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Field Columbian Museum

Publication 44.

Geological Series. Vol. I, No. 7.

NEW MINERAL OCCURRENCES.

11.

CRYSTAL FORMS OF CALCITE
FROM JOPLIN, MISSOURI.

BY

Oliver Cummings Farrington, Ph.D.,
Curator, Department of Geology.

Chicago, U. S. A.
February, 1900.

221
221
224

TABLE OF CONTENTS.

New Mineral Occurrences, -----

Inesite, ----..'..

Caledonite, -------

Gay-lussite, . . . 226

Kpsomite, - - - ..... 22g

Golden Calcite, ---.... 22Q

Dolomite Used as Indian Money, ..... 2\o

Crystal Forms of Calcite from Joplin, Mo., - - - 232

Localities of Large Crystals, - - . . . 232

Forms of Large Crystals, ...... 233

Forms of Smaller Crystals, ' * * • - • 237

Forms of Twinned Crystals, ...... 238

NEW MINERAL OCCURRENCES.

1NESITE.

SAN CAYETANO MINE NEAR VILLA CORONA, STATE OF DURANGO. MEXICO.

MUSEUM No. M 5>

A specimen of inesite from the above locality was first secured
by the writer in the spring of 1896 while at Villa Corona. Having
later determined the mineral by its blowpipe characters as inesite,
a request was sent to Mr. John D. Almy, one of the proprietors of
the mine, to procure more specimens if possible. Through his
kindness, and that of Mr. W. H. Schlemm, a few more specimens
were obtained, and were generously placed at the writer's disposal
for study. The rarity of the mineral makes the find of interest, as
it is known at only three other localities in the world, viz. : The
manganese mines at Nanzenbach, northeast of Dillenburg, Ger-
many; the Harstig mine, Pajsberg, Wermland, Sweden,* and
Jakobsberg, Nordmark, Sweden. t In the specimens from the San
Cayetano mine the mineral occurs partly in cavities and partly in-
tergrown with calcite and a flesh-colored manganesian calcite.
These fill narrow veins in what is probably an altered andesite.
The inesite occurs in tufts of radiating crystals which are of the
characteristic flesh-red color. The most characteristic pyrognostic
reaction of the mineral, noted by the writer, is, that when heated
in the closed tube it becomes opaque, gives off water, and falls
to powder. The crystals are of slender, prismatic habit, averaging
about 5 mm. in length. None were found doubly terminated, the
attachment at one end preventing the development of faces there.
A total of seven forms was identified, as follows:

a (100), b (010), c (001), g (2oi), ' d (on),

k (n. 0.12), and s (946).

Of these the forms k (n. 0.12) and s (946) are new. The form/*
occurred on several crystals, the form s was found on but one. The

♦Dana's Mineralogy. Sixth Edition, p. 564.
••■First Appendix to Dana's Mineralogy. 1899.

221

222

Field Columbian Museum — -Geology, Vol. i.

table following gives the measurements by which these forms were
identified, together with measurements of the other forms noted.
The calculated values given with them are deduced from Scheieb's
ratios as quoted by Dana.*

No. of
Measurements.

Limits.

c : s=ool : 946 ....

g: $=201:946

a: s— 100: 946

d : $=011:946

b' :s—oio: 946

c : £=001: Tf.0.12.
A : a' =11.0.12: 100.
a : g=ioo :20i . . .
g : £=201 :ooi . . .
b' :d=olo : oil. . .

d:c=oil : 001

c : b=ooi : 010. . .
a: b=ioo :oio . . .
b.a'=oio : Too. . . .

79° 48' — 80° 42'
520 36'— 550 34'

11° 47' — 12° 27'

34° 36'— 35° 9'
480 27' — 500 40'
46° 25'— 46° 30'
820 48"-84° 35'
8o° -86° 33'
970 25' — 100°

Observed.
34°

13° 23'
19° 47'
45° 20'
84° 30'
8o° 26'
52° 25'

12°

34° 36'
48° 34'
46° 30'
820 50'

820 30'

97° 25'

The crystal faces were found in general
to be fairly flat and bright, except the clino-
pinacoids, which were always vertically stri-
ated, so that no very satisfactory measure-
ments could be made from them. The usual
habit and development of the crystals is illus-
trated in Fig. 1. Fig. 2 shows a completed
crystal giving the new forms, k (11. 0.12) and
s (946) in their relative development.

Calculated.
34° 10'

13° 30'
190 48'
45° 21'
84° 33'
8o° 9'

53° 9#'

120 5'

34° 36K'
49° 23'
47° 22'
83° 15'
82° 35'
97° 25'

a c /
'/ ■ 1

\ 9

—1, 6

a 1

Fig. 1— Inesite.

Fig. 2— Inesite.

An analysis of the mineral was made by the writer. For this
purpose about two grams were laboriously separated from the calcite
in which it was largely embedded. Experiments were first made
upon the temperature at which water was driven off in order to deter-
mine, if possible, the nature of its existence in the mineral. About a
gram of the finely powdered mineral was heated at successively
increasing temperatures until practically constant weight was

♦Dana's Mineralogy, p. s6s.

Feb. 1900. New Mineral Occurrences — Farrington. 223

obtained at each. The following are the percentages of loss obtained:
At no0, 3.88%; at 2400, 1.94%; at 3100, 0.10%; at faint redness,
1.00%; total, 6.92%. Of the above amount, 5.99% was taken up
again by the mineral on exposure to ordinary air. This amount may,
therefore, be regarded as water of crystallization. On continuous
heating at faint redness, the mineral turned dark and showed a gain
in weight doubtless from oxidation of manganous compounds. It
was evident, therefore, that water could not be correctly determined
by loss upon ignition.

A direct determination was made, therefore, upon a separate
portion by Penfield's method,* a blast lamp being used for the final
heating. This determination gave 8.20% of water. It could be dis-
tinctly seen on application of the higher heat of the blast lamp that
more water was given off at the high temperature, showing beyond
question that some of the water was present as water of constitution.
If the percentage of water taken upon exposure to air, 5.99%, be
regarded as water of crystallization, then the remainder, 2.21%, may
be considered to denote the percentage of combined water. This
agrees well likewise with Barwald's observations, he having found
1.97% of water given off above 3000. It is evident from the above
experiments also that determination of water as loss upon ignition
would certainly give too low a result. This may account for the low
percentage, 7.17%, obtained by Flink.

The remainder of the analysis was performed by the methods
commonly employed for the analysis of silicates. A sodium carbon-
ate fusion was made, the bases separated from silica by solution with
hydrochloric acid, iron precipitated by ammonia, manganese by bro-
mine and calcium by ammonium oxalate. Results of the analysis
with ratios are as follows :

, — „r ati0 _ — ,

SiO* 4489 748 748 1.64

MnO 36.53 5i7l

FeO 2.48 034! 699 1.53

CaO 8.24 148]

MgO tr.

H,Ocryst 5-^9 336) 4$6 u

H,Oconst 2.21 i2of

100.34
Sp. Gr. (det. by Thoulet's solution) — 2. 965.

The ratio of Si 02 : R O : H20 is thus nearly 1.5 : 1.5 : 1. Consid-
ering the ratio of water of crystallization to water of constitution
s 3 : i, and of Mn : Ca = 4 : 1, the formula can be expressed as

♦Amer. Jour. Sci., 3rd Ser., Vol. 48, p. 30.

«

224 Field Columbian Museum — Geology, Vol. i.

4 H20, 6 (Mn, Ca) O, 6 Si 02, or H2 (Mn, Ca)6 Si6 019 + 3H2 O. Cora-
paring the percentages called for by the formula, with the writer's
analysis calculated to ioo% (reckoning Fe O as Mn O), the results are
as follows :

Analysis Calculated
Theory. to ioo.

6 Si Os 42.91 44.76

|(6MnO) 40.51 38.86

J(6CaO) 8.00 8.21

4H,0 8.58 8.17

100. 100.

Here the greatest discrepancy to be noted is in the percentage
of Si 02, which is noticeably higher in the analysis than the theory
calls for. Mn O is also a little lower. Yet it is believed that this
formula better agrees in general with analyses of the mineral and bet-
ter expresses its constitution than any hitherto proposed. Flink's
formula, 2 (Mn, Ca) Si 03 -f- H2 O, reckons all the water as water of
crystallization, which is clearly incorrect. Moreover, the percent-
age of Mn O called for by his formula, 41.4%, is larger than has
ever been obtained. Barwald's formula, R (ROH)2 Si3 08 + acl->
gives percentages nearly like that proposed by the writer, but the
compound represented by such a formula would less resemble other
zeolites in manner. of constitution than does that of the writer's
formula. Moreover, one would expect a darker color if the molecule
Mn OH were present in the mineral.

CALEDON1TE.

STEVENSON-BENNETT MINE, ORGAN MTS., NEAR LAS CRUCES, NEW MEXICO.

MUSEUM No. M 5486.

A single specimen of this mineral was picked up by the writer
on the dump of the Stevenson-Bennett mine in the spring of 1896.
It is the only specimen ever found there, so far as I am aware. It
is also the second or possibly the third occurrence of the mineral
reported in America. It is known to occur* at the Cerro Gordo
mines in California, and has been reported from Mine la Motte,
Missouri, but the report needs confirmation. In the specimen
secured by the writer the mineral is in the form of several distinct

♦Dana's Mineralogy, p. 925.

Feb. 1900. New Mineral Occurrences — Farrington. 225

crystals which occur on a piece of the quartz gangue common at
the mine. With the caledonite crystals are associated crystallized
cerrusite, massive galena, linarite, and wulfenite. One of the crys-
tals of caledonite is of good size, being 5 mm. in length in the
direction of the vertical axis, and 3 mm. in length in the direction
of the macrodiagonal axis. The other crystals are smaller. All
are developed prismatically in the direction of the brachydiagonal
axis, and are attached by its extremity. The crystals are of a deep
bluish-green color and transparent. They are penetrated to some
extent by cerrusite, which shows as darker spots when seen under
a lens. These portions also turn brown when fragments of the
mineral are heated in the closed tube. Other pyrognostic charac-
ters of the mineral, noted by the writer, which may be added to
those given by Dana, are: In the closed tube it decrepitates, becomes
black and opaque, and gives off water. Fuses easily B. B. with
intumescence to a black globule.

The crystals were fairly well suited for goniometric measure-
ment, and the following forms were found, the position and letter-
ing being that given by Dana:

b (010) x (201) s (223)

c (001) / (012) t (221)

m (no) e (on)

The development of the different crystals was found to be qifite
constant, the prominent forms being c, b, m and s. The most per-
fect crystal was considerably striated parallel with the direction of the
brachydomes, also in the direction of the zone of the pyramids and
prism. Owing to these striations but few really accurate measure-
ments could be obtained, but a few were secured which are of inter-
est as supporting the correctness of the ratios obtained by Busz*
from a study of the caledonite of Leadhills. The following are the
measurements which it was possible to make with accuracy, and
for comparison are given the values as calculated by Busz:

Measured. Calculated.

d:m = (oio):(iio) 47° 26' 470 2.5' 30'

W.;;/"'=(lI0):(lI0) 85° 12' 85° 9'

s:s'" =(223): (22$ 66° 35' 66° 30' 34*

^/jr=(ooi):(2oi) 710 52' 71° 53'

X :x'=(20\)\ (201) 360 15' 360 14'

The crystals were carefully studied also in the hope that some
measurements might be found which would throw some light on the

*Neues Jahrbuch fur Min. Geol. u. Pal. iSqs, Band I, />. in.

226 Field Columbian Museum — Geology, Vol. i.

disputed question as to whether the mineral crystallizes in the ortho-
rhombic or monoclinic system. Owing, however, to the incomplete-
ness of the crystals on account of their attachment, or to the stri-
ations on the faces, only one reliable set of measurements bearing
upon this point could be obtained. These were measurements of the
zone c:x:x' :c' =(ooi) : (201) : (201) : (001), as already quoted. Com-
pleting this zone by difference, the angles are :

r.-.x = (ooi) : (201) — 710 52'.

x:x' =(201) : (20i) = 36° 15'.

x:c' —{t.6\) : (ooi) = 7i° 53'.

Thus the brachydiagonal is an axis of binary symmetry and the
mineral must be regarded orthorhom-
bic. As noted by Busz also, the habit
of the crystals gives the impression of
orthorhombic symmetry.

The usual development of the
crystals is shown in Fig. 3. ThSt[
shown in the direction of the brachy-
diagonal is necessarily estimated, as!
no crystals doubly terminated in the
direction of this axis were found. The
general resemblance in habit to that

of cerussite from Rezbanya* figured fig- 3— caiedonite.

by Schrauf will be noted.

GAY-LUSSITE.

SWEETWATER VALLEY NEAR INDEPENDENCE ROCK, WYOMING.
MUSEUM No. E 9695.

On dissolving in water the native carbonate of soda found in the
Sweetwater Valley, Wyoming, a residue of clay and minute crystals
is left. Some of the latter were kindly forwarded to the writer by
Prof. W. C. Knight of the University of Wyoming, who was the first
to notice the crystals, so far as I am aware. A test of the pyrognos-
tic and crystallographic characters showed the crystals to be undoubt-
edly gay-lussite. They are microscopic in size, none that I found
being as large as the head of an ordinary pin. More exactly, none

♦Dana's Mineralogy, p. 287.

Feb. 1900. New Mineral Occurrences — Farrington. 227

exceed one millimeter in the direction of greatest length. They are
colorless and transparent and remain so with the exception of a
slight deliquescence on exposure to air. In distilled water, however,
they turn white and in a short time become pulverulent from solution
of sodium carbonate. The crystal forms are well developed and the
faces fairly sharp and bright. In habit the crystals are somewhat
different from any heretofore described on account of the relative
subordination of e (on) and the relative greater prominence of r (112)
and c (001).

The following forms were found :

c (001), m (no), e (on), r (112).

They were identified by the following measurements :

No. of
Measurements. Limits. Observed. Calculated.

m:m'"=\\o:\io 5 110° 41 -m° 11 no° 59' 1110 10'

r.-/«=ooi: no 2 83° 25- 830 30' 830 30' 830 30'

cr=\oo: 112 2 430 13- 430 20' 4^° 20 43° 20'

<r./=OOl:01I 7 540 10- 540 52' 54° 45' 54° 45'

e:e' =01 1 : oil 5 108° 59-1090 23' 1090 23' 1090 30'

r:r'=ii2: 112 2 69 ° 34' 69° 34' 690 29'

m.'tf=iio:oil 4 420 17- 420 25' 420 25' 420 21'

e : /— on:Tl2 4 270 22- 27° 29' 270 25' 270 44'

m : t~ 1 10: 1 12 2 530 10- 530 22' 530 10 530 10'

The accompanying figure (Fig. 4) shows the usual development
of the crystals. This development was quite constant for all that

Fig. 4— Gay-lussite.

Fig. 5— Gay-lussite.

were examined. Fig. 5 shows the same forms in horizontal projec-
tion on the plane of the clinopinacoid. Here is better shown, too, the
relative greater length of the crystals in the direction of the clinodi-
agonal axis. The faces of the prism w (no) are usually duller in
lustre than the others, and the basal plane c (001) is often striated
parallel to the edge c r.

228 Field Columbian Museum — Geology, Vol. i.

EPSOMITE.

NEAR WILCOX STATION, 65 MILES NORTH OF LARAMIE, WYOMING.
MUSEUM No. M 6126.

An account of the above occurrence of epsomite was given the
writer by Prof. W. C. Knight of the University of Wyoming, in a
recent letter. He writes: "A deposit of epsomite, which is of
variable depth, covers an area of 90 acres near Wilcox Station,
Albany County, Wyoming. In the spring the area is covered with
water to the depth of a foot or more, forming a small lake, but on the
advent of summer the water evaporates rapidly and an abundant
deposit of beautifully crystallized epsomite is left."

A few of these crystals were received from Prof. Knight at the same
time by the writer, but not being able to study them immediately,
they became, through deliquescence, unfit for thorough crystallographic
investigation. I have thought it desirable, however, to publish an
account of the occurrence so that any who may visit the locality may
improve the opportunity to secure material whose forms may admit
of exact determination. The crystals received by the writer are from
8 to 15 mm. in length and are of elongated prismatic habit. Many
are doubly terminated and have pyramidal planes which plainly show
sphenoidal symmetry. The habit of the crystals and the fundamental

Fig. 6— Epsomite.

forms are shown by Fig, 6. The determination of the pyramid
z (in) depends on a measurement secured as follows :

Measured. Calculated.

m. -z= 1 10: in — 50° 30' 50° 55'

While some of the crystals have only the simple development
represented in the figure, others are evidently more highly modified,
but owing to the deliquescence previously referred to, it was found
impossible to determine the forms.

Feb. 1900. New Mineral Occurrences — Farrington.

229

GOLDEN CALCITE.

BAD LANDS, SOUTH DAKOTA. MUSEUM No. M 5904.

On breaking open the concretions found in beds of Fort Pierre
shale in the region of the Bad Lands, South Dakota, the internal
cavities are often found to be studded with crystals of calcite of a
more or less golden yellow color. While this occurrence of calcite
has been known for some time, the form of the crystals has not
heretofore received description. A large quantity of the crystals
having been collected by the Museum Expedition to the Bad Lands
of 1898, I have examined them with the following results: In form
the crystals are all simple rhombohedrons having the symbol /,-2R.
This symbol is sufficiently established by the relation of the cleav-
age rhombohedron to the crystal form and by several measurements
ranging from 1010 25' to 1010 35' for/ :/=o22i a 2021. The cal-
culated value is 1010 9'. No planes could be found which were
suited to accurate measurement, even the most favorable giving only
dim and elongated reflections. The most interesting feature of the
crystal form is the distortion which it exhibits. Although some of
the crystals show a normal development of the rhombohedron, the
greater number are lengthened out along an axis normal to one of
the rhombohedral planes. The appearance is therefore that of a
monoclinic crystal made up of a prism and basal planes. This
apparent prismatic form is made more striking from the fact that
the crystal usually rises more or less perpendicularly from its plane
of attachment. The apparent basal plane is usually more or less
curved, and has a somewhat
pearly lustre. The prismatic
planes are often curved as well.
The length of the apparent
prisms varies from a few milli-
meters to about 2 centimeters.
The form of these crystals is
represented in Fig. 7. Another
form of distortion is shown in
Fig. 8. Here the lengthening
out has taken place in two direc-
tions, so that an apparently flattened rhombohedron
results. The planes of such crystals show a curving

Fig. 8-Golden Calcite.

Fig. 7— Golden

7— Gold
Calcite.

230 Field Columbian Museum — Geology, Vol. i.

similar to those previously described. The color of the crystals of
all types varies from a pale yellow to a deep orange. Some are per-
fectly transparent, but the majority are translucent to opaque. The
yellow color is probably due to the presence of iron, as on heating
the crystals turn black and become slightly magnetic. Other quali-
tative tests likewise indicate the presence of considerable iron.

DOLOMITE USED AS INDIAN MONEY.

NEAR LAKEPORT, LAKE COUNTY, CALIFORNIA. MUSEUM No. M6387.

Specimens of dolomite from the above locality, and of the
" money " made from it, were collected by Dr. G. A. Dorsey, Curator
of Anthropology of the Museum, during a visit made in 1889 to the
Porno Indians, a tribe of the Kulanapan stock who inhabit the region.
The material has long been used as a medium of exchange among
these Indians, but I cannot learn that it has been hitherto described.

The mineral occurs in the form of nodules, or boulders, roughly
oval in shape, and from four to eight inches in diameter. They are of
■ a rusty yellow color upon the surface and the local Indian name for
them, Pol' -ka-be, means rusty color. A freshly fractured surface
shows a pure white color, except for occasional rusty seams, and
lustre like that of unglazed porcelain. The texture is compact an,d
fracture flat conchoidal. A determination of the specific gravity of a
pure white fragment gave G. = 2.878. Dr. Dorsey did not visit the
mine whence the dolomite is obtained, but was informed that it was
situated on the east shore of Clear Lake, a few miles southeast of
Lakeport.

While the mode of occurrence cannot be stated with certainty,
it is probable that it is as residual boulders in a reddish clay.

A partial analysis by the writer gave Ca O, 28.27%, Mg O,
22.46%, and Fe O, 1.18%. These percentages are nearly those of
a typical dolomite.

The use of the mineral by the Indians as a medium of exchange
is a long established custom, and the value at which they esteem a
well worked piece is nearly equal to its weight in gold. In order to
make the money, symmetrically shaped cylindrical pieces are cut out
from the crude boulders. These are burned and the burning brings
out reddish streaks of color doubtless from oxidation of the iron,

Feb. 1900. New Mineral Occurrences — Farrington.

231

which adds to the beauty of the pieces in the eye of the Indian. The
pieces are then polished and perforated and pass as money, the local
Indian name for them being Po. Many of the small pieces are also
used as beads for necklaces and other ornaments. Fig. 9 shows the
appearance of two typical pieces of Po.

Fig. 9.

CRYSTAL FORMS OF CALCITE FROM JOPLIN,

MISSOURI.

Large crystals of calcite from Joplin, Missouri, have been known
for some years to collectors, and have become widely distributed in
collections. The crystals are remarkable, not only for their size,
but for their transparency, varied color and the perfection of their
crystal form. So far as I can learn no crystallographic study of
these calcites has ever been published. Photographs of some of
the crystals, together with some general statements as to the occur-
rence of calcite in Missouri, are to be found on pp. 457-9 of Vol.
VII, of the Reports of the Missouri Geological Survey. There is
also mention, on p. 567 of the same volume, of calcite crystals of
large size occurring in Crystal Cave, Joplin, and some description
of the cave is given. No crystallographic details are given in this
account, however, the crystals being simply described as scaleno-
hedral or rhombohedral. The present study of some of the crystal
forms can in no sense be considered a complete one, since the only
material undertaken to be described is that comprised in the Mu-
seum collections, and some crystals that were kindly loaned for
examination, through Prof. J. P. Iddings, by the University of Chi-
cago. Having, however, cursorily examined a large number of
crystals from this locality as exhibited in collections, both in this
country and in Europe, I may say that I have found them to be
remarkably uniform in character, and hence believe the character-
istic forms to be largely comprised in the types here described.
The specimens in the Museum collection have been obtained from
various sources, chiefly by purchase or exchange, but some were
collected at the mines in Joplin during the spring of 1898 by Mr.
H. W. Nichols, Assistant Curator of Geology.

LOCALITIES OF LARGE CRYSTALS.

The large crystals known to collectors are chiefly of two types,
differing in color and form. Those of the type which I may desig-
nate as Type No. 1 are characterized by a delicate violet to wine

yellow color, often showing within a deeper yellow or violet light.

232

Feb. 1900. Crystal Forms of Calcite — Farrington. 233

These came from the Blakie No. 2 mine. The crystals which may
be designated as Type No. 2 are characterized by a deep amber
yellow color ranging to colorless. They come from the Crystal
Cave, Ino mine. These two mines are quite near one another, and
are both located in Leadville Hollow, within the city limits of Joplin.

FORMS OF LARGE CRYSTALS.

Type I . — Crystals of this type are very simple in form. They
are made up of the common scalenohedron v, -(-R3,* truncated by
the flatter scalenohedron /, -\-}(K^. The average development of
the forms is illustrated in Fig. 1, PI. xxviii, it being drawn one-half
size from one of the crystals in the Museum collection. Such a
size is usual to crystals of this type. The following are averages
of measurements of several angles on crystals of this type, as made
with a contact goniometer:

23i~4=

3"i24=

2131 =

ion =

3~i2~i =

23U =

101*1 = 30

The surfaces of the crystal planes on these crystals are, in gen-
eral, flat and bright and of uniform lustre. They are, however, more
or less irregularly marked similar to the planes shown in Fig. 2,
PI. xxviii, and reentrant angles resulting from abortive terminations
often occur. While the crystals are often doubly terminated, as
illustrated in the figure, more commonly only about half of the com-
plete crystal form is present, the plane of attachment being a rhom-
bohedral or a basal plane. Numerous planes of rhombohedral cleav-
age pass through the crystals, and the light reflected from them often
brilliantly illuminates the interior. Many crystals are also often iri-
descent from interference colors produced by parting along cleavage
planes. Irregularly shaped grains of marcasite from one to two milli-
meters in diameter often occur scattered through the outer layers of
the crystals. Other associated minerals, often well crystallized and
found more or less in contact, are galena, dolomite and chalcopyrite.
A group of this character, now in the Museum collection, is shown in
the frontispiece.

*The letters used are Dana's.

t:f

=2134

/./v

=2134

t:v

=2134

t : cleavage

=21*34

v :i/

=2131

v : vv

=2131

v : cleavage

=2131

sured.

Calculated

42°

4i° 55'

22°

20° 36^'

36°

35° 56'

160

160 29'

74°

750 22'

35°

35° 36'

3°°

290 2'

234 Field Columbian Museum — Geology, Vol. i.

Type 2. — Crystals of this type are characterized, as has been said,
by an amber yellow color. This may be deeper or paler. The size
of the crystals is also remarkable. Some are known 2^ feet (.76
meters) in length, and the average size of those seen in collections is
from 6 inches (.15 meters) to 1 foot (.30 meters) in length. Those
seen in collections are rarely, if ever, doubly terminated, only about
half of the complete crystal being present. Some account of the
mode of occurrence of these crystals in a cave as well as a plan of
the cave is given, as already mentioned, on p. 567 of Vol. vii,
Reports of the Missouri Geological Survey. For the following fur-
ther information I am indebted to Mr. Henry Weyman, the present
owner of the cave : " The cave is from 250 to 300 feet long, from 40
to 60 feet wide and of an unknown depth in places, i. e., we have
never been able to measure the bottom, as only a part of it is above
water. The whole opening is covered with crystals of various sizes,
leaving no place on any of the roof or wall exposed and going down
as far as can be seen in the water. At one place a slab covered with
large crystals has fallen from the roof at some time, and since then
new crystals have formed on the roof where the slab has been broken
away; also new crystals have formed on the broken side of the slab
after it had fallen down. The largest crystals, I should think, would
measure 2 to 2^ feet long. The greater part of the crystals are
doubly terminated, ending in very sharp points. The cave was dis-
covered by mining after lead and zinc ore, when a shot put in the
bottom of the drift broke through the roof of the cave and so exposed
the mass of beautiful crystals. This is so far the only opening allow-
ing admittance to the cave. It is our intention to preserve the cave
in its present state and make access to it more convenient to visitors."
It is also stated in the account previously mentioned* that the cave
is remarkable for the entire absence of stalactites of the usual type.
Since these are absent it is probable that the cave at the time of for-
mation of the crystals was filled with water holding carbonate of lime
in solution, from which crystallization took place. Had the cave
been only in part filled with water, the dripping waters would doubt-
less have formed stalactites of the usual type.

The form of the crystals of Type 2 is primarily determined by
the common scalenohedron v, -\- R3. This may alone constitute the
crystal or its form may be slightly or highly modified. A common
modification is the truncation of the apex of the scalenohedron by the
rhombohedron <?,-^ R. Fig. 2, PL xxviii, represents a combination

♦Report of the Missouri Survey ioc. cit.

Explanation of Plate XXVIII.

Fig. I. Crystal of Type I. Fig. 2. Crystal of Type 2.
Joplin Calcite. Joplin Calcite.

One-half natural size. One-half natural size.

Mus. No. M5513. Mus. No. M5621.

FIELD COLUMBIAN MUSEUM.

GEOLOGY, PL. XXVIII.

FIG. 1

Calcite, Joplin, Mo.

LIBRARY

UNIVERSITY OF ILLINOIS

URBMA

Feb. 1900. Crystal Forms ok Cai.cite — Farrington. 235

of these forms together with the rhombohedron /, - | R, as seen on a
crystal in the Museum collection. There is also present one plane
of the negative rhombohedron /,-2R.

Some measurements made on this crystal with the contact goni-
ometer are as follows :

Measured. Calculated.

v. I - 2131 : 0445 = 43°-44' 44° 6'

v :/= 2131 : 0221 = 35°~38' 37° 41'

e : / = 01T2 : 0445 = n°-i2° 120 2'

e xv — OlTa : 2131 = 45°-52° 50° 36'

As has often been observed on calcites from other localities, the
planes of the rhombohedron c,-l/2 R are, in this crystal, striated
parallel to the edge r/r'. They are also somewhat rounded. The
curious sporadic occurrence of the plane / and the accompanying
imperfect growth of planes seems to be quite common for Joplin
crystals showing the above combinations. At least the writer has
noticed the same appearance on several other similar but smaller
crystals. It would be interesting to know the nature of the molecular
forces which would uniformly produce degradation of this sort. The
planes of the scalenohedron v on the crystal are in general flat and
bright, but show peculiar markings suggesting stages of growth.
These markings are quite irregular in form and seem to have no
angular values whatever. They follow, however, so far as they have
any arrangement, the lines of the cleavage rhombohedron. Partings
along planes of this rhombohedron are to be seen through the crystal
and the surface of attachment is usually characterized by cleavage
planes.

Other crystals of Type 2 are more highly modified than the one
just described. Fig. 1, PI. xxix, represents one such crystal now in
the Museum collection. Here the primary scalenohedron v, -J- R3 is
modified by the scalenohedrons n, -f- R£ and w, -J- | R2, also by
the positive rhombohedronsr, -(- R and M, -{-'4R, and by the negative
rhombohedron /,-|R. Only about half the complete form is present
in the specimen. In Fig. 2, PI. xxix, is shown the completed ideal
form which would be produced by these combinations. Some of the
measurements made on this crystal with the contact goniometer are
as follows :

Measured. Calculated.

v : r =2131 : iofi = 300 290 2'

v : M = 2131 : 4041 = 180 190 24'

r : M = ioil : 4041 = 310 310 \ox/l '

v : l = 2131 : 0445 = 44° 440 6'

r

: /

—

IOII

I

:/'

=

0445

V

: n

—

2131

n

:n'

—

4153

n

: If

—

4153

V

: w

—

2131

w

:iv' .

=

3145

<w

: «A

=

3145

236 Field Columbian Museum — Geology, Vol. i.

Measured. Calculated.

0445= 40° 39° 4'

4045 = 650 64° S3JA '

4153 = !7° 14° 28^ '

45I~3 = 78° 78° 5'

5^43 = 19° 180 7'

3145 = • 33° 33° 50'

4l35 = So" 49° 23 '

5~i43 = l6° l6°

The planes of r are further identified by their evident parallelism
to the cleavage planes.

An interesting peculiarity of the specimen is the surface differ-
entiation of the planes. Thus the planes of the scalenohedron v and
the negative rhombohedron / are flat and bright ; those of the scalen-
ohedrons n and w are striated parallel to the adjoining edges of the
unit rhombohedron, and the planes of the unit rhombohedron and
the rhombohedron M are rough. The differentiation closely follows
and beautifully illustrates the law that crystallographically equivalent
planes are similarly affected. An examination of the rough planes
reveals but little in the way of symmetrical etching figures. The
roughness is caused chiefly by delicate pitting, which is also wholly
irregular. There are to be seen occasional pits, however, which are
larger than the others and which have a definite pyramidal shape.
They are different in form from the etching figures usually produced
artificially on calcite by hydrochloric acid. The boundaries of the
pits lie parallel to the bounding planes of the unit rhombohedron.
Their character is illustrated in the accompanying figure (Fig. 10).

Fig. 10— Growth figures on plane of +R. Calcite, Joplin, Mo.

Explanation of Plate XXIX.

Fig. i. Crystal of Type 2.
Joplin Calcite.
One-half natural size.
Mus. No. M5515.

Fig. 2. Completed ideal form of crystal
shown in Fig. I.

Fig. 3. Crystal of Type 3.
Joplin Calcite.
Mus. No. M5511.

Fig. 4. Crystal of Type 5.
Joplin Calcite.
Mus. No. M5824.

FIELD COLUMBIAN MUSEUM.

GEOLOGY, PL. XXIX.

FIG. 2

FIG. 3

FIG. 4

Calcite, Joplin, Mo.

LIBRARY
UNIVERSITY OF ILLINOIS

URBANA

Feb. 1900. Crystal Forms of Calcite — Farrington. 237

FORMS OF SMALLER CRYSTALS.

None of the following crystals have the large size of those of the
types above described. They show, however, characteristic combi-
nations which warrant their description as types.

Type 3. — Crystals of this type are illustrated in Fig. 3, PI. xxix.
As is usual with the Joplin crystals they are not highly modified,
being made up solely of the scalenohedrons v, + R3 and w, £ R2.
The specimens of these crystals in the Museum collection come
from the Pelican mine in Joplin, occurring with sphalerite on the
characteristic chert breccia of the region. A large group is shown
in the frontispiece. The largest single crystal is not over 4 inches
(10 cm.) in length, and from this the crystals grade to a very small
size. Measurements of the planes made with the reflecting goniome-
ter are as follows:

Measured. Calculated.

V : v' =2131:2311= 75° 25' 750 22'

v : v ▼ =2131 : 3I21 = 350 36' 350 36'

v: v vi=3~i2i : 321!= 460 53' 470 \l/2'

w.w' =3145 : 3415= 50° 58' 49° 23'

w.-a/v=3i45 : 4135= 150 59' 160

The most striking characteristic of these crystals is the fact, repre-
sented in the figure, that the planes of scalenohedron v are smooth
and brilliant, while those of w are rough. This differentiation of
planes is constant for all the crystals which have come under the
writer's observation. The rough planes do not show definite etch-
ing figures, but rather under a lens series of troughs crossing one
another and following the lines of the cleavage rhombohedron. In
the writer's opinion the roughness is due to irregularities of growth
of the crystals rather than to etching. The reasons for this opinion
are: First, it is difficult to conceive of any etching agent which
could leave the planes of one scalenohedron so entirely untouched
while those of the other were so deeply corroded. Second, on sub-
mitting the crystal to the action of weak vinegar as an etching agent
the planes of the scalenohedron v were affected much more rapidly
and noticeably than those of w. The etching produced by the vine-
gar on the planes of V was in the forms of troughs or striae follow-
ing the lines of cleavage, on 7a there occurred only a slight additional
roughening of the planes. It is, therefore, in the writer's opinion,
not always correct to speak, as is usually done, of the rough planes
as etched planes. They will often be more correctly described by
the term imperfect or incomplete planes.

238 Field Columbian Museum — Geology, Vol. i.

Type 4. — The only crystals of this type in the Museum collec-
tion come from Leddy's Lease, Central City, about 5 miles from
Joplin. They are, however, a characteristic type for the Joplin dis-
trict. They are scalenohedral in character, often doubly termi-
nated, colorless, and frequently reach a length of from 2 to 3 inches
(5-7.5 cm.). The forms characterizing the type are v, +R3 domi-
nant with e,-}4K, /,-2R and 2,-nR, subordinate. A characteristic
feature is the habitually rounded and cross striated character of the
planes of /. In fact this form often grades into a scalenohedron of
large indices, the symbols of which it is impossible to determine.
The planes of / likewise usually widen toward the apices of the
crystal, so as to crowd out the planes of v, and themselves define
the termination of the crystal. Fig. 1, PL xxx, sufficiently illustrates
the average development of planes on crystals of this type, although
the one figured is a twin crystal and larger than the average of the
type.

Type 5. — Crystals of this type are of rhombohedral development.
Type specimens in the Museum collection come from the Meadow-
croft mine, Joplin. They are colorless, and not over 1 inch (2.5 cm.),
in length. They are made up of the negative rhombohedrons 7/,-4R
and/,-2R dominant, with the latter truncated by e, -J^R. A typical
crystal is shown in Fig. 4, PI. xxix. The planes of /and rt are con-
siderably curved, and admit of only approximate measurement. The
symbol of/ was, however, sufficiently determined by its relation to
the cleavage rhombohedron, and that of rt was determined from the
mean of measurements of ten crystals, which gave e : ^ — 0221 : 0441
= 49°. The calculated value is 49° 32'. The planes of e are usually
smooth and bright, those of/ are deeply striated parallel to the edge
fy, and those of rt parallel to the longest diagonal of the rhomb.
Rounding of the planes of the three rhombohedrons e, /and rt into
one another is common. One crystal showed an intermediate rhombo-
hedron between e and/ but it was impossible to obtain a measure-
ment sufficiently satisfactory to determine its symbol. In some
crystals again the rhombohedron /is absent and the crystal is made
up of only the forms rh -4R and e, -^R.

FORMS OF TWINNED CRYSTALS.

Only a few twinned crystals were noted among those examined.
The larger number of those noted are twinned upon the basal plane.
These occur of both Types 3 and 4. The crystal chosen for special
study was of Type 4, and is from the collection of the University of.

Explanation of Plate XXX.

Fig. i. Basal twin of Joplin Calcite. Fig. 2. Ideal form of twin shown
One-half natural size. Fig. I.

University of Chicago collection.

FIELD COLUMBIAN MUSEUM.

GEOLOGY, PL. XXX.

FIG. 1

FIG. 2

Calcite, Joplin, Mo.

LIBRARY
UNIVERSITY OF ILLINOIS

HQRfi N \

Feb. 1900. Crystal Forms of Calcite — Farrington. 239

Chicago. The crystal is shpwn in Fig. 1, PI. xxx. Measurements
made in the zone of the negative rhombohedrons on this crystal with
the contact goniometer are as follows:

Measured. Calculated.

^.■77=0112:0775 = 280 270 51'

77.-/=o775 :o22i = 9° o° I'

e : /=OM2 :022I = 360 36° 52

e : 2"=oi 12 : 0.1 1. T i.i= 59K" 58° 29

The determination of JS" rests rather on its occurrence on other crys-
tals of this type which could be measured with a reflecting goniome-
ter, than on the value obtained on this crystal, it being presumed
that the same plane was most likely to occur again.

The peculiar distortions and striations exhibited in this crystal
are illustrated in the figure. How far these have caused it to depart
from the normal form may be seen by comparing Figs, i and 2, PI.
xxx. The tendency shown in this crystal for the two individuals of
the twin to grow by one another and partially complete themselves,
is quite common among the Joplin twins. Further struggles of the
molecular forces are illustrated by the number of abortive planes of
e, -^R, these being so numerous as to produce cross striations on
/, -2R. The latter planes are further rounded from the tendency to
produce scalenohedral forms.

Another and the only other type of twin crystal noted has e,
-J^R as the twinning plane. Such twins occur among a group of
calcite crystals formed together on a specimen in the collection of the
University of Chicago. The crystals of this group are in general
scalenohedral in form, colorless to amber in color, and vary from
1 to 2 inches (.3 to .6 cm.) in length. Many are simple crystals
made up of v, +R3 dominant, modified by e, -^R, /, -2R, and a
form new to calcite, fl, -20R. * Others are intermediate in charac-
ter, and are the result, doubtless, of one individual pushing by
the other, as twins on the base have already been shown to do. Such
a crystal is represented in Fig. 1, PI. xxxi, the crystal being drawn
in the position of the negative scalenohedron in order better to show
the elongation in one direction. This elongation characterizes the
true twins as well. In this crystal on the side toward the observer,

♦The letter given to this form was chosen in accordance with Goldschmidt's system, Dr
Charles Palache having kindly indicated to me what the appropriate letter, according to this sys-
tem, would bo. I do not feel called upon to apologue forthus combining Oana'sand Goldschmidt's
lettering, f deem it essential that new forms should be lettered in accordance with Goldschmidt's
system in order to avoid conflict of letters, but the common forms are, and are long likely to be,
better known by Dana's letters.

240 Field Columbian Museum — Geology, Vol. i.

although the lower part of the crystal is quite incomplete, the bound-
ary planes are evidently those of a twin crystal. On the reverse side,
however, the development is that of a simple crystal.

The completely formed twins resemble in many respects those
from Guanajuato, described by Pirsson.* The twinning plane is the
same, the lengthening out in one direction is similar, though not to
the extent of the Guanajuato crystals, and the proportional develop-
ment of the faces is analogous. The Joplin twins, however, differ
notably from those of Guanajuato in their development at the apex of
the salient angle. In the Guanajuato twins the scalenohedral planes of
the two individuals of the twin are prolonged at the apex of the sali-
ent angle until they meet in a point. In the Joplin twins, however,
the scalenohedral planes of each individual have only a normal devel-
opment, and there is no prolongation to an apex. Some crystals
occur in which one individual has grown by the other at the salient
angle in the direction of the vertical axis of the individual, this being
but another illustration of the curious tendency which has been pre-
viously noted. There is, however, no prolongation at the end of the
twinning plane. The Guanajuato twins are usually attached at the
salient angle, while the reverse is true of the Joplin twins. The
attachment of the Joplin twins by the reentrant angle often takes
place at the end of a projecting process of calcite, usually more or
less bounded by crystal planes, and seeming to serve as a sort of stem
of crystal growth.

As regards the size of the twin crystals, it may be said that the
longest noted measures 3 inches (.75 cm.) from end to end of the
vertical axes. The lengthening out of the same crystal makes it
about 1 inch (.25 cm.) long in the same direction. The combination
of forms which make up these crystals has already been indicated.
The determination of the new form fl' , - 20R, rests upon its evident
location in the two zones v v' and em and upon a very accurate
measurement with the contact goniometer of the angle e : 12' =
0221:0.20.20.1 = 24°. The calculated value is 23° 59'. The form
usually has rounded planes. The determination of the other forms
likewise rests upon measurements made with the contact goniome-
ter, but these correspond so closely with calculated values, and the
analogy of the occurrence of the forms is so similar to that of the
other Joplin calcites that there can be little doubt of their being cor-
rectly identified. The form/2, -£R, is quite sporadic in its occur-

"Amer. Jour. Sci. 3d Ser., Vol. 41, p. 61.

Explanation of Plate XXXI.

Fig. i. Partially twinned crystal of Fig. 2. Twin crystal of Joplin Calcite.
Joplin Calcite. Twinning plane e,-}£ R.

University of Chicago collection. University of Chicago collection.

Fig. 3. Same crystal as Fig. 2, drawn in
the position of the negative scale-
nohedron.

■FIELD COLUMBIAN MUSEUM.

GEOLOGY, PL. XXXI.

FIG. 2

FIG. 3

Calcite, Joplin, Mo.

LIBRARY

UNIVERSITY OF ILLINOIS

URSANA

Feb. igoo. Crystal Forms of Calcitk -Farrington. 241

rence, appearing sometimes as a single plane, more often as two, and
only once in its full number of three planes.

In conclusion, the following list includes the forms noted on the
Joplin calcites by the writer :

rtion,+£ n, 4153, 1 1 +R|

J/, 4041, +i.ff t/,2iji, i8 +/?3

w, 3145. V

'.on 2 -;./v' /,2i34, J« +|7?2

/. 0443 -I*
^.0/75 I* -f}A>3

f, 0221 -2 A*

9,0441 4 A'
2?, 0.1 1.1 1.1, -1 1 A'
.Q, 1. 20.20. 1, -20 A'

It is evident that the largest variety of forms occurs in the zone
of negative rhombohedrons. Indeed, it is hardly likely that the
above list includes all the negative rhombohedrons which occur, as
several measurements made by the writer indicated others, although
they could not positively be identified. The positive rhombohedrons
are of rare occurrence and have little to do with determining the
forms of the crystals. Among the scalenohedrons, v, + R3, is almost
universally present and is usually the dominating form. This
scalenohedron in connection with e, -| R, and/, -2R, determines the
habit of most of the Joplin crystals.

UNIVERSITY OF ILLINOIS-URBAN*

3 0112 061063910