iron. This agrees with the microscopic observations,
and shows that in the process of alteration much iron is removed and stored
up elsewhere.

Lime is either absent in the peridotites, or less than 5 per cent in the vast
majority. The cases in which higher percentages are found are apparently
due to incorrect analyses, or, in the main, to the picrites and two serpentines
which are associated with gabbro, and may possibly be altered forms of it —
a conclusion to which their relatively high contents of alumina and lime
point. The picrites show their near relation to the basalts in the same way.
19.50 per cent of lime (the highest) was found in the typical lherzolite from
Vicdessos, in an analysis published in 1815. It is thought that here the lime
and magnesia were poorly separated, or else the peridotite has been in some
way modified by the limestone through which it was erupted. No other
peridotite contains over 13.61 per cent of lime.

The magnesia percentage is relatively high but variable, and it tends in
the meteorites and picrites to lie below 30 per cent, and in the other perido-
tites to be above that. Of course, the nearer the rock comes to being a pure
olivine one, or to be entirely altered to serpentine, the more nearly the
percentages correspond to the typical ones for those minerals. Part of the
variability in the percentage of magnesia is undoubtedly owing to poor
analyses.

Chromium, nickel, and cobalt are quite commonly present, as are also
phosphorus and sulphur in the meteoric forms. Sometimes copper and tin
are found. The more highly altered the peridotites, the more apt is water

ITS ORIGIN. 189

to be present, and in the serpentine rocks it appears in general to vary from
8 to 16 per cent.

In general, the peridotites are relatively low in their percentages of silica,
alumina, and lime; high in magnesia; and variable in iron and _ specific

gravity ; the unaltered forms being higher, in both cases, than the altered.

Section IX. — Peridotite. — Its Origin.

« Are the peridotites sedimentary or eruptive?” is an exceedingly impor-
tant question, and one which, in the case of serpentine, has been frequently
argued.

That the peridotites are sometimes eruptive, the cases cited by Bonney,
Diller, and the present writer, for Cornwall, the Troad, and Lake Superior,

are clear, explicit, and decisive —that they occur in dikes, in intrusive

tongues, and in uplifting, altering, eruptive bosses, showing the same char-
acters as do other eruptive rocks, especially those of a coarse-grained charac-
ter like gabbro and granite. That the peridotites are in part eruptive we
should, then, consider a settled fact; but another case still remains to be
considered: the association of these rocks with schists.

Where schistose rocks are associated with the peridotites, especially the
serpentine variety, their relations would appear to be accounted for in the
following ways :— .

1. They may occur as eruptive rocks which, with their associated country
rocks, have later been altered, producing a general apparent blending of all
into a single series; as it is well known has taken place with the older erup-
tive basaltic rocks — diorite, diabase, melaphyr — which has caused them
also to be looked upon as interbedded sedimentary rocks, in common with
their associated schists.

2. All may have come from the alteration of eruptive material, — the len-
ticular patches being the remnants of the altered rock. This would be in
accordance with the well-known mode of alteration of olivine rocks, in which
occur clear grains of unaltered olivine surrounded by the serpentine and
other secondary minerals which often give to the rock a schistose character.
We might as well claim that these clear olivine grains were produced by the
metamorphosis of the serpentine and schistose material, when the reverse is
known to be the case, as to claim that the patches of olivine rocks in schists

190 PERIDOTITE.

were produced by the metamorphosis of the schistose material, when the
reverse is probably true.

3. All other eruptive rocks are subjected to denudation, and their débris
piled up somewhere with other associated sedimentary beds; hence there is
every reason to believe that we have detrital peridotitic rocks, the same as
we have detrital basaltic ones.

All three of the preceding methods are probably correct for some cases,
but which method is to be advocated in each case is to be determined by the
study of the locality in question. ;

Although as yet it does not seem to be proved that peridotic volcanoes
have existed, and peridotic ash may not have been formed, we should look
for all the intermingling of the eruptive peridotic material with its own débris
and with that of other rocks, the same as previously set forth in general
terms for rocks of this origin (ane, pp. 22-24). We should then expect to
find the peridotites occurring in dikes and eruptive masses, in altered schis-
tose or foliated rocks, in detrital beds, and in every form and every associa-
tion that it is possible for eruptive rocks and their débris to exist in. The
study of these occurrences would, however, be expected to be just so much
more obscure than is the study of the basaltic rocks, as the former are more
basic and easily alterable than the latter.

That serpentines are produced from the alteration of peridotic rocks, is
the testimony of all lithologists who have studied their structure with the
microscope, and it is one of the most fixed facts in the science. That serpen-
tines are not produced in other ways may perhaps be looked upon as an open
question at the present time, although there would seem to be no proof of
any other mode of origin. In the case of any mineral formed by secondary
changes, more or less migration of the mineral material is apt to occur,
and in this way the secondary serpentine is frequently found in veins,
and in other localities outside of the rock from whose alteration it was
produced.

That serpentines have come from chemical precipitates from ocean waters,
is a view which certainly does not appear to have any proof in its behalf, and
one which probably arose from the confounding of veinstone-serpentine or
migrated serpentine material, with that produced by the alteration of perido-
tites m sifu. The production of serpentine by the alteration of olivine and
its removal and storage in fissures and adjacent rocks, brings in connection
with the peridotites the difficult problems belonging both to eruptive rocks

ee

ITS ORIGIN. 191

and veinstones; and the phenomena of both would appear to explain the
mysteries hovering about the serpentine question.

The writer has been unable to find anything in the published reports of
the Canada Geological Survey to substantiate the often repeated statement,
that this survey had proved, prior to 1858, that the Canadian serpentines
were in stratified sedimentary deposits. The geologists of that survey appear
to have assumed, without proof, that the serpentines were so deposited, and
worked out their geology on that supposition. Then, finally forgetting the
basis on which the assumed stratification was placed, they afterwards declared
that they had proved these rocks to be stratified ; but the correctness of that
statement is not here allowed. And in this connection it may be said that
Dr. Hunt’s “ Geological History of the Serpentines” is looked upon here as
having the same inaccuracies that all his other papers have been found to
contain, when the present writer has had occasion to critically examine their
contained statements, both of fact and opinion (ane, p. 38).*

The question now arises: Can serpentine result from the alteration of any
rock except the peridotites? In the preceding pages it has been shown that
olivine is the chief producer of serpentine, but that in olivine rocks enstatite
and even diallage are changed to serpentine, although more slowly than the
olivine. It has also been shown that in the cumberlandite more or less
serpentine had been formed during the alteration of this olivine-magnetite
rock. So, too, it is well known to lithologists that the olivine of the basaltic
rocks is subject to alteration to serpentine, which, in the gabbros and other
old basalts, produces a rock imperfectly serpentinous. It would seem, then,
that any rock containing olivine or enstatite, may become more or less ser-
pentinized, although it would appear that, outside of the peridotites proper,
true serpentines that are not veinstones, rarely, if ever, occur.

The reader is further referred, for the literature and general discussions
of the serpentine question by others, to Roth’s “ Ueber den Serpentin und
die genetischen Beziehungen desselben,” + Riess’s “ Ueber die Entstehung
des Serpentins,’ + and the lithological text-books of Rosenbusch and
Zirkel.

The production of talcose rocks or talcose schists, as early advocated by
Genth (ante, p. 119) appears to be one of the results of the alteration of

* See also “ Azoic System,” Bull. Mus. Comp. Zoél., 1884, vii. No. 11; and Bonney, Geol. Mag., 1884 (3),
i. 406-412.

¢ Abh. Berlin. Akad., 1869, ii. 329-861.
t Zeit. Gessam. Natur. Berlin, 1879 (3), iv. 1-18.

192 PERIDOTITE.

—_

peridotites, especially those containing pyroxene minerals; but the present
writer’s studies would indicate to him that the most common source that
yields by alteration our soapstone or steatite rocks, is to be sought in our
gabbros and coarser crystalline diabases (diorites). The purer talcose rocks
would appear to come from the former source (the peridotites), the more
impure ones from the latter (the basalts).

From the evidence in the preceding pages, it is probable that some actino-
litic and other schists result from the alteration of the peridotites, although
in general the amphibole schists appear to belong to other groups.

The formation of impure dolomites from peridotites would seem to have
been clearly shown in the preceding pages, but how far this will account for
the common association of magnesian limestones with serpentine, is a problem
for the future. One thing, however, appears clear, that such limestones are
produced on a small scale, and sometimes on a more extended one in connec-
tion with the general alteration of peridotites into serpentine.

It is not the part or intention of the writer to explain the modes of
change in these rocks. It is rather his part to give the facts observed, and
for the mineral chemist to engage in the work of explanation, unless he can

impeach the facts presented.

Section X.— Peridotite. — Its Classification.

As previously stated (ante, pp. 84, 85), all rocks of this class are here
grouped under one species or type — pervdotite ; while for the modifications
produced by the variation in mineral composition, varietal names are em-
ployed, in deference to the views of those who make species out of every
mineral variation in rocks. Since, so far as practicable, these variety names
are the same as the specific names of other lithologists, and have the same
general limits, no difficulty will arise in their use, whether the person em-
ploying them looks upon each division as a specific or a varietal term. |

In accordance with the methods of this work, peridotite is defined as
including all meteoric and terrestrial rocks of every age, which are composed
essentially of olivine, with or without pyroxene minerals, and iron ores
including picotite.

It has not been customary to base any varietal distinction on the iron
ores, or hardly to look upon them as essential, although they are universally

ITS CLASSIFICATION. 193

present, or nearly so. The varietal distinctions (specific, of other lithologists)
are founded on the pyroxene minerals and on the alteration-products. Thus
dunite is the term given to the form of peridotite which is essentially com-
posed of olivine ; saxonite to that composed of olivine and enstatite ; /herzolite
to that composed of olivine, enstatite, and diallage ; duchnerile to that com-
posed of olivine, enstatite, and augite: enlysite to that composed of olivine
and diallage ; and picrite to that composed of olivine and augite.

Under these varieties are classed all the forms produced by alteration, so
far as they may retain sufficient original characters for their identification ;
when they do not, then they are placed under a variety name belonging to
the produced form. Thus, serpentine is given as the variety name for all the
altered peridotites in which serpentine forms the essential constituent; /a/c
schist to all in which tale holds a similar part; and in the same way any
variety produced by alteration can be designated by its common name when
its derivation is known.

It is, however, expected that future studies will lead to the discovery
of every mineralogical combination that can be formed by the principal
silicate constituents of peridotite. These combinations, so far as now
known grade into one another, and it is to be expected that all other dis-
covered ones will do the same. Hence, if the ordinary methods of nomen-
clature should be followed, the number of species or varieties of peridotite
would be great and their separation difficult. However, the present writer,
as he has previously stated, does not place any stress upon the subdivisions
now made on a mineralogical basis in peridotite, but adopts them as a con-
venience only in the present state of lithological science; and they can
readily be replaced by the general employment of the specific name —
peridotite.

The mburgite of Rosenbusch has not been placed here with the peridotites,
for its microscopic structure is like that of some of the porphyritic glassy
basalts, and differs much from the peridotites. While its percentage of silica
is like that of this species, its contents of alumina and lime ally it to a more
acidic group; although it is not improbable that it belongs to the picrite
variety. Except in its abundant olivine, limburgite microscopically closely
approaches some of the andesites; but, taking its characters as a whole,
the majority of them appear to be basaltic, and with that group it will here
be classed until further evidence can be procured.

The fragmental states of the peridotites are indicated for the unaltered

25

194 PERIDOTITE.

and altered forms by the respective varietal terms, ¢u/a and porodite, or, if
desirable, their adjective forms, yfuceous and poroditie,

Below is given a table showing the classification of all the rocks more
basic than the basalts, so far as now known, but it admits of the ready addi-
tion of other varietal names, and even of specific ones, if future studies shall
indicate such divisions. The three designated classes of varieties are of course
not entirely distinct, since in alteration a mineralogical change enters, and
that change or alteration is the basis of the two divisions of the fragmental
forms, while these may partake of the mineral characters of the mineralogi-
cal varieties, and belong to them.

Tible showing the Classification of the Rock Species preceding the Basalts.

Species. Mineralogical varieties. Alteration varieties. ese om vari-
Siderolite. os es a FEES Bo Bee eK Porodite.
2 Pallasite
Pallasite. : Meee ;
Cumberlandite. Actinolite Schist.
Dunite.
Saxoniie. 5
: Serpentine.
Te Lherzolite. : Tufa.
Peridotite. i Tale Schist. ;
Buchnerite. Se ae : Porodite.
: Actinolite Schist.
Eulysite.
Picrite.

This seeming confusion or crossing of names is due to the present state of
lithology, and the necessity of bringing the nomenclature into accordance with
the general usage and prejudices of lithologists, since an abrupt departure
from their nomenclature would only repel, and the inconsistencies can later be
remedied by the dropping of all varietal names which the advance of the
science shall render superfluous, as the writer now believes many of them to
be. Thus, for instance, it is here considered that in peridotite, the terms
peridotite, serpentine, and tale and actinolite schist, with the adjectives tufaceous
and porodilic, will express every essential form of these rocks now known,
and by their use alone a proper conception of their relations would be ad-
vanced, |

CHAPTER lV.

THE BASALTS.

Section I. — The Meteoric Basailts.
VARIETY. — Basalt.

Stannern, Moravia.

TsCHERMAK has described the Stannern meteorite as a granular rock, showing an
evident fragmental structure. According to him, it is not a homogeneous crystalline
rock, but one composed of rock fragments of three different kinds: coarse-grained frag-
ments, radiated finer-grained fragments, and compact fragments.

The coarser-grained fragments are chiefly composed of anorthite lamin and augite
columns united together. Some of the anorthite crystals show very fine twinning, but
most have broad twin laminze which are sometimes bent. Besides the colorless anorthite,
and the brown to blackish augite, Tschermak observed a colorless isotropic mineral, which
is probably the same as the mineral he had described as an isotropic labradorite (maske-
lynite) from the Shergotty meteorite. Minute grains of chromite, iron, and pyrrhotite
occur inclosed between the other minerals ; and black forms were seen in the augite.

The fragments, of an evidently radiated texture, are composed of anorthite laminz
interspersed with augite needles. Black grains occur in these fragments.

The compact fragments formed a gray mass, which in several points showed a radiated
fibrous structure, and which contained the before-mentioned black grains.

The groundmass which unites these fragments is composed of anorthite and augite
grains, and black particles.*

Tschermak later stated that this meteorite was closely like that from Juvenas, but finer-
grained ; but it did not contain either the unknown silicate or pyrrhotite found in ‘hat.+

The specimens of this rock in the Harvard College Mineral Cabinet, resemble in
structure, on macroscopic examination, some diabases, but are of a much finer grain;
the general crystalline arrangement is the same.

Constantinople, Turkey.

The Constantinople meteorite was found by Tschermak to be an ash-gray, nearly
compact rock, composed of compact small fragments and fine radiating masses.

It was seen under the microscope to be composed of anorthite, pryoxene, pyrrhotite,
and chromite. Its microscopic structure agrees with the Stannern meteorite, as also does
its chemical composition.

* Min. Mitth., 1872, pp. 83-85. + Die mikros. Besch. der Meteoriten, 1883, i. 7.
~ Min. Mitth., 1872, pp. 85-87.

196 BASALT.

Jonzac, France.

The Jonzac meteorite is stated by Tschermak to have a fragmental structure, and
under the microscope is seen to be composed of lamelle of anorthite and columns of
augite. ‘lhe former has distinct bounding lines, while those of the augite are indistinct.
Lying between these crystals are small grains of the same minerals, filling the interspaces.
The anorthite is often cloudy from minute brown glass inclusions, and black grains arran-
ged parallel to the length of the crystal. The augite when clear has a greenish-brown
color, but it is often traversed by fissures, and rich in violet-blue, and brown, dust-like
particles, — chromite and pyrrhotite, possibly. The meteorite further contains pyrrhotite,
chromite, and iron.*

Petersburg, Lincoln Co., Tennessee.

The Petersburg meteorite is, according to Professor Shepard, of an “ash-gray color, with
a slight intermixture of pearl-gray, for the basis of the stone.” Porphyritically inclosed
in this groundinass are crystals and grains, which, from Shepard’s and Smith’s descrip-
tions, appear to be augite, plagioclase, and olivine. Some chromite and a garnet were
reported.f

Tschermak states that it is composed of anorthite, augite, and a yellowish silicate like
olivine.

The specimen in the Harvard College Cabinet macroscopically closely resembles the
Stannern meteorite.

Frankfort, Franklin Co., Alabama.

The Frankfort meteoric stone, according to Professor Brush, presented a gray ground-
mass with a pseudo-porphyritic structure, having black, green, white, and dark-gray spots
on it. Professor Brush determined the minerals as follows: the black one as chromite ;
the white as anorthite or chladnite (it is more probably feldspar than enstatite); the
green and gray as olivine (probably some augite also); and, in addition, a little nickel-
iferous iron, and pyrrhotite (troilite). This rock seems to be a basalt, to which its chemical
analysis refers it.§

Variety. — Gabbro.

Lwotolaks, Finland, Russia.

The meteorite from Luotolaks was found by Professor F. J. Wiik to be composed of
metallic iron; colorless anorthite; grayish-violet augite, inclosing long black microlites ; and
olivine, with little irregular cavities.|| He refers this meteorite to the basic eruptives.

Tschermak describes it as a tufaceous mass, which, in an earthy, friable, gray ground-
mass, holds splinters and grains of greenish, whitish, and dark color, as well as basaltic
(eucritic) fragments. He looks upon it as a volcanic ash. It contains, according to him,
anorthite holding little rounded glass inclusions; augite in brownish grains, with black
needle-formed inclusions; bronzite in very pale, greenish splinters, almost free from
inclusions ; olivine, chromite, pyrrhotite, and iron. 4]

* Min. Mitth., 1874, pp. 168, 169.

t+ Am. Jour. Sci., 1857 (2), xxiv. 184-137; Safford’s Geol. Reconn. of Tenn., 1856, pp. 125-127;
Geol. of Tenn., 1869, pp. 520, 521.

{ Min. Mitth., 1874, p. 170. § Am. Jour. Sci., 1869 (2), xlviii. 240-244.

|| Neues Jahr. Min., 1883, i. 8384; Ofversigt Finska Vet. Soc. Forh., 1882, xxiv. 63, 64.

€’ Die mikros. Besch. der Meteoriten, 1883, i. 7, 8.

THE METEORIC BASALTS. — GABBRO. 197

Missing, Bavaria.

The Massing meteorite is said by Professor C. W. Giimbel to be of a grayish-white
color in the interior, and to contain olivine in yellowish-green to clear-green, round, and
irregular grains, which sometimes show parallel fissuring.

He refers to feldspar a white, glassy, transparent, or dusty, cloudy, strongly-fissured,
rarely parallel-striped, evidently cleavable mineral. A wine-yellow to grayish-green, or
pale, reddish-brown glassy mineral is regarded as belonging to the augite group. It is not
dichroic, and is sometimes in long fibrous forms, and filled with numerous little bubbles.
Besides these, chromite, pyrrhotite, and iron were found. All these are cemented by a fine,
dust-like, granular, gray groundmass.* ,

Tschermak states that the Massing meteorite is similar in character to that from
Luotolaks, and contains anorthite, brownish, yellowish, and greenish-gray augite, bronzite,
chromite, pyrrhotite, and greenish splinters of olivine.t

Juvenas, Ardéche, Franee.

According’ to Rammelsberg, this meteorite is composed of anorthite, augite, chromite,
pyrrhotite, and possibly a little apatite, and titanite. It is similar to the Stannern form,
but coarser.f ose states that the nickeliferous iron is in a very minute quantity.§

The specimen in the Harvard College Cabinet looks macroscopically more like a
gabbro than the Stannern form, and it has a coarser texture.

This meteorite is figured by Fouque and Lévy, as being composed of anorthite, enstatite,
augite, and magnetite,|| and having a structure like some norites.

Tschermak states that it shows a crystalline to tufaceous structure under the micro-
scope, and is evidently of a brecciated character.

The anorthite in it is well-crystallized, part being water-clear, and part cloudy and
white, owing to rounded and fine needle-formed glass and other inclusions arranged
parallel to the bounding planes. The crystals often show in polarized light a compli-
cated twinning. Some of the inclusions hold bubbles and black grains. Rarely gas-
pores were seen.

The augite is brownish-black, owing to numerous black, and rarely brown, needle-
shaped and rounded inclusions. The brownish rounded inclusions are regarded as glass.
Some irregular grains of a pale-brown color are referred to diallage. A pale-brownish
silicate, sometimes having a fine lamellar structure was observed. Small amounts of
pyrrhotite and nickeliferous iron were also found by Tschermak.{

Shergotly, India.

A description of the microscopic characters of the Shergotty meteorite was given by
Professor Tschermak in 1872. The stone is granular, with the grains nearly of the
same size, and on the fractured surface it has a yellowish-gray color. In the thin section
five different minerals were recognized: 1, a brownish cleavable mineral similar to augite ;
2, a glass-clear isotropic mineral; 3, a yellowish, anisotropic mineral, very rare; 4, an
opaque black mineral — magnetite; 5, an opaque metallic yellow mineral, extremely rare.

* Sitz. Miinchen Akad., 1878, viii. 82-40. + Die mikros. Besch. der Meteoriten, 1883, i. 8.
¢ Ann. Physik Chemie, 1848, Ixxiii. 585-590 ; 1851, Ixxxiii. 591-593.
§ Abh. Berlin. Akad. 1863, pp. 126-184. || Min. Microg., 1879, plate LV. figure 1.

Die mikros. Besch. der Meteoriten, 1883, i. 6, 7; Min. Mitth., 1874, pp. 169, 170.

198 BASALT.

Of these the first formed the principal portion of the stone. It is traversed by number-
less fine fissures parallel to the cleavage. It is of a grayish-brown color, anisotropic, and
shows only feeble pleochroism. In cleavage and optical characters it is similar to diopside.
It is quite commonly twinned. While the mineral is regarded as augitic, Tschermak
thinks, from its chemical composition, that it is different from any terrestrial compound.

The second mineral possesses conchoidal fracture, and is inclosed in and subordinate to
the augitic mineral. Its form is that of a distorted cube. The hardness is a little less
than that of orthoclase, while its chemical composition is similar to that of labradorite.
Tschermak proposed for it the name maskelynite. The third mineral is intergrown with
the first, is traversed by parallel fissures, and is orthorhombic in crystallization. It is
referred to bronzite (enstatite).

The fourth mineral lies between the other minerals or is inclosed in the maskelynite.
It is pitch-black, semi-metallic, with a conchoidal fracture, black streak, and is strongly
magnetic. This mineral is regarded as magnetite. The fifth mineral is referred to
pyrrhotite. The section as figured by Tschermak resembles some of the gabbros.*

Later, Tschermak speaks of the brownish mineral as augite, and of the maskelynite as
a glassy state of plagioclase. T

Péwlowka, Sardtow, Russia.

This meteorite has been described by Mr. Th. Tschernyschow, as composed of a
brittle ash-gray groundmass, formed by a crystalline-granular mixture of feldspar, ensta-
tite, and diallage, holding porphyritic grains of these minerals and olivine. The feldspar
shows polysynthetic twinning, and is referred to anorthite. It is in irregular and ledge-
formed masses. The diallage is either colorless or brownish-gray, with cleavage planes,
and an absence of dichroism. The enstatite shows a fine parallel cleavage striation, and
holds chromite (?) in black grains arranged parallel to the cleavage lines. Sometimes the
feldspar predominates, and at others the pyroxenes; and of the latter, sometimes the
enstatite and sometimes the diallage is most abundant.

The olivine occurs in clear-green grains. Besides the above minerals, there were seen
also nickeliferous iron, pyrrhotite, and chromite, in grains and crystals. It also contains
the cloudy-gray friction-product of Tschermak, but which the present writer regards as a
base. £

This meteorite is placed, from the above description, with the basaltic meteorites,
although the entire correctness of the microscopic diagnosis is perhaps questionable.

i

Le Teilleul, Manche, France.

This meteorite, according to Daubrée, is composed of plagioclase (anorthite), enstatite,
diallage, olivine, iron, pyrrhotite, and chromite.

The feldspar is colorless, twinned, and presents similar inclusions to those found in the
feldspar of gabbro. On chemical tests the feldspar is referred to anorthite. The enstatite
shows two cleavages, is of a pale-greenish color, and contains opaque inclusions. The
diallage is of a darker color than the enstatite, and contains inclusions of oxide of iron or
troilite, as well as other forms similar to those common in diallage, and arranged parallel
to one another. The olivine is colorless. §

* Sitz. Wien. Akad., 1872, Ixv. (1), 122-185; Min. Mitth., 1872, pp. 87-95.

+ Die mikros. Besch. der Meteoriten, 1883, i. 7.

} Zeit. Deut. geol. Gesells., 1883, xxxv. 190-192.

§ Comptes Rendus, 1879, lxxxviii. 544-547; Neues Jahr. Min., 1879, pp. 905, 906.

=.

THE METEORIC BASALTS. — GABBRO. 199

Bishopville, South Carolina.

The meteorite which fell at Bishopville, South Carolina, March, 1843, has been regarded
as an interesting and peculiar one. Professor C. U. Shepard, in 1846,* described from it,
under the name of Chladnite, a mineral which he regarded as a ter-silicate of magnesia,
and as forming over two-thirds of the stone. The color is snow-white, rarely tinged with
gray. Lustre pearly to vitreous, translucent, H. 6—-6.5. Sp. Gr. 3.116. Fuses without
difficulty before the blowpipe to a white enamel. He further describes as apatoid, small,
yellow, semi-transparent grains having a hardness of 5.5, and very rare. A third mineral,
which he names ‘éodolite, is of a pale, smalt-blue color, vitreous lustre, and brittle. Hard-
ness 5.5-6. Fuses easily with boiling into a blebby, colorless glass. The iodolite was
found only in a small quantity.

Later, Shepard gave a fuller account of this stone, holding that it contained, chladnite
90 per cent, anorthite 6 per cent, nickeliferous iron 2 per cent, and 2 per cent of mag-
netic pyrites, schreibersite, sulphur, iodolite, and apatoid. f

The stone was next investigated by W. Sartorius von Waltershausen. He described
the principal mass as a white siliceous mineral, forming a finely crystalline mass, with
here and there little points showing metallic lustre, also grains of magnetite and brown
oxide of iron. The hardness of the white mineral is given as 6, and the specific gravity
as 3.039. His results indicated that the siliceous portion of the meteorite was composed
of 95.011 per cent of chladnite, and 4.985 per cent of labradorite. The former he found
to be monoclinic, and related to wollastonite in specific gravity, color, texture, hardness,
and crystalline form.¢ Later, Professor J. Lawrence Smith stated that, from some of his
investigations, “chladnite is likely to prove a pyroxene ;” § and subsequently published a
further discussion, in which he said of chladnite: “It is identical in composition with
Enstatite of Kenngott.” || Earlier than Smith’s last paper, some investigations were
made upon this meteorite by Professors Carl Rammelsberg and Gustav Rose. The
former held that the yellowish-brown and bluish-gray particles (the apatoid and iodolite
of Shepard) arose from the oxidation of the nickeliferous iron or the alteration of the
pyrrhotite.

Rose’s examination showed that the chladnite fused before the blowpipe only on the
the edges to a white enamel.4]/ Rammelsberg, in the continuation of his work, further
declared that no feldspar was to be found in the stone.** Through the courtesy of Mr.
John Cummings and Professor A. Hyatt, the Curator of the Boston Society of Natural
History, I have been permitted to make a microscopic examination of a small portion of
this meteorite now deposited in the collection of that society.

The portion examined is a grayish-white mass, resembling, as Shepard remarked,
a grayish-white granite (albitic), with brown and black spots.

Under the microscope it is seen to be composed of an entirely crystalline mass of
enstatite, augite, feldspar, olivine, pyrrhotite, and iron.

The structure is essentially granitic, and it appears to belong to the gabbro (norite)
variety of basalt.

The enstatite is clear and transparent. It shows a longitudinal cleavage parallel to the
line of extinction, and in some specimens this is crossed by a cleavage at right angles. It

* Am. Jour. Sci., 1846 (2), ii. 380, 381. + Ibid. 1848 (2), vi. 411-414.
~ Amn. Chem. Pharm., 1851, Ixxix. 369-374. § Am. Jour. Sci., 1855 (2), xix. 163.
|| Ibid. 1864, xxxviil. 225, 226. q Abh. Berlin. Akad. 1863, pp. 117-122.

#* Thid. 1870, pp. 121-123.

200 BASALT.

also has a cleavage which is often well marked, and divides the mineral into rhombic
forms, with angles, as approximately determined by several measurements, of 73° and 107°.
The principal cleavage is parallel to the longer diagonal of these rhombs. It is this
rhombic cleavage, probably, which has led observers to believe that chladnite crystallized
in the monoclinic and triclinic systems.

The enstatite is found to contain many glass inclusions with polyhedral outlines, the
planes being presumably, as usual in such cases, the planes of the inclosing mineral. While
many of these inclusions are arranged in the enstatite parallel to the cleavage planes,
others are placed at every angle with those planes. The glass inclusions carry bubbles,
microlites, and rounded lenticular forms. The latter are frequently at the end of the
inclusion, and in some cases, show the cherry-brown color of some chromite. This mate-
rial, besides forming inclusions in the glass, is in lenticular and irregular rounded grains
in the enstatite itself. It sometimes extends in a series of grains across the entire enstatite
mass, and at others is in isolated forms. These inclusions, microscopically, are seen to be
composed of a centre of nickeliferous iron or pyrrhotite, surrounded by a band of dark
material, — chromite or magnetite, possibly. These ferruginous materials are in many
cases surrounded by a yellowish-brown staining of iron, which sometimes extends over
considerable of the mass and along the fissures. Numerous vacuum or vapor cavities were
observed, which were arranged in one plane of the enstatite. The inclusions are seen to
be crossed and cut by the cleavage and fissure planes of the enstatite, showing that they
were of prior origin to the fissures.

The feldspar stands next in abundance to the enstatite, and is in irregular masses held
in its interspaces. It is water-clear, and almost invisible by common light. Much of it
is seen to be plagioclastic, but the twinning bands are so exceedingly fine, and the polar-
ization colors so bright, it does not, as a rule, show well this character, except with high
powers, and when the mineral is near the point of extinction.

The feldspars contain numerous yellowish-brown, dark, and almost colorless inclusions,
which are sometimes irregularly scattered, but more commonly are arranged in bands,
similar to those of the fluid inclusions in quartz. These glass inclusions are of various
dimensions, and many contain a small bubble. Some microlites were also seen.

In the feldspar at one end of a section, the enstatite was found in minute crystals ex-
tending outward from a centre, forming stellate or rosette-like forms. The structure is like
that observed in terrestrial rocks, in minerals formed from alteration or solution. This
apparently might have been produced in this case, either by the rapid crystallization of
enstatite material in a liquid feldspathic mass, or by secondary alteration through water-
action on the rock itself’ The absence of any other signs of alteration, except of the
ferruginous materials, seems to negative the latter supposition. The ferruginous alteration
can probably be accounted for by the absorption of moisture by this friable fissured stone
since it reached the earth.

The bands of inclusions were seen in several instances to extend from the feldspar
through the enstatite, and in one case, to pass into another feldspar on the opposite side.
This indicates that the cause of these inclusions was a general one for the rock-mass, and
not limited to any one mineral. Enstatite was found in a few cases inclosed in the
feldspar.

The monoclinic pyroxene or augite is less abundant, and its determination less sure
than is the case with the enstatite and feldspar. It is crossed by fissures in a very irreg-
ular manner, but shows in some cases the approximately right-angled cleavage of augite.
Its optical characters appear to be those of that mineral, but its polarization is more bril-

.

THE METEORIC BASALTS. — GABBRO. 201

liant than terrestrial augite, and resembles olivine. All the transparent minerals of the
section are clearer, and lighter-colored than their mundane representatives, and hence tend
to show in polarized light clearer and more brilliant colors. The augite is not, however,
quite so water-clear as the enstatite, but has a very faint tinge of yellowish-green. The
ferruginous inclusions are the same in this as in the enstatite.

The determination of the olivine is more doubtful, since it is seen only in small irreg-
ular-grains and masses, which hold the same relation to the other minerals that the olivine
of terrestrial gabbros usually does to its associated minerals. From this, and the fact that
it optically has the characters of olivine, it is here assigned to that species.

From the description of the mineral constituents of this meteorite, it would seem that,
regarding the presence of the feldspar, Messrs. Shepard and Waltershausen were correct,
while Rammelsberg was not. It shows the inability of the ablest mineralogical chemists
to draw correct conclusions regarding the mineral constituents even of an unaltered rock.
The trouble appears to reside in the instrument used —a defect in the method.

Chladnite ought no longer to be regarded as enstatite of the purest kind, as stated
in most mineralogies, but rather as a mineral aggregate of which enstatite, feldspar,
and augite are the principal constituents. While these observations gave an approximate
solution of the Bishopville meteorite puzzle of twenty-seven years standing, it would
be well if some one having larger amounts of this meteorite could make a chemical
analysis of it as a whole, and also analyze the minerals by the modern microscopic,
specific-gravity, chemical method.*

This stone, from the above observations, is, in its mineralogical composition, structure,
bubble-bearing glass inclusions, and microlites, like a terrestrial eruptive rock, and it is
presumable that it had a similar origin.

There are many who hold that the terrestrial eruptives are produced by the aqueo-
igneous solution of chemical precipitates from the primeval ocean or thermal springs, or
from sediments buried under the ruins of the earth’s crust. Would it not, then, be in
order for these scientists to explain the formation of this meteorite in the same way ?
Now if this body was thrown from the sun or a similar globe, by eruptive agencies,
would it not then be proper for these writers to speculate how this sun commenced
with a cold, inert surface, and a solid interior; and how, later, by its being blanketed
by its own detritus, it had been raised to its present intensely heated condition ?—
a speculation which is in entire accord with methods formerly advocated by ardent
Wernerians to account for the heated condition of the earth.

Since the publication of the preceding description of this meteorite, Tschermak
has published independently another description. He recognized the presence of
enstatite, plagioclase, and pyrrhotite.}

Manegaum, India.

The Manegaum meteorite was described by Maskelyne in 1863, as composed of a
probable olivine and an opaque white or yellowish-white mineral. The latter occurs
as a flocculent network, in round spherules, in fragments, and along the lamin of the
erystals of other minerals. Some pyrrhotite and chromite (?) were observed. ¢

In 1870, Maskelyne determined the supposed olivine to be enstatite, to which he

* Am. Jour. Sci., 1883 (3), xxvi. 32-36, 248.
+ Die mikros. Besch. der Meteoriten, 18838, i. 9, 10; Sitz. Wien. Akad., 1883, Ixxxviii. (1), 363-365.
t Phil. Mag., 1863 (4), xxvi. 135-139.

26

2()2 BASALT.

also referred the opaque flocculent white mineral. Minute amounts of iron were
found. The analysis and composition as given are not satisfactory, and it is thought
that a more extended microscopic examination would throw some light upon the
subject. This, like the Shergotty meteorite, is probably closely like the gabbros in
structure.*

Busti, India.

According to Tschermak, this is composed of crystals and fragments lying in a fine-
erained, splintery groundmass, all composed of diopside, enstatite, plagioclase, nickel-
iferous iron, oldhamite, and osbornite.

The diopside predominates, and has a gray to violet color, and contains rounded
and needle-shaped crystals arranged parallel to the fibrous cleavage. These inclusions
are the cause of the violet color.

The enstatite is in colorless splinters, and in gray cloudy forms replete with inclusions.
These often show a polyhedral contour, and are filled with a pale-brownish glass, bear-
ing bubbles. The plagioclase occurs only sparingly, and is colorless and nearly free
from inclusions. The oldhamite only appears in a portion of the rock in rounded
erains having a cubic cleavage; the osbornite in octahedrons in the nickel-iron,
which occurs only sparingly.t

Shalka, India.

Tschermak describes this meteorite as composed of a clear-gray, somewhat friable
mass, With inclusions of larger, greenish-gray, bronzite grains, and blackish chromites.
Under the microscope the larger bronzites are seen to lie in a groundmass of bronzite
fragments. This mineral often contains brown glass inclusions or opaque grains.
The last are arranged in the fissures in the bronzite, and are referred to pyrrhotite.
Some greenish-yellow grains, regarded by Rose as belonging to olivine, were placed
by Tschermak under bronzite, on account of their cleavage and action in acid. t

Lbbenbiihren, Westphaha.

The meteorite of Ibbenbiihren consists of a grayish-white, granular mass, in which
large and small grains of a light-yellowish-green mineral are unequally distributed.
From the chemical analysis and physical character of this mineral, Von Rath referred
it to bronzite, and to the same mineral he assigned the groundmass, regarding the
entire meteorite as composed of bronzite (diallage). §

According to Tschermak,|| the bronzite forms the principal portion of the stone,
and occurs in irregular grains of varying size. Some thin laminz were referred to
augite, and some little colorless grains filling the interspaces between the bronzite
grains were looked upon as plagioclase, or possibly tridymite. The inclusions are in
part reddish-brown glass, and in part opaque grains referred to chromite and iron. |

Greenland.

On account of its interest in connection with the occurrence of metallic iron in
basalts, a description of the iron-bearing basalt of Greenland is placed here in con-
nection with these basaltic meteorites.

* Phil. Trans., 1870, pp. 211-213. + Die mikros. Besch. der Meteoriten, 1883, i. 9.
{ Die mikros. Besch. der Meteoriten, 1883, i. 10. § Monats. Berlin. Akad., 1872, pp. 27-36.
|| Die mikros. Besch. der Meteoriten, 1883, i. 10.

THE GREENLAND BASALT. 203

The descriptions are in part taken from the writings of others, in part from sections
belonging to the Whitney Lithological Collection, and in part from sections very kindly
sent me by Professor J. Lawrence Smith on his own motion. These sections were
the ones which had been used in the preparation of his “Mémoire sur le fer natif du
Groenland, et sur la dolérite qui le renferme.’ *

One section, from Assuk, is composed of a gray groundmass, sprinkled with little
rounded spots of a darker gray color, and porphyritically holding grains of feldspar,
magnetite, and iron. The groundmass is composed of predominating minute augite
crystals, in a matrix of clear glass, containing minute feldspars and elongated trichites,
similar to those seen in quartz and iron ores. The structural appearance is that of a
mass out of which the pyroxene material had mainly crystallized, leaving a colorless
glass, which in part had yielded feldspar crystals before congelation. The feldspar
crystals are, so far as observed, all plagioclase. A greenish secondary product not only
occurs in association with the iron ores, but also in detached masses and bordering
fissures. Its color varies from a bright grass-green to a dull dirty-green. Occasionally
it is found to be isotropic, but oftener to exhibit aggregate polarization, and it may be
classed under that convenient name for these variable secondary products — viridite.
Little, rounded pale-pinkish isotropic grains occur. They are apparently foreign, and
are considered to be garnet. A few large porphyritic crystals of feldspar were seen,
which are filled in the interior portion with inclusions — microlites, magnetite, glass, ete.

The darker rounded masses observed in the section by the naked eye appear to
be of the same composition as the rest of the section, but with smaller crystals on
the whole, and with much finely-disseminated magnetite dust.

This rock has been described by Steenstrup { and Tornebohm, ¢ the former giving
a plate. Tornebohm regards the augitic mineral as enstatite, stating that it is optically
orthorhombic. In the section above described, the mineral is clearly monoclinic in its
optical characters, although it is perfectly possible that a rhombic pyroxene exists in
connection with the augite. The iron ores occur in small rounded and irregular
grains, partly native iron, partly magnetite and pyrrhotite. Usually a border of mag-
netite surrounds the metallic iron.

The Ovifak basalt (dolerite) is described by Tornebohm as composed of plagioclase,
augite, olivine, titaniferous iron, and a glassy interstitial material. The augite is in
pale, clear-brown, almost colorless, irregular particles between the feldspars. Olivine is
found sparingly in little grains, which as a rule are fresh and unchanged. Bubble-bearing
glass inclusions occur in the augite, olivine, and feldspar. The titaniferous iron is in
elongated staff-like masses. The interstitial glassy masses appear only sparingly in
the angles, and as wedges between the above mentioned minerals. When fresh it
is of a fawn color and usually filled with microlites or dark spheres. Besides these
minerals there occur metallic iron, pyrrhotite, and a silicate rich in iron. This last
varies from a green to a dark-brown color. The metallic iron appears, in part, in
silver-white grains, often associated with magnetite, and sometimes with schreiber-
site. The pyrrhotite has in reflected light a yellowish-gray color, and is in larger
and smaller grains associated with the other iron ores.

The silicate rich in iron falls into two divisions: one a beautiful grass-green
color, isotropic, and allied to chloropheite; the other a rusty-brown mass, sometimes
isotropic, and sometimes anisotropic, and here referred to hisingerite. §

* Ann. Chimie Phys., 1879 (5), xvi. 452-505. + Min. Mag., 1877, i, 143-148.
+ Bihang Kongl. Svenska Vetens. Akad. Handl., 1878, v., No. 10, pp. 18-21. § Ibid. pp. 1-22.

204 BASALT.

Only a few additions will be made to Tornebohm’s description from Dr. Smith’s
sections. The Ovifak sections have the usual structure of a diabase or dolerite ;
divergent crystals of plagioclase lying in and dissecting the irregular masses of pale
brown augite, iron ores, olivine, ete, which form the interstitial material between
the feldspars. The minerals are the same in general characters as those described
by Toérnebohm. In some cases the glass shows the globulitic structure common in
basaltic glass.

This basalt is more or less altered in the different sections, presenting many of
the characters of a diabase, and the green and brown silicates, replacing glass, olivine,
iron, ete.

Much graphite occurs in scaly aggregations of a black color with a lustrous reflec-
tion in reflected light, and associated with a brown and violet-red mineral which has
been referred by Tornebohm to spinel; but in the section examined by myself, part
has been found not to be isotropic, and has been considered by Dr. Smith to be corundum
(l. c. pp. 484486).

The reader is further referred to the before-mentioned full and excellent descrip-
tion of Tdérnebohm for a more extended study of this basaltic rock; as well as to the
writings of Tschermak.*

One section in the Lithological Collection shows a grayish-white groundmass filled
by rounded grayish-black masses. These dark spots are seen under the microscope
to be composed of plagioclastic feldspars, filled with an irregular network of granules
and masses of magnetic and native iron, the whole closely resembling the structure
of some portions of the Estherville meteorite (Plate III. fig. 6). The interstitial
portions between the rounded feldspathic-iron masses are filled by the normal basalt,
composed of ledge-formed plagioclase crystals, cutting a mass of yellowish-gray augite
grains, violet-brown globulitic glass, magnetite, and the viriditic products.

In some parts of the section the large plagioclase crystals are free from the iron,
and contain glass inclusions and minute pores. A little olivine, some large augites,
and yellowish-brown hisingerite (?) was seen in this portion of the section which has
a doleritic or diabasic structure, while other portions have that belonging distinctively
to the fine-grained basalts.

Another section from the same hand-specimen shows in part of its mass the same
basaltic structure as the preceding, of plagioclase, augite, magnetite, base, and secondary
materials ; but the remaining portion is a coarsely crystallized mass of olivine, plagioclase,
augite, iron, and magnetite. The olivines are in irregularly rounded grains, traversed by
fissures. They are sometimes clear, and at others stained yellowish, and are altered along
the fissures to a yellowish and brownish serpentine. The augites are pale-yellowish, and
with the olivines contain bubble-bearing glass inclusions, iron, magnetite, etc. The usual
secondary products occur to some extent. Some of Professor Smith’s sections have parts
similar to these last two sections, except the coarsely crystalline olivine-bearing portion ;
but his are more altered, and contain a larger amount of secondary products.

Two of Dr. Smith’s sections from Pfaff-Oberg are seen to be composed of lath-shaped,
divergent plagioclase crystals, lying in a granular groundmass of augite, olivine, ete., with
various secondary products. In one section is a large grain of iron, of an irregular cel-
lular structure, and holding in its cells pyrrhotite, olivine, feldspar, etc.

The preceding descriptions show that the coarse and fine crystalline structure

* Min. Mitth., 1874, pp. 171-174.

THE METEORIC BASALTS. — THEIR STRUCTURE. 205

is not dependent on age, or on any especial depth of the mass at the time of the
erystallization ; also that diabase, dolerite, and basalt are not distinct in age, but
merely relative terms, indicating coarseness in crystalline texture and extent of alter-
ation; for sections of these Greenland basalts could be pronounced, by taking certain
portions of them, to be basalt, dolerite, diabase, and possibly gabbro.

Since this work is published in parts, it has seemed best to place in the
first portion, so far as possible, all relating to meteorites, and to end the
first part before taking up the terrestrial basalts.

Owing to the views of Professor Tschermak, that nearly all the mete-
_orites are tufas, the preceding descriptions are affected by that view,
since most of the microscopic study has been done by him. It appears
to the writer that the basaltic meteorites display in general the structure
of friable, rapidly crystallized basalts, apparently quickly cooled, and never
bound together by the subsequent products of alteration; few if any of
them being fragmental. From this point of view, their general structure
in the basaltic variety would be described as divergent, lath-shaped plagio-
clase feldspars, lying in a groundmass of pyroxene (augite, diallage, and
enstatite) grains, with some base, feldspar, and iron ores.

So far as the gabbro type of the meteorites is concerned, the description
of the Bishopville form would serve as a general statement of their collective
characters, varied by the predominance of any one of the mineral constitu-
ents. The Bishopville form is certainly not fragmental in structure, and it
does not seem to the writer that the other meteoric gabbros are so ; hence they
may be defined as crystalline-granular masses of feldspar, pyroxene (au-
gite, diallage, and enstatite), with various ores of iron, and with or without
olivine. In these, however, certain of the constituents may predominate,
to the partial or complete exclusion of others. This is no more than the
observed variation occurring in different portions of the same terrestrial
rock.

Although mineralogically the basaltic meteorites could be divided into
many varieties, the same as the perid@otites have been, it seems to the
writer unnecessary. The terrestrial basalts were divided in the first place
chiefly on structural characters and differences in external appearance,
and the recently introduced terms, norite, olivine-gubbro, and olivine-norile,
appear to be superfluous and unnecessary, although consistent with the
common mineralogical nomenclature of rocks, since structurally all can
readily be classed under the variety gabbro.

206 BASALT.

Many changes in the arrangement of the meteorites may hereafter be
made by the writer, if ever opportunity should be afforded for an ex-
tended microscopic study of them. At present he has tried to arrange
them as best he could with the means at his command.

Although all the chemical analyses found of the basaltic meteorites have
been arranged in a table, they are too few and too imperfect for any satisfac-
tory discussion.

Section Il. — The Pseudo-Meteorites.

A NUMBER of supposed meteorites have been described, which so far
as their general characters and chemical composition show, belong to the
species trachyte and rhyolite. For these the meteoric origin has been
denied in every case, and perhaps the Igast stone is the only one which
has any claims to be considered even of doubtful meteoric origin.

Waterville, Maine.

This pseudo-meteorite has been studied by the present writer. It is in the form
of a small triangular cinder-like mass, cellular, laminated, and on the fresh fracture,
of an ash-gray color. The laminated appearance is produced by a series of flattened
cells surrounded by a black vitreous mass.

The original surfaces are coated with a gray, red-brown, and bluish-black crust formed
by fusion.

It was claimed that this stone was picked up shortly after falling, hence it became
necessary to examine its characters to see how long it might have been exposed to
atmospheric action. The portion of the fused crust which lay uppermost on the
ground is seen under a lens to have been worn and polished the same as siliceous
rocks are when long exposed to rain; while the remaining parts are found to be
coated to some extent by earthy material, the same as rocks are when lying in a dry,
sandy soil. Its cavities contain in places a fine, brown, matted mass, formed by the
fibres of growing plants, and under the microscope their vegetable character can
readily be distinguished.

The specimen, then, when picked up by Captain Crosby, could not have been a
newly detached mass, but had been for a lone while partially buried in the soil,
and of course could not have been a portion of the meteor seen shortly before the
specimen was found. It remains, then, to consider the very improbable supposition —
is it a fragment of a meteorite which fell at some former period? Microscopically
it is seen to be a cellular, glassy mass, which has beeun to devitrify, and presents
the appearance of a slag-like body which has been long exposed to the action of
atmospheric agencies. The sections were cut across the lamination, and showed a
fluidal structure parallel to it. A few quartz grains which were cracked and fis-
sured were seen. Near the fissures numerous ferruginous globulites had been de-
veloped, and the quartz showed evident signs of having been exposed to strong heat.

ao.

se

™

Lee

THE PSEUDO-METEORITES. 207

Adjacent to the flattened, as well as some other cells, is 2 black and brown ferruginous
material.

The sections show not the slightest characters belonging to any meteorite that has
yet been examined microscopically, either by myself or by others, so far as can be
ascertained by their published descriptions. It is apparently a slag.*

Richland, South Carolina.

This so-called meteoric stone is reported to have fallen in 1846. This when cut
was, according to Professor C. U. Shepard, of a “uniform yellowish-white color, much
resembling that of common fire-brick. A few minute grains of transparent quartz
are visible throughout its substance, which is otherwise perfectly homogeneous. It
is close-grained and rather firm in texture.” This description, and the chemical
analysis given by Shepard, coupled with one by Rammelsberg denotes a structure
similar to that of the rhyolites, for such a description could be given of many of
them.t

Rammelsberg regards the Richland stone as a clay, or possibly a fragment of a
brick. A microscopic examination by a competent lithologist ought to readily deter-
mine the character and origin of this stone.

Igast, Livoma, Russia.

This stone is looked upon by Professors Grewingk and Schmidt as an authentic
meteorite, and they made a chemical analysis of it, showing that it contained a little
over eighty per cent of silica.

Professor F. J. Wiik also accepts it as a meteorite, and states that in the thin sections it
shows a fine-granular, dark-colored groundmass, the dark color owing to little magnetite,
porphyritically inclosing larger crystals of quartz, orthoclase, and oligoclase. The quartz
contains fluid cavities with movable bubbles, and the plagioclase shows fine parallel
cleavage lines as well as the usual twinning. By a high magnifying power is shown
in the groundmass little colorless elongated crystals, and minute crystalline grains.

Professor E. Cohen regards it as a doubtful meteorite. §

Lasaulx describes this as a stone rich in a basaltic glass base, in which lie inclosed
numerous grains of plagioclase, microcline, and quartz. The groundmass is composed
largely of a brown glass, rich in magnetite grains, some showing quadratic sections,
and others a dendritic structure. The groundmass further contains numerous little
spear-. or ledge-shaped plagioclase crystals, and yellowish-green irregular grains of
augite—all showing fluidal structure. The entire groundmass appears as the product
of the fusion of quartz and feldspar, the rudiments of which are now inclosed, with
the later crystallization of plagioclase and augite out of the molten magma.

Many of the crystals show distinct rounding through the fusion of their edges.
The larger plagioclase fragments are mostly ragged, slashed, and irregular, while the
minute quartz grains are commonly perfect, and smoothly rounded. The plagioclase
crystals are generally clear and free from inclusions; only an external rim of disjointed
glass inclusions lies about them. The brown glass penetrates into the fissure in the

* Am. Jour. Sci., 1883 (3), xxvi. 36-38. + Proc. Am. Assoc. Adv. Sci., 1850, iii. 147, 148.

¢ Archiv Nat. Liv-, Ehst-, Kurlands, 1864, iii. 421-554.

§ Neues Jahr. Min., 1883, i. 384; Finska Vet. Soc. Forh., 1882, xxiv. 63. Archiv Nat. Liv-, Ehst-, Kar-
lands, 1882, ix. 158.

208 BASALT.

crystals, and in general the rock appears similar in character to one produced by the
partial fusion of an inclosure of sandstone, granite, or some other rock, in basalt.
After further description, Lasaulx decides against its meteoric character, and appar-
ently justly.*
Waterloo, Seneca Co., New York.

The so-called meteorite of Waterloo, described by Shepard,t is considered by
Rammelsberg to be a clay. t

Concord, New Hampshire.

The meteoric stone of Concord, described by Professor B. Silliman, Jr., § is now
preserved in the collection at Yale College.

A macroscopic examination by the writer convinces him that it is a portion of the
consolidated scum or froth of some slag, and this opinion seems to be held by others. ||

It would be a matter of the greatest interest to prove the fall of
meteorites more acidic than the basaltic variety, and it is not impossible
that further microscopic studies will reveal that some already known are
of the andesitic type.

* Sitz. nieder. Gesell., Bonn, 1882, xxxix. 108-110. + Am. Jour. Sci., 1851 (2), xi. 39, 40.
+ Jour. Prakt. Chemie, 1862, Ixxxv. 87, 88. § Am. Jour. Sci., 1847 (2), iv. 353-356.
|| G. W. Hawes, Geol. of N. H., part iv., p. 24.

—

ee

EXPLANATION OF THE TABLES.

TABLE I.—Chromite and Picotite. pp. ii-v.

Tus table contains one hundred and twenty analyses of chromite and picotite, arranged in the
ascending order of the percentage of chromic oxide. Since the object of the table is to show the mutual
relations of the two minerals, and their variations, many of the analyses given of chromite are of the more
impure forms, — commercial ores (/).

TABLE II.— Siderolite. pp. vi-xv.

This table contains one hundred and ninety-three analyses of meteoric and terrestrial irons, arranged
in the descending order of their percentage of iron. The irons which are supposed to be meteorites, but
which have not been known to fall, have been marked by an interrogation point placed after the term
Meteorite. No variety names proper occur in this species; but for convenience the meteoric irons
known to have fallen, the supposed meteoric irons, and the terrestrial irons, are distinguished from one
another by terms placed in the “ Variety ” column.

When several analyses are given for the same locality, no attempt is made to arrange them beyond
this: the analysis first found in the search for the analyses is placed first, and the others follow in
the order in which they were seen; except in cases in which the analyses strikingly differed in value,
owing either to internal evidence or to the reputation for accuracy of the analyst; then the best is
placed first, but the order of the others still remains in the order in which they were found.

TABLE III.—Pallasite. pp. xvi, xvii.

This table contains twenty-four analyses of meteoric and terrestrial pallasites. The doubtful meteor-
ites are designated as in the preceding table, while the terrestrial forms are given their proper variety
name, — Cumberlandite. But few of these analyses are accurate exponents of the constitution of the
rock mass, the majority being rough approximations only. The analyses are arranged in ascending order
of the percentages of silica.

TABLE IV.—Peridotite. pp. xvili-xxxi.

This table contains two hundred and forty-four analyses of terrestrial and meteoric peridotites. In
the “ Variety” column is given the name of the variety so far as known, and when the specimen is a
meteorite it has been designated by an asterisk prefixed to the variety name. The meteorites whose
variety is not known are designated by the term Meteorite, and the terrestrial peridotites, whose variety
is also unknown, are given the names which the analysts have applied to them.

The analyses have been arranged in the order of the percentages of silica ; but when more than one
exists for the same locality, they have been arranged as stated for Table II.

The specific gravities in this and the other tables have been taken from any available source, when
the analyst has given none; but it has been found impracticable to designate the source from which
they were obtained, although many are from C. Rumler’s determinations, which with analyses are to be
found in the works and tables of Partsch, Buchner, Rammelsberg, and Roth, to which I am deeply
indebted.

Many analyses of meteoric forms have been made in such a manner that no determination of the
complete chemical constitution is possible, owing to the omission of necessary data for recalculation, and
all such have been omitted. Many others have been recalculated with more or less approximation to cor-
rectness, varying according to the data; matters in which the numerous analyses of Dr. J. Lawrence
Smith have been particularly unfortunate. The recalculations have mostly been made by the aid of
a four-place table of logarithms, and therefore partake of its imperfections.

TABLE V.— Part I. The Meteoric Basalts. pp. xxxii, xxxiii.

This part contains thirty-one analyses, arranged in order of their percentages of silica.
97

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ll ANALYSES OF CHROMITE AND PICOTITE.
TABLE I.— Analyses oi
= =

Name. Locality. Analyst. Publication.
Chromite. Kynouria, Greece. A. Christomanos. Berichte Chem. Gesell. Berlin, 1877, i. 843-350.
Picotite. Kosakover, Bohemia. F. Farsky. Verh. Geol. Reich., 1876, pp. 207, 208.
Picotite. Kosakover, Bohemia. " es ue os £ ie
Picotite. Hofheim, Bavaria. Hilger. Neues Jahr. Min., 1866, p. 399.
Picotite. L. Lherz, France. F. Sandberger. Neues Jahr. Min., 1866, p. 388.
Picotite. L. Lherz, France. A. Damour. Bull. Soe. Géol. France, 1862 (2), xix, 414.
Chromite. Near Athens, Greece. A. Christomanos. Berichte Chem. Gesell. Berlin, 1877, i. 848-350.
Chromite. Pirzus, Greece. . 4 * he s ss
Chromite. Alt-Orsowa, Hungary. Alfr. Hofmann. Neues Jahr. Min., 1878, p. 8738.
Chromite. Delos, Grecian Archipelago. A. Christomanos. Berichte Chem. Gesell. Berlin, 1877, i. 843-350.
Chromite. Seres, Macedonia. ee “s es os : % *4
Chromite. Gythion, Greece. oe 2 3 v3 ~ ss a es
Chromite. Cerigo, Ionian Isles. #2 - if us cs ss es tg
Chromite. Hungary. J. Clouet.* Ann. Chimie Phys., 1869 (4), xvi. 90-100.
Chromite. Mt. Hymettus, Greece. A. Christomanos. Berichte Chem. Gesell. Berlin, 1877, i. 848-350.
Chromite. Australia. J. Clouet. Ann. Chimie Phys., 1869 (4), xvi. 90-100.
Chromite. > Salamis, Greece. A. Christomanos. Berichte Chem. Gesell. Berlin, 1877, i. 848-350.
Chromite. Corinth, Greece. os db a G “ 4 si
Chromite. Vrysi, Greece. “ “ “ “ “ “ “ «“
Chromite. Vache Island, W. Indies. P. Berthier. Ann. Chimie Phys., 1821, xvii. 55-64.
Chromite. Var, France. J. Clouet. Ann. Chimie Phys., 1869 (4), xvi. 90-100.
Chromite. Loukissia, opp. Chalcis, Greece. A. Christomanos. Berichte Chem. Gesell. Berlin, 1877, i. 348-350.
Chromite. Loutraki, Greece. Rs fe
Chromite. Locris, Greece. “c “ “ “ “ “ “ “ec
Chromite. Perachora, Greece. ee ee se oe ee 5 st
Chromite. Peky, Greece. “ “ “ce “ “ “ce “ “c
Chromite. Bare Hills, Baltimore, Md. Henry Seybert. Am. Jour. Sci., 1822 (1), iv. 321-328,
Chromite. Alt-Orsowa, Hungary. Alfr. Hofmann. Neues Jahr. Min., 1875, p. 875.
Chromite. Christiania, Norway. J. Clouet. Ann. Chimie Phys., 1869 (4), xvi. 90-100.
Chromite. Shetland Isles. “ “ “ “ “ “ “

Chromite (Magnetic
Chrome Sand).

Chromite.
Chromite.
Chromite.
Chromite.
Chromite.
Chromite.
Chromite.
Chromite.
Chromite.
Chromite.
Chromite.
Chronite.
Chromite.
Chronite.
Chromite.
Chromite.
Chronite.
Chromite.
Chromite.
Chromite.
Chronite.
Chromite.

Chromite.
Chromite.
Chromite.

Chromite.
Chromite.
Chromite.
Chromite.
Chromite.
Chromite.
Chromite.
Chromite.
Chromite.
Chromite.
Chromite.
Chromite.
Chromite.

Chester, Penn.

Drontheim, Norway.
Volterra, ‘Tuscany.
California.

Cerasia, Eubea.
Haziskos, Greece.
Var, France.

Volo, Thessaly.
Troezene, Greece.
Epidaurus, Greece.
Nauplia, Greece.
Dryope, Greece.
Olympus, Thessaly.
Franklin, Macon Co., N. C.
Shetland Isles.

Volo, Thessaly.
Poros, Greece.
Baltimore, Maryland.
Baltimore, Maryland.
Haziskos, Greece.
Tinos, Grecian Archipelago.
Ural.

Australia.

Wilmington, Delaware.
Bolton, Canada.
Liitzelberg, Kaiserstuhl, Ba-
varia.
Limne, Eubeea.
Andros, Grecian Archipelago.
India.
Mourtia, Eubeea.
Alt- Orsowa, Hungary.
Ural.
Ekaterinburg, Russia.
Lake Memphramagog.
Haziskos, Greece.
Sagmata, Greece.
Ur al.
Salonica, Turkey.
Samiue, Grecian Archipelago.

T. H. Garrett.

J. Clouet.
C. Bechi.
J. Clouet.
A. Christomanos.

“ec “

L. N. Vauquelin.

A. Christomanos.
“ “ee

ce “e
“ce “
“c “
F. A. Genth.
J. Clouet.
A. Christomanos.
Hermann Abich.
J. Clouet.
A. Christomanos.
Schultz.
J. Clouet.
T. Sterry Hunt.
A. Knop.
A. Christomanos.
“ “cc
J. Clouet.
A. Christomanos.
J. Clouet.
J.Clouet.

T. Sterry Hunt.
A. Christomanos.
“

ey

A. Christomanos.
“ce

“es

Am. Jour. Sci., 1852 (2), xiv. 47.

Ann. Chimie Phys., 1869 (4), xvi. 90-100.

Am. Jour. Sci., 1852 (2), xiv. 62.

Ann. Chimie Phys., 1869 (4), xvi. 90-100.
Berichte Chem. Gesell. Berlin, 1877, re 843-350.

Jour. Mines, 1801, x. 521--524.
Berichte Chem. Gesell. Berlin, 1877, re 343-3 0.

“ “ce “c oe “ “oe
“cc « “ce “ “oe “
“ce “ ce “ “e “ee
“ce “ce “ “ “ “ce

Geol. of North Carolina, 1881, ii. 31.
Ann. Chimie Phys., 1869 (4), xvi. 90-100.
Berichte Chem. Gesell. Berlin, 1877, i, 843-850.

Ann. Physik Chemie, 1851, xxiii. 835-342.
Ann. Chimie Phys., 1869 (4), xvi 90-100.
Berichte Chem. Gesell. Berlin, 1877, i. 843-350.

Kokscharow’s Material Min. Russ., 1866, v. 163.

Rammelsberg’s Handbuch der Mineralchemie, 2d
ed., 1875, p. 142.

Ann. Chimie Phys., 1869 (4), xvi. 90-100.

Report Prog. Geol. Canada, 1847-48, p. 164.

Neues Jahr. Min., 1877, pp. 697-699.

Berichte Chem. Gesell. Berlin, 1877, a 848-350.

Ann. Chimie Phys., 1869 (4), xvi. 90-100.
Berichte Chem. Gesell. Berlin, 1877, i. 8343-850.
Ann. Chimie Phys., 1869 (4), xvi. 90-100.
Kokscharow’s Material Min. Russ., 1866, v. 164.
Ann. Chimie Phys., 1869 (4), xvi. 90-100. .
Report Prog. Geol. Canada, 1847-48, p. 164.
Berichte Chem. Gesell. Berlin, 1877, i. 1 343-350,

Kokscharow’s Material Min. Russ., 1866, v. 163.
Berichte Chem. Gesell. Berlin, 1877, i. 343-350.

* This and all others of Clouet’s analyses are stated to be the mean of a number of analyses.

;
é
a

ANALYSES OF CHROMITE AND PICOTITE. lil
ymite and Picotite.
en BLAS
Al,O3. MgO. Cr,0). Fe,0s. FeO. SiO, CaO. Miscellaneous. | Total.
|
30.17 iMag EMMA le Gale ea: se 2.30 26.01 13.26 CO,+H,0 = 4.45. ) 98.20
50.34 17.87 BAGO |e ee betas cs O27 Salen (crc seins Was shes SiTaoceet aa oases | 100.00
52.47 18.23 TUT els sear 21.42 LO ee al | ea Are oF a LEBER Te 3g 100.38
53.93 23.59 7.23 11.40 Seley. | WAC SSC ROPER Laer eh rotor rcerr ore 100.00
65.24 10.18 OUR) Yatersievaiete a 24.60 1) Sl Re a | mere Ee ay eee eee eB a 100.00
56.00 10.80 SOMA. covstaiecsvara 24.90 PaO lates esendestere Oh ehia Shy se tohe awe areata Dia tale ace 101.20
20.80 11.78 9.80 2.72 7.00 4.85 5.59 FeCO, = 37.75. 100.26
14.78 6.12 16.80 29.06 12.05 6.17 10.55 CO, =: 2.21, HzO = 1:90. 99.65
16.110 21.101 17 096 D100 2 EN ee 14.211 SOUND eretraea' sz, kA cet a baie a oa a eek 99.317
3.85 25.40 sTbiauiebe tyinlaeevoraiels cress 16.81 26.70 7.20 CO, = 2.80. 100.49
1.12 28.71 7 elst a Apes aol 5.60 SDE |, agelaete CO, = 35.05. 100.28
trace. 10.60 21.16 trace PLEO 12.04 24.56 CO, = 18.14. 100.46
0.48 10.92 31.20 27.72 14.79 PESO elt seiascalee Mn,0, = 4.18. 100.59
16.77 14.85 ASW cictniee cee 29.60 Te NR Veer ial (ull Pe (De, Nee ya 100.00
20.50 12.08 OR AES IME Alb leecorsteveKoise 23.84 7.67 2.01 CO, = 1.053. 99.88
18.00 17.40 reels bar |b cian lehereters 23.40 SiQUr. uh ss ctersta cisco Ne ora oeaeaes 5 a Math tecrahe «shale date 100.00
19.81 9.18 33.50 trace. 24.71 4.63 8.80 CO, = trace. 100.63 |
22.79 13.65 34.75 0.90 16.81 9.43 ZZ © OW inate acetate ae ace w eae 100.35 |
24.71 7.81 SOO lWhecares-ee 25.62 3.56 1.55 CO, = 0.62. 99.47
C0 i 86.00 SAAD | eae ee OO WA Siar aes. |) ene a eee etter ee av aite 100.00
13.15 12.538 OOF Ill ateiece ra oe: 34.79 EO h(a ore 6.22 leer omtome aie tae ta vaste 100.00 |
17.00 3.08 87.31 3.80 35.12 2.82 trace Mn,0,=— 1.12 100.25
7.70 16.22 38.12 1.06 27.40 SiDBD » baits crak wien Pewee s ait eee oe etiee arc iaiaes 98.73
27.83 10.47 39.05 0.85 18.05 See, pee Sw are Mn,0;,=1.45 99.80 |
5 92 14.07 39.33 0.75 27.70 ING aes BR Fey ss cP he bc Sw ais vdlaidis Se oe tona eae G 99.42 |
20.14 10.60 UME tat oaya 28.20 1b) An eR Une ene PN er I 100.35 |
1200 eee 39.514 BH WOE Clones ie TO:5OG: | o:c:2 arscorttone fries delat e. sania MPA iat wicicltarsiae o 99.116 |
20.626 17.065 89.574 NG. DOS) | |Peiceeesta LOIS Ase AOS oon [hace eee Peg tat lahat 98.023
4.80 13.23 ACO ogee serevc are me 37.77 AE OU me ihe Tece etre chs || ena date. ose hectel teresa aden darn eae 100.00 |
10.15 16.86 TPES (WEES be okayscs-0 23.14 RSENS” ALR areata Mla Bes SN dale @ ator arco lols 100.00 |
COCCI CR Eee 41.55 62.02 Morera Sse 1.25 ielas\ ew ate War Reape Deve emia avalera aati 104.82
12.00 21.28 ADO 0M eras wets. 19.72 Bie acerove sos Sete caal tee Meare oP ew operat alse ore ain to ater 100.00
1 OY ae eee ages ARM aL 1s ale asses 33.93 ARTE lhc cto te areree WLS Teceiatateate wrer lees avece oha-aiata of ace 100.65
13.60 14.88 OTN livaiaers: coetecs 23.84 PLR Mac ze eek ls crctarere ai etaicts: orecm, ate e/obe ele in) a 100.00
10.97 15.27 42.60 trace 19.62 9.31 DD aa ies see Net Mens. «ar theres SoS Sum aia 99.97
22.64 aT ADE SO toenails. cece 19.33 2.02 SCR foc crateoein fiers Wiel a ate inde «le Recess 100.64 |
2113 ee ee 43.00 ASO er erareie ahaa OS ee saree | Recs ride Sa Aeic aera 100.00 |
212 3.18 ASE Dias ol eiatcte's-0 30.62 2.31 UH ee Cee ay rar rye Retold a Gran 100.33 |
9.60 12.85 ASUZSE Maleate’. ass 20.90 6.95 4.70 CO, = 0.88. 99.03 |
11.53 21.06 43.40 trace 20.56 ACh Ulare, covetars dia. 1a Bissn oj eateries Sed ere/a ule. o'e' a > wiai 101.42 |
20.15 7.77 ENDO Bil Pais tetccc ote 20.92 6.92 treCeS We hts Colla ante oe vaea we sec 99.26
10.25 15.25 en Oe oe as, 21.27 5.42 trace Mn,O3 = 1.95. 100.32 |
23.84 0.77 AV SOM lite aeictcts.< Sete imran a ore LECEN ) LE Paniersh cia citel cleric aw eda 99.96 |
22.41 15.67 44.15 5.78 GAL Ori COMREMEE EP a seas irae I assay shale «” J) WNOMehelsioreiete bita NeW eel o\eve'wid w mete 99.77 |
TAT 17.3 et (Dai |e tees alaic 24.93 Cred iinas cs Ser crecer aed Mima ee eo cea are olan eae ate ore 100.00 |
19.14 3.00 AAS Opell Winters cross 31.85 PPS Rie ate re at of Mina aeons Saray fete lore =, <:els aes 100.84 |
9.69 11.89 gO NCO) al Neca ean 21.41 5.50 5.74 CO, = 1.25. 100.29
13.85 9.96 AAG ae lied sietehe 18.97 (Reet leccici chek [Rae cities cee aidtnase Malcicla ho ous 98.25
5.40 4.09 A OOty || erate closes 42.3 OE a ik). armnee rh Call Peeee ria ob Cs cote swiwhs ace e 100.00
2222) 11.64 AESOM SA ha oalec os 6 14.59 GTAC MIS hetop a. Peal oe bree eiberetens tae cette 99.95
10.72 6.28 ADS ti tavciacia.s ote 23.97 12.42 TRACE lee contele oot x. anne WANS Sie male ace 98.71 |
3.60 23.77 ARAM |e dererc icra 21.88 [Sey jy a Se Area eel| | Wi Rd RI CRERNIE Oak | - aeete 99.91 |
7.29 6.28 AEA Gian onl feratsss\s ste.e Are) Mel tra eco ab saa rerdicjcielon! [ta oe we gains + Se De = ose 102.42
|
6.66 2.06 ABD Oe alt cwoxsix-e © ave 42.78 CYTO, 5 no era RES so: Gr A SR SR Re / 100.00
3.20 15.03 co ae er a | eseeee ih cagetgen weeds Nahas ees 99.21
20.06 20.55 ONC Mase lier sictater cic « TADS | etichare oo se I c-eratare: Sfaratece [hy ater Stet ameter ince (eaiemtaal Steet sink etiote 100.25
_ 0eBRE 8.71 14.23 Army ies alone cies cieia « 23.17 Gey | cater cy le aptetiecunoralnts algal we aleenteied 99.70
a Sad 4.27 CSSD 0d ee Asie || ath 8 ee atl Re oO MR PTCR TIA AM Rien ar a 100.32
. 9.30 6.00 ATOM ee Mes aie cr sicis = 85.70 TiO Oey ei en teil Ree nate: BE Pash ia 100.00
8.93 2.88 47.66 trace 84.87 Sy all Wipeeecie er ated, ce Sekar §- Sah aA EEG ahs 99.71
12.60 15.09 Chota ila | (SPR meen 18.33 TAT Ad Mapes Sem cote Mma ay EE yc COE Reed Toi | 100.00
10.20 4.68 CAS 1(010 etl Wee ee 29.20 TOU G16) MMSE oe) Cth, eek” My te PARRY rk SS 8 2 ' 100.08
6.77 13.40 AOR Hee ers: exe acs 23.27 ACh Tent <a ic ese cad [aa eee etatttee cea oan wie ices 100.00
11.30 18.13 PAO Eya Levee sn; 3) 0% EOS ue erent a | 2c Ser Pre id ere naa g afta gical ae etal 100.46
21.57 8.90 SOB MM dice saa « 15.79 113 pia en Meee Fe) 1 Raia ee IRR Re i Pr 99.44
14.25 1.80 50.50 0.97 23.96 2.75 4.80 CO ,= 0.75 | 99.78
5.00 11.53 (YO LESI0 | ol Meee a 27.00 COON Sagal eerste et Leen? CISCO PLAIN AOC | 99.23 )
11.87 15.72 BOS O eae sibeiwe ts 15.92 BOO) ey tS cc ace Wc center cectak recive aiticiae | 99.21
6.14 17.05 SRSOT ears ue e's 22.75 9 Wt ieee eden cu tieaieriets seacons | 100.00
‘ *:

ANALYSES OF CHROMITE AND PICOTITE.

Name. Locality.
Chromite. Vache Island, W. Indies.
Chromite. Chester Co., Penn.
Chromite. Ural.

Chromite. Philadelphia, Penn.
Chromite. Tanagra, Greece.
Chromite. Polyhieron, Macedonia.
Chromite. Monterey Co., Cal.
Chromite. Papades, Eubeea.
Chromite. Jannina, Epirus.
Chromite. Styria.
Chromite. Karahissar, Asia Minor.
Chromite. Orenbourg, Russia.
Chromite. Wiasga, Ural.
Chromite. Ural.
Chromite. Hibbard’s,near Media, Delaware
Co., Penn.
Chromite. Ural.
Chromite. Albania.
Chromite. Tinos, Grecian Archipelago.
Chromite. Roraas, Norway.
Chromite. Vatondos, Eubeea.
Chromite. Broussa, Asia Minor.
Chromite. Plattsburg, N. Y.
Chromite. Texas, Lancaster Co., Penn.
Chromite. Smyrna, Asia Minor.
Chromite. Krieglach, Steiermark.
Chromite. Pyli, Kubeea.
Chromite. Shetland Islands.
Picotite (Chrom- Dun Mountain, New Zealand.
picotite).
Chromite. Texas, Lancaster Co., Penn.
Chromite. Broussa, Asia Minor.
Chromite. Tarasska, Ural.
Chromite. Mt. Rossipnaia, Ural.
Chromite. Viatka, Russia.
Chromite. Alt-Orsowa, Hungary.
Chromite. Oita, Japan.
Chromite. Ural.
Chromite. Asia.
Chromite (Crystal- | Baltimore, Maryland.
lized).
Chromite. Haziskos, Greece.
Chromite (Chrome {| Chester, Penn.
Sand).
Chromite. Mourtia, Eubcea.
Chromite. Baltimore, Maryland.
Chromite. Texas, Chester Co., Penn.
Chromite. Ural.
Chromite. Ural.
Chromite. Berezof, Siberia.
Chromite. Massachusetts.

Analyst.

J. Clouet.
Henry Seybert.

P. Berthier.
A. Christomanos.
“ “ec

E. Goldsmith.
A. Christomanos.
“ce “ce

J. Clouet.

“ec

A. wide -

PC ee ey

“ “

ee ee

A. Christomanos.
ae “ce

P. Collier.
Franke.

A. Christomanos.
M. H. Klaproth.
A. Christomanos.
T. Thomson.
Theodor Petersen.

C.F. Rammelsberg. |
A. Christomanos.

eee wee wwe ee ww ee

J. Clouet.

Alfr. Hofmann.
T. Haga.

Alfr. Hofmann. —
Hermann Abich. |

A. Christomanos.
Isaac Starr.

A. Christomanos.
L. E. Rivot.
T. H. Garrett.

Cr ey

A. Moberg.
C. H. Pfaff. |

TAB A r
Publication.

Ann. Chimie Phys., 1869 (4), xvi. 90-100.
Ai. Jour. Sci., 1822 (1), iv. 821-823.
Kokscharow’s Material Min. Russ., 1866, v. 16:
Ann. Chimie Phys., 1821, xvii. 55-64,
Berichte Chem. Gesell. Berlin, 1877, if 343-350

Proc. Phila. Acad. Nat, Sci., 1873, p. 365.
Berichte Chem. Gesell. Berlin, 1877, i. 848-350,

Ann. Chimie Phys., 1869 (4), xvi. 90-100.
‘“ “c “c “c “a ““

“cc “ “ “ “ce “

Ann. Mus. Hist. Nat., 1815, vi. 325-331.
Kokscharow’s Material Min. Russ., 1866, v. 163.
Sec. Geol. Survey Penn., B, 1874, p- 43.

Kokscharow’s Material Min. Russ., 1866, v. 163,
Berichte Chem. Gesell. Berlin, 1877, i. 345-36 0.

Ann. Mines, 1829 (2), v. 316 (ante, p. 185).
Berichte Chem, Gesell. "Berlin, 1877, i. 343-350. |

Am. Jour. Sci, 1881 (3), xxi. 123.
Rammelsberg’s Handbuch der Mineralchemie,
2d ed., 1875, p. 142.
Berichte Gao. Gesell. Berlin, 1877, i. 343-850. —
Mineral Korper, 1807, iv. 132-136.
Berichte Chem. Gesell. Berlin, 1877, i. 343-850.
Ann. Mines, 1827 (2), i. 280. ’
Jour. Prakt. Chemie, 1869, exy. 137-140.

Handbuch der Mineralchemie, 2d ed., 1875, p. 142
Berichte Chem. Gesell. Berlin, 1877, i. 343-350,
Kokscharow’s Material Min. Russ., 1866, v. 163.

“ee “cc “ “ ce “

Ann. Chimie Phys., 1869 (4), xvi. 90-100.
Neues Jahr. Min., 1878, p. 878.

Jabresb. Chemie, 1881, p . 1862.

Kokscharow’s Material Min. Russ., 1866, v. 163.
Neues Jahr. Min., 18738, p. 873.

Ann. Physik Chemie, 1831, xxiii. 835-342.

Berichte Chem. Gesell. Berlin, 1877, i. 8343-350
Am. Jour. Sci., 1852 (2), xiv. 47.

Berichte Chem. Gesell. Berlin, 1877, i. 343-350,
Ann. Chimie Phys., 1850 (3), xxx. 200-208.
Am. Jour. Sci., 1852 (2), xiv. 46.

Kokscharow’s Material Min. Russ., 1866, v. 163.

Kokscharow’s Material Min. Russ., 1866, v. 162.

Jour. Prakt. Chemie, 1848, xliii. 114-128.
Jour. Chemie Physik, 1825, xlv. 101, 102. _

ANALYSES OF CHROMITE AND PICOTITE.

61.50
63 37
63.59
63.80

64.00
62.25
63.40

64.17
77.00

eee eee ee

rs
sete eee
eee
stew e we

wee twee

sete ewes

ee
ee

weet eee

eoeeeree

see eee ee

Oe obo Cro bo
Wome
SSS8R

DON by
SKHBS

stew ene

tee eee

ee ew eee

see ewe

were eee

eee eee

see eee

eee e tees

ee ey
ee
Ce ee
ee ed
ee ee |
ee ee ay
ee ee
ee ee ae
ee

Ce ee a a ey

NiO, = 0.14, CoO, = trace,
MnO = 0.39.

i ee ae

ee aes
ey
Ce ee es
ee ay

a es
ee ee ed

es

ee as

trace.

ee

ee)

ee)
|
ee)
Pe

ee

Total.

100.60
99.326
100.33
99.00
100.69
99.94
99.60
99.71
100.06
100.00
100.00
100.00
100.00
100.08
100.45

101.34
100.14
100.00
98.951
101.48
100.12

100.278 |

99.16

100.37
98.50
99.43

100.00

101.22

97.53
100.54
99.34
100.61
100.05
100.25
100.00
99.588
99.12
100.06
99.171
99.45

100.29
100.425

99.985

99.60
104.33

99.76

99.40
99.40
100.88

101.01
101.00

|

Variety. Locality.

A CLASSIFIED LIST OF COMPLETE (BAUSCH)

Analyst.

Publication.

Meteorite 2)Scriba, N. Y.

Meteorite 2
la, Mexico.
Meteorite ?
Tenn.

Meteorite ?;Bedford Co.,

) ite 2
Meteorite ? Siberia.

Meteorite ?;)Durango, Me

Meteorite ?

Meteorite 2) Yanhuitlan,

Meteorite @| Ashville,

Meteorite ?)/Mexico.

Hacienda St.
sa, Mexico.

Meteorite ?

Meteorite | Water Co., Ala.

Bonanza, Coahui-

Campbell Co.,

Pa.

Petropawlowsk,

X.

Prambanan,Java.

Oa-

xaca, Mexico.
Bun-

combe Co., N.C.

Ro-

Meteorite ? Black Mt., Bun-
combe Co., N.C.

sé Ruff’s Mt., New-

Murfreesboro
Rutherford
Tenn.

Sarepta, Sara
Russia.

Coahuila, Me

Heidelberg,
den, Ger.

Mexico.
Chesterville,

Chester Co.,
Ivanpah, Cal.

Meteorite ?)Cachiuyal,

cama, Chili

“

Mezquital,
rango, Mex

berry, S. C.

ugh,

Coz
tow,

X.

Losttown, Chero-
kee Co., Ga.

Ba-

San Gregorio,

S.C.

Macon

Us Auburn,
Co., Ga.
Meteorite ?)/Duel Hill, Madi-
son Co., N.

C.

Denton Co., Tex.

Ata-

. Wayne Co., Ohio.

San Francisco del

Du-
ico.

C. U. Shepard.
C. U. Shepard.

C. U. Shepard.
J. L. Smith.
C. U. Shepard.
Sokolowskij.

Iwanow.

\

M. HW. Klaproth.

F. John.
M.vanderBoon Mesch.

EE. H. von Baumhauer.

L. R. de la Loza.

C. U. Shepard.

F. A. Genth.

H. Wichelhaus.
C. U. Shepard.
C. U. Shepard.
G. Troost.

J. Auerbach.
J. L. Smith.
C. U. Shepard.
R. Wawmkiewicz.
J. L. Smith.
C. U. Shepard.
C. U. Shepard.
C. U. Shepard.
B.S. Burton.
j W. P. Riddell.
i A. Madelung.
J. Domeyko.
J. L. Smith.

A. A. Damour.

Am. Jour. Sci., 1847 (2),
iv. 74, 75.

Am. Jour. Sci., 1841 (1),
xl. 866-3869.

Am. Jour. Sci., 1867 (2),
xliii. 884, 385. :
Am. Jour. Scei., 1855 (2),
xix. 159.

Am. Jour. Sci., 1828 (1),
xiv. 183-186.

Archiv. Kunde Russ-
land, 1841, i. 317.

Ibid., 1241, i. 723-725.

Beitrage, 1807, iv. 101,
102.

Jour. Chemie Physik,
1821, xxxii. 263, 264.

Archives Neéerl., 1866, i.
468.

Ibid., pp. 465-468.

Proce. Phila. Acad. Nat.
Sci., 1876, p. 126.

Am. Jour. Sci., 1839 (1),
xxxvi. 81-84.

Am. Jour. Sci., 1854 (2),
XVili. 239, 240.

Ann. Physik Chemie,
1863, exviii. 6381-634.

Am. Jour. Sci., 1847 (2),
iv. 82, 88.

Proc. Am. Assoc. Adv.
Sci., 1850, iii. 152-154.

Am. Jour. Sci., 1848 (2),
v. 351, 352.

Sitz. Wien. Akad , 1864,
xlix. (2), 497.

Am. Jour. Scei., 1855 (2),
xix. 160, 161.
Am. Jour. Sci., 1869 (2),
xvii. 234. :
Ann. Chemie Pharm.,
1862, exxiii. 252-255.
Am. Jour. Sci., 1871 (38).
ii. 835-838.

Am. Jour. Sci., 1849 (2),
vii. 449.

Am. Jour. Sci., 1880 (8),
xix. 381, 382.

Am. Jour. Sci., 1869 (2),
xlvii. 280-283.

Am. Jour. Sci., 1877 (3),
xii. 489.

Trans. St. Louis Acad.,
1860, i. 623.

Buchner, Meteoriten,
1863, p. 193.

Comptes Rendus, 1875,
Ixxxi. 597.

Am. Jour. Sci., 1864 (2),
XXXVili. 885, 386.

Comptes Rendus, 1868,
Ixvi. 573, 574.

“Sp. Gr.

7.265
7.50

6.50-7.50,
8.00
831

7.261
7.01-7.10

96.71

93.77
94.95

96.58182
96.50

96.17

95.92
96.072

96.04
96.00
96.00

95.937
95.82
95.759
95.472
95.01
95.00
94.98
94.58.
94.24

92.099
93.92
93.61
95.38

§4.02466 5.42982 trace.

2.07 PaO PRR | wen Ao: :
7.00
696 Sod ra | Sea :
3.20) || aie, c:0-/| rele een eater te =
6.50 | 2.00 myereiae le ereretoh arene
2.86 eh. haces aceon =
5.91
483 |r| asec
1.832 Bebo ance |hocnaaaec
2:60—|trace.|< sre |0RACe| “eee ae
5.07 | 0.42 pat | Waser ee
“B67 = | eagle eee ‘
3.263 |:0:55 |OSG| i oe Nea ee rete :
2.52 eth Ces. omen ere se eater eee
3.121% }traces| sae) BRAC: eee jase
LAO Sedcore oe Paso iad aig oe -
2.657 Elta ye 1.315
3-18), || O:S5i Os ie eee erie stetalers
3.66 |trace:} ssremeliese eats ie
010 | 1.256/024}.......,
4.22 .).0.51) HOWOB a) rected ete oe
5.00 |trace:| 22.26. | seec| opscense
4.52 OO Tate AGM Smee ere
3.015 0120), c= eile ents :
5.17 [0:37 ONS eeaeeceee eae
7.53, |trace.| 0.001) «<5. |e ne. a
4.93 | 0.39 | 0.085) . nie ataistel
6.01 | 0.73 | 0.18 ~eyfaemee ante
5.89 _| 0.39 | 0.23.4 <2 5 iene

F Cr,0,
trace.
wae | trace.

.... |trace?| trace.

OBZS TT Pevereteh |) sici<'s

TPACE:| oo06
.. | trace
. c
ee eeee

—__

ANALYSES OF METEORIC AND TERRESTRIAL ROCKS.

Al. Ca,

trace. | trace.

0.09

trace.

0.20 | trace.

SiO, | Al,0;| CaO

0.0056 |0.61015 0.60815) ****

0.50

trace.

O02 WW sicies

Mg. | Mn. |

trace: |...

Vil

. 2) ie Sal i ean ere ar)
Cl. | As Undet. Total. |
We

Insol. | Loss. Miscellaneous.

ee ants lade de ced nie de dem eeee Meese 99.89 |
etd scr reer |According to Heddle itcon-| 99.97
| tains nickel, potassium,

and traces of sodium,|

silicon, sulphur, carbon,
phosphorus? and tin?
Phil. Mag., 1862 (4), xxiv.
541

roe | era a Cr,0,, Co, Mg, and
| P=210.

eces | te eee selesccesesccesreessessseessss

| |

100.00 |
100.52

1.56 99.00

ee ee |

99.36
|100.03
101.08

100.00
100.00
100 00

/

i a

ey

100.00
100.00

100.00
99.80

99.66
100.00

coee ler eeeees

es

0.20 |trace?

a

ey

a
ey
ee

ec

ee ee es

ee ee ee
ee ee
weee [eee esses

phite.

Ce ee

ei 2.276

www ea [ee wwe marl eee eee eee rete ee eeeeeeee

enee ewes eeeefeeeecesresesreenesesereeons

vill A CLASSIFIED LIST OF COMPLETE (BAUSCH)

TABLE W

Variety. Locality. Analyst. Publication. Sp. Gr. Fe. Nip | 2Goulm rs S. | P, Fe, Ni.

Meteorite ?, Lion River, Great| C. U. Shepard. Am. Jour. Sci., 1853 (2),| 7.45 93.80 6.70 | .... |trace.|trace.|...oemm
Namaqualand, xv. 1-4.
South Afriea. |
e Schwetz, Weich-| C. Rammelsberg. Ann. Physik Chemie,| 7.77 93.18 5.07 {LOD | cose | Serene eee
sel River, Prus 1851, Ixxxiv. 153,154.
sia.
& Nelson Co., Ken-| J. L. Smith. Am, SOUr:SCl.. LOGOS 2)i ite orem 93.10 | 6.11 | 0:41 |,0105) | S05) See
tucky. xxx. 240.
= . | ( F. E. Geinitz. Neues Jahr. Min., 1876,| 6.21 93:04° | 6.16 |<... 90.2280 soos eee
“ Nenntmannsdorf, j pp. 608-612
Saxony. ) G. E. Lichtenberger. /Sitz.Isis, Dresden, 1873,) ........ 94.59 5.31“) ...6 2 | oe
p- 4. ;
we Lick Creek, Da-| J. L. Smith and J. B.|Am. Jour. Sci., 1880 (8),) ........ 93.00 | 5.74 | 0.52 | 0.86; |trace| ...) cee
vidson Co., N.C. Mackintosh. xx. 324-326.
ss Coahuila, Mexico.| J. L. Smith. Am. Jour. Sci., 1869 (2),| 7.692 92.95 |6.62 | (0:48) | Q2020" o-oo crite
xlvii. 383-385.
w Not known. C. U. Shepard, Jr. Am. Jour. Sci., 1881 (3),) 7.589 92.923: | 6.071 | 0:539) . 502) -eee 0.562
xxii. 119.
w Pittsburg, Penn. F. A. Genth. Am. Jour. Sci., 1876 (8),| 7.741 92.809 | 4.665 | 0.395) 0.251] 0.037] ...... 3
xii. 72, 73.
s Tabarz, Thurin-| W. Eberhard. Ann. Chem. Pharm.,| 7.737 92.757 | 5.693 | 0.791) 0.862) .... 0.277
gia, Germany . 1855, xevi. 286-289.
" Guilford Co.,N.C.| C. U. Shepard. Am. Jour. Set. 184 (1); 267 2S) O2 eTown ed 146" traces ieee ses artemis ine
xl. 369, 370.
a: Angara,Jeniseisk,| M.A. Gobel. Bull. Acad. St. Peters.,| ........ 92:6846| 7.1038)|trace.| 0.163) ....].....0<6
Siberia. 1874, xix. 544-554.
{ L. E. Rivot. Ann. Mines, 1854 (5), vi.) - 428 } 92.30 | 6.20 ‘trace.
x, Caillé, Var | 554, 555. ‘i 92:70. | 5.60. |trace:)** sa tes ele one oeeee
Aiesncs 4 J. Boussingault. Comptes Rendus, 1872,| 7 ¢4 ; 89.53 | 9.76 : 4
, | Ixxiv. 1287-1289. ’ 89.73 =| O90. [°° 2 aie een ceca = |
| V. de Luynes. Ann. Mines, 1844 (4), v.| ......+- $768 | 7.87 |\2...c0] seen were enn een
161-164. :
e Southeastern Mis-| C. U. Shepard. Am. Jour. Sci., 1869 (2),|7.015-7.112| 92.096 | 2.604 |trace.|trace.| .... 5.00
souri. xlvii. 238, 234.
4 Rio Juncal, Ata-| A. A. Damour. Comptes Rendus, 1868,) 7.697 92.03 || 7.00) ‘| 0:629)(Oi2te es ot sree arian |
cama, Chili. Ixvi. 569-571. f
Fickentscher. Buchner, Meteoriten,| 7.781 91.90. | 5.72 -] J ..2c4|Remretetl lie eet ete eene
S Bemdego Creek 1863, p. 144. e ;
Bahis. Brasil. | W. H. Wollaston. Phil. Trans., 1816, pp.| 7.73 95.10. «| (8/90 | ce Seiierecren le oleten lite ena
oa Seal 270-285. ree
{| Wohler & Martius. |Phipson, Meteorites,| 7.468 88.46 8.59 stared || aetna eam
1867, p..94. |
os Sizipilec, Mexico.| C. Il. L. v. Babo. Buchner, Meteoriten,| ........ 91.89. | 6.82_- 1 1.585) SS ceuctrstel ince estan
1863, p. 141.
Meteorite. |Braunau, Bohe-| Duflos & Fischer. Ann. Physik Chemie,| 7.7142 91.882 | 6.517 |(0:520| acer een tee
mia. 1847, xxii. 475-480. |
Meteorite ?)Dakota. C. T. Jackson. Am. Jour. Sci., 1863 (2), 7.952 91.735 | 6.532 |trace.) 0.01 .
xxxvi. 259-261. ee } 91.735-4' 7.08 .../trace: 0015 se ee eee |
(C. A. Joy. Ann. Chem. Pharm. ........ | 91.635 | 5.846 | 0.809] 0.195] .... | .......0
a Cosby Creek, | 1853, Ixxxvi. 39-43. .
Cocke Co., 4 C. Bergmann. Ann. Physik Chemie,} 7.257 91.898 | 6.704 | 0.332] 0.089] .... | .......0 me
Tennessee. | 1857, c. 254, 255. |
a | C. U. Shepard. Am. Jour, Sci., 1842 (1), go9q {| 9380 | 4.66 |
xliii. 854-368. : U| 94.088 | 4.444 | o°°* [799 5S StS S
Chulafennee, Cle-| J. B. Mackintosh. Am. Jour. Sci., 1880 (3),} ........ 91.608 | 7.868 | 0.50 | 0.17 |... |. 3 cece
burne Co., Ala. Xe
Sf Atacama, Chili. E. Ludwig. Denks. Wien. Akad.,| °7.7586 91.58 | 7.14 >| 0.41 OBS a eet oe
1872, xxxi. 187-195. °
( J. Boussingault. Comptes Rendus, 1872,| 7.73 91.50 | $8.68 | ss... |/ceteeu| certs inert
| Ixxiv. 1288, 1299.
i Lenarto, Hun- | A. Wherle. Rammelsberg, Hand-| 7.79 90.90 | 8:60 | 0:665)). Soe aecmine ere in
gary. worterbuch, 1841, p. ;
423.
| P. A. v. Holger. Zeit. Phys. Maths, 1880;) ........ 85.04 —| 8:12° |'3.69 | che eter
vii. 129.
Meteorite. Rowton, Shrop-| W. Flight. Phil. Trans., 1882, pp. : 91.25 8.582 | 0.371 ai wie) | fete jal epee
shire, Eng. 804-8060 SOR pie oe ie 91.016 | 9.077 | <a.) saa eee
Meteorite Santa Rosa, New| Rivero and Boussin- Ann. Chemie Phys.,| 760 ( pe a sone] betee |) ake:
Granada. gault. 1824, xxv. 438-4438. 7.30 H G14 : | 8.59

. | trace.

"| Cr,04
0.063) trace.
* | 0.063) trace.

trace.) ..

ANALYSES OF METEORIC AND TERRESTRIAL ROCKS.

0.01

0.77

SS ee ee

1.63

Mg. | Mn.| Cl.
trace
Gil, :2

trace.

0.092) ....

0.23 | 0.61

As. | Insol.

|

Loss.) Undet. | Miscellaneous.

pr Bee KO = trace.

O.008: Fired [sie cs viet aasin'ad« alaiee ta Aina ee tana
eo haleyamtets ae Mean of closely agreeing
analyses.
Byicdeccrt cl Metre errer rer rcre errr
welt [as esisienslaqioncocccesccasesese eves!
areal ele [apa aterewiele Fe,0,+FeO == 0.75.
Analysis imperfect.
ULAGCE? fh heroic, |ecstale ict sla Sere mae aisivale gic vs me caee
!
0.59
O25 ttt ttt tlseee tees tee eeeee eee e wees
BS cel braratcc Trace of Fe,O3.
(tot IR CM on BR Gonal hebenciooco-rotne emotes
Ril in oboseal Gc oo cotceencs Sem encrnse a
A h6 jloke omen doceb oor coc Che one cnn |
ne qe|lseee Sade Cu+ Mn+ As+Ca+ Mg
+S5i+C+Cl4+S=2072.
e@eoee |e eee eeeerieon ee ee ee see ee eeeeeeeee vee
Sisal aeeaoe Graphite = 0.798.
0.10
O10 | crttcrrt ttt fies te tess t ete e reese sees
ara w |e mcoimia Siete Seine sl ma Salaie aaa e heraitele G |
ORO ie cont (a ateiers call elamaaws <einia sete a's ieee x
bene feeeeeees Analysis incomplete
eo feweeeeeee e as
0.28 were lene eoeelever nesses esestseeeaeesene

Total.

100 00
100.098

99.67
99.42

99.90 |
99.62
99.07 |
100.095 |
98.33%
100.38
96.645
100.00
99.40
99.20
100.00
100.00
100.00
99.70
99.86
100.00
100.00 |
100.00
99.79
100 00 |

98.34
98.888

99.673 |

99.198

98.56 |
98.577 |

99.646 |
99.53 |
100.38
100.10

Meteorite ?

“

“cc

Meteorite.

x
Variety. Locality.
Meteorite ?)Lagrange, Old-
ham Co., Ky.
Meteorite. |Charlotte, Dick-

son Co., Tenn.
Jewell Hill, Mad-

ison Co., N. C.
Mexico.

Red River, Texas.

Obernkirchen,
Germany.

Smith’s Mt., Rock-
ingham Co.,N.C.

20 miles from Fort
Pierre. Nebraska.

Rasgata, New Gra-
nada.

Colorado.

Russell Gulch, Gil-
pin Co., Col.

Franklin Co.,Ken-
tucky.

Szlanicza, near
Arva, Magura
Mts., Hungary.

Xiquipilco, Mex.

Toluca, Mexico.

Salt River, Ken-
tucky.

Lenarto, Hun-

gary.

Marshall Co.,Ken-
tucky.

Seeliisgen, <Aus-
tria.

Brazos River,Tex.

Hraschina, near

Agram, Croatia.

A CLASSIFIED LIST OF COMPLETE (BAUSCH)

Analyst.

J. L. Smith.
J. L. Smith.
J. L. Smith.
J. L. Smith.
{ B. Silliman, Jr., and
+ . 8. Hunt.
(C. U. Shepard.
F. Wohler.
(J. L. Smith.
LF. A. Genth.
A. Madelung.
| H. A. Prout.
{ Rivero and _ Boussin-
gault.
| F. Wohler.
C. T. Jackson.
J. L. Smith.
J. L. Smith.
A. Lowe.

4 C. Bergmann.

|

A. Patera.

Evan Pugh.
W. J. Taylor.
| H. B. Nason.

E. Uricoechea.

F. Wohler.
W. 4H. Brewer.
{ W. S. Clark.

|

4 A. Wehrle.

|

| P. A. v. Holger.

J. L. Smith,

A. Duflos.

C. Rammelsberg.
W. P. Riddell.
A. Wehrle.

Publication.

Am. Jour. Sci., 1861 (2),
Xxxi. 265, 266.

Am. Jour. Sci., 1875 (3),
x. 849-352.

Am. Jour. Sci., 1860 (2),
xxx. 240.

Am. Jour. Sci., 1868 (2),
xIVe mie

Am. Jour. Sci., 1846 (2),
ii. 8372-374.

Am. Jour. Sci., 1829 (1),
xvi. 217-219.

Gottingen, Nachrichten,
1863, pp. 864-367.

Am. Jour. Sci., 1877 (8),
xiii, 213, 214.

Am. Jour. Sci., 1877 (3),
xiii. 214.

Buchner, Meteoriten,
1863, p. 197.

Trans. St. Louis Acad.,
1860) i. Vil, 712:

Ann. Chimie Physique,
1824, xxv. 442, 443.
Ann. Chem.
1852, Ixxxii. 248-248.

Am. Jour. Sci., 1867 (2),
xliii. 280, 281.

Am. Jour. Sci., 1866 (2),
xlii. 218, 219.

Am. Jour. Sci., 1870 (2),
xlix. 331-835.

Neues Jahr. Min., 1849,
p. 199:

Ann. Physik Chemie,
1857, c. 256-260.

Neues Jahr. Min., 1849,
p: 109:

Ann. Chem. Pharm.,
1856, xevili. 883-386.

Am. Jour. Sci., 1856 (2),
xXxxii. 374-376.

Jour. Prakt. Chemie,
1857, Ixxi. 123.
Jour. Prakt. Chemie,

1854, Ixiii. 317, 318.
Ann. Chem. Pharm.,
1857, Ixxxii. 248-247.

Proc. Am. Assoc. Ady.
Sci., 1851, iv. 36-88.

Clark, Metallic Meteo-
rites, 1852, p. 40.

Clark, Metallic Meteo-
rites, 1852, p. 40.

Buchner, Meteoriten,
1863, p. 153.

Am. Jour. Sci., 1860,
xxx. 240.

Ann. Physik Chemie,
1848, Ixxiv. 61-65.
Ann. Physik Chemie,
1848, Ixxiv. 443-448.
Trans. St. Louis Acad.,

1860, i. 628.
Clark, Metallic Meteo-
rites, 1852, pp. 42-44.

Pharm.,

Sp. Gr. Fe. Ni. Covers Ss.
7.89 91.21 7.81 | 0.25 | 0.05
Tete 91.15 8.01 | 0.72
svete aaiehine 91.12 7.82 | 0.48 | 0.08
Tile 91.103 | 7.557 | 0.763] 0.02 | trace.| .....
7.40
7.89 90.911 | 8.462
7.548 90.02 9.674 E
7.12 90.95 | 801 064
7.78 90.88 | 8.02 |0.50 | 0.03
eerecictreke 90.68 9.07 0.14
7.741 90.764 | 7.607 | 0.889) trace.
7.785 94.288 | 7.185 trace:| ‘see
7.60 90.76 | 7.87
7.88-7.17 | 92.385 6.71 | 0.25 | 0.35 | trace.
7.692 90.65 | 7.867 | 0.01
TZ 90.61 | 7.84 | 0.78 | 0.02
7.692 90.58 8.53 | 0.86 | 0.05
ate 90.471 | 7.321 trace.
91.561 | 7.323 trace.
ei steraya 77.182 | 4.739 0.434/15.359] .....
89.42 861
7.814 93.13 5.94
94.12 5.43
bet A 90.43 7.62 | 0.72 |0.15 } 0.03
87.89 9.06: | LOT Ge aaa.
yelstieoe 90.72 8.49 | 0.44 |0.18-] ....
HY FeS.
Soteihon 90.133 7.241 0.376) trace.
sey See tye pas 90.40 5.02 | 0.04 | 0.16
Cate Aci 86.073 | 9.016 | 0.769] ....
90.23 9.68 ae
ee 90.51 9.05 a
91.07 9.68 ae
91.14 | 9.05 ‘
7.13 90.153 | 6.553 | 0.502] .... | 0.482] ....
7.98 90.883 | 8.45 | 0.665) ....
7.72-7.80 | 85.04 812 | cisSnieee
aie taratateyste 90.12 8.72 | 0.82 | 0.10
7.63-7.71 | 90.00 | 5.808 | 0.434) ....
Fe+Mn
7.7845 92.327 | 6.228 | 0.667) one
Ba ate 89.993 |10.007 |trace.|....
7.785 89.784 | 8.886 | 0.667] ....

— | ——-— ——_—_— xX“ -——“—| —| | @“«~[ WX |—_—

0.01

Ca Mg.

0.35 | 0.65

-.+- | MeO

trace.

trace.

0.145] ....

0.63 | 0.23 | 0.61

0.912)...

Insol. | Loss.) Undet. Miscellaneous. | Total.
|

ANALYSES OF METEORIC AND TERRESTRIAL ROCKS, xl

|

wee e lew ee ww ee

Q
Les}
>
=,
=
I
="
=
ar
S
lol
=

UO eee 0.22 99.41
mils ter etantalee og Schreibersite, graphite,etc. 100 46
0.88

ee

eee e fewer eee el ee ee teers eee reese eeeeeeee

A CLASSIFIED LIST OF COMPLETE (BAUSCH)

Analyst.

xl
Variety. Locality.
Meteorite. |Hraschina, near

Meteorite ?

“

Agram, Croatia.

Burlington, Otse-
golConwN. Ye

Ocatitlan, Oaxaca,
Mexico.

Cooperstown,
Robertson Co.,
Tennessee.

Putnam Co., Ga.

San Luis Potosi,

Mexico.
Carthage, Tenn.

Washington Co.,
Wisconsin.

Butler, Bates Co.,
Missouri.
Istlahuaca, Mex.

Cambria, Niagara
Co., New York.

Rokitan, Bohe-
mia.

Victoria West,
Cape Colony,

South Africa.

Staunton, Augus-
ta Co., Virginia.

Elbogen, Bohie-

mia.

Nobdenitz, Alten-
burg, Germany.

Babb’s Mill,Green
Co., Tenn.

Tejupilco, Mex.
Howard Co., Ind.

Misteca, Oaxaca,
Mexico.

M. H. Klaproth.
= A. v. Holger.

W.S. Clark.

C. H. Rockwell.
I. U. Shepard.

C. Bergmann.

J. L. Smith.

C. U. Shepard.
P. Murphy.
E. Boticky.
G. Bode.

cE L. Smith.
J. L. Smith.
M. Bocking.

{ C. Rammelsberg.
B. Silliman, Jr., and

T. S. Hunt.

| D. Olmsted, Jr.
J. Stolba.

K. R. v. Hauer.

J. L. Smith.

(J. W. Mallet.
|

—

(J. R. Santos.
J. J. Berzelius.
M. H. Klaproth.
J. F. John.
A. Wehile.

| P. A. v. Holger.
H. B. Geinitz.

( G. Troost.

C. U. Shepard.

( W.S. Clark.

— A

M. Bocking.
J. L. Smith.

C. Bergmann.

Publication. Sp. Gr. Fe. Ni. | Co.*} -P. | (SiR ane
Beitrige Mineralkorper,| 7.73-7.80 | 96.50 | 3.50 «aan
1807, iv. 99-101. ;
Rammelsberg, Hand-| 7.824 83.29 {11.84 | 1.26 «aa
worterbuch, 1841, 422.
Metallic Meteorites,| 7.728 89.752 | 8.897 | 0.625 otal
1852, pp. 61, 62. 7
Am. Jour. Sci., 1844 (1),| ........ 92.201. | 8,146 |°..2..) | woe lee ae F
xlvi. 401-405.
Am. Jour. Sci., 1847 (2),) ........ 95.20 | 2.125 a
he (AG iter
Jour. Prakt. Chemie,| 7+ 89.71 | 8.538 | 0.56 | 0.17 om
1857, Ixxi. 57, 58. ,
Am. Jour. Sci., 1861 (2),) 7.85 89.59 | 9.12 | 0.35 | 0.04 oan
Xxxi. 266.
Am. Jour. Sci., 1854 (2),| 7.69 89:52 |, 8:82 .-|tracetl) emo teeter eee “a
xvii. 831, 382.
Proce. Phil. Acad. Sci.) 7.38 89.51 | 8.05 | 1.94 0.45 i]. as eae a
1876, pp. 123, 124.
Neues Jahr. Min., 1866,) 7.478-7.50| 89.465 | 7.721 | 0.245 0.093) 0.401) ...... <
pp. 808-810.
Ann. Rep. Smith. Inst.,| 7.8272 89.22 |10.79 .|trace| (697 Sone oa
1869, pp. 417-419.
Am. Jour. Sci., 1869 (2),| 7.82 91.08 | 7.20 |0.53 | O44 |. ... |...) ce
xlyii. 271, 272.
Am. Jour. Sci., 1877 (8), 7.72 89.12 |10.02 | 0.26 | O12) SNe
xiii. 213. 3
Neues Jahr., Min., 1856,| 7.882 89.073 | 7.29 | 0.978] .... |0.855) 0.9727
p. 304.
Mon.Berlin.Akad.,1870,| ........ 89.06 |10:65 | 0:08 | ..:. +O:17 |) 2.2 sae
p. 444.
Am: JounSet., 1846 (2))| 5.2... 92.583 | 5.708-|-.00 |imeee | © © oen}ipie seen
li. 874-376.
Am. Jour. Sci., 1845 (1), 7.5257 95.54 | 5.037 < Bi eeeroven) poke a a
xlviii. 3888-392. = } 94.224 | 6.353 PaPeites
Sitz. Wien. Akad., 1864,| 6.005 89.00 | 8.84 1.08) «<-.ceee
xlix. (2), 480-485
Sitz.Wien. Akad., 1864,| 6.394 96.00 oes oe
xlix. (2), 480-485.
Am. Jour. Sci., 1873 (3),| 7.692 88.83"... 110.14 |'0:553/0:28) |< Searle eee ”
v. 107-110.
7.853 88.706 |10.163 | 0.396} 0.841) 0.019] .......,
Am. Jour. Sci., 1871 (3), | 7.855 88.365 |10.242 | 0.428) 0.862) 0.008! .......
ii. 10-15. | 7.839 89.007 | 9.964 | 0.387) 0.375) 0.026) .......
Am. Jour. Sci., 1878 (3),] 7.688 91.489 | 7.559 | 0.608) 0.068) 0.018) ....... :
xv. 837, 388.
Ann. Physik Chemie,| 7.74-7.87 | 88.231 | 8.517 | 0.762) .... |trace.| 2.2117
1834, xxxili. 185-137.
Beitrage Mineralkorper,| 7.80-7.83 | 97.50 | 2.50 | ....|]....| -e-- | weeenoum
1815, vi. 806-308.
Jour. Chemie Physik,| 7.76 87.50. | 8.75 | 1-858] ccc lc seni ieee en
1821, xxxii. 253-261.
Buchner, Meteoriten,| 7.78 89.90 | 8.485 | 0.609) 5.26 | eu. |0seeee
1863, pp. 151, 152.
Buchner, Meteoriten,| ........ 94.69 | 2.47 | 1.59 aoe
1863, pp. 151, 152.
Neues Jahr. Min., 1868,| 7.06 88.125 | 1.84 |trace.|.... oer:
pp. 459-463.
Am. Jour. Sci. 1845:(1),)) . 2... 60 87.58 |12.42 see
xlix. 842-344.
Am. Jour. Sci., 1847 (2),| 7.548 85.80 {14.70 sae
iv. 76, 77. |
Metallic Meteorites, 7.839 80.594 |17.10 | 2.037) .... oot ose
1852, pp. 65, 66.
Neues Jahr. Min., 1856,) 7.326 87.092 | 9.801 | 0.766) .... | 0.79 0.73
p. 304.
Am. Jour. Sci., 1874 (3),| 7.821 87.02 12.29 | 0.65 | 0.20 o + sans
vii. 891-395.
Jour. Prakt. Chemie,| 7.20, 7.58, | 87.122 |10.049 | 0.745) 1.23 | 0.553) ..... aa
1857, Ixxi. 57. 7.62

MgO
trace.

002) :...
0.004 | 0.002) ....

trace.
trace.

eoenre Baeei eee aie ree eoree
Ae.) 0.12
1.821] trace.

0.19 0.88

trace. | trace. | trace.

TTACe@.| sacs

0.279 |trace.| ....

aeieienaces

CTACCL oc aie

0.45

0.039

1.40

ANALYSES OF METEORIC AND TERRESTRIAL ROCKS.

Loss. Undet. | Miscellaneous.

ee

ee ee ee

Loss+S = 2.175.

ee ee or

[ewww eee

0.05

Sn+P+S+Mg+Ca
— hala :

ed

ry

eo lew ee ee eel ee ee eee eee etree sree eee re

ey

ee ey

ee

ecee [cee a tere |soeeeseeeeneeseseesesseee
eee eee

woes [econ ee er|scoeeseseesereeetesseeeee

coce becocveeeel|seeeneevresneseteeesereeee

weece jee eeeese|esneeeseeeseeosseseseeesese

wove [ec eereteleseeeestesesesesseseeeses

eone jeceeeceesleceseeoeseesessseeeeseeees

Xill

100.00
100.00

3
oy
o

X1V

Variety. Locality. Analyst.

Publication.

Bohumilitz, Bohe-
mia.

Meteorite ?

Pp. A. v. Holger.
| J. J. Berzelius.

J. Steinman.

( C. Bergmann.

se Zacatecas, Mex-

2 S. N. Manross.
ico.

UH. Miiller.

T. Nordstrom.
G. Lindstrom.
F. Wohler.

R. Nauckhoff.

Terrestrial Southern Green-
Iron. land.
J. Lorenzen.

J. L. Smith.

Meteorite ?/Claiborne, Clarke

A. A. Hayes.
Co., Alabama.

C. T. Jackson.
E. Uricoechea.

Baumhauer and

Seelheim.

a Cape of Good
Hope. A. Wehrle.
M. Bocking.

P. A. v. Holger.

a Los Angeles, Cal.) C. 'T. Jackson.
Santa Catharina,
Brazil.
a Oktibbeha Co.,
Mississippi.

W. J. Taylor.

A. FE. Nordenskiold.

G. Forchhammer.

Guignet and Almeida.

Zeit. Physik Math.,1831,
ix. 823-328.
Ann. Physik Chemie,

1883, xxvii. 118-132.
Am. Jour. Sci., 1851 (1),
xix. 384-386.
Neues Jahr. Min.,

p. 297.
Ann. Chemie Pharm.,
1852, Ixxxi. 252-255.

Quart. Jour.Chem. Soc.,
1859 (1), xi, 286-240.

Geol. Mag., 1872 (1), ix.
518.

1856,

Gebk Mag., 1872 (1), ix.
518.

Geol. Mag. 1872 (1), ix.
518.

sche: Jahr. Min., 1879,
p- 853.
Min. Mitth., 1874, p.125.

Zeit. Deut. Geol. Gesell.,
1888, xxxv. 695-7038.

Ann. Physik Chemie,
1854, xciii. 155-159.

Ann. Chimie Phys.,1879
(5), xvi. 452-505.

Am. Jour. Sci., 1845 (1),
xlviii. 145-156.

Am. Jour. Sci., 1838 (ie
xxiv. 332-337.

Ann. Chem. Pharm.,
1854, xv. 252.

Archives Néerland.,
1867, ii. 876-384.

Zeit. Physik Math., 1835
(2), iii, 222-229.

Ann. Chemie Pharm.,
1855, xevi 243-246.

Zeit.Physik Math.,1830,
viii. 283.

Am. Jour. Sci., 1872 (3),
iv. 495, 496.

Comptes Rendus, 1876,
Ixxxiii. 917-919.

Am. Jour. Sci., 1857 (2),
Xxiv. 2938-295.

Sp. Gr.

7.61-7.71
7.146
7.48
7.55
7.20
7.50
7.625

6.36, 6.86

7.05, 7.06
6.24
§.82

ee ew weee

5.75, 6.40,

6.50

6.635-7.944
7.708
7.665
7.604
7.318
7.9058

7.75

6.854

Fe.

86.67

orn ||

83.67

92.473
93.775

94.06
85.09

92.35

89.84
91.30
90.91

84.49
86.34
95.24
80.64
58.25
91.71
91.17
82.02
59.77
93.89
92.41
95.15
95.67
92.46
92.68
92.23
94.11

93.39

93.16
90.17
88.13
92.45

83.572
66.56
81.20
82.77
85.608
81.50
78.90
80.74
64.00
37.69

A CLASSIFIED LIST OF COMPLETE (BAUSCH)

Ni. | Co. | P
8.12 | 0.59
7.83 | 0.60
5.667 | 0 235
3.812 | 0.213
4.01
9.89 |0.76
HO
7.38

5.96 |0.62|....
5.82 |041 | 0.25
5.65 | 0.42 | 0.23
2.48 |0.07 | 0.20
1.64 | 0.35 |0.07
1.24 |0.56 | 0.03
1.19 | 0.47 | 0.15
2.16 |0.30
1.74 Ogee
1.82 |0.51
1.39 |0.76
160 |0.39]....
2.55 | 0.54
0.45 |0.18
0.34 | 0.06

trace’) 6.
0.92 | 1.93 | 0.07
2.54 | 0.58
273 |\O84 Fis
2.85 11.07
1.56 |0.25 | 0.18
201 |0.80 | 0.32
6.50. | O79
2.13 |1.07 | 0.25
288 | 0.43 | 0.24
12.665
24.708 A
15.09 | 2.56 | 0.09
14.32 |2.52 | 0.26
12.275 | 0.887] ....
15.23 [2.01 | 0.08
15.28 | 1.00
15.73
36.00
59.69 | 0.40 | 0.10

TABLE:

seer

ANALYSES OF METEORIC AND TERRESTRIAL ROCKS. XV

| | "
Si. Al. Ca. | Mg. | Mn.| Cl. | As. | Insol. Loss.| Undet. / Miscellaneous. Total.
)
0.32 | 0.41 | 0.13 | 0.46 th a Se Ze = 0.10. | 98.16
0.42 | 1.08 | 0.10 | 0.58 MASH es Se baa Be = 0.12. | 99.16
: ee | citns ob 9a ote a Maen 100.00
5 CO Vs a ie aes vrais ive vd wo \ae iatp Gadee eal 100.00
Sa ge syvele 'Graphite, etc. = 1.12. | 100.00
‘ Spc ORIOMICRACE- Irae mesh setied tire cet Li are-»3", bawinshdialeis C+ Fe=0.33. Chromite) 100.62
; = 148
mr FE LE Ce) oe ae entre 100.16
wait aiate Actas TOME etter H b ciclererresd [oe at ais ows eee oe 99 63
SiO, <<. | trace. Neal eee ee COR EEPEP CERRY ere a 99.97
0.50 aimsye en oeee ila ofl | sate 8 eee POCO dl Oct ee eee a> E 100.50
-... | trace. | trace, |. 0.04 ON Gigel ears eta ie OLOD Nitere tess) foteere! «oye K,O = trace. Na,O = 100.00
SiO, trace. SiO, = trace. |
0.66 | 0.24 | 0.48 | 0.29 1.16 SS es eee K,0 =0.07. Na,O =0.14. 100.00
trace. Fit eee ed pe moe Peni eed Saree K,0=0.08, Na,O=-0.12,In- 99.79
sol.+Si0,—0.59, H—0.07.
at dod Weber ~cod “ll spéeull- aes Gal octane poet cere med Meee Eoerer a ae Silicates + Cr + Cu=6 08, 100.13
0.26 1.4 0.50 | 0.33 0.16 6.07 H =0.28 FeO+Fe,0,=30.43, Na,O 102.64
SiO, | Al,O, —0.09, Ni0+Co0—0.44.
0.81 1.21 AAO WALEA boc 'c cedaunallvs acre acetal a pares ae ae 99.52
SiO, | Al,05 |
0.46 2.12 “6 OST TO ite rar Necansraier nal cia rerare ete eee eo | 99.43
SiO, Al,O3 :
0.59 1.08 ; SOS dae isn FR te Sheil severe attra teers alee erolaere | 95.41
SiO, | ALO;
0.389 | 3.79 Za Desalter oat eee Morass ciate Reto a ae late eee ee <ila & 89.60
Si,
OAG Gos. EAS ir aha renee eserois masta: aeteuts «abe eiatuial wave suakate 2 99.73
SiO, | Al,O,
0.90 | 0.60 : TE LO rate coer at ot. Cate ll naraatare. stabs @ d/eccoece. taketh waleyne 100.46
SiO, | ALO;
Os) Obl" (eet. ae Meter ars reul liters cee PLO We {isare eotll alors cfaye'e|| ow ete talertie @aiance cnc cte ee | 99.74
SiO, |
EADS olf comers bere ara bc paren Re Iee lester LE LODIM|' ctovelos Merete tier cie||(nin's ol Guibiercle Sia wld ww a ween « 100.25
SiO, |
0.24 on ROOM kee hatororare S clid oasis seara, oa tins s e aateel s 100.57
Si,
OSS Re athe Fs (OUR Pe asor lesciecteea aco Me erCo tae Ten ccpe are 98.80
SiO, | Al,O,
0.64 | 0.64 IEGOEL Pore soles Ker ccotat tales Metatet a atcinteietan anes x <te cueimrg’s 99.63
aoc c ULGIBIE Tr eactetay [iatetersy asia | iticieta dre abtors eRe, wi ater lec 98.87
SiO,
0.38 é sogy essed esa ANRAE ae yah ol Oat ce CARPE eect eaee 98.57
SiO. : ee CHOP | eeiGek | SG CR lade SSROMER ACCOR AenOOc Cerri. 99.18
1.54 mis ae inal |S Rae Re ORCA aOR 2 99.13
SiO, . trace. 0.08 SNE abe vhs Silicates = 4.20. 99.03
1.51 . | trace. | trace. re fed Eee CAE AP Ea Sete Othe SERIE ie Sr ET et
OO0FG-< > OAGE i cteewrs FeS, = 2.395. 100.00
. 1.48 Ciel eee eo Cr,03+Mn = $.24 99.988
tees . GOO. na Lanleuian dete <a caves inte madeae eae sare 99.89
pene ete ePURe eteve Bis aielad |stats wi ilimersc|Lacea: | wase | «xa levecencialecvendvcsecssestseacenas 99.87
eepereee eeaneen een | eray Se lel all tatcteic) "Iiiscciere |laiwis| ewiels || weve, | vveie [ee ceumeclscccacaccanacecusaneqens 98.77
C Eran I cee ee crey Wiha ofaraell Pare esail) aieiste, fe aiersisi, |) oo Sof felvacismvie|ec es cacwamawenegewrenioner 99.56
Bistare 1.41 | 0.15 1.76 TiSaaliec «cnicelne emema vee wa acne Welney © 100.00
: he ed TR Bea OP ae P, ete. = 3.52. 100.00
: | Serre le sieeMe eee, [cata Ishinae eee cai exsciay assis eemnieaas 100.00
REAM OSMEIPS Ae cs ei [iecice | see alte ccae [cone [omestemelseseucdennsceusvadaseees 99.19

XVl

Variety. Locality. Analyst.

Meteorite ?|Tucson, Arizona.| J. L. Smith.

Tucson, Arizona.| G. J. Brush.

Bitburg, Eifel,
Prussia.

\\ F. John.

F. Stromeyer.

Brahin, Minsk,
Russia.

A. Laugier.

Von Kobell and
Rivero.

Atacama, Chili.

Langhult, Swe-
den.

Cumber-
landite.

B. Fernqvist.

Meteorite?|Singhur, Deccan,| H. Giraud.

India.

Anderson, Hamil-
ton Co., Ohio.

(J. J. Berzelius.

Krasnojarsk, Si-
beria.

A. Laugier.

L. Howard.

Atacama, Chili. C. A. Joy.

T. Drown.

Cumber-
landite.

Iron Mine Hill,
Cumberland, R. 1.

C. T. Jackson.

Cumber-
landite.

Taberg, Sweden.} B. Fernqvist.

Meteorite ?/Sierra de Chaco,

I. Domeyko.
Atacama, Chili.

Rittersgriin, Sax-| C. Winkler.

ony.
Lodran, India. G. Tschermak.

Hainholz, Prussia.

L. P. Kinnicutt.

M. H. Klaproth.

{ R. H. Thurston.

|
|

Publication.

Am. Jour. Sci., 1855 (2), xix.
161, 162.

Proc. Cal. Acad. Sci., 1863,
iii. 80-35.

Jour. Chemie Physik, 1826,
xlvi. 386.

Jour. Chemie Physik, 1826,
xlvi. 386.

Buchner, Meteoriten, 1863, p.
129.

Korrespondenz-Blatt Verei-
nes Regensberg, 1851, v.
112.

Clark, Metallic Meteorites,
1852, pp. 17-19.

Akerman’s Tron Man., Swe-
den, 1876, p. xxxii.

i A CLASSIFIED LIST OF COMPLETE (BAUSCH)

Silicates

Edin. Phil. Jour., 1849, xlvii.|4.72-4.90|} 19.50

56, 57.

Ann. Rep. Peabody Mus.
Arch., 1884, iii. 881-384.

Ann. Physik Chemie, 1834,
xxxiii. 123-155.

4.72

Dict. d’Hist. Nat., 1818, xxvi.
259.

Mém. Mus. Hist. Nat., 1817,
iii. 841-352.

Dict. d’ Hist. Nat., 1818, xxvi.
259.

Am.Jour.Sci.,1864(2),xxxvii.| 4.35
243-248.
Communicated by M. Stan-|3.56-4.05
dish, Esq., 128 Broadway,
New York City.
Bull. Mus. Comp. Zodl., 1881,
vii. 185. ;
Geol. Survey R. I., 1880, pp.|3.82-3.88
> 52-54.
Akerman’s Iron Man., Swe-
den, 1876, p. xxxii.

Ann. Mines, 1864 (6), v. 431-
451.

Nova Acta Leop. Acad., Hal-
le, 1878, x1. 333-282.

Sitz. Wien. Akad., 1870, 1Ixi.
(2), 465-475.

C. Rammelsberg. |Mon. Berlin. Akad., 1870, pp.

322-32

20.01

20.43

Fe,035,.| FeO. | TiO. | Al,O,

43.45

Fe+Ni| FeS

23.54

Fe+Ni
50.406

26.787

Fe+Ni
82.50

29.41

33.24

39.00

14.10

FeS
7.226

FeS
7.40

4.12 | 22.20

6.30 | 5.55.

ANALYSES OF METEORIC AND TERRESTRIAL ROCKS. XVil

.|Mn0O.| P,0,;.| S. | Cr203.| Ni. Co. | Cu. | Sn: | H,0. | Loss, Misce!laneous. | Total. |
| ee eS Oe a —e : —— |
17,
FIZ rareforeters OA ee ero Mee Ole O09) 10.0006) 200600006 Analysis of a portion freest from silicates. 100.12
P; r. f |
OOM iiracasiricen) O07) | 0:44) 0.08)... Tine) c ce ool eccc es Cl trace: J. acasecnuweanewaraien | 99.08
'
og eee CU CC ORR Salinas eee Pe SRS OO eet sa. ove cameos neat |
ere irs EWI ogee aot. 2229) 200: | sca cee dew-seatececsesoececsccest tees [LOOMD |
Cr. z /
ee te. ohics esc cs cofindesc[ee--.| « 100.50 |
pcre Boreas 15a. | teade| 1.50 ; eee Ae 5 i eked Mead i rae aces
Insol.
Bet Nee ai|leie,.cleievel| aictateracell!stacve)s's 5.73 |... ceeleeeeceleceees|eeeeee| U.20 |Recalculated on the supposition that the) 98.58
silicates compose one third of the mass)
as they appear to do in the specimen
| Insol. | seen by the present writer.
Pirerevetelteiaicts ciel occetereal |» ecersl ai 4.80 |....eeJeeeeeeleseees}se++++) 0.15 |Recalculated on Clark’s supposition that) 99.63
the silicates compose one half of the
| mass.
OSOm MOMS | O:0L9i| et ., cerel sc. s os Hartoroe's | RAS ag | oleio'a, te Mt eee el | GEODETIC iac CE BONO ice CE Crete 99.137
SE nn ar nee 4.24 he Paes. ..eeee/eeeee{Amalysis very imperfect. 92.98
> | |
(EXECS | Gaon pl loeeroe §.33 | 0.22 | trace. he | Semin Recalculated on the supposition that the 99.94
| silicates compose one half of the mass.
| a . Insol.
Seen aria cleo aa 6,866 | 0,228 | 0.033 leeeeee| O.24 |Mg = 0.025, Mn = 0.066, C = 0.021,101.27
| SnO = 0.09. Recalculated on the sup-,
| | position that the silicates comprise one
half of the mass.
EEG Pees Sarat ee ele oo canacen sa eee on anayseas) OOOO
on a Pe Uh i a) ae eer Pea ea CST es Peep Coe, Pena or een MEP Fi =e
Sone ee rer Ga Veet er ee .50 |i... soca cecaceseadaceescceceonsess | 99.25]
Brett atetan{totediaiearetal | Mrctetatate| [eM stencyellisucais\ele'll-foie atefell) wists sie cille'eleie’e »'lts a0 oo Recalculated, but, owing to some doubts 100.95
regarding the original, the recalcula-
tion is probably faulty.
26 1d05] 46 Soo BOaess| ot colod aoeaer OLONS3 | raeter<! tetete mis |e» <= - Fe,Ni,P P,P Fe,Si Cr,0;+FeO 97.032
0.149, 0.274, 0.169, 0.323.
Recalculated.
Bava Sie ni slata ata ONDE acta cisilnfaicree ne |u'ne ain fs vas Me Peeccsislascece Recaléulated... 2.0.5 die eecuceincsccden | 99.462
or ERO See eee eeWe ocsics |. sefvecs.»| 2.86, |,.....|CryO,+FeO = 0.60. 98.72

A CLASSIFIED LIST OF COMPLETE (BAUSCH)

XVill
Variety. Locality. Analyst.
F. Pisani.
Meteorite. |Orgueil, France.
| |S. Cloez.
Meteorite. Murcia, Spain. S. Meunier.
Meteorite. Nobleborough, J. W. Webster.
Maine.
Meteorite. Cold Bokkeveld, oe
South Africa. | M. Faraday.
{ J. J. Berzelius.
Meteorite. |Alais, Gard, Commission French
France. Academy.
{ L. J. Thenard.
Meteorite. /Ornans, France. F. Pisani.
Meteorite. |Little Piney, Mis-| C. U. Shepard.
souri.
Meteorite. |Dacca, India. T. Hein.

*Saxonite. |Gnadenfrei, Sile-| Galle and Lasaulx.

sia.

Meteorite. |Kernove, Morbi-| F. Pisani.
han, France.

Picrite. Bystryc, Teschen.| J. Pdésch.

Meteorite. |Klcin-Wenden, C. Rammelsberg.
Germany.

Meteorite. |Heredia, Costa I. Domeyko.
Rica.

Meteorite. |Petrowsk, Staw-| H. Abich.
ropol, Russia.

Meteorite. |Kichstadt, Bava-| ( A. Schwager.
ria.

| M. H. Klaproth.
*Buchnerite. Grosnaja, Terek,) Plohn.

Caucasus.

Serpentine.|Calagrande, Tus-| A. Cossa.
cany.

Meteorite. Saurette, Vau- A. Laugier.
cluse, France.

Meteorite. |Kaba, Hungary. F. Wohler.

Meteorite. |Meno,Alt-Strelitz,| J. L. Smith.
Mecklenburg.

*Lherzolite. |Zsadany, Banat. W. Pillitz.
Serpentine. |Chester, Mass. BE. Hitchcock.
Meteorite. |Epinal, Vosges, | L. N. Vauquelin.

France.
Meteorite. |Khettree, Rajpu-| D. Waldie.
tana, India.

Meteorite.
Meteorite.

*Dunite.

Vernon Co., Wis-
consin.
Borkut, Hungary.

Chassigny, Haute

Marne, France.

J. L. Smith.
J. Nuriesdny.

A. A. Damour.

-|Am. Jour. Sci., 1876 (3),

Publication.

Comptes Rendus, 1864,
lix. 182-135.

Comptes Rendus, 1864,
lix. 37-40.

Comptes Rendus, 1868,
Ixvi. 639-642.

Boston Jour. Phil., 1824,
i. 3886-389.

Sitz. Wien. Akad., 1859,
xxxvy. 5-12.

Phil. Trans., 1839, pp.
83-87.

Ann. Physik Chemie,
1834, xxxiii. 113-123.

Ann. Physik, 1806,xxiv.
195-208.

Buchner, Meteoriten,
1863, p. 20.

Comptes Rendus, 1868,
Ixvii. 663-665.

Am. Jour. Sci., 1840 (1),
xxxix. 254, 255.

Sitz. Wien. Akad., 1866,
liv. (2), 558-561.

Mon.Berlin.Akad.,1879,
pp. 750-771.

Comptes Rendus, 1869,
Ixviii. 1489-1491.

Sitz. Wien. Akad., 1866,
liti. (1), 272.

Ann. Physik Chemie,
1844, Ixii. 449-464.
Anales de la Universi-
dad de Chile, 1859, xvi.

325-339.

Bull. Acad. St. Péters-
bourg, 1860, ii. 403-
422, 433-439.

Sitz. Miinchen Akad.,
1878, viii. 25-82.

Mem.Acad. Berlin,1803,
pp. 42-45.

Min. Mitth., 1878, pp.
153-164.

Rie. Chim. Roe. Italia, 2.992-3.025

“1881, p. 132.
Ann. Mus. Hist. Nat.,
1842, iv. 249-257.
Sitz.Wien. Akad., 1858,!
Xxxiii. 205-209.
Am. Jour. Sci., 1876 (3),
xii. 207-209.
Zeit. Analyt. Chemie,
1879, xviii. 58-68.
Geol. Mass., 1841, p.160.

Ann.Chimie Phys.,1822,
xxi. 824-328.

Jour. Asiat. Soc. Bengal,
1869, xxxviii. (2), pp.
252-258.

xii. 207-209.

Sitz. Wien. Akad., 1856,
xx. 398-406.

Comptes Rendus, 1862,
lv. 591.

re

38.599

3.45-3.55

3.4852

26.051

29.224

29.50
30.80
28.90
31.22
‘30 00
21.00
31.23
31.37

32.05

82.11

32.95
33.01
29.03
33.10

33.16

39.31
37.00
33.78
34.02
83.863
34.00
34.24
384.75
34.88
34.91
55.00

sly

35.24
35.28
35.30

7

TABLE I

Al,O3.| Fe. Fe,0y.| FeO.

0.90

1.2498

0.51

4.70
2.05
6.22
2 36

4.32
0.49
2.54
1.60

3.19
15.83
3.75
1.25

4.22

2.31

3.44

3.46

7.562

5.88

2.23

* The prefixed asterisk indicates that the specimen is a meteorite.

13.63

14.90
2.50

- | 8380 |21.60 | ae

14.236) 19.063) 2.4

5.228) O.

ia

29.94 | 19
33.22 | 1.6
29.03 | 0.8

wees {88.00 | oe

40.00

24.71 | 23

- | 17.26 |
23.88 | 1.
14.88 | 2.01
1170 | 18

2.75 | 7.62 | 1361
6.90 | 28

16.97 | 11
18.59 | 14

5 0."
16.60 | .... ja
28.86 | 3.22.

4.78 | 29.07

12.078] 15.345, 4

ase. 126.20 |
Al,O,+FeO

17.34 1.

11.09 | 3.

1027 | +:

31.87 |...

11.16 | 2

wees | 15.64] 2

4.71 | 1

26.70 | .

1¢
x 7
<a ANALYSES OF METEORIC AND TERRESTRIAL ROCKS. xix
i. .
bite.
7
Na,0.| K,0. Cr,03, Ni. Co. "Cus Sn) P S. 10. Miscellaneous. Total. |
3 meeronmorco) | | | | |. ie ae
moss | 2.26 | 0.19 0.49 2.26 5.75 |.... H,SO,= 1.54, H,SO, = 0.53,| 100.00
* ; : Cl = 0.08, H,O + organic
he Cr,03 NiO CoO matter = 10.81.
11} 1.9302 1.823 | 0.5265) 0.2892 2.6057 0.0904| .... 4.6466 | 7.812 H,SO, = 2.3345, Cl=0.0776.| 99472)
ithe” * Organic matter—=641. Am-
Cr,0;+ FeO monia—=0.1042. H,O=7.812.
0.85 | trace. 0.92 1.56 hich leaieietee (th aee, «ee eS == 20.52. 99.758
| -
case). 4.00 2.30 ral ee BPA MC TR sin nin ten Sealed 98.50 |
1.23 0.76 1.30 trace. | 0.03 | .... |trace.| 3.38 C = 1.67. Bituminous matter) 98.79 |
i . :
trace. 0.70 0.82 trace. dae IE VRBO oc capita «wise ee Cake 5 22 wks 100.44 |
C,0,+FeO NiO ——— :
‘A 0.63 1.38 0.80 ho) Oe i ee
Cr,03 Ni
2.00 2.00 .|C =2.50. H,O0+loss=9.50. | 100.00 |
NiO
eas : 1.00 2.50 3.50 . |C = 2.50. H,O+loss = 18.50.) 100.00 |
eos FeO+Cr,03 NiO
0.55 0.40 2.88 trace.|....|trace.| 2.69 |.... |Fe, Ni = 1.86. 99.42 |
Ni, Cr, Co
PEER eto cis? || ates e:si5'o abel 4.28 .... |S+P?+loss = 4.73. 100.00 )
Ge 32.5... sistas 1.63 0.11|....| 0.05] 0.78 . |NiO = 0.86. 98.47 |
PO; Sf
0.70 0.57 3.92 trace. GEOG lM CoM teeret cd [(c rat oXat niece cleeichn 6m) =totaiatta a clasts a aca 99.85
——_——— Cr,0;+FeO : FS
Lal trace. 1.55 {VACE.| 2 ess EUS Nae as rotatel Seto cawtelats olsiou 9 a/aeds sae 100.77
SIE ENE een! Oe, aera 4.23 |CO,= 11.97, Li,O =trace.| 98.70
Rock altered.
0.28 | 0.38 0.62 2.37 OSC OG: naan: laciscie< ele cb eielela\(ee'a'sls = walateas'a 100.01
eee) O08 | wes com. 1.51 . |Recalculated. 99.87
NiO S$n0,
HAO OG) a Sasc0e «cece 3.81 TOS epee ba lh) |C = trace: 99.24
1.04 | 0.40 0.15 0.94 1.42 |.... |Fe+P = 24.64. 99.15
nenotogeers 1.50 . oss, ete. == 4.50. 100.00
2 ERLE 0 Met Me A ae ae ae 0.17 |FeS = 5.87, CO, = 0.68. 100.00
Fresh portion.
PCOS MEO) SU Nctts eet, wleterty: It ickew. c'< elon sane 0.17 |CO, = 0.68. Exterior portion.) 100.07
P.O
at aN Se ee et de _ |Ti0, = 0.686. Ignition =5.868,| 99.913
a Rftiaet stl ate! oe es cas BS! ’ | an 9.00 . |H,O+loss = 3.31. 100.00
Cr,0;+FeO a =
2, 170.80 | ~ 0.89 1.37 trace.| 0.01 . |trace. . |FeS = 3.55, C = 0.58. 98.50
Ramee ete lac cdc ees 1.36 0.02 |trace.! .... |trace. . |FeS = 4.24. Recalculated. 98.99
0.31 | 4.31 0.94 2.77 ‘\trace.| 0.68 | 0.45| 2.64 |e > 021, Mn = 1.64, Cr,03+| 100.79
eO = V.ob. |
PEE hae PEI asi yes ss 9.45 Loss = 0.46. 100.00
NiO =
; . 0.25 0.50 2.25 . (Ca0+K,0 = 1.25. | 96.87 |
0.87 | trace. 0.40 1.26 0.21 0.12| 1.76 _|Cr = 0.10. Loss = 2.00. 101.31 |
1 Ce ES Cae eed 28 0:07 |trace.|.... |trace.| .... | s+ | FeS = 4.60. Recalculated. | 100.51 |
Cr O F O ———— | Oo ~ 2
191 | 066 |? 6.64 184 0.08 | 0.03| 0.89 |.... |Ni+Mn=0.78 Recalculated| 9846 |
. 0.66 EN Sc e's» | . (Chromite +Pyroxene = 3.77. | 99.59 |
+ Probably a misprint for 3.05. Buchner, Meteoriten, 1863, p. 46.

A CLASSIFIED LIST OF COMPLETE (BAUSCH)

XX
Variety. Locality. Analyst.
*Dunite. |Chassigny, Haute] L. N. Vauquelin.
Marne, France.
Meteorite. |Warrenton, Mis-| J. L. Smith.
souri.
{ F. Crook.
|
Meteorite. |Ensisheim,Elsass, 4 C. Barthold.
Germany. |
Foucroy and Vau-
: | quelin.
Serpentine. Radauberg, Harz.| <A. Streng.
Meteorite. |Stilldale,Dalecar-| G. Lindstrém.
lia, Sweden.
Meteorite. |Albarello, Mode-| P. Maissen.
na.
Meteorite. |Buschof,Kurland,| Grewingk and
Russia. Schmidt.
Serpentine. Proctorsville,Ver-| A. A. Hayes.
mont.
( G. Werther.
*Lherzolite. |Pultusk, Poland. | 4 C. Rammelsberg.
>
G. vom Rath.
Meteorite. |Muddoor, India. F. Crook.
{ F. Stromeyer.
|
Meteorite. |Erxleben,Prussia.| 4 €. F. Bucholz.
M. H. Klaproth.
{ A. Kuhlberg.
|
Meteorite. |Lixna, Russia. { T: von Cotten:
|
| A. Laugier.
(J. L. Smith.
*Saxonite. |Iowa Co., Iowa.
Giimbel and Schwa-
' ger.
Meteorite. |Nulles, Tarrago-| L. de la Escosura.
na, Spain. |
Meteorite. |Ohaba, Transyl-| £. Bukeisen.
vania.
Meteorite(?)| Mainz, Hesse. F. Seelheim.
Meteorite. [Nanjemoy, Mary-| G. Chilton.
land. |
Meteorite. |Hizen, Japan. T. Shimidzn.
‘ G. Lindstrém.
Meteorite. |Hessle, Sweden.
A. E. Nordenskjold.
*Tufa. Chantonnay, Ven-| C. Rammelsberg.
; dée, France.
Meteorite. |Blansko, Moravia.) J. J. Berzelius.
Serpentine.|Duporth, Corn.| { J: H- Collins.

wall, England.

J. A. Phillips.

Publication.

Ann.Chimie Phys.,1816,
i. 49-54.

Am. Jour. Sci., 1877 (3),
xiv. 222-224,

Chem. Const. Met.
Stones, pp. 21-26.
Jour, Physique, 1800,

1. 169-176.
Ann. Mus. Hist. Nat.,
1804, iii. 108-112.
Neues Jahr. Min., 1862,
.. pp- 541, 542.
Ofversigt Kongl. Veten.
Forhan., 1877, p. 35.

Gazzetta Chemica, 1880,

Kee:

Archiv Nat. Liv-, Ehst-,
Kurlands, 1864, iii.
421-554.

Proc. Bost. Soc. Nat.
Hist., 1856, v. 340.
Schriften K6nigsberg
Gesell., 1868, ix.35—40.
Mon.Berlin.Akad.,1870,

pp. 448-452.

Neues Jahr. Min., 1869,
pp. 80-82.

Chem. Const. Met.

Stones, pp. 33-36.
Ann. Physik, 1812, xlii.
105-110.

Jour. Chemie Physik,
1813, vii. 1438-174.
Beitrige Mineralkorper,

1810, vi. 803-306.

Archiv Nat. Liv-, Ehst-,
Kurlands, 1867 (1), iv.
1-32.

Ann. Physik Chemie,
1852, Ixxxv. 577.

Ann.Chimie Phys.,1824,
xxv. 219-221.

Am. Jour. Sci., 1875 (3),
x. 862, 363.

Sitz. Miinchen Akad.,
1875, v. 313-880.

Phil. Mag, 1862 (4),
Xxiv. 586-538.

Sitz. Wien. Akad., 1858,
Xxxi. 79-84.

Jahrb. Vereins Natur.
Nassau, 1857, xii.
405-410.

Am. Jour. Sci., 1825 (1),
x. 131-185.

Trans. Asiat. Soc.Japan,
1882, x. 199-208.

Ann. Physik Chemie,
1870, exli. 205-224.

Ann. Physik Chemie,
1870, exli. 205-224.

Zeit. Deut. geol. Gesell.,
1870, xxii. 889-892.
Ann. Physik Chemie,
1834, xxxiii. 8-25;
1865, exxiv. 213-234.

Min. Mag., 1877, i. 224.
Min. Mag,, 1877, i. 224.

2.64
2.86

Si0,.

33.90
35.63
35.647
42.00
56.00
35.67
35.71
35.913

36.011

36.10
36.25
35.85
41.54
36.256
36.52
86.625

35.50

36 824
36.582

33.20
34.00
36.34:
36.98
36.43
36.60"
36.70

36:72
36.75
36.83

36.75
37.08

36.89

87.077

37.09
85.74

Al, 03.

2.650
2.385

1.30
1.00
0.63
1.18
0.84
0.28
13.49

0.10
1.89
2.38

2.00
1.11

2.47
2.386

19.90
12.23

* The prefixed asterisk indicates that the specimen is a meteorite.

TABLE I
Fe. Fe, 0). FeO. a
31.00 | aa
1.78 30.44 | 14
8.00 34193] 1.7
20.00 24
30.00 | 1.4
6.04 | 4.95 | 0.1
21.10 10.29 | 16
4.332 24.313 20
7.918 20.978 0.70
31.07 2.6
15.55 | 3.85 | 12.12 | 1.5
1L5t Res 14.04 | 0.28
10.691 17.97 | 0.81
24.415) .... | 5574] 188
13.75 0.7
31.00 : 0.
16.824] .... | 13.929) trae
17.572 . | 12.385) trace
26.00 22.00 | 0.5€ |
40.00 05
11.16 93.98 | a
10.27 22.39 | 18
22.50 | 18.55 |... | om
21.40 1.75 | trae
5 31.89 | trace
60.30 | 09
15.85 |. 8.84 | 19
20.08 | . 10.85 | 2.8
16 42 13.36 | 1.4
16.29 13.49 | 2.6
9.77 | .... |15.99 | 18
16.089] .... | 14.945) 18
sede aca 2.02 tra
4.68 aes |

mw | cece

my

Peace weer

0.24

0.11

——

0.77
0.62 | 0.15
1.637| 0.44

0.60
0.95 | 0.89
1.84
: 0.33 | 0.285
584] 0.705) 0.741
O25) 252.
0.680 | trace.
0.759 | trace.
1.40 | trace.
0.82 | 0.57
"0.98
2h:
0.97 | 0.16
0.94
1.03
atl
Le |

|| 0.98 | 0.25 | trace.

art

ANALYSES OF METEORIC AND TERRESTRIAL ROCKS,

Cr,0;,+FeO
0.29

0.158
0.246

1.00
Cr,0;+FeO

0.759

0.632

ed

0.49
CryO,+FeO
0.59
Cr,03+FeO
0.56
0.46

0.07

0.66

Oe Ce at CRY

a

2.05
2.00
3.50
trace.
2.27
2.364

2.184

Ni. Co. |} Curl. Sm | P.
0.21 0.01
1.23 1.0138
2.40 ah aaa
CuO PO;
etavaletovetevece PACE: 5b, oe 0.08
1.61 O17 0.01
0.73 O05 +...
1.513 trace.|.... . |0.011
1.69
PA
0.65 . |trace.
1.162
1.579
0.50
0.25 e
1.725 0.120
1.690 0.163
2.00
1.50° trace.|...
1.30 0.08
2.05
1.43
1.80 . |trace.
NiO P.O;
2.08 trace.|trace.| 0.60
NiO
4.10 Mee inert: fey ke trersres
2 Eee eee aes | es
1.76 0.15 0.384
Cu0+Sn0
yma is) 0.02 0.02 0.15
198 trace. 0.01 trace.
B38 trace. 0.02 trace.
11 pSan | See TAs hes
0.866 0.06 0.079
P.O;
Sh Anh hope ares 0.21
Se astactecrs 0.18 |

2.204
2.052

3.50

6.80

0.87
trace.

2.24
0.056

ere eecesesesteseseeseesesesese

XXI
H,0. | Miscellaneous. Total.
noe 3 Re oe 98.90
---- |NIO=1.17, CoOO=0.24, FeS| 100.53
= 347. Recalculated.
Fie a.e marek, ta a owiele aolae Ane eee 99.564
Lanieis Heep va Violets ampie eer Relea 97.00 )
BW eisteset aicylielas sos ole custard Oreo aaa 105.30 |
12.04'Cr,03+FeO = 1.37. 100.04
--|Cl= 004, NiO = 020, P,0,} 100.00 |
..-» |Loss = 0.84. 99.999
. |Graphite+Sn0O,+loss = 0.146; 100.00 !
6.61 |\CO, = 17.05, FeO0+Mn-+ete.| 99.91 |
AE fede pina 3 99.97
. |Recalculated. 99.39 |
. Insol. = 0.04. Recalculated. 99.01 |
Rarer’ he cjs cle siola a diaie wininict ala ive asia tin 99.518 |
EM | size suns ia) a(wiataiocaini awidim o'pin ate al'¥" 4 99.642
. |FeS = 21.625. 100.00 |
. |S+loss = 3.75. 100.00
.. |Mn = 0.547. 99.827
. |Mn = 0.302. 107.974 |
. |Mn = trace. 100.20
. |Mn = trace. 101.80 |
_ [Lig = trace, FeS=5.82. Re-| 98.71 |
calculated.
. |FeS = 5.25. Recalculated. 99.85
. |FeS = 2.34, Insol. = 0.79. 98.20 |
. |FeS = 13.14. 100.11
1.51 |Fe, Ni = 2.18, FeS = 3.86. 100.05 |
. |Recalculated. 109.66
. |NiO = 0.80, FeS = 5.91, Mn} 99.01
ere ties. Cl = 0.04. 100.84
. |C = 0.52 100.00
. |C = 0.86 | 100.00
BE OR er Qt ee es er | 97.09 |
... |NiO= 0.207. Analysis eS 99.243
lated by Von Reichenbach. |
8.65 |TiO: = trace. 99.31
10.01 100.04

XX

.A CLASSIFIED LIST OF COMPLETE (BAUSCH)

Lherzolite.

Meteorite.

Meteorite.
Olivinfels.
*Saxonite.

*Saxonite.

Serpentine.
Meteorite.
Meteorite.

Meteorite.

Meteorite.

*Tufa.

Meteorite.
Meteorite.
Serpentine.
Meteorite.

Meteorite.

Meteorite.

Serpentine.
Serpentine.

Meteorite.

Silesia.
Presque Isle,
Michigan.
Adare, Limerick
Co., Ireland.
Alessandria, Pied-
mont.
Kalohelmen, Nor-
way.
Gopalpur, India.

Tourinnes-la-
Grosse, Lou-
vain, Belgium.

Lynnfield, Massa-
chusetts.

Kakova, Hun-
gary.

Bandong, Java.

Dundrum, Tippe-
rary Co.,Ireland.

Smolensk, Russia.
Orvinio, Italy.

Pohlitz, Reuss,
Germany.

Castalia, Nash Co.,
North Carolina.

Blanford, Mass.

Saint Mesmin,
Aube, France.

Chateau-Renard,
France.

Mauerkirchen,

Bavaria.

Varzi, Italy.

Kynance Cove,
Cornwall, Eng.

Charsonville, Loi-
ret, France.

Meteorite.

Meteorite.

*Saxonite.
Serpentine.

Meteorite.

Meteorite.

Drake’s Creek,
Sumner Co.,
Tennessee.

Aukoma
fer),
Russia.

Waconda, Kansas.

(Pillits-
Livland,

Monteferrato,
Italy.

Richmond, Vir-
ginia.

Ausson, Haute Ga-

ronne, France.

(
|
{
|
(

Variety. Locality. Analyst.
Picrite (Pa-|Fichtelgebirge, H. Loretz.
leopicrite).| Bavaria.

Serpentine. | Reichenstein, G. L. Ulex.

J. D. Whitney.
R. Apjohn.

G. Missaghi.
Hauan.

A. Exner.

F. Pisani.

C. T. Jackson.

E. P. Harris.

C. L. Vlaanderen.
S. Haughton.

M. H. Klaproth.
J. Scheerer.

L. Sipécz.

F. Stromeyer.

J. L. Smith.

I. Hitchcock.

F. Pisani.

A. Dufrénoy.

A. Schwager.

F. Crook.

Imhof.

A. Cossa.

Ss. Huston:

L. N. Vauquelin.
E. H. Baumhauer
H. Seybert.

Grewingk and
Schmidt.

J. L. Smith.

A. Cossa.

C. Rammelsberg.
A. A. Damour.
E. P. Harris.

Publication.

Gumbel’s Die palaoli-
thischen Eruptivge-
steine des Fichtelge-
birges, 1874, p 40.

Zeit. Deut. geol. Gesell.,
1867, xix. 248.

Am. Jour. Sci., 1859 (2),
xxvill. 18.

Jour. Chem. Soe., 1874
(2), xii. 104-106.

Ann. Physik Chemie,
1863, exviii. 861-363.

Verh. Geol. Reich.,1867,
pp. 71, 72.

Min. Mitth., 1872, pp.
41-45.

Comptes Rendus, 1864,
lviii. 169-171.

Proc. Bost. Soc. Nat.
Hist., 1856, v. 318.
Chem. Const. Meteor-
ites, 1859, pp. 22-84.
Comptes Rendus, 1872,
Ixxv. 1676-1678.

Proc. Roy. Soc., 1866,
xv. 214-217.

Ann. Physik, 1809,
REKULAZLOS 2

Ann. Physik, 1808, xxix.
214.

Sitz. Wien. Akad., 1875,
lxx. (1), 464.

Jour. Chemie Physik,
1819, xxvi. 251, 252.
Am. Jour. Sci., 1875 (3),

x. 147, 148.
Geol. Mass., 1841, p.160.

Comptes Rendus, 1866,
Ixii. 1326.

Comptes Rendus, 1841,
xiii. 47-53.

Sitz. Miinechen Akad.,
1878, viii. 16-24.

Chem. Const. Meteoric
Stones, pp. 26-30.

Sitz. Miinchen Akad.,
1878, viii. 17.

Ric. Chim. Roce. Italia,
1881, pp. 162-164.

Phil. Mag., 1855 (4), x.
254.

Ann. Mus. Hist. Nat.,
1811, xvii. 1-15.

Ann. Physik. Chemie,
1845, Ixvi, 498-503.
Am. Jour. Sci., 1830 (1),

xvii. 826-328.

Archiv Nat. Liv-, Ehst-,
Kurlands, 1864, iii.
421-554.

Am. Jour. Sci., 1877 (3),
xiii. 211-213.

Rie. Chim. Roe. Italia,
1881, pp. 148, 149.
Mon. Berlin. Akad.,
1870, pp. 453-457.
Comptes Rendus, 1859,

xlix. 31-86. .

Chem. Const. Meteor-

ites, 1859, pp. 44-51.

3.621-4.23
3.815

eee wees

8.519
3.066-3.57

3.70

3.6046

{ 8.675
(3.600

3.4938
2.601

eeeeeeee

8.484-3.487
3.647

3.40-3.60
2.55
8.3713

3.51-3.57
38.50

SiO.

37.12

37.16
37.25
87.26
37.403
37.42
37.44
37.47

37.50
37.62
37.65
37.80
388.00
39.00

38.01
36.82

88.0574
38.06
38.09
38.10
38.13
38.14

25.40
38.22
38.29
38.40
38.503
40.00
38.593

388.61
38.70
38.71
38.72
38.46

Al,03.| Fe. |Fe,03.| FeO. | Cat

4.96

1.43

2.03

8.65
0.10

2.52
3.65

2.25
3.96
0.85
1.00

2.22
2.31

3.4688

2.12

8.00
3.82
2.51
1.705

trace.

3.60

4.807
2.466
2.491

1.09
0.58
2.17
1.85
2.25

* 'The prefixed asterisk indicates that the specimen is a meteorite.

TABLE Ij

~8.92 | 7.62 | 61
eee
10.66
6.75 |14.14 | ..0
16.24 8.95 | 3.61
19.37 12.831] 3.14
ess |...
20.96 11.94 | 1.60
11.05 13.89 | 2.61
2.50 |...
7.11 | .... | 22.47 | 0.69
4.95 | 4.30 | 16.87 | 1.06
19.57 7.92 | 1.82
17.60 | 25.00 | .... | 0.7
17.75 | 17.60 | ..
22.34 6.55 | 2.3
22.11 9.41 | 231
17.4896] .... | 4.8059] ...
14.02 18:10 | 2
6.75 :
4.94 17.21 | 1.0
7.70 | .... |29.44 | 0.14
... [25.70 | 2.2
23.32 | 2.1]
2.33 | 40.24 A
wee. | 14.05 | trace
.. | 1850 | J
25.80
12.816 .... | 10.029) 0.7
12.00 12.20
25.667 2.519) 0.4
4.60 22.81 | trac
3.19 | 7.26 | trac
6.45 | .... [1817 | Qi
8.63 16.93 | 08
7.13 18.00

“MnO. | Na,0.| K,0

0.40 | 0.40 | 0.49
1.16
0.79 0.12
0.62 | 0.21

2.26
1.76 | 051
Bald -| 1.07
0.96 | 0.50
146 | 0.31
0.96 | 0.26
0.55 | trace.
3.13
0.86 | 0.27.
1.00 | 0.48
0.242 | 0.145
0.594 | 0.025
0.341 | 0.24
1.07 | trace
0.57 | 0.11
0.10 | 0.18
ry m

ANALYSES OF

Cr,03. Ni. Coma@r. || Sn.|) -P.
| P.O
ete ce | On ae 0.10
G60 SS AOCe ere
1.75 2.73 0.10
0.845 1.077 trace.
; NiO
bieiete o. Prishin 0.23
trace. 1.80 0.10
CryO3+Fk eO
0.71 1.80 0.17
Gi, Leo Ae Fes eae
0.07 1.24 0:10) |trace:|..... 0.01
eee?
1.03 0.14
Cr,0,-LFe0
1.50 1.03
mintarevesorereioie 0.40
Sayers aaa 1.25
rte a ace 2.15
Ree Ore e 8.04
0.1298 1.3657
misiehe clei abe a2 0.06 |trace.| .... |trace
GOLERO Retr Gretel errs
O7E Sia? | BCR Ree
WE erac te 3 1.55
(116542 gra ee eee Ae 0.14
Cr,0;+FeO
CORIO a ie rae
Lek eis ae 1.20
Chaes © NGG ae aa
re Ps Rites \ireget a: alka ove oc F
1.50 6.00
1.874 1.495 0.162 0.065
— NiO |
0.833 2.166 heen
0 487 1.878 trace. . | 0.015
Mate wr aeietdars 0.64 0.10 |trace.| .... |trace
NiO
0.30 trace
cee Cae 1.18
Gr 0, FeO
83 0.96
Gn ds
0.78 1.02 0.06 . |trace.

METEORIC AND TERRESTRIAL RO

3.831

trace.

2.13

5.00
1.804
2.453

3.492] ....

2.10

+ Probably a misprint for 3.601.

CKS.

Miscellaneous.

5.04 |TiO, = 0.40, CO, = 0.09.

12.15 |FeAs = 2.70.

10.89 |Analysis of soluble portion

only.
. |FeS = 6.54, Re-
calculated.

ee a

V = trace.

oh ete Meer aes |

|
i

XXIlil

98.60

100.34
98.85
99.12
98.327
99.73

98.90

| 99.72

nies 2 eae on

15.C0 |CaCO; = 4.00. | 100.00
... |Graphite=0.14. Necalculated.| 101.13
Be Sieg) Mince Ort Hear eer | 98.33
... |FeS = 4.05. Recalculated. | 98.99
3... |Loss, ete. = 3.00. 1006.00
. |Loss, etc. = 4.50. 100.00
alsin sana cela Gali aia" 101.42
heteselhl eraiete eleiaie eles cia oanst xin cites aint 100.95
. |Li,0 = trace. 98.92 |

14.77 |Loss = 0. 20. 100.00
. |FeS = 2.99. 99.00
Fob oh Se Goi BOR SURE DCCC EE ICSC: 99.97
. |Fe+Ni = 6.30. 100.75

. |Fe+Ni = 3.745. 98.436

. |S+loss = 2.08. 100.00

PAS GEN are, 3) o-ai2s sino a spquminl tele aieh. casep 09.00
PROG a oc cies cipin castes ees ante wom 98.12
ofa SASS camitor heer Lie 98.70
Cu0+Sn0,+NiO = 2.528 100.00

cn nl Ret eae Scenes itatatai wala nies os 95.931
Graphite +TiO,+loss = 0.115. 100.00

|
. |Li,O = trace, FeS = 3.85. ey 98.38
calculated.

. (Ignition = 18.23. 99.70
aloe! | etna Car eee rae, nintetn ayeMareiais ea s'4 98.15
. |P+Fe+Ni, etc. = 2.00, FeS =| 99.05

3.74. Recalculated.

; ne =2.51. Recalculated. 98.01

XXIV

|
Variety. | Locality.
Meteorite. ‘Ausson,Haute Ga-
| ronne, France.
Picrite. Schonau, Neutit-
schein, Moravia.
Serpentine. Neurode, Silesia.
Serpentine. River Oisain, Ti-
| mor.
Serpentine. Lizard, Cornwall,
England.
Meteorite. Rakowska, Tula,
Russia.
Dunite. Sondmore, Nor-
way.
Picrite. ‘Sohle, Neutit-
schein, Moravia.
Serpentine. Prato, Italy.
Meteorite. Linn Co., Iowa.
Meteorite. Cynthiana, Ken-
tucky.
*Buchnerite. Alfianello, Bres-
cia, Italy.
Meteorite. Sétif, Algeria.
Serpentine. Rio Marina, Elba.
Meteorite. |Utrecht, Holland.
Serpentine. Longone, Elba.
Meteorite. Parnallee, India.
Serpentine. Rio Alto, Elba.
Dunite. Karlstatten, Aus-)
tria.
Meteorite. |Honolulu, Hawaii,
Sandwich Isls.
Meteorite. Villeneuve, Ales-
sandria, Italy.
Meteorite. |Girgenti, Sicily. |
Serpentine.| Valle Tournan-
; che, Piedmont.
Serpentine. | Montemezzano,
Italy.
Olivinfels. |Kraubat, Steier-
mark.
Serpentine.| Portoferraio,
Elba.
Meteorite. |Swajahn, Kur-
land, Russia.
Meteorite. |Nerft, Russia.
Meteorite. |Pohgel, Kurland,
Russia.
Serpentine |Ballinahineh
Quarry, Conne-
; mara, Ireland.
Meteorite. |Schénenberg, Ba-
4 varia.
Meteorite. Sokol Banja, Ser-

via.

A CLASSIFIED LIST OF COMPLETE (BAUSCH)

Analyst.

Filhol and Leyme-
rie.

F. IX. Szameit.

G. vom Rath.

Pufahl.
J. A. Phillips.

P. Grigoriew.
W. C. Brogger.
G. Tschermak.

A. Cossa.
{ C. Rammelsberg.
C. U. Shepard.
J. L. Smith.
H. von Foullon.
S. Meunier.
A. Cossa.
E. H. Baumhauer.
A. Cossa.
E. Pfeiffer.
A. Cossa.
Kouya.
A. Kuhlberg.

Bertolio.

G. vom Rath.
A. Cossa.

A. Cossa.

H. Wieser.
A. Cossa.

A. Kuhlberg.

A. Kuhlberg.
A. Kuhlberg.

J. A. Galbraith.

C. W. Giimbel.
S. M. Losanitch.

Publication.

Comptes Rendus, 1859,
xlviii. 198-198.

Sitz. Wien. Acad., 1866,
liii. (1), 266.

Ann. Physik Chemie,
1855, exv. 553.

Sammi. Geol. Mus. Lei-
den, 1884, ii. 109.

Phil. Mag, 1871 (4),
xli. 101.

Zeit. Deut. geol. Gesell.,
1880, xxxii. 417-420.

Neues Jahr. Min., 1880,
ii. 187-192.

Sitz. Wien. Akad., 1866,
liii. (1), 263; 1867,
lvi. 274, 275.

Ric. Chim. Roe. Italia,
1881, pp. 151, 152.
Mon.Berlin.Akad.,1870,

pp. 457-459.

Am. Jour. Sci., 1848 (2),
vi. 408-405.

Am. Jour. Sci., 1877 (8),
xiv. 224-227.

Sitz. Wien. Akad., 1883,
Ixxxviii. (1), 483.

Comptes Rendus, 1868,
Ixvi. 513-519.

Ric. Chim. Roe. Italia,
1881, pp. 134, 155.
Ann. Physik Chemie,
1845, Ixvi. 465-498.
Ric. Chim. Roe. Italia,
1881, pp. 136, 137.
Sitz. Wien. Akad., 1863,
xlvii. (2), 460-463.
Ric. Chim. Roe. Ttalia,
1881, pp. 135, 136.
Sitz. Wien. Akad., 1867,

lvi. 277.

Archiv Nat. Liv-, Ehst-,
Kurlands, 1867 (1),
iv. 1-82.

Comptes Rendus, 1868,
Ixvii. 322-826.

Ann. Physik Chemie,
1869,exxxviil.541-545.

Ric. Chim. Roe. Italia,
1881, p. 120.

Ric. Chim. Roce. Italia,
1881, p. 150.

Min. Mitth., 1872, p. 79.

Ric. Chim. Roe. Italia,
1881, pp. 137, 138.
Archiv Nat. Liv-, Ehst-,
Kurlands, 1867 (1), iv.
1-32.

Ann. Physik Chemie,
1869, exxxvi. 448, 449.

Archiv Nat. Liv-, Ehst-,
Kurlands, 1867 (1),
iv. 1-82.

Jour. Geol. Soe. Dublin,
1852, v. 188.

Sitz. Miinchen Akad.,
1878, viii. 40-46.

Berichte Chem. Gesell.
Berlin, 1878, xi.96-98.

2.961

2.57-2.59

ecee wees

eee wrens

2.59
3.57-3.65
2.61
8.115
2.61
38.011

8.5309
3.3964

3.29
5.594
2.80
2.56
2.889
2.53

3.4341 j

Si0,.

56.28
38.72
38.78
38.81

38.86
88.58

38.87
38.87
388.90

38.94
38.96
52.34
88.99
39.14
39.20
39.21
39.301
89.58
39.408
39.58
39.61

39.65

39.661
39.72
39.76
39.77
39.87
39.932

39.97
40.414

40.00

40.05
39.556

40.12

40.13
40.14

* The prefixed asterisk indicates that the specimen is a meteorite. ~

TABLE IV

Al, O3.| Fe. |Fe,03.| FeO. | CaO,
1.82 | 8.30 | 2.82 | 15.388 0.55
10.19 6.80 | 6.14 | 10.87
3.06 14.19
1.14 5.80
2.95 1.86
3.06 1.95
2.66 | 5.67 e\ Rees
10:30)". ciel) ceeoU
1.18
2:00 | 18-51 eS aeee
8.98
0.22 | 5.36
0.98 | 11.81
1.64
trace. 7.87
2.252) 11.068) ....
trace.
2.578) 9.88
7.65
1.68 !
1.98 | 6.45
0.415) 20.70 | .
1.44 | 10.40
5.11
trace. 1.76
0.89 9.76
trace. 6.899
8.06 +1) 6.15: | ssn...
8.798) 8.322) .. a
3.52 | 8.86] .... | 15.98 | 0.08
8.94 | 10.15 | .... | 14.11 | trace
3.299) 8.835 14.962) 0.188
trace.| .... | .... | 3.47 | tae
5.57 | 13.77 17.12 | 2.31
§.82 25.54 | ..6

ANALYSES OF METEORIC AND TERRESTRIAL ROCKS. XXV

nO. Na,O. | K,0. Cr,03. Ni. Co. | Cu.| Sn. | P. | S. HO. Miscellaneous. | Total. |

RUMEN Meter ots || gaiala 6, 1/0 "eee 0.72 siseePil\eiiew lice'on [ard | 1.82) | .. aphecalenlated,

|

}

PREIOIEM |fa CEN diplll|(© ctetolvreye eiecorst-l’ cee y sieve ee sees |ecee loess | ese! oe. | 3.96 |/TIO, = trace, CO, = 2.93, Or-| 100.27
ganic material = trace.

0.1) | 0.29 | ........0. | ceeeeeeeee .-- \Ignition = 7.74. 99.55

99.73

0.12 | trace. Be AS anc ais 3s wee. | 0.04] ....|0.08 | .... 114.87 |TIO, = 0.16. 99.92

0.77 |-0.33 0.08 0.28 eee Bere rs. (tier alta Mees. [LODE Lok ole oc xe aa cre dee oD nny’ asoee 100.30
0.76 | 0.30 0.08 0.3 OPA ed eres el Mee ds nc (LDS bacnccies «ace dt bdatdabauude aco 99.97

Cr,0,+FeO
2.04 | 0.37 0.81

1.45 0.82 |....|....|0.12 | .... | .... |Mn= trace, C = 0.13, FeS =| |
6.16.

S
8

ee es ae rio, Pe Semen see wk 3... | eo Ome= D8 99.10 |

-ong |p ego 0.29 trace. eereel|reta= = ilreeel-1)|"ereterel| lelee's | ewe | kNtION —-1 5.00. 99.84 |

Mie SetTaACG:|| Gece cscs 1.08 eter Wate scid lerestaullteyerc of | re. |e oat eie! RRECRICDIAtCE. 100.00 |
—_——s+seseo ;
Me ote ea | aie, oc cvsictecote 1.46 etree Pare Ve hears, o)\Plesie-«.)| Neves on'| «sere [ RES == 0.00. Recaleulated: 98.21

O49 } +. 5% 0.15 0.50 ONT eran tes te arotea Wale oon aie | «see (Pes 5.00) Recalculated. 101.77 |
Wom | OO! wc ee ees 1.09 eee siete retc aU far aeal) sh ds Were aon'|'tctcle-se secant sai amnd ot wa ma 100.42 |
OSL ORT INT oe accreted Brien ecterrulicereis all gates || @eeetl = manthe-aNiv== G.oc, Kes — o.04. 99.84 |

OPA TagmMllitete singe ces aus Bere eee elect Seles arevihio -Felerss ||) sereren| Lp DETON)— 12.54. 99.44

YY -_-——_—s4Y> «

1.895 | 0.152 0.656 1.242 0.025 0.005} 1.897] .... |MnO + NiO = 0.609, CuO-+} 100.00

SnO, == 0.256. i

eee we Cae aOR emsviniinas tl. seaehh<woeil <= |-aeds,pliO,' == trace, Ienition = 12.85 99.78

Cr,0,+FeO

1.907 | 0.547 trace. } 0.904 0.06 |trace.|trace.| 0.10 | 2.712 |0.684 |CoO, = 0.06, Zn = trace, NiO} 100.00
== 0.724.

Rit SR aro sha raYaunss5 ads Hanae ecreet |) uct |. se vin -| ema, BION — 12,92. 100.45 |

Cr,03;+FeO — |
0.88 | trace. 1.35 1.63 Severeitae atc] CLUE | AO Ste Ran card aides ssa an eelocaawene 98.09 |
= SS ae ae NiO B02
4.151 0.036 6.3871 --+. |trace.| .... | 0.597} 0.503] .... (Cl = 0.105, Loss = 0.537. 100.00
Cr,0;+FeO
1.00

BOG! -\...-)-+--|«ss+ |---| 206 |.... |Recaleulated. 98.45 |
Sit). thaee: trace. Seat ax cite tcl) nies | MD oc once cata s ane deenins onsen 99.72

feel. 3. x DOSEN ices. ee ieee tes |. s.| -... ba daaienition== 19M 99.71

tat aisles ~atchesee a -0'hais 0.66 PTs [ick oVetl (SAV F. oy||| akatcte || sere: )|| OABUehale « tinain cio’ v's alate ge eenelwe e's 100.11

ee Gop OPAL st5.c Sas. « Bere Nieania Wawel aieidlc | scat s{ be vies | 1Og== trace; Ignition==18.047.) ‘106.685

eco
0.64 | 0.09 0.64 1.45 eoee |... | 0.01 | 1.88 | .... [Mn = 0.05. 98.30
0.568 | 0.038 0.478 1.255 bierete [ieee |\QL005| 1-298 |, «.... in == O08, 98.269
CeO Bet |

93.258

0.765| 0.123| ~ 063 | 1.58 ..ee|..-. |0.06 | 2.35 |.... [Mn = 0.09.
9 98.811 |

0.630 | 0.072 0.848 0.981 e+ | see | 0.059) 2.565] .... [Mn = 0.167.

trace.|---- | .... | 0.05 | 2.02 |.... |Mn =0.10. | 99.40
<2 a oa eee PA aaa ale Rt bacsert. <ai> TARO EOy =a. OR 98.99

| 2.20 | 0.73 0.60 1.47 ees & Ela sed ee re OBOn)| LOS) | we Ss fone Manisa guiness gee eeu cesaus 100.00
0.26 | 0.06 0.04 0.92 QiOF » jie 'sisinil|) sca rot trace.

A CLASSIFIED LIST OF COMPLETE (BAUSCH)

Variety. Locality. Analyst.
( A. Kuhlberg.
Meteorite. |Bachmut, Jeka-
therinoslaw, Bic. Giese
Russia.
= Wohler.
*Buchnerite.| Tieschitz, Mora- | J. Habermann.
via.
Serpentine. |Fohrenbiihl, Ba- | G. Schulze.
varia.
Serpentine. Orford, Canada. T. S. Hunt.
*Saxonite. |Goalpara, India. N. Teclu.
Picrite. Dillenburg, Nas-| G. Angelbis.
sau.
Serpentine. | Heiligenblut, Ca-| R. v. Drasche.
rinthia.
Serpentine. |Lizard Point, T. S. Hunt.
Cornwall.
Serpentine.|Favaro,Piedmont.| A. Cossa.
Serpentine. |Levanto, Italy. C. T. Heycock.
Meteorite. |Doroninsk, Sibe-| J. Scheerer.
ria.
R. F. Marchand.
Serpentine.| Fahlun, Sweden.
J. L. Jordan.
Serpentine. |Sprechenstein, E. Hussak.
Tyrol.
Meteorite. |Rochester, Indi-| J. L. Smith.
ana.
Meteorite. |Dhurmsalla, S. Haughton.
India.
Picrite. Freiberg, Neutit-| P. Juhasz.
schein, Moravia.
Serpentine./Talof Copper Ivanoff.
Mine, Ural.
Serpentine. |Ober-Steiermark, | H. Hofer.
Austria.
Serpentine./Col de Pertuis,} A. Delesse.
Vosges, France.
Serpentine. |Corio, Piedmont.| A. Cossa.
Serpentine. | Verrayes, Pied- A. Cossa.
mont.
Serpentine. |Sprechenstein, E. Hussak.
Tyrol.
Meteorite. |Zaborzyca, Vol-| A. Laugier.
hynia, Russia.
Meteorite. |Searsmont,Maine.| J. L. Smith.
Serpentine. |Heiligenblut, Ca-| R. von Drasche.
rinthia.
Meteorite. |Krahenberg, Ba- eS
is | A. Schwager.
Dunite. Bonhomme, Vos-| B. Weigand.
: ges, France.
Serpentine. | Neurode, Silesia. Fickler.
Meteorite. |Stewart Co., J. L. Smith.
Georgia.
Serpentine. |Syria. S. Haughton.
Serpentine.| Villa Rota, Italy. | A. Delesse.

Publication.

Archiv Nat. Liv-, Ehst-,

Kurlands, 1867 (1),
iv. 1-32.
Ann. Physik, 1815, 1.

117, 118.

Sitz. Wien. Akad., 1862,
xlvi. (2), 802-3806.

Denks. Wien. Akad.,
1879, xxxix. 187-201.

Zeit. Deut. geol. Gesell.,
1883, xxxv. 451.

Am. Jour. Sci., 1858,
xxv. 219.

Sitz. Wien. Akad., 1870,
Ixii. (2), 852-864.

Inaug. Dissert., Bonn,
1877, p. 9.

Min. Mitth., 1871, p. 8.

Am. Jour. Sci., 1858,
XXvi. 239.

Ric. Chim. Roe. Italia,
1881, pp. 125-127.
Geol. Mag., 1879 (2),

vi. 867.

Mém. Acad. St. Péters-
bourg, 1818-14, vi.,
Hist., p. 46.

Neues Jahr. Min., 1845,
p. 831.

Neues Jahr. Min., 1845,

p. 831.
Min. Mitth., 1882 (2),

v. 67.

Am. Jour. Sci., 1877 (3),
xiv. 219-222.

Proc. Roy. Soe., 1866,
xv. 214-217.

Sitz. Wien. Akad., 1866,
liii. (1), 265.

Neues Jahr. Min., 1847,
p. 207.

Jahrb. Geol. Reichs.,
1866, xvi. 443-446.
Ann. Mines, 1850 (4),

xviii. 341.

Ric. Chim. Roce. Italia,
1881, pp. 123, 124.
Ric. Chim. Roc. Italia,
1881, pp. 115-118.

Min. Mitth., 1882 (2),

Wo (0)

Ann. Chimie Phys.,
1824, xxv. 219-221.
Am. Jour. Sci., 1871 (38),

ii. 200, 201.
Min. Mitth., 1871, p. 9.

Sitz. Miinchen Akad.,
1878, viii. 47-58.

Sitz. Miinchen Akad.,
1878, viii. 47-58.

Min. Mitth., 1875, p. 187.

Sitz. Wien. Akad., 1867,
lvi. 274, 275.

Am. Jour. Sci., 1870 (2),
1. 889-341.

Phil. Mag., 1855 (4), x.
254

Ann. Mines, 1848 (4),
xiv. 79.

eeeescece

er

eee eww ee

40.209 | 2.884| 8.105
88.971 | 2.554) 8.928
44.00 | 3.00 | 21.00
838.71 | 2.78 | 12.00
40.23 | 1.93 | 10.26
40.80 | 1.30

40.30

40.36 8.49
40.37 | 9.86

40.39 | 1.68

40.40 | 0.65

40.43 | trace.
40.47 | 4.35

40.50 | 3.25

40.52 | 0.21

40.82

40.55 | 2.70

40.61 | 0.10 | 9.45
40.69 | 0.60 | 6.88
40.79 |10.41

40.80 | 3.02

40.81 | 1.09

40.83 | 0.92

40.88 | trace.
40.90

40.86

40.90 | 2.08

41.00 | 0.75

41.04 0.86 13.16
41.05 | 1.67

41.12 | 3.22 | 10.37
59.08 | 2.08 4.43
41.13 | 0.84

41.13 |13.56

41.15 | 2.17 6.09
41.24

41.34 | 3.22

* The prefixed asterisk indicates that the specimen is a meteorite.

Al,03.| Fe. |Fe,03.| FeO. | Cal

TABLE Ij

22.374) 0.0
15.236) trae

1.385

2.05

7.68
45.00

8.82

3.86

A me
ANALYSES OF METEORIC AND TERRESTRIAL ROCKS. XXVIl
. | Na,O. K,0. Cr203. Ni. Co. | Cu. | Sn. | P. S. | H,0O.| Miscellaneous. | Total.
ge teh.) | <——_--—___ o™ | |
0.519 | trace. 0.644 1.195 sees | veoe | 0.042) 2.516] .... [Mn = 0.228. | 98.936 |
0.784 | trace. 0.939 1.293 sees | ecee | 0.051] 2.221] .... |Mn = 0.185. 97.782
« | ’
EEN, Ge 250 | 02. | ---- fence | ecee| see | eee [S-+Cr,0,—=1.00,Mn=1.00. | 90.50
- , ——— +- ——~ '
0.45 | 0.18 2.00 1.09 ~es- |... /0.02 | 1.81 |....|Mn=1.00. Recalculated by| 98.76
P,0; A. Kuhlberg.
BS Ares San fs la ors ch wwiatons 1.31 Pe te et ta tae amO bss, .ladversien edscee ced nanaeneepame | 99.02
0.90 seh Ben erecta nara tert W cece tr ctche a! EOLOO: | ce, oa cts peletalelelsletan Wadia alate woe | 99.56
Ni
P trace trace. Mesias): latent o diaveitin ae's,9'0, plain o oboreltaa 100.00
Mie tas eed tera) nn ce | n> --)| -->+ | «<> | nae. (C= O72, H— O18, Reealet| 10108 |
lated by Teschermak.
SerTOe POLS Ah llr tata epeietsts cyave lll wes, o1s Sooo nie Ey OE WISN eo ct in’u wicks ae ciate oe ara went s ats 99.77
RP cerca bad teste eth crareraiy |S sresaveqaiean arare OSG no taon «acetate noctatnan 100.13 |
Cr,03+FeO NiO
TAT 0.15 Ignition = 13.90. 100.00
NiO
Rear |e aae trace. 0.06 Breen |Weerren tere col lteva cat saicrare. OGD" S:crle wrerele oe ae be oe oeeeige ea wie am 100.25
NiO :
esa 0.49 ME one cet oe. eilicsieiee ol en ee) [LigO--BeS. "TROL 100.11
2.00 10.00 Peete eetiRem ere: ||| eine | Gola | sate. |a0Ss == LkS: 100.00
ES OAOCE OL | MarR 18.85 |C = 0.30. 99.94
SER eR Yor' rere voles caatsucrey® NSBR eR ce Ge cieite casera oe stciviere nist Oe
3 GAPE Oe | Bee eae ee SYA) ae ere ee ear erie ee perry LO UC
(Rea 0.05 0.42 0 Obuilbstec leekeielitcaslmc.c% | avo. eS: 38.00: Recalculated. 101.85
Cr,03+FeO
0.39 | 0.21 |- 4.16 1.54 eee Pe ater al! cs lls aie eet sea |MeS — 0.01.9 Mecalculated. 99.14
MNT SN oin5 orale te-ncaieho| a bid wis oo eee Pree einen ss ca" | a2) 4,08 |COy = trace. 99.3
Ae EO OE oo acne 1D Oa Vs eee iceaceams Sra aca Mime as otalain. el ete: s are 99.24
are CES Miah otters iararae sls TG 2Gi aaa. eet ones aon faire aainis 98.53
(MGI = oe oisistc aire nic Ignition = 10.70. 100.00
NiO
i trace 0.51 Bates URS Tae Recon are aabiaic ninnid winieia ag v'e'ste 98.92
NiO P.O;
4 0.02 0.08 trace. SOLO) epee crate\aierare.pieie Rs argh =, ere ep tee 100.43
' 2 0.03 0.09 trace. EEOC. 7. ScacSexeatebecee a awe | 100.05
Mearoratal Revove arSoul| Bro chcvavave svoretehellt. hictess/ateiore. e bez FUE ees. sore tccvc siaete aa Iamlacnin sain kia [eee
Meters HIM savers 0.75 1.00 Pen pee ee |e el ACOON lc oe elfen ov me a. os eee alee de wie we 109.40
-_—-_-——”
0.86 Undt. 132 0.06 |Undt.| ....|Undt.| .... |.... |Li,O=trace. Recalculated. | 98.61
whe ne | Oe ae eran Wig Parra Ailleerices see .... [Ignition = 8.45. 100.60
SnO,
Ons) 1222 0.89 1.56 Rey ees OTST!) 2a! ia cccelcecsecliecclevieonas eee eccahiass 100.32
1.81 | 1.48 Gi abe... RM erat er ol at: |S2s [oc soc Sats ode ds aan ooh <n 99.25
NiO c
. | trace. | trace. a trace. trace. Meee eed 8 Ss Slee oaeegas See geanceneenaw ay 100.50
To0,+FeO |: |
Pamioss) sib ol 2.....c. $901.4 ye ees geet 102.40
1.06 | trace.| ........ m4 0.85 0.05 |....]....]..c.| wece | esos [FeS=6.10, Li,O=trace. Re-/ 100.59
calculated.
SSE SC erOge Coll Seo aga PIG teen caer satan atwer een whe 99.09
ease WPACE MIRE. Sov ec. es TDNOGiikss loves cwvctwde cavetteaen acts 99.57

XXVull
Variety. | Locality.
Picrite. ‘Schriesheim, Ba-
| den.

Serpentine. Hillswick Ness,
Scotland.

Serpentine. Windiscl-Matrey, |
Tyrol.

unite. Franklin, Macon,
Cos N.C:

Meteorite. |Mezo-Madaras,

Serpentine. |
Lherzolite. |

Serpentine.

Meteorite.

Meteorite.

Dunite.
|
Lherzolite.

|

Serpentine.

Meteorite.

*Lherzolite.

Serpentine.
Serpentine.
Lherzolite.

Meteorite.

Serpentine.

Lherzolite.

*Lherzolite.

Schillerfels.

Dunite.

Picrite.
Serpentine.
Serpentine

Picrite.

'Goujot,

Transylvania.

Kiihstein, Bava-
ria.

Germagnano,
Piedmont.

Dillenburg, Prus-,

sia.

Serpentine.|Malenker Thal,

Graubiindten.
Renazzo, Ferrara,
Italy. |

\Krahenberg, Ba-

varia.

Webster, Jackson
Co., N. C

Mohsdorf, Sax-
ony.
Radau, Harz.

Guernsey Co.,

Ohio.

New Concord,
Ohio.

Vosges,
France.

Poldnewaja, Rus-
sia.

Harz, Germany.

Middlesborough,
Yorkshire, ing.

Findel Glacier,
Zermatt, Swit-
zerland.

Germagnano,
Piedmont.

Mocs, ‘Transylva-
nia.

Altthal, Transyl-
vania.

Dun Mt.,near Nel-
son, New Zea-
land.

Sdhle, Neutit-
schein, Moravia.

Zermatt Thal,
Switzerland.

Aberdeen, Scot-
land.

Ty Croes, Angle-
sey.

A CLASSIFIED LIST OF COMPLETE (BAUSCH)

Analyst.

Cc. W. C. Fuchs.
M. F. Heddle.
R. v. Drasche.

T. M. Chatard.

| { Wohler and Atkin-

son.

| |C. Rammelsberg.

G. Schulze.
A. Cossa.
Cc. Schnabel.

L. R. v. Fellenberg.

A. Laugier.
G. vom Rath.

F. A. Genth.

Leuckart.

A. Streng.

J. L.. Smith.
(J. L. Smith.
| D. M. Johnson.
| A. Madelung.

A. Delesse.

A. A. Losch.

F. Kohler.

W. Flight.

V. Merz.

A. Cossa.
F. Koch.
J. Barber.

{ A. Schrotter.
A. Madelung.
V. Slechta.

S. Haughton.
J. B. Hannay.
J. A. Phillips.

Publication.

‘Neues Jahr. Min., 1864,
| pp. 826-332.
(Min. Mag., 1880, iii. 21.

|
|

Min. Mitth., 1871, p. 4.

‘Geol. North Carolina,
1881, p. 42.

Phil. Mag., 1856 (4), xi.
141-148.

Zeit. Deut. geol. Gesell.,
1871, xxiii. 784-737.
Zeit. Deut. geol. Gesell.,

1883, xxxv. 447.
Ric. Chim. Roe. Italia,
1881, pp. 112, 1138.
Rammelsberg, Hand-
worterbuch, 4, Supp.,
1847, p. 200.

Neues Jahr. Min., 1867,
DloT.

Ann.Chimie Phys.,1827,
xxxiv. 139-142.

Ann. Physik Chemie,
1869, exxxvii.828-336.

Am. Jour. Sci., 1862 (2),
xxxiii. 199-203.

Neues Jahr. Min., 1876,
pp. 232, 233.

Neues Jahr. Min., 1862,

. 540.

Am. Jour. Sci., 1861 (2),
xxxi. 87-98.

Am. Jour. Sci., 1861 (2),
Xxxi. 87-98.

Am. Jour. Sci., 1860 (2),
xxx. 109-111.

Buchner, Meteoriten,
1863, p. 105.

Ann. Mines, 1850 (4),
Xviil. 342.
Zeit. Kryst., 1881, v.

591

Neues Jahr. Min., 1862,

896-899.

Vierteljahr. Nat. Ge-
sells. Zurich, 1861, vi.
369-372.

Ric. Chim. Roce. Italia,
1881, p. 111.

Min. Mitth., 1883 (2),
v. 248.

Sitz. Wien. Akad., 1867,
lvi. 266-275.

Zeit. Deut. geol. Gesell.,
1864, xvi. 341-344.
Zeit. Deut. geol. Gesell.,
1864, xvi. 341-344.
Sitz. Wien. Akad., 1866,

liii. (1), 270.
Phil. Mag., 1855 (4), x.
254

Min. Mag., 1879, ii. 194.

Quart. Jour. Geol. Soc.,
1883, xxxix. 256.

p. 641.
Phil. Trans., 1882, pp.|

See ©) ee) 6's

eee e ew ee

eee eee ne

weer ceee

ee eee wwe

eee teens

ween ewe

41.89
40.74
41.99
42.02
42.24
42.25
51.25
40.591
42.26
42.34
42.36

42.59

42.53
42.27
42.44
4245
42.13

42.70
42.74
42.77
42.80
42.69
42.85
42.88
42.91

42.94
42.79

Al, O;.

6.63

0.06
trace.
trace.

6.734
13.89

0.28

0.28

5.825

2.84
trace.

7.48

10.42

0.65

10.87
10.98

* The prefixed asterisk indicates that the specimen is a meteorite. ©

Fe.

18.10
12.12

6.51

9.31

9.309,
8.803
5.778.

TABLE I

Fe,0;.| FeO.

13.87 | 6.80 | 7.4

2.422) 1.163} trac

2.63 | 6.31 | 18
7.49 | 0.1
4.61 | 1.80
15.44 | 1.68

3.85 | 4.67

2.95 | 10.38 | 1.7

.... 126.95 | 8.34
7.96

43.00
19.53
7.39
7.26

9.143] 1:659
3.19
25.03 ;

.2.. | 25.03] Of
25.204

5.819 18.133

0.29 | 1.98

1.03

3.34

6.27

0.77

8.47

3.40

Iu nO, | Na,0.] K0.

=

ee) 050.1 send. .0 st

1.76 | trace. 0.54

1.20

3 ; 0.32

aie 0.48

1.50
Cr,03;+FeO

1.00 0.91
1r,0,-+FeO

| 0.36 | 0.44 4.68
STE gia ee ER ete Ci
OR Gia Ah” Feet, OY

trace

trace

eels trace.
Cr,03+FeO

138.27
indie | Undt: |... ce csc

toe Bee 0.25
Cr,O3;+FeO

1.20 1.56

0.50 | 0.10 trace
trace minisic chia clare’el aio lacccets
Ores) Gs |, ccverers bees
a
meO98: | O10 | .ccoeee ee ‘

ees
ae! Ey

ee

1.32
1.822
2.36
0.235

weer e ee reee
er
eee ete sees
seme ee wees

0.01

trace.

0.045 |trace.| ...

trace.

ANALYSES OF METEORIC AND TERRESTRIAL ROCKS.

aAIX
H,0. Miscellaneous. Total. at |
100.63 8 |

ROBB: si wa larniain weds peo aiew aaa eae 99.478 |
.... |CO, = 0.41, Ignition = 11.88. | 100.45 |
. Ignition = 1.72. 100.66 |

- |Graphite = 9.25, S+P+Cr,0,! 100.00
= 2:02.
2.27 . |\N1O = 0.06. Recalculated. 100.85
9.02 |\CO, = 0.86. 100.23
SBD NOE eictee > cle ere ae Iu hare a are 3.2 2 101.09
WEGSiees «co eevee ot cat ase a owas 100.87
REI zrcvva es a oe tee aE leet, eine 101.55
TOO: | Saeed 2th eee oe ae. 104.50
PA . |Recaleulated. 98.68
. |Cr,03,+FeO0+SiO, = 0.58, Ig-| 100.21
nition = 0.82.
- \Cr,03+Fe0+Si0, = 1.83, Ig-| 100.18
nition = 0.76.
CU 8G a Se ear oe pages oi he A 99.951
GS: Oe mee aor tne Sots oe Pee ee aa 100.20
.... |trace.| 0.06 . |Recaleulated. 101.01
0.001} 0.118} .... |Recalculated. 101.264
fraces! TSE OMS) S22 ses aed doceee sees casa ce 103.819
. NiO = 0.812. 99.501
. |Ignition = 9.42. 100.00
Re eee ess are Oe ee ea din’s widle's 100.13
PRON odo serate che cen ewe etice ss 100.26
Recalculated 98.08
SOM ret aoe Corr a aronies cart nare ain aoe 100.78
USAT Rete on ocak dans ese eee alae 100.84
RS 428" |ioeree meta cia cieeneln aa telata ates 100.69
BS SIO ee tte oy ax cis ce aids) alg arm Ge 100.83
PE GO ule se sacle oka ee, Sat anaes mee ataaree 100.86
SBd 5 ea oe nt ouetetawayaasva ad 98.54
SO:4T 2:61 Mn = 0.57, Li,O=trace, C?=| 99.51
DOS ha en eeoce soma awakes wwe 98,87
0.57 |CoO = trace 100.15
meer He © Se Nee, eer cr cre 100.i7
PO;
trace. 2.70 |Cl = trace, CO, = 5.88. Rock| 99.09
altered.
1264 ee CO siroas atanckuets cGgaes 99.84
PA leetee PBO ES cass pha eens hee kadeite 99.96
P,0; s
. \trace. 3.44/Ti0, = trace, CO, = 2.65. 99.95
3.43 |'TIO, = trace, CO, = 2.65. 99.89

aie trace.

a

Variety.

Locality.

Lherzolite.
Meteorite.

Serpentine.
Serpentine.
Serpentine.

Serpentine.

Meteorite.
Serpentine.
*Lherzolite.
Meteorite.
Meteorite.

Serpentine.

Meteorite.

Meteorite.

Meteorite.

Lherzolite.
Meteorite.
Meteorite.
Lherzolite.
Picrite (Pa-

leopicrite).
Meteorite.

Lherzolite.

Peridotite.

Meteorite.

Dreiser Weiher,
Kifel.
Lissa, Bohemia.

Westfield, Mass.

Germagnano,
Piedmont.

Gornoschit, Rus-
sia.

East Goshen,
Chester Co.,
Penn.

Sienna, Italy.

Haaf-Grunay Is-
land, Scotland.
Knyahinya, Hun-

gary.

Danville, Alaba-
ma.

Uden, North Bra-
bant.

Saxony.

Harrison Co., In-
diana.

L’ Aigle, Orne,
France.

Sauguis-Saint-
Etienne, Mau-
léon, France.

Vicdessos,France.

Forsyth, Georgia.

Bremervorde,
Hannover.

Baldissero, Pied-
mont.

Ottenschlag, Aus-
tria.

i\Moresfort, Tippe-

rary Co., Ire-
land.

Corio, Piedmont.

St. Paul’s Rocks, |
Atlantic Ocean.)

Cabarras Co..

fe H. von Baum-|Archives

North Carolina.

A CLASSIFIED LIST OF COMPLETE (BAUSCH)

Analyst. Publication.

Ann. Physik Chemie,
1870, exli. 512-519.
Beitrage Mineralkorper,

1810, v. 246-253.
Geol. Mass., 1841, p. 160.

C. Rammelsberg.
M. H. Klaproth.
E. Hitcheock.

A. Cossa. Ric. Chim. Roce. Italia,
1881, pp. 121, 122.
Rose, Reise nach dem

Ural, 1857, i. 245.
Am. Jour. Sci., 1866 (2),
xlii. 272.

F. v. Schaffgotsch.
S. P. Sharples.

M. H. Mlaproth.
M. F. Heddle.

Mem. Acad. Berlin,1808,
p. 38-42.
Min. Mag., 1879, ii. 106.

E. H. von Baum-/Archives Néerland.,
hauer. 1872, vii. 146-153.
J. L. Smith. Am. Jour. Sci., 1870 (2),
xlix. 90-93.

Baumhauer and /Ann. Physik Chemie,

Seelheim. 1862, exvi. 184-188.
A. Vogel. Gelehrte Anzeig. Mun-
chen, 1844, xix. 116,
116.
J. L. Smith. Am. Jour. Sci., 1859 (2),

xxvili. 409-411.

Néerland.,
hauer. 1872, vii. 154-160.

Foucroy and Vau-j/Ann. Mus. Hist. Nat.,

quelin. 1804, iii. 101-108.

S. Meunier. Comptes Rendus, 1868,
“> Ixvii. 873-877.

H, A. v. Vogel. Jour. Mines,1813, xxxiv.

Am. Jour. Sci., 1848 (2),
vi. 406, 407.

Ann. Chemie Pharm.,
1856, xcix. 244-248.
Rie. Chim. Roc. Italia,

1881, p. 105.
Min. Mitth., 1877, p. 278.

C. U. Shepard.
F. Wohler.

A. Cossa.

A. Gamroth.

W. Higgins. Phil.Mag.,1811,xxxviii.
262-268,

A. Cossa. Rie. Chim. Roc. Italia,
1881, pp. 109, 110.

J. S. Brazier. Neues Jahr. Min., 1879,
pp. 890-894.

L. Sip6cz. Rep. Challenger Exp.,
Narrative, 1882, ii.,
App. B.

(J. S. Brazier. Rep. Challenger Exp.,

Narrative, 1882, ii.,

App. B.
Proc. Am. Assoc. Adv.
Sci., 1850, iii. 149-152.

C. U. Shepard.

ey
eeeeeeee

weer eens

3.607
3.49-3.626
3.369

3.25-3.833

3.60-3.66

SiO.

42.98
43.00
43.03
43.44
43.734
43.89

44.00
44.003
44.30
44.47
44.579

44.70
43.10

44.80
44.81
53.00
44.879

45.00
45.00
45.40
45.68
45.93

46.00
48.25

46.46
47.15
45.84

43.50

56.168

Al,O3.| Fe.

1.74
1.25 | 29.00

0.42
0.813

2.58

4.26

8.90
21.61

42.00
39.00

* The prefixed asterisk indicates that the specimen is a meteorite.

Fe,03.

8.08
0.91

0.108

36.00

12.00

1.87

4.022

z
— | —_—$—$—< — | —$ | $$ ——— | $s | | — a |

ANALYSES OF METEORIC AND TERRESTRIAL ROCKS.

* = 7
a Na,O.| K,0.| Cr,0;.
Cr,03+FeO
as 1.00
1TACC.)| sas trace.
Cr,03+FeO
1.00 | 0.658 0.80
0.49 | 0.62 trace.
Cr,03+FeO
0.94 | 0.49 0.76
eal te oles 0.145
Brey laisse 0.17
PAO OBB al os sides crereve
Cr,03+FeO
1.23 | 0.85 0.60
trace. | 0.454 0.012
eeee 0.50
71) 66 V6
1.18 | 0.37 0.31 -
0.26
moor | 0.22) i) oc. eicels
a aiateie trace
ell iereeete 0.42
trates tACC |... cee wee
. ma :

XXXi

Ni. Co. | Cu.| Sn. | P. | S. | H,0.| Miscellaneous. | Total
Bre leataicrete-a: 6 a Ssidtodeadetncdtdldennnae eae i eae
0.50 S+loss = 3.50. 100.00
Roo ie,wralsice's 13.93 |Loss = 0.42. 100.00
alata aterereye - E EZOG craves sates'ael hace d nicte'a eee creas 100.82
A aricrelereatert UO LO ios colaae ciate ade ad i eeddeda ace | 100.00
Ghieren cere LOAD elt ad coeur viene cated pate a Nae

0.60 Loss = 5.40. 100.00
alah oiaieteneie oi LB 2OR sal, catels noted Sols eae de eaten ee Uy On
oo lataainieieie.s FeS = 2.22, Fe+Ni=5.00.| 98.282

Recalculated. |

oes 0.01 |trace.| .... |trace.! 0.98 . |Li,0 = trace. Recalculated. 99.84

Ni

0.29 Seve Ni+Fe+S=1.767, FeS=0.718.| 99.424 |
ce nagdearaie, axe 11.20 |C = 0.192. 99.27
afelerastel sires 12.40 |C = 0.20. 99.61

0.65 0.02 |trace.| .... |trace.| trace.|.... |Recalculated. 104.86
nieiete etret 6 cafe Fe+Ni = 8.00, FeS = 1.80.) 101.93

Recalculated.

3.00 Di (Oe ra aeiccal |eiatere sta stars a che io Mo aimee Mer eedicicn a 104.00

evar Navditters eve AB : Al,03+Fe,0; = 0.604, Fe+Ni 100.474
= 8.05, FeS = 3.044.
SDE ee Loss = 6.00. 100.00

0.96 . |Crg0s+loss = 0.14. Recaleu- 99.66

lated.
1.89 Undt.|....|.... |Undt.) Undt.| .... |Graphite = 0.14. 100.00
rd Nah Necatois ‘ Oat geet ace Awake a & Sctcall Oe ae
Reto tales ‘ (Eis ec siscs ta a aren et ciate laren aaa wre hac 100.81
1.50 % A ALO \Wcye sul set eants cute vslojatwaiels siaars'e'~<adake 105.75
VAS: dC)" bette el ee ee ee on eee ee 102.00
Sainaetecne ap UID ake dat eae Oaee cael Fae
a tesetetarite ora % é = Loss = 0.50, CaS = 0.29. 100.00
NiO
1.06 : POG" | raisc caetos Os Mieesidacin ce ee mit 101.89
weer esos ee eee ece CaSO, = 0.96, Ca,;P,0,= 0.28, 100.00
CaCO, = 0.47, Ignition =
4.20.

pterclae Bietans Ras A wee. [Fet+Ni = 6.32, FeS = 3.807,) 100.00
Loss = 3.394.

XXXil

Variety.

Locality.

A CLASSIFIED LIST OF COMPLETE (BAUSCH)

| Analyst.

Basalt.

Basalt.

Basalt.

Basalt.

Gabbro.

Gabbro.

eee eee

Gabbro.

Gabbro.

Gabbro.

re es

Gabbro.

Gabbro.

Jonzac, France.

Stannern, Iglau,
Moravia.

Constantinople,
Turkey.

Petersburg, Lin-
coln Co., Tenn.

Juvenas,Ardéche,
France.

Shergotty, India.

Charkow, Russia.

Frankfort, Frank-

linCo., Alabama.

Kuleschiowka, Pol-
tawa, Russia.

Shalka, India.

Busti, India.

A. Laugier.
{ C. Rammelsberg.
| M. H. Klaproth.
J. Moser.
| L. N. Vauquelin.
iE. Ludwig.
J. L. Smith.
{ C. Rammelsberg.
j A. Laugier.
lr. N. Vauquelin.
KE. Lumpe.
fe Crook.
[ J. Scheerer.
1 Schnaubert and
[ Giese.
G. J. Brush.
J. Scheerer.
C. Rammelsberg.
N.S. Maskelyne.
H. Piddington.
(N.S. Maskelyne.
1 W. Dancer.

{ A. Schwager.

Massing, Bavaria.| 4

.| Manegaum, Khan-

deish, India.
Vavilovka, Kher-

son, Russia.
Ibbenbiiren,

Westphalia.

Bishopville,South
Carolina.

{ Imhof.
N.S. Maskelyne.
R. Prendcl.
G. vom Rath.
{ C. Rammelsberg.
| J. L. Smith.
W. S. v. Walters-

hausen.

C. U. Shepard.

TABLE V.— Basal

Publication. Sp. Gr.
: | : gas 3.12, 3.0778,
Mém. Mus. Hist. Nat., 1820, vi. 233-240. 3 0897

Ann. Physik Chemie, 1851, lxxxiii. 591-598.) 2.90-3.20
Beitrige Mineralkorper, 1810, v. 257-263. 2.95-3.16

Ann. Physik, 1808, xxix. 3809-327. 3.077-3.1529
Ann. Chimie, 1809, Ixx. 321-330. 38.19
‘Min. Mitth., 1872, pp. 85-87. 3.17
Am. Jour. Sci., 1861(2), xxxi. 264-266. 3.20

Ann. Physik Chemie, 1848, xxvii. 585-590. )

Ann. Chimie Phys., 1821, xix. 264-273. 8.099-3.148
‘Ann. Chimie Phys., 1821, xviii. 421-423. J

Min. Mitth. WS7iL, ppithby 00. |e nn ere ets
Chem. Const. Met. Stones, pp. 30-88. | ..........
‘Mém. Acad. St. Pétersbourg, 1813-14, vi. 3.00

Hist., p. 47.
Ann. Physik, 1809, xxxi. 816-322. 8.4902
Am. Jour. Sci., 1869 (2), xlviii. 240-244. 3.381

Mem. Acad. St. Pétersbourg, 1812, v., Hist., 3.539
pp. 22, 23.
Mon. Berlin. Akad., 1870, pp. 316-822. 3.412

Phil: Dranss 1871) elxis S6GNS6ie a nal ieeeeee eet
Jour. Asiat. Soc. Bengal, 1851, xx. 299-314. 3.66

Phil. Drans:, L870, cx) 198=2ilee Se el eercaee Sore
Phil. Trans., 1870, ex]. 193-211. | SoSsioesanc
Sitz. Miinchen Akad., 1878, viii. 52-40. 3.8636
\Sitz. Miinchen Akad., 1878, viii. 34. 3.365
‘Phil. Trans., 1870, elx. 211-218. > 3.198
Mém. Sci. Nat. Cherbourg, 1877-78, xxi.|.........-

205-207.

Sitz. nieder. Gesell. Bonn, 1871, xxviii. 142-| 3.40-3.48
IMon. Berlin Akad., 1861, pp. 895-900. | ....eee0ee
|Am. Jour. Sei., 1864 (2), xxxvili. 225,226. | s.....s..5
Ann. Chemie Pharm., 1851, Ixxix. 869-374. 3.039
Am. Jour. Sci., 1846 (2), ii. 380, 381. 3.116

Si0,.

46,00
48.30
48,25
46.25
50.00
48.59
49.21

49,23

| 40.00

40.00

60.21
86.211

67.140
70.41

1,05.

11.05
12.55

8.05
1.60

Fe. | Fe€

Re
eeeeee| OO

see eee

trace.
10.00

ANALYSES OF METEORIC AND TERRESTRIAL ROCKS. XXXili

2

. The Meteoric Basalts.

| CaO. | MgO.| MnO.) Na_O.| K,0. Cry03. Ni) P50,.| §. |-H,0. Miscellaneous. Total.
eo 12.80 |. ..... | eee, 1.00 iret Eee Paes ae nal We o's Cuca Saw Lov os eee ee ' 102.40
Cr,0,+FeO
6.87 | 0.81 | 0.62 | 0.23 i 2 a el a Weel => teed s sj is2 2s ews cavieees ' 100.61 |
|
SOA Aad Pa (ea onan i Beene eee Ce | Ae ay 1) ree ae a | 100.00
Cr 03 |
OS a eo) tele gl RE aan Daa ae Raia BIG. oes dusins + cases eee | 100.00 |
Bee. I rote ere lax es sloe- eRe | cost cle occscawudcsecessccccscesercorscese) 10100 |
Cr,03+FeO
6.16 | trace. |1045 | 0.16 ete bere chenss [Wate Wacelst yo. .<..0ecet ace: a: 99.82 |
; P
(2.518 Gal eae ee (OSSD lal CR ee ee trace. | trace.| 0.06 |...... [eee eee e eee ee eeee eens teen cece eeeees 99.23 |
ead |... OeOte | OR4T A tk. os 0.28 | 0.09 |...... PSN SO ile oo uaa cdc sco 101.61 |
0.80 | 6.50 |...... 0.20 O00 2) ied jaan 1 el eee (agrees () tt Oy eae See ee oe eee 92.20 |
Joc kc ec ASS SOPk Se Soe Sonyeel cae! Coenen Pr we eees Na,O+K,0+Cu+Cr,0,+S = 11.60, 100.00 |
| : Fe-+Mn = 27.00. :
I ore NC fo) ee. s'c|ocaaiels sxe cs lecessscie sa ceascsuceedeacccccceceecce 100.22 |
ql , P

455)24.114)...... 0.223 | 0.109 0.237 1-30) | trace: | trace.|.... 2. Col tiacent eo coes cetaceans oc celia ee 99.778 |
_- sos) heigl aaa ee BO |...s+-|.0+0]..++++/Mmg03 = 4.20, Loss = 3.00. .......--| 100.00 |
EE Mingle = COON Re a ee orc eal os - 99.43 |
She SER BRE rath hn AE ae ct ge ae

CaO+MnO-+loss = 2.95. ........000- 100.00

Mean analysis of the crust and interior. 99.98

Cale we = TR zac leaks 22 99.997

As = trace. Analysis of the crust. / 98.12
Li,O = 0.019, CaS = 4.133, CaSO, = 100.18
0.442

CaCl = 0.01, Na,S 0.76, Li,O—trace, 99.47
Ca3PO, = trace, CaSO, = 1.58.

|
|
|

EON cer at tote Rete win pisivia maton aieta ates 99.72 |
Mossteten—sl OG: 1c ciraleanis.s ae tele es ' 100.00
Cr 03+ FeO
oo el eee ee NR oat GA) VF ota cis dake denne +sdncsasge'sseovss-| SOOMD
f aaa s ase | .

18.54 | trace. 1.14 trace. OE OME Bctertteralines.ciers,|'s baie 0's HeS' =: 2Bie akc wdicingaee wetus er ee Ah | 99.68
eae eee Ta eC) races | cd cos |e soc. [eevee es cens cee kimecescwileencedceass | 100.77 |
34.80: | 0.20 | 1.14] 0.70 |........ rac | nogeee | ceca OeGee leaden (Remition:== 0:80. <0. = ex'au dae wnwa senate’ | 99.79 |
Pe ties 3 2 et a (ee Wish) =~ Gxnekra. drs nian oad ae eamnacl es 100.61 )

(74) | (URIs lnc oebee bene lPadodol eoceus pognoe aeacad) Li, O-== trae@s ase ec cc ve svwnneqnatuns | 100.23

(Aad SL 42, 2 ae ee Gagitscrol eter hee coe aaa

| TGs. 4 2c0 an0]'3 Se atin one eas SOScnn Eee Berean Paweeins Reppsyicmaere oa ise cer ie ek 100.05

PLATE I.

Fic. 1. Pallasite. Aracama, Bonivia.
PAGES
A tracing made from the polished surface of a specimen. The coloring is conventional in this
and in the next three figures. The yellow portions are the olivine grains, while the gray
reticulated portion indicates the metallic ivon and pyrrhotite, —since no distinction of the
different constituents was possible in a tracing except to divide them into silicates and
metallic portions. js: js <= 4. sg gi 8 De eee 70

Fig. 2. Pallasite. KRASNOJARSK, SIBERIA.

Tracing, as in Big. Des a. ee ee) Ga Pe ee oo. Ss ae

Fies. 3,4. Pallasite. Rirrers@rUn, SAxony.

Tracings of two opposite sides of the same polished slab. All these tracings are of natural size
and form, so far as it was possible to make them. . «. . . . +: . 6 « «6 w « =) ee

Fic. 5. Pallasite, -Cumberlandite. Iron Mine Hitt, CuMBERLAND, RHopE ISLAND.

A slightly magnified portion of a section. The dark portions represent magnetite, and the light
parts the olivine with a minute portion of feldspar. While in the four preceding figures the
sponge-like structure of the metallic parts with the enclosed silicates could alone be shown,
in this and in the following figures the minerals are in general differentiated, and the fidelity
of the lithographer’s work, in representing the form, structure, fissuring, coloring, etc. of the
natural section, will be appreciated by all familiar with such rocks. This figure shows the
same sponge-like structure as the preceding figures, but with the metallic iron replaced by
ita oxidized form. . s,< 6. ease agg Ries a eget ne

Fia. 6. Pallasite, —Cumberlandite. Iron Mine Hitt, CumBrerianp, RHopE IstanpD.

This figure is from a section of the same rock-mass as the preceding, and shows the same general
structure ; but the olivine of Fig. 5 is here replaced by serpentine, which retains the outlines
of the former, and marks its fissures by secondary magnetite grains, . . . .. . . =. + #£478,79

PLATE |

M.E.Wadsworth, del.

x
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“*, pea oe tates 5 2. . fete ,
thy Be Thin? 3 Ps .
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es ie »
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aid bige 2] SUAS 507 PtH
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he

PLATE II.

Fic. 1. Pallasite, -Cumberlandite. [ron Mine HILL, CuMBERLAND, RoopE IsLanp.
PaGES

This figure illustrates a more highly magnified intermediate stage in the same rock-mass, lying
between that presented in Figs. 5 and 6 of Plate I. The dark portion represents the mag-
netite sponge which holds the lighter silicates. The brownish portion represents the smoky,
fissured, somewhat altered olivine, which is surrounded by a grayish and white actinolite,
produced by the alteration of the olivine on its borders. The ragged character of the mag-
netite borders, as shown in the figure, also indicates that it is associated in the change, or
affected by the alteration. 2... 0. 60. = 4.) SUS se

ess

raps...

Fic. 2. Pallasite, —Cumberlandite. TABERG, SWEDEN.

eee

This shows the same general structure of magnetite enclosing silicates, principally olivine, as
the three preceding figures. The reddish-brown spots at the bottom of the figure represent a
secondary mica (biotite) produced in connection with the magnetite. . . ..... =. 81

Oe a

2 se

Fig. 3. Pallasite, — Cumberlandite. Taprera, SWEDEN.

ree OF byw

This figure represents a more highly altered portion of the same section as that shown in Fig, 3.
The magnetite is less in amount, having been partially removed, and the reddish-brown
biotite more abundant, while the silicate portions are more altered. sips 81

pix aon

Fig. 4. Peridotite, —Saxonite. Iowa County, Iowa.

The grayish and brownish parts represent the granular groundmass of olivine and enstatite
sprinkled with ferruginous particles and enclosing the steel-gray masses of metallic iron. .
The orange-brown represents the ferruginous staining. A little to the right of the centre
of the figure is represented an olivine chondrus composed of the colorless olivine grains held
in a grayish base. . ©. 6 6 "5s ac ;

. . . ‘
Fig. 5. Peridotite,--Saxonite. Iowa County, Iowa. an

This represents one of the larger chondri, composed of olivine and enstatite, which blends at the
lower portion of the figure with the general groundmass. ‘The enstatite and olivine grains
are held in a gray base, which is here given too dark a shade. The metallic iron and the
ferruginous staining are represented by the steel-gray and orange-brown colors. . . . . . 86-88

Fic. 6. Peridotite, —Saxonite. Kwyaninya, Huneary.

This shows a granular groundmass of chondri and olivine and enstatite grains, partially stained
by ferruginous material to an orange- and yellowish-brown, One chondrus-is shown extend-
ing from the centre towards the right of the figure, which consists of a fan-shaped mass of
grayish fibrous base, held in and cut by enstatite bars. At the base is shown a portion
of another chondrus composed of radiating bands of enstatite and base. Towards the bottom
of the figure, and at the left of the centre, is shown an elongated fissured enstatite crystal. The
metallic iron grains are indicated as before. . «| 7. Ms 4. ey ee ee

ES OPO ER a OM 1 8

+4

MEM.MUSEUM COMP ZOOL.VOL.XI.

M.E.Wadsworth, del

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PLATE III.

Fic. 1. Peridotite,— Lherzolite. Puntuskx, PoLanp.

This shows a portion of a section with two chondri at the base of the figure, while the remaining
upper portion is made up of an aggregate of chondri, olivine, enstatite, diallage, pyrrhotite,
and iron grains. The larger and darker chondrus is composed of aggregately polarizing
fibrous enstatitic material. This chondrus shows rounded indentations, and on its left is
another form, composed of alternating colorless enstatite ribs and bands of gray base with
minute iron granules. The dark portions of the figure represent the iron and pyrrhotite, and
the yellowish-brown the ferruginous staining.

Fic. 2. Peridotite, — Lherzolite. PuLtusk, PoLAND.

This displays the structure of a chondrus composed of olivine, enstatite, iron, ete., cemented by a
gray base. This chondrus occupies the chief portion of the figure, but towards the bottom its
gradual passage into the groundmass is shown. The ferruginous materials are colored as
in Fig. F.0D

Fic. 3. Peridotite, — Lherzolite. PuULTUSK, POLAND.

The brownish-black central portion is pyrrhotite surrounding a steel-gray pear-shaped mass of
metallic iron. Surrounding the pyrrhotite is the chondritic groundmass of the meteorite,
partially stained yellowish-browm. . - . =)... )s)@uuemees cu eee

Fic. 4. Peridotite, —-Saxonite. Waconpa, Kansas.
This shows a mixed granular groundmass of olivine, enstatite, iron, and pyrrhotite, which is
more or less stained a yellowish- and reddish-brown from the oxidation of the iron.. . . .
Fic, 5. Peridotite, —Lherzolite. EstTHERVILLE, Emmet Co., Iowa.
This shows a grayish and a greenish-yellow groundmass of olivine, enstatite, and diallage, with
dark-colored iron and pyrrhotite, surrounding a larger crystal of diallage.. . . . . .

Fig. 6. Peridotite,—- Lherzolite. EstHervitiz, Emmet Co., Iowa.

This represents a semi-sponge-like mass of iron and pyrrhotite with enclosed grains of olivine,
diallage, and enstatite. On the left is figured a crystal of enstatite with its inclusions and
characteristic cleavage ; while on the right is a crystal of diallage showing its cleavages.
The yellowish-brown ferruginous staining is to be seen in some portions of the figure., . .

PAGES

94, 95

94, 95

94, 95

93, 94

97-101

97-101

MEM. MUSEUM COMP ZOOL.VOL.XI.

M_E.Wadsworth, del.

PLATE: TVs

Fic. 1. Peridotite, —Lherzolite. New Concorp, GUERNSEY Co., OHIO.

This shows a grayish, crystalline, granular mass of olivine, enstatite, and diallage, containing
dark grains of iron and pyrrhotite. The groundmass is stained by the oxidation of the
iron to a reddish- and yellowish-brown. . “ss. 0. 408 = =) geen

Fie. 2. Peridotite, —Dunite. FRANKLIN, NorTH CAROLINA.

This figure represents a granular mass of olivine traversed by fissures, giving it a grayish appear-
ance. A little below the centre, and also on the left of the figure, are two dark chromite
grains. This, with the ten preceding figures, presents the structure of the unaltered peridotites.

Fig. 3. Peridotite,— Dunite. Werxsster, NortH CAROLINA.

This represents an early stage in the alteration of the peridotites, in which a greenish and
yellowish fibrous serpentine has been formed along the fissures of the olivine, leaving color-
less grains in the interstices of the serpentine network. A further stage in the alteration is
the change of some of the interstitial grains to a pale yellow serpentine. The reddish-brown
grains sprinkled with black granules show the picotite, while the minute black grains in and
about the serpentine indicate the magnetite produced during the process of the conversion of
the olivine into.serpentine. . 20s = sa Sh se

Fig. 4. Peridotite,—Saxonite. ANDESTAD Srz, AuRE, Norway.

This figures a further change in a peridotite, in which the chief portion is altered to a greenish
serpentine containing clear grains of unaltered olivine. In the upper portion of the figure
is a partially altered enstatite traversed by fissures and containing much secondary magnetite
dust. This enstatite is also partially altered to serpentine. Dark magnetite dust is shown
in connection with the olivine grains, while dark grains of chromite are figured in the
Berpentine, . 26. 6 6 6% 2) a) eee er

Fic. 5. Peridotite, —Serpentine. HiaH Bripan, New JErsey.

This represents an extreme stage in the process of the alteration of a peridotite, in which is
shown a yellowish and grayish serpentine mass blotched with aggregations of dark iron-ore
grains. Extending across the figure is an irregular pronged grayish band, formed by serpen-
tinized olivine traversed by numerous fissures filled with dust-like granules of iron ore.
Enclosed in this gray band are greenish spots of partially altered olivine grains. . . . .

Fic. 6. Peridotite, —Lherzolite. Jarna River, SAN DomINeo.

This shows a grayish-white serpentine mass holding dark patches of iron ore The yellowish-
brown mass to the right of the centre is a diallage crystal altered to serpentine, the four white
spots indicating the unchanged portions. The other yellowish-brown and greenish spots are
serpentinized pyroxenes and olivines, while the gray irregular band on the left is a partially
altered mass of diallage and feldspar. . . .° Jct ge So =) seen

. .

118

119, 120

126, 127

157

\V

PLATE

MEM.MUSEUM COMP ZOOL. VOL.XI.

i ER al I Re, al ae iy

iE Wadsworth, del

i

PLATE V.

Fic. 1. Peridotite;— Lherzolite. CoLtusa Co., CALIFORNIA.
PAGES

This represents one of the earlier stages in the alteration of a peridotite, showing a fissured granular
mass of olivine, enstatite, and diallage traversed by a network of pale grayish serpentine,
which borders the fissures. The mass is traversed by brown bands of serpentine, containing
iron-ore dust along the medial lines. Dark grains of picotite or chromite lie in the upper
part of the figure... 6 ie es

Fia. 2. Peridotite, —Lherzolite. Conusa Co., CALIFORNIA.

This shows a further alteration in the same type of rock as Fig. 1. In this the outline of the
olivine can be distinguished by the yellow serpentine bands, while a later formation of ser-
pentine shows in the orange-brown interior portions which retain in part grains of colorless
unaltered olivine. The brown serpentine bands with their medial line of iron-ore dust are
more abundant and better marked than in Fig. 1 ; while much of this secondary black dust
is disseminated through the section. . .- .° . s 90 2 eh Se te

Fig. 3. Peridotite,— Lherzolite. Coniusa Co., CALIFORNIA.

The principal portion of the figure represents a crystal of enstatite from the same section as that
given in Fig. 2. The cleavage lines with their bordering gray and brown alteration products
run more or less vertically, — the latter containing considerable fine black ore-dust. On the
right and left of the upper portion of the figure are shown portions of serpentinized olivine,
like that given in Fig. 2. The two portions are connected by a yellowish branching vein
of serpentine. The dark brown and black grains are picotite or iron ores. . . . . . . . 181,182

Fig. 4. Peridotite,— Serpentine. La Vreaa, San Dominao.

This indicates a further stage of alteration than that shown in Fig. 2. The brown bands with
their medial ore-dust remain, and are connected by finer brown bands marking the fissures
in the original olivine ; while the interstitial olivine has been replaced by yellow serpentine.
Towards the bottom of the figure, on the right and left, are represented two grayish-white
altered enstatites. The series is continued in Figs. 2, 4, and 5 of Plate VI., and in Fig. 2
of Plate VII. 2.0. ee ee 154

Fig. 5. Peridotite, — Serpentine. HicH Bripar, New JERSEY.

A grayish-white mass of serpentine containing disseminated dark iron-ore grains and dust ; and
traversed by a band of serpentinized enstatite or diallage crystals, which are surrounded and
cut by a brown serpentine holding black ore-dust . . . . . .... +. + + ~~ » 166,157

Fia.6. Peridotite,—Serpentine. Hicu Brirpcr, NEw JERSEY.

This is from the same section as Fig. 6, and contains the same serpentine groundmass which, in
places, is stained yellow. Scattered through the groundmass are iron ores and brown ser-
pentine pseudomorphs after olivine containing ore-dust, and showing part of the original
olivine fissures by the traversing bands of grayish-white serpentine . . ... . . . . 156,157

MEM. MUSEUM COMP ZOOL.VOL XI. PLATE

dbl i
he

6S Sin. ;

M_E.Wadsworth, del

PLATE VI.

Fig. 1. Peridotite, Serpentine. Santiago, San DomIneo.

This shows at the base a brownish and yellowish reticulated serpentine mass, while above lie
yellowish and brown pseudomorphs of serpentine after olivine grains which are surrounded
and cut by colorless serpentine. In all the serpentine masses, particularly the upper por-
tion, are disseminated black grains and dust of ironoree . . . . + . - "

Fic. 2. Peridotite,— Serpentine. LyNNFIELD, MASSACHUSETTS.

This forms one of a series with Figs. 1, 2, and 4 of Plate V. In this the brown serpentine bands
no longer appear, but their former position is marked by the lines of black iron ore. The
pale flesh-tint indicates serpentine which encloses the yellowish central rounded spots of
serpentine which has replaced the last altered olivine grains. At the top and bottom of the
figure are to be seen patches of pale serpentine in which the alteration has been carried so far
that the yellowish portions have disappeared and the color been rendered uniform, — the con-
stant tendency in the serpentinization of peridotites. The black grains are the iron ores... .

Fig. 3. Peridotite, — Lherzolite, Serpentine. P1Lumas Co., CALIFORNIA.

This shows a yellowish and grayish serpentine in which are lying black iron ore and the fibrous
remains of enstatite crystals, which are best seen in the centre of the figure’... .. .

Fic. 4. Peridotite, —Lherzolite, — Serpentine. Inyo Co., CALIFORNIA.

This exhibits a brownish reticulated serpentine, holding in its interstices serpentine of a lighter
color. This belongs to the same series as Fig. 2. In the serpentine lies a large fibrous
crystal of altered enstatite, filled with black granules of iron ore precipitated during the pro-
cess of alteration, ‘The same ore is also to be seen in the serpentine. . .

Fic. 5. Peridotite, Serpentine. PiLumas Co., CALIFORNIA.

This shows a grayish-white reticulated mass of serpentine containing disseminated black iron-ore
dust of a secondary nature ; also some larger black primary grains of iron ore. The upper half
of the figure is traversed by veins of yellow serpentine, one of which cuts an iron-ore grain.

Fia. 6. Peridotite, — Lherzolite,— Serpentine. PLuMAs Co., CALIFORNIA.

This figure is from the same section as Fig. 3, and illustrates the formation of a serpentine vein.
This, in the form of a brownish-yellow obliquely banded serpentine, crosses the central por-
tion of the figure, while heaped up on both sides are to be seen the aggregations of expelled
iron ores mixed with yellow and colorless serpentine... . .-. . + » « « « «© «© =

1 Whitney’s Auriferous Gravels, 1880, p. 459.

Paces

. 153, 154

160

142

132

158

142

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4

VI

PLATE

MEM. MUSEUM COMP ZOOL.VOL.XI.

M.. Wadsworth, del

PO AOE Gt So Py eat *,

PLATE VII.

Fic. 1. Enstatite. Conusa Co., CALIFORNIA.

This is figured from the same rock as Figs. 2 and 3, Plate V. It indicates the manner in which
enstatite is altered to serpentine. ‘The longitudinal cleavage runs from side to side, and is
crossed by the vertical fractures. The unchanged enstatite is colorless, but upon the borders
of the cleavage planes and cross fractures the mineral has been altered to a greenish and
yellowish serpentine. A yellowish serpentine vein runs from the upper left-hand portion of
the figure to the centre of the base. . . «+ « = = ©) sl) 2 Rees

Fig. 2. Peridotite,— Serpentine. WurstrieLp, MasscHUSETTS.

This continues the series formed by Figs. 1, 2, and 4 of Plate V., and Figs 2, 4, and 5 of Plate VI.
Here the serpentine is of a pale yellow without trace of the usual network, and much of the
black iron ore has been arranged in the form of a rectangular grating. . . . . . . . +

/

Fia. 3. Peridotite, —Lherzolite. Presqus Isun, MicHiaan.

This shows a grayish and greenish partially serpentinized enstatite containing black iron ore and

PaGEs

. 131, 132

159, 160

holding rounded olivines. These are fissured and rendered opaque in portions owing to the

precipitations of magnetite dust along the borders of the fissures. Greenish and yellowish
serpentine is also to be observed in connection with both the enstatite and olivine. .

Fig. 4. Peridotite, — Lherzolite, — Serpentine. Presque Istz, MIcHIGAN.

\
This is drawn from a portion of the same continuous rock-mass as Fig. 3, and represents a more
highly altered state of the rock. The enstatite and diallage are largely replaced by greenish
serpentine, bluish-green and yellowish biotite (?), gray dolomite, and black iron ores. The
olivines are in part still more opaque from the rejected iron ore, and they have so far been
changed to serpentine that comparatively few clear, unaltered, interstitial fragments remain.
The structure is confused, and the distinctness of the minerals confused by the alteration. .

Fig. 5. Peridotite, —Lherzolite,— Dolomite. Presqur IstE, MIcHIGAN.

This is from the same continuous mass of rock as Figs. 3 and 4, and displays a further stage in
the alteration. The groundmass is formed by a grayish mass of secondary granular dolomite,
which holds yellowish, bluish-green, and brown pseudomorphs of serpentine and ferruginous
material after olivine. . 3... 42 4s) 8 4) S) Pe Ree

Fia. 6. Peridotite, Serpentine. Firztown, Berks Co., PENNSYLVANIA.

This shows a yellow serpentine mass containing grayish and colorless grains of olivine. The
brown masses represent secondary dolomite grains formed in the serpentine, but the lithog-
rapher has given them much too dark a color, since the grains figured are of a cloudy-gray
to brownish-gray color. 2... wet os. SeacE Ngee a

136

136, 137

137

152

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PLATE VIII:

Fic. 1. Peridotite,— Lherzolite. Basts, Harz.

The first five figures of this plate form a series in the order of their numbers, showing progressive
alteration in the same type of rock. Fig. 1 shows a yellowish enstatite mass holding colorless
fissured grains of olivine, some of which contain brown picotite grains. The olivine cracks
sometimes extend into the adjacent enstatite, and even across this into the contiguous olivine.
The greenish color of the enstatite near the upper right-hand olivine grain marks an altera-
tion state. The color of the enstatite probably marks the begiuning ofa change. . . . .

Fie. 2. Peridotite,—Lherzolite. Bast, Harz.

This shows a further change in the same rock as Fig. 1. The color of the pyroxene minerals is
deeper and much iron-ore dust has appeared, as one of the first products of alteration, along
the fissures of the olivine. Bands of black ore-dust and yellowish serpentine cross the lower
portion of the figure. Yellowish and greenish serpentine replaces portions of the silicates.

Fic. 3. Peridotite, —Lherzolite. Curistrania, Norway.

A brownish altered enstatite and diallage mass, holding greenish serpentine pseudomorphs after
olivine. The structure produced by the formation of the serpentine along the olivine fissures
is distinctly shown, while colorless interstitial fragments of olivine remain in portions of the
pseudomorphs. The bluish band on the right of the figure marks a border of alteration
between the original olivine and enstatite. Much black iron-ore dust is to be seen, par-
ticularly in the altered olivine, but it is not so abundant as it isin Fig.2.. ..... .

Fic. 4. Peridotite, —Lherzolite, —Serpentine. Gsdrup, Norway.

The pyroxene minerals are changed, having a brownish color, while in part they are replaced by
a grayish-white to colorless magnesium-carbonate, as shown on the left of the figure. The
olivine is altered more than it was in the preceding figure, only a very few granules remaining
unchanged in the yellow serpentine. The iron-ore dust has diminished in amount, but
sufficient remains to mark the original fissures in the olivine. The lithographer in his en-
deavor to be exact, has reproduced on the left and towards the bottom of the figure three
bubbles which were in the balsam, but which, it is needless to say, were not in the original
drawifig, 206 5 ek hh ee a ee

‘Fic. 5. Peridotite, — Lherzolite, — Serpentine. Bastr, Harz.

This shows a brownish altered pyroxene mass containing yellow serpentine pseudomorphs after
olivine. The change has progressed further here than in the preceding. The serpentine
has a more uniform and paler color, the iron ore diminishes in amount, and the olivine is
entirely changed.) «0% 6) Gs oe 1s i oe a

Fie. 6. Peridotite,— Picrite. Hrrporn, Nassav.

On the right of the figure is a brownish augite crystal containing olivine grains, some of which
is altered to greenjsh, bluish, and brownish serpentine and biotite. Part of the olivines show
the commencement of alteration only by the production of iron-ore dust and colorless serpen-
tine along the fissures. At the base of the augite is shown a greenish alteration product,
while a large olivine is attached to the upper portion. The groundmass is a yellowish, gray-
ish, bluish, and greenish serpentine, holding partially altered olivines, brown biotite scales,
and black iron ores... 5s ea ee i et ca ene

PaGEs

133, 134

. 133, 134

134, 135

135

. 138, 184

150

MEM. MUSEUM COMP ZOOL.VOL.XI. PLATE. VIII

M.E.Wadsworth cel.

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