EXCHANGE
KENTUCKY
GEOLOGICAL SURVEY
J. B. HOEING, STATE GEOLOGIST
IN CO-OPERATION WITH
UNITED STATES
GEOLOGICAL SURVEY
GEORGE OTIS SMITH, DIRECTOR
REPORT ON THE PHOSPHATE ROCKS
OF CENTRAL KENTUCKY
FRANKFORT, KY.
1915
v;
THE STATE JOURNAL COMPANY
Printer to the Commonwealth
Frankfort, Ky.
THE CENTRAL KENTUCKY PHOSPHATE FIELD
By
W. C. Phalen.
TABLE OF CONTENTS
Page
Introduction 1
F'ield work 2
Geography and topography 2
Geology 4
Stratigraphy 4
Description of formations 6
"Wilmore" and Bigby (?) limestones 6
Flanagan limestone 7
Brannon cherty member 7
Woodburn phosphatic member 9
Rocks overlying the Flanagan limestone 11
Structure 11
Discovery of the field 12
The phosphate rock 15
Type of rock 15
Mode of occurrence 16
Distribution and character of the phosphate beds 21
Sections and analyses of phosphate rock 23
Wallace district 23
District west of Midway 29
Frankfort and Forks of Elkhorn district . 31
Lexington district 32
Localities to be prospected 36
Method of prospecting 40
Method of collecting samples 43
The local quarry industry as a guide to prospecting 43
The composition of the phosphate rock 44.
Origin ; 46
Source of the phosphate 46
Original mode of occurrence 46
The method of concentration 48
The brown phosphate rock industry 52
General conditions 52
Grades of commercial brown phosphate rock 54
Preparation of phosphate rock for market 55
Removal of overburden 56
Costs of removal of overburden 57
Methods of mining 58
Working cutters 59
The cost of mining phosphate rock 60
Page
Washing and drying 61
Conservation of fines 62
The phosphate industry at Wallace, Kentucky 03
Transportation facilities 61
Raw rock phosphate 65
Phosphatic limestone as a source of phosphate 66
The future of low and intermediate grade phosphate rock 67
General remarks 67
Chemistry of process 68
Experimental work in the west 69
Chemical methods 69
Electrical methods 71
The future outlook for Kentucky 74
Bibliography 77
Mohawkian Rocks.
Phosphatic area
near Midway.
Rocks above Mohawkian
Geologic Map of Central Kentucky, showing the distribution of
Mohawkian (Middle Ordovician) Rocks.
Scale: 1 inch=10 miles.
THE CENTRAL KENTUCKY PHOSPHATE FIELD
By W. C. PHALEN.
INTRODUCTION.
Tho object of .this report is mainly to present to the
public, unfamiliar with Kentucky's resources, data and
information of general interest bearing on the phosphate
deposits of the State. In it are described the location and
geographic distribution, the extent, and relative im-
portance of the deposits under present conditions of the
phosphate and fertilizer industry, and what may be ex-
pected of them as time 'goes on and new processes for
working them are developed. The methods of mining
and preparing brown rock phosphate for market as
practiced in the neighboring state of Tennessee are also
briefly outlined, for without doubt Tennessee practice
and experience will be utilized when the Kentucky de-
posits come to be more generally worked.
The element phosphorus is one of the three es-
sentials of the commercial fertilizers of the present day.
It is supplied to plants in the form of acid phosphate,
raw ground rock phosphate, basic slag, and various bone
products, such as steamed bone meal, raw bone meal,
bone ash, and bone black. Of these various substances
acid phosphate is the most largely used. It forms one
of the principal ingredients of nearly all commercial
fertilizers. It is prepared from the naturally occurring
phosphate rock and the essential ingredient in this rock
is calcium phosphate which is also often referred to as
bone phosphate of lime or bone phosphate, or simply
abbreviated to "BPL". Any or all of these terms, which
mean the same thing, will be used in this report.
Any extensive deposit of phosphate rock in the
I 'nited- States is either of present or prospective import-
ance. Those in central Kentucky, though not yet worked
to any marked extent, occupy a wide territory, are of
intermediate grade, and therefore constitute a reserve
supply of inportance. They were investigated by the
writer in 191.4 and 1915 and the following descriptions
summarize the results obtained.
This report is primarily an economic report and the
geologic features are only considered in the light that
they throw on the economic problems involved.
FIELD WORK.
The field Avork on which this report is based was
done in September and October, 19.14, and in June, 1915.
It extended over the better known phosphate area lying
between the towns of Versailles and Midway, Wood-
ford County, especially in the vicinity of Wallace. Con-
siderable work was also done west and northwest of
Midway, between the Louisville and Nashville Eailroad
and South Klkhorn (/reek. Studies were also made in
the vicinity of the Forks of Elkhorn Creek, Franklin
County, in and around Lexington, Fayette County, and
in a few isolated localities which will be mentioned in
the subsequent descriptions.
The writer gladly acknowledges the efficient help
rendered him by Mr. P. B. Winn, of Lexington and Win-
chester, Kentucky, in the field work, and also the many
valuable suggestions made by Professor A. M. Miller,
of the State University at Lexington. References to the
work of Miller will be made at the appropriate places
in the text.
During the course of this work nearly two hundred
shallow drillings weie made, the cores carefully sampled,
and analyses of the samples together with others were
made in the laboratories of the United States Geological
Survey by W. 0. Wheeler and E. M. Kanini.
GEOGRAPHY AND TOPOGRAPHY.
The greater part of the territory discussed in con-
nection with the Kentucky phosphate field occurs in the
Georgetown quadrangle. This quadrangle comprises a
large part of Fayette, Woodford and Scott, and small
parts of Franklin and Jessamine counties. Studies were
also made in parts of Franklin County off the northwest
corner of the Georgetown quadrangle and in the vicinity
of Pine Grove Station, Clark County. The phosphate
areas within the Georgetown quadrangle in Franklin
County have been studied by A. M. Miller* and descrip-
tions of the phosphate areas themselves have been pre-
pared by A. E. Foerste.f The writer acknowledges the
help received from the reports of these geologists and
due credit is given to them in the proper places in these
descriptions.
The low broad hills and the rolling topography are
characteristic of this beautiful country, which is of the
type known to geologists as a peneplain. The important
phosphate deposits occur at the surface of this old pene-
plained aica, that is, an area which has long been ex-
posed to erosion and which has been worn down to an
approximately level surface with most of the broad level
hill tops now between 900 and 1,000 feet above sea.
The rocks in this section containing the phosphate
are entirely limestones. The exposure to weathering of
a soluble rock, such as limestone is under ordinary con-
ditions, has here brought about fundamental changes in
which have been involved the removal of a large part of
the country rock. The removal of this rock has been ac-
complished both by chemical and mechanical means.
Limestone as it usually occurs is mixed with more or less
of insoluble hydrous silicates of aluminum (clay). The
limestones in this region contain also the insoluble phos-
phate rock. The -limestone has been removed, probably
largely in the form of the soluble bicarbonate Ca H.,
(CO*) 2 and the clay left after the solution of the Ca CO3
hos been carried off, in part at least, mechanically. There
is scarcely any doubt that some phosphate rock has been
carried off in this manner and thus wasted for all time.
In recent times the rate of removal of the residual
material, clav and phosphate rock, has been slower than
its accumulation, and in some places as revealed in na-
tural exposures and drillings, it is 10 or more feet thick.
In many other places, of course, the basal limestone out-
crops.
The principal streams within the areas under dis-
cussion are North and South Elkhorn Creeks and their
tributary branches. Fortunately South Elkhorn Creek is
not too remote to be considered as a possible source of
*MiJlpr. Arthur M., Geology of the Georgetown quadrangle; Kentucky
Geological Survey. Series 4, Vol. 1, Pt. 1, 1913. po. S17-364. Geology of
Franklin County; Ky. Geol. Survey, Series 4, Vol. 2, Pt. 3, 1914, pp. 11-87.
fFoerste, A. E. The phosphate deposits in the upper Trenton lime-
stones of Central Kentucky; Ky. Geol. Survey, Series 4, Vol. 1, Pt. 1,
1913, pp. SfH-Ui.
wash water, great quantities of which are needed in
phosphate mills for washing purposes. In a limestone
region where sinks abound and where much of the drain-
age is below ground, the presence of a stream like South
Elkliorn Creek may prove to be of the greatest economic
importance to an industry requiring a very cheap and
abundant water supply. The topographic and geologic
map shows the great paucity of important streams ex-
cept South Elkliorn Creek in the neighborhood of the
phosphate deposits.
The meandering character of the Elkliorn Creeks is
pronounced. The presence of streams would be hardly
suspected when the country is viewed from a hilltop.
Only the dense growth along them indicates their courses.
There seems little doubt that the irregular stream courses
have been inherited or retained from a period in their
history when they flowed over a low broad plain. As the
region has been elevated they have cut down or deepened
their channels, but this has taken place with few excep-
tions along their original courses. Such streams are
said to have intrenched themselves, and their meanders
are known as intrenched meanders.
GEOLOGY.
STRATIGRAPHY.
The following notes on general stratigraphy and
structure of the quadrangle are compiled largely from the
reports of Prof. A. M. Miller, as the writer spent less
than three months in the area, working chiefly on the
economic problems of the phosphate beds alone.
The country rocks associated with the phosphate
rock deposits are all limestones of different lithology
and degrees of purity. The chief foreign ingredients in
them are clay, chert, and the phosphate rock itself. They
are all of marine origin and belong to the middle part
of the Ordovician system; their total thickness is ap-
proximately 330 feet.
The best stratigraphic section in the vicinity of the
area which the writer knows of is on the hill road at the
Old Crow Distillery near the mouth of Glenn's Creek. The
locality is about 5 or 6 miles wrest of the w^est boundary
of the quadrangle. The following illustration (Figure 1)
900-
^^\
ED EM - 32
1 i i
1 1 I
L ir:_-J'-' —
CYAJTH/ANA-38'.
-i J __j r
ii / I
.
Jykl^
X-
~ T ~
P£RRVV 1 LLE. /O'-
• i ' i ' [ ' r1 r
' 1 '
i t i
'
iii
W O OD B U /? A/ - 39.
/ i r
_ — — -
11 i
s* ^
i i i
*"*
, i i
I ' '
i ' '
l t i
BfiAASA/OA, - ft.'
J^iA^L
-O -V JJ
i > —
J ! i
1 >
I l L
B/GBY - 7v5T
/ 1
i t i
t i
j_ i i
i !
) i i
{ t
700 _
J L J
i l
1 i
I • i
| t
t 1 '
• »
\A/// -AA O ft f — 7ft
i » i
t «
i ii
i i
If i
i i
i i i
; i
J l '—
11 i _
/V EfRM / TA G£ - 3J £"
' T
( A}
{ . 1 I..
' 600-
i 1
1 1 J
! t
CUflOSVILLE- SO.
1 } t
t>/x^I
j ^
) 1 1
TYR OA/E - 4 o.
1 1
1 L
Lerf-L or GLCMJ C«.
I f
Plectambonites rugosus
Cyclonema varicosum
Hebertella sinuata
Constellaria teres
Stromatocerium
Columnaria halli
Rhynchotrema inaequivalve
Stromatocerium reef
Rhynchotrema inaequivalve
Prasopora simulatrix
Dalmanella bassleri layers
Fig. 1.
Geological section exposed at the Old Crow Distillery from level
of Glenn's Creek to top of hill on North Side of the creek, taken along-
steep road intersecting the pike at the distillery. (After A. M. Miller.)
Ky. Geol. Survey, Series IV, Vol. 1, Part 1, 1913.
represents the section at this locality as given by Pro-
fessor Miller.
The phosphate deposits of the Georgetown quadran-
gle occur chiefly in the beds to which the name Woodburn
is applied in the section quoted in Fig. 1. These beds,
together with the underlying Brannon bed of Miller,
correspond to the Flanagan chert of M. R. Campbell in
the Richmond folio of the United States Geological Sur-
vey.
DESCRIPTION OF FORMATIONS.
" WILMORE" AND BIGBV ( ?) LIMESTONES.
The rocks of this area to which the names Wilmore
and Bigby have been applied by Professor Miller con-
sist of thin-bedded limestones with some shale between the
layers. There is no distinct lithologic or stratigraphic
break between them. The name "Wilmore is preoccupied
by the Wilmore sandstone member of the Conemaugh
formation, and it is therefore quoted in this report. The
rocks called Bigby by Professor Miller are correlated
by him with the Bigby limestone of southwestern Tennes-
see. As this correlation is not established the name Big-
by ( ?) limestone is used in this report. The total thick-
ness of these formations within the Georgetown quad-
rangle is about 90 feet. Of this total thickness 65 to 75
feet belong to the Bigby (?) limestone and the rest,
namely 15 to 25 feet, belong to the "Wilmore." Accord-
ing to Miller the "Wilmore" is characterized by the
brachiopod Dalmanella bassleri and the "chocolate
drop" or hemispherically shaped bryozoan Prasopora
simulatrix.
The Bigby (?) formation contains more abundantly
them any other formation the brachiopod Rhynchotrema
inaequivalve. Hebertella frank fort en sis, another brach-
iopod, is also abundant in the Bigby (?) and upper part
of the "Wilmore," reaching its culmination lower down
in the section than RhyncHotrema inaequivalve. At the
top of the Bigby (I), and confined to a vertical range
of not over 10 feet, is a very characteristic assemblage
of fossils comprising two bracMopods, Dmprthis ulrichi
and Strophomena vicina, a bryozoan of globular habit,
Cyphotrypa frankfortensis, and a large coralline fossil
Stromato cerium pustulosuni, together with other bryo-
zoa.
"The coralline fossil Stromato cerium putulosum is
usually so abundant at this horizon as to indicate that it
formed .a reef in this region in the ancient Ordovician
sea." It is especially abundant in the northern part of
the Georgetown quadrangle and as far south as the lati-
tude of Midway. In places it is as much as 6 feet in
thickness and as its top is practically at the base of the
next overlying formation (the Flanagan), it has an
economic, as well as stratigraphic significance, for the
reason that all important phosphate deposits are likely
to be found either close above or close below it. Accord-
ing to Foerste phosphate rock also occurs locally in the
upper part of the Bigby ( .') limestone.
FLANAGAN LIMESTONE.
The term Flanagan chert was given by M. R. Camp-
bell in the Richmond Folio of the United States Geo-
logical Survey to the next overlying formation. The
term was applied to the rocks occupying the interval
between the Lexington and Winchester limestones, the
latter terms being practically the same as Linney's
Trenton and Hudson formations as used in the latter ?s
reports on the counties in the blue grass region for the
Shaler and Procter Kentucky State Surveys.
According to Miller* only the lower 13 to 15 feet
of the Flanagan consists of siliceous limestone which
forms chert on weathering. The cherty character is not
at all conspicuous excepting as the result of ordinary
atmospheric weathering processes where the beds are
at the surface. The remainder of the Flanagan con-
sists of 30 to 40 feet of thin-bedded, granular, phosphatic
limestone. The lower cherty beds are herein called
Brannon cherty member, and the upper or phosphatic
beds are called Woodburn phosphatic member.
BRANNON CHERTY MEMBER. — The beds to which
Miller has applied the name Brannon in his description
of the rocks of the Georgetown quadrangle consist of 13
to 1.5 feet of siliceous limestone which forms chert on
weathering. The beds are named for exposures at
*Miller, A. M., Geology of the Georgetown quadrangle; Ky. Geol. Sur-
vey, Series IV., Vol. 1, Pt. 1, 1913, p. 324.
Brannon Station, on the Queen and Crescent Railroad,
a short distance south of the southern boundary of the
Georgetown quadrangle. These rocks are regarded by
Miller, Foerste and Ulricli, as representing the lower
or cherty part of Campbell's Flanagan chert.
It is the upper part of the Brannon, with its highly
contorted or bouldery layers (see PI. 1 and "2) that is so
characteristic and it is this portion which furnishes
most of the chert at its weathered outcrop. AVhen freshly
exposed the Brannon is very firm and hard and requires
blasting to remove it. It is a good water bearer and con-
sequently its outcrop is generally marked by the pres-
ence of springs. The Big Spring at Versailles is at this
horizon and also what are known as the Maxwell or Sink-
ing Springs at Lexington. The Big Spring at Spring
Station is also near this horizon. It is pre-eminently the
formation occurring in the numerous sinks found in this
quadrangle. This latter association may be due to its
tendency to resist temporarily destruction by solution
and to form, therefore, the root's of caverns. Later, when
brought to the surface by denudation, it goes to pieces
rapidly, is decomposed into chert and the roof of the
cavern falls and a sink results. There are instances
where the collapse of a cavern roof has taken place
suddenly and has entrapped grazing stock.
As may be inferred from the behavior of this lime-
stone under conditions of weathering, natural exposures
of the firmer layers are rare. The best exposures are
along railroad cuts and in other artificial excavations
and in sinks of rather recent development. The Brannon
is splendidly exposed in a cut on the Cincinnati, New
Orleans and Texas Pacific Railroad (Queen and Crescent
route) in Lexington near the Virginia Avenue (Lottie
Street) bridge. It is usually a spring horizon and the
water comes out directly above the contorted limestone
layer which is from 1 to 1% feet thick at this locality.
The cherty phosphatic layer shows above the contorted
layer, but very little of it is in massive form. (See
plate 1.)
Near where the photograph was taken the phos-
phatic layer is 8 to 1.0 feet thick, but owing to the pres-
ence of considerable wash the exact thickness is not
readily ascertained.
The Brannon resembles a sandy limestone at this
locality and thin bands of blue shale up to 2 feet in thick-
ness were observed. It is very irregularly bedded — a
condition especially noticeable where the base of the
upper or contorted layer rests on that containing the
blue-drab shale. This contact is so irregular that non-
conformity or even faulting is suggested. In addition
to this locality, eight other localities where the Brannon
outcrops are listed by Miller.
The Brannon is of interest because in most instances
it forms the base of the richest phosphate deposits of
this region.
WOODBURX PHOSPHATIC MEMBER. — The strata to
which the name Woodburn has been applied by Miller
are described by him as consisting of "about 30 to 40 feet
of thin bedded, granular, phosphatic limestone. The
name comes from the celebrated Alexander estate, in
Woodford County, where the beds are said to be very
typically developed, especially as regards their most
distinctive feature, the possession of phosphate. The
most conspicuous fossil in this formation is the coral,
Cohimnaria lialli. It is commonly found in a silicified
condition weathered out from its matrix and found loose
in the deep, dark red soil formed from the decay of the
limestone at its horizon. Another very common fossil in
this formation is the very small gastropod Cyclora
minula. This fossil occurs only as phosphatic casts of
the inside of the shell, and its presence in association with
the more phosphatic phases of the rock suggests strongly
that the animal which formerly inhabited the shell played
an important part in the original segregation of the phos-
phate of lime from the sea water. ' ' According to Miller,
Foerste and Ulrich, the Woodburn is equivalent to the
upper and major part of the Flanagan chert of Camp-
bell.
At the old workings of the Central Kentucky Phos-
phate Company at Wallace, a good opportunity is pre-
sented to study the stratigraphic position of the phos-
phate rock deposits themselves. From the data which
Foerste* obtained he concluded that "the diggings so
far made by the Phosphate Company, at their
*Foerste, A. E. The phosphate deposits in the upper Trenton limestone
of Central Kentucky; Ky. Geol. Survey, Series IV., Vol. I., Pt. I., 1913,
PP. 412-413.
plant southeast of Wallace, belong- to the upper part of
the Benson or Bigby bed, and not to the Woodburn bed.
This is confirmed by the latest diggings made at the
plant. Here the basal part of the Brannon bed was ex-
posed about half way up the hill slope, above the level
of the first three strips of phosphate rock, 50 feet wide,
so far removed. Here Dinoilldx ubiclil and Stromato-
cerium occurred in the upper part of the phosphate rock,
beneath the base of the Brannon layer, clearly indicating
the geological horizon. The phosphate rock struck
northeast of the house1 on the Steele farm, about a mile
and a quarter east of Wallace Station, however, belongs
to the upper part of the Woodburn horizon.
"It is evident that, locally, weathering away of the
Woodburn bed has resulted in the concentration of phos-
phatic material at the top of the next underlying lime-
stone, which in this case is the Benson or Bigby bed. It
is interesting that, at the only locality at which so far
any actual commercial development of the phosphate
field has been undertaken, the only workable rock so
far exploited should belong to the Benson and not to the
Woodburn horizon. Aside from this limited area in the
neighborhood of Wallace, there are also other localities
at which phosphate rock occurs in the upper part of the
Benson bed, but by far the greater part of occurrences
of phosphate deposits, taking the field as a whole, occur
in the Woodburn bed, and this is especially true when
the un weathered rock is taken into account. This sug-
gests the origin of the most of the phosphatic deposits
in central Kentucky in the Woodburn horizons, although
locally concentration may have extended downward into
the upper part of the Bigby.
"The occurrence of StropJiomena vicina in the phos-
phatic layers in the upper part of the Stark quarry, a
mile and a half south of Wallace, suggests that these
layers also belong to the upper part of the Benson sec-
tion."
The phosphatic rock deposits are proved, therefore,
to extend through a considerable stratigraphic interval.
It is clear from the descriptions that the phosphate bear-
ing beds cannot be represented on the map by a single
line, and not very readily by a band as in ordinary geo-
logic mapping.
The Woodburn abounds in sinks. ~ *
10
ROCKS OVERLYING THE FLANAGAN LIMESTONE.
Only the lower member of the formation overlying
the Flanagan is of interest or importance in this report
for the reason that it occurs close above the phosphate
rock horizon and thus may prove of great assistance in
helping to locate it. This member is a gastropod horizon.
In western Woodford and adjacent parts of Franklin
County the shells of gastropods are massed together in
a ledge of cherty limestone about 5 or 6 feet thick. In
its massive condition this limestone is found in the
western and southwestern parts of the Georgetown quad-
rangle south of South Elkhorn Creek. Its former pres-
ence in the southwestern quarter of the area — that is
in the region south and west of South Elkhorn Creek-
may be readily traced by means of its outliers and the
abundance of gastropod chert debris found in the soil.
The latter on account of its resistant character may
even be found over areas from which the formation has
long been removed by weathering, if it ever existed in
these parts. Where it occurs as a distinct horizon the
phosphate rock bed should be looked for below it on the
hiils.
STRUCTURE.
The area of the phosphate deposits is on the western
flank of the Cincinnati geanticline — a broad, low dome
toward the center of which the rocks outcropping be-
come lower and lower in the geological time scale. The
rocks in this region, therefore, dip from west to north-
west at very low angles — so low that the dips cannot
be determined instrumentally, that is with a clinometer,
but must be reckoned over broad areas on the basis of
actual elevations on particular beds. The average rate
of this dip is about ten feet per mile and the main streams
fall at approximately the same rate in the same direction,
thus running over approximate dip slopes. It follows,
therefore, that the highest lands are found in the south-
east part of the region and the lowest in the northwest.
The relief in the Georgetown quadrangle is about ;>50 feet,
the difference between 1050 feet along the Nicholasville
pike in the southeastern part of the Georgetown quad-
rangle, and 700 feet, the approximate elevation of South
Elkhorn Creek where it leaves the quadrangle.
11
The uniformity of dip to the northwest has been
interfered with in places by disturbances which have re-
sulted in faults. Most of these are of slight vertical
throw and of limited extent in surface outcrop. They
are "tension or normal77 faults and have a wide drag
zone, for which reason the stratigraphic throw is great
compared with the vertical. Most of those located occur
in pairs, one of which may be considered the primary
and the other the secondary or compensating fault. An
illustration of other minor movements in the rocks is
shown in Plate III. The faults so far as known do not
involve those areas where the important phosphate de-
posits are found.
DISCOVERY OF THE FIELD.
There seems to be no question but that the distinc-
tion of having called attention to phosphate in the lime-
stones of central Kentucky belongs to Dr. Eobert Peter,
Chemist of the Kentucky Geological Survey, under the
administration of N. S. Shaler. This wras done as early
as April, 1849, in the Albany Cultivator of NewT York.*
It was Dr. Peter also who first pointed out the associa-
tion of phosphate and cyclora and the dependence of the
soils of the blue grass region for their fertility on the
presence of phosphate rock.
In the report by Dr. Peter to State Geologist Shaler,
dated February, 1877, there is given the analysis (No.
1778) of a phosphatic limestone from McMeekin7s quarry
(see Plate IV.) on the Newtown pike, 3 miles north of
Lexington. The specimens were collected by Dr. Peter
himself and the phosphate layer was reported by the
quarryman to be as much as 1 foot thick. The rock is
described as being somewhat friable, of a bluish gray
color, but brownish gray on the wreathered surfaces, as
containing many microscopic marine univalve shells and
as adhering strongly to the tongue. The phosphates in
this limestone were found to contain as much as 31.815
per cent, of the weight of the rock of phosphoric acid,
which is equivalent to 69.452 per cent, calcium phos-
phate.
*Ky. Geol. Survey, Chemical Analyses A, Part I., 1890, p. 246. Ky.
Geol. Survey, Chemical Analyses A, 1877, pp. 65-66. Also described as
Vol. 4, new series, Reports Geol. Survey of Ky., pp. 65-66.
12
The composition of the sample was as follows :
Analysis of the Fayette County Phosphate Rock, Dried at 212° F.
Phosphoric acid, lime, magnesia, alumina, and iron
oxide 85.270
Calcium fluoride not est
Carbonate of lime 9.180
Carbonate of magnesia .371
Silica and insoluble silicates 4.780
Alkalies, organic matter, etc., not estimated 3.99
100.00
In his observations on this rock, Dr. Peter makes
the significant statement "the subject is worthy of
further investigation, especially in view of the agricul-
tural and commercial value of the phosphate for use
as fertilizers. As is well known, the abundant phosphates
of the rock substratum is one of the main causes of the
great and durable fertility of our blue grass soil so-called,
as well as of the superior development of the animals
reared and nourished on its products."
At the time the specimen of phosphatic limestone
whose analysis is given above was collected, the quarry
was not in use and the statement that the layer of rich
phosphatic rock was as much as a. foot thick could not
be verified. When the quarry was again opened and
worked for turnpike material in 1877, a more complete
examination was made by Dr. Peter with the following
results :
Phosphatic Limestone From the McMeekin Quarry, Northwest Side
of Newtown Turpike, 3 Miles North of Lexington, Taken
From Irregular Layers About 1 Foot in Thickness.
Composition Dried at 212° F.
Lime carbonate 49.160
Magnesia carbonate .090
Phosphates, with AIX^FeAi, etc. (containing 21.018 per
cent, phosphoric acid) 46.540
Siliceous residue 2.820
Organic matter and loss 1.390
100.000
13
The analyses given above and others indicated an ir-
regular distribution of phosphate, and so 11 other
samples were selected from portions of the phosphatic
layer. The quantity of phosphoric acid (PoO.-,) in these
11 samples varied from 5.053 per cent, to 21.940 per
cent., and averaged 15.89(3 per cent., pointing to an ir-
regular distribution and an irregular local origin.
Interest in the occurrence of phosphate rock and
phosphatic limestone in Kentucky did not develop at
once, or at least lead to further field exploration or in-
vestigation. The discovery and the commencement of
work in the Tennessee phosphate field in 1894-1895 quick-
ened interest in phosphate rock deposits in general. The
association of calcium phosphate layers at the top of
the so-called Tienton limestone near Lexington with cer-
tain organic remains was pointed out by A. M. Miller
as early as February, 1896.* During the summer of 1904,
Miller was engaged in field work for reports on the geo-
logy of Jessamine, \Voodford and Franklin counties.
These reports, except that for Franklin County, were
never published, but in that on "YToodford County he re-
ferred to the phosphate deposits and their exceptional
richness at the top of the so-called Trenton in the terri-
tory between Midway and Versailles.
In a report by the former director of the Kentucky
Geological Survey, Charles J. Norwood, f it is stated
that "Professor Miller discovered the exact representa-
tive of the rock phosphate beds of Mt. Pleasant, Tennes-
see, some examples running* as high as 72 per cent, phos-
phate, and having* definitely differentiated them, he was
able to trace them over considerable areas." Thus the
fundamental studies made by Professor Miller entitle
him to the credit of suggesting the possibilities of this
region as the site of potentially important phosphate
rock deposits. $
*Miller, A. M. The association of the gastronod e-enus cvclora with
phosphate of lime deposits. Am. Geol., Vol. XVII., 1896, pp. 74-76.
fKy. Geol, Survey Kept, on 'the progress of the survey for the years
1904-1S05, pp. 25-26.
tit has been stated that in the summer of 1915, a negro while digging-
post holes on the farm of H. L. Martin, near Midway, discovered what he
considered nhosphate rock, similar to the brown phosphate rock in
Tennessee. Mr. Martin verified the negro's oninion. See Gardner, James
H., Min»s and Minerals, November-. 1912. p. 207: Waggaman, W. H., U. S.
Dept. of Agriculture, Bureau of Soils, Bull. No. 81, Marcli 20, 1912, p. 24.
14
THE PHOSPHATE ROCK.
TYPE OF BOCK.
Phosphate rock occurs in a variety of ways and has
been designated by a variety of names in the different
states where found. The Ordovician phosphate rock of
central Kentucky belongs entirely in a class known as
brown phosphate rock, first so-called in middle Tennes-
see. It occurs as a distinctly laminated residual deposit,
al^o as filling solution cavities or pockets in a more or
less phosphatic limestone. (See Plates V. and VI. and
Figure 4.)
The rock itself occurs in porous or loosely coherent
plates and whore exposed, naturally or artificially, these
plates vary in thickness from the very thinnest up to
those a few inches thick. The more massive rock is re-
ferred to as lump, plate, or hard rock. The latter may
also occur in thick heavy slabs of several inches, or even
a foot or moie in thickness. This massive type is not
common in Kentucky. It was observed in a natural ex-
posure on the Louisville Southern Railway near the
Cahill place, about a mile and a half west of Lexington
and on the Harkness estate (Walnut Hall) east of Cane
Bun and near the Fayette-Scott county line in the north-
east nart of the Georgetown quadrangle. Doubtless it is
found in many other places that were not seen.
Usually the plates or slabs are separated from each
other by layers of loosely cemented or porous material
consisting of phosphate rock in a fine state of division
mixed with more or less clay. The explanation of this
form of rock will be made clear under descriptions of
origin. The material is termed phosphate muck and is
found between individual plates, especiallv in fresh ex-
posures or drill holes. Muck, or the soft mixture of
phosphate and clay, often is found just above the lime-
stone on which the phosphate rock stratum rests.
There is also another form of brown rock known as
phosphate sard, some of which is very rich in cilcium
phosphate and is therefore of commercial value. Mix-
tures containing varying proportions of plate rock, sand
rock, and muck constitute what is included under the
term brown phosphate rock.
The color of the rock varies from a drab through a
grayish and yellowish brown to a deep brown or almost
15
black. The muck layers so often found overlying the
limestone at the bottom of the numerous holes drilled by
the writer, are usually nearly black, and in some cases
it was thought that the dark color might be due to the
presence of hydrous oxides of manganese which are a
very common constituent of the soils in the blue grass
region. The thickness of the beds will be described under
mode of occurrence.
MODE OF OCCURRENCE.
Brown rock phosphate deposits depending on their
manner of occurrence, have been designated as "blanket"
and "collar" deposits/* The latter have also been called
Fig. 2.
Blanket phosphate deposit on low, flat hill. Showing the development
of "horses" and "cutters."
Fig. 3.
"Collar" or "run" phosphate deposits formed on steep hillside.
"hat band" or "rim" deposits. The name suggests the
character of the formation. The term "blanket" applies
to the nearly horizontal deposits of considerable areal
extent, while those designated "hat band" or "rim"
occur within a limited vertical zone on the hillsides. (See
Figures 2 and 3.) The character of the deposits depends
*Hayes, C. W., U. S. Geol. Survey, Folio No. 95, 1903, pp. 5-6.
1G
on the topography or lay of the land; and it is obvious
that the blanket deposits are the most extensive, and
with other conditions the same, are the most valuable.
It is also obvious that there cannot be any sharp or ar-
bitrary division between blanket and collar deposits, but
that the one type may merge imperceptibly into the
other.
At the old workings of the Central Kentucky Phos-
phate Company, the predecessor of the United Phosphate
& Chemical Company, near Wallace, there are good il-
lustrations of the collar type merging into the lolanket
type of deposit. The workings here are not very exten-
sive, at least not enough to indicate to one who has
not prospected the area, whether the deposits cover the
entire hill where wrork has been done and hence belong
strictly to the blanket type. The drilling done in the
course of this investigation, and the information gathered
from talking with land owners who are acquainted with
conditions from local drilling, seems to indicate that the
deposits belong to both the collar and blanket types, and
that the former are probably the more numerous.
It was stated above that the type of the deposits
depends on the topography. The topography in this part
of Kentucky is gently undulating, or rolling. A study of
it shows clearly that it has resulted from the dissection,
or cutting down of a gently sloping surface which orig-
inally was more than 1050 feet high in the southeastern
part of the Georgetown quadrangle, and more than 850
or 900 feet high in the northwestern corner. Such topog-
raphy affords the best conditions for the formation of
residual phosphate deposits, providing the other requi-
site conditions are fufilled. The Lockport quadrangle
to the northwest furnishes an example where geological
conditions are similar to those in the Georgetown quad-
rangle, but where the topography is such as to preclude
the possibility of the formation of phosphate rock de-
posits owing to its rugged character, except at the very
outcrop. It follows, therefore, that the economic im-
portance of such deposits should be slight.
The phosphate rock deposits are always associated
with limestone and it is from a phosphate bearing lime-
stone that they are considered to be derived. The orig-
inal phosphatic material occurs in definite bands in the
17
limestone mixed with calcium carbonate. (See Plate VII.)
It is believed without much doubt that these highly phos-
phatic bands are original, and that they were laid down
alternately with bands of limestone containing less phos-
phate, or none at all.
With the leaching of the limestone the insoluble
phosphate rock and the other insoluble materials orig-
inally present, which are chiefly clay, silicified fossils,
and chert debris, have slumped down slowly onto the
underlying limestone. The capping of clay has resulted
from the similar changes which have taken place in
higher clay bearing or argillaceous limestone beds. In
the writer's opinion no other theory or hypothesis is re-
quired to explain the formation of the phosphate de-
posits. Solution has taken place along joint planes more
rapidly than in the other places and has led to the
formation of so-called "cutters" or "horses." (Plate
IX.) Horses are the limestone masses projecting into
the phosphate rock layers, the latter of which curve over
them in arches, as will be observed from the illustrations
(Plates V. and X.) and in the cutters between the
horses the phosphate rock deposits often show abnormal
thickness from the mechanical slumping down from the
flanks of the horses. (Figure 4.) This behavior of the
phosphate rock leads to great variations in the thickness
of the deposits and necessitates most thorough prospect-
ing before the average thickness over a given area can
be closely estimated. Splendid examples of the irregular
limestone surface underlying the phosphate rock are to
be seen at the old workings near Wallace (Plate IX.),
and in sections at many quarries in the region, among
which may be mentioned the Haggin quarry at Elmen-
dorf, east of Maysville pike; the Stark quarry on the
Versailles-Midway pike; the James P. Headley quarry
just outside of Lexington city limits and east of the
Russel Cave pike, and doubtless at many other quarries
over the entire region.
Actual exposures of limestone and overlying phos-
phate are not very common. The mode of occurrence,
therefore, cannot be studied as closely as desirable from
the commercial point of view from either outcroppings or
quarries. Drilling operations and the digging of pits
are necessary to throw the maximum light on the mode
18
I . 1.
r-
r^-r
t . 1 "J
T r~r
i . .1
iLS I
>. I . r
"_;•" '• t ''^^j^g^m'lg
Fig. 4.
C— Clay -seam. S— Soil. L.S.— Limestone. J — Jointing. P— Phosphate.
DEVELOPMENT OF CUTTERS.
Scale — 1 inch=20 feet approximately.
Showing the development of cutters after J. S. Hook,
"The Resources of Tennessee."
Vol. IV, No. 2. April, 1914. P. 64.
of occurrence. The former method of prospecting will
be described under the proper heading.
The overburden of the phosphate rock consists, as
has been stated, chiefly of clay mixed with different ma-
terials like chert debris, silicined fossil remains, etc. This
overlying soil contains small quantities of lime phos-
phate. The following section was measured on the Louis-
ville Southern Railway near the Cahill place already
referred to as about 1V> miles northwest of Lexington:
Section of Phosphate Rock on the Louisville Southern Railway Near
the Cahill Place, 1'/2 to 2 Miles Northwest of Lexington. .
4' .Overburden.
3' 6" Massive phosphate rock.
3' 9" Clay.
3' 6" Limestone and blue shale.
A sample of the overburden gave less than 2 per
cent, phosphoric acid. A sample of overburden from
station No. 11, near Hulett's, gave less than 1 per cent,
phosphoric acid. A sample collected from a thickness of
S1/^ feet in excavating for a telephone pole at the road-
side :>4 of a mile northwest of Hillenmeyer Station, gave
less than 2 per cent, phosphoric acid. Though the over-
burden contains but little phosphate, its possibilities as
a filler in making commercial fertilizer ought not to be
lost sight of, for it is this soil that renders the blue grass
region so productive.
The abundance of iron and manganese oxide con-
cretions in the soil overlying the phosphate rock is worth
remarking. A notable quantity of these concretions oc-
curs near Station No. 11, or Hulett's, on the interurban
trolley line between Lexington and Nicholasville. Here
a layer of the concretions 3 feet thick was observed. The
top soil in the entire blue grass region is shot through
with manganese concretions, usually of small size. These,
no doubt, were originally disseminated in the limestone
and have been segregated during the process of weather-
ing.
The presence of manganese is of interest since it has
been considered to have some fertilizer value. An
elaborate series of experiments has been carried on by
the Bureau of Soils, IT. S. Department of Agriculture,
20
having in view the determination of the effect of man-
ganese salts on grain and vegetable growth. Both pot
and field tests were made and the conclusion was reached
that crop growth in unproductive sandy loam was stimu-
lated by the addition of 5 to 50 parts of manganese to
a million of soil, whereas no effects were noticeable when
a productive loam soil was used. In some tests an actual
decrease in yield was attributed to the addition of man-
ganese salts.*
DISTRIBUTION AND CHARACTER OF THE PHOSPHATE
BEDS.
A somewhat restricted district in the vicinity of
AVallace a few miles south, southeast, and southwest
of Midway, Woodford County, is the only one of promi-
nence within which phosphate rock is known to occur
to any great extent. Between Midway and Spring Sta-
tion, along the Louisville and Nashville Railroad, and
on certain farms to the north of the railroad, is another
area where phosphate rock has been found in some
quantity. The limits of these areas have not been very
accurately determined, but enough drilling has been done
to indicate that locally, very important deposits of phos-
phate rock should be expected. When it is recalled that
brown rock phosphate may be expected to run from 600
to 1,000 tons per acre per foot of thickness, small acre-
ages may prove of great importance if the phosphate
deposits are thick enough and of good quality.
In the fields and districts named there are many
small areas in which the phosphate bed is lacking, or too
thin to be of value, or perhaps is overlain by a cover too
thick to remove profitably. Some prospecting has been
done throughout all the areas and the distribution of
the phosphate is quite well known in certain tracts. The
work has been done privately, and hence the records are
not available. As an example of the quantity of phos-
phate rock occurring in this region, it has been told the
writer that 16,000 to 18,000 tons of phosphate rock were
produced from a five-acre tract at "Wallace, that is to
say an average of 3,600 tons per acre. It has also been
stated that 1,200 to 1,400 tons per acre foot are found
i rer, J. J. and Sullivan, M. X. The action of manganese in soils,
U. S. Dept. of Agriculture, Bull. 42, 32 pages, 1914.
21
in this region, and the excess over that usually occurring
in the Tennessee brown rock field is due to the greater
hardness and density of the Kentucky rock as compared
with that in Tennessee. For the accuracy of these figures
and statements the writer cannot vouch.
Outside of the Wallace area and that to the west of
Midway, phosphate rock is known to occur in and around
Lexington, Fayette County. Phosphate rock deposits are
also known in the vicinity of Georgetown, Scott County,
near the Forks of Elkhorn, Franklin County, near Ver-
sailles, Woodford County, and near Pine Grove Station,
Clark County. The results obtained from prospecting
in these different areas are outlined beyond and com-
ments made as appears necessary.
In this report the Wallace area will be understood
to include the area between Midway on the north and
Versailles on the south, with Wallace as a geographical
center. It will comprise the territory between South
Elkhorn Creek on the east and an indefinite boundary
west of the Versailles and Midway pike. It was near
Wallace — a short distance to the east of it and near the
Georgetown- Versailles branch of the Southern Railway
—that the first phosphate of the Kentucky field was mined
and sold. The low rolling topography of this region af-
fords ideal conditions for the development of commercial
phosphate deposits, assuming its original presence in the
limestone. The region is also notably fertile and in the
district along the Midway- Versailles pike the name "as-
paragus bed" of the blue grass region has been applied,
owing to its marked degree of fertility. "
The following sections, together with the map, show
the general distribution of the phosphate rock together
with its character, variations, and composition as deter-
mined chiefly by prospecting with the drill.
All sections and analyses numbered 100 or over re-
fer to drill records and the samples obtained from them.
22
SECTIONS AND ANALYSES OF PHOSPHATE ROCK.
Wallace District.
No. 8. Central Kentucky Phosphate Co., y2 mile east of Wallace
Crossroads, Woodford County, Ky.
No. 9. Central Kentucky Phosphate Co.
No. 10. Central Kentucky Phosphate Co.
No. 11. Central Kentucky Phosphate Co.
No. 12. Central Kentucky Phosphate Co.
No. 8—
4 y2 ' — Overburden.
2V2'— Phosphate rock, 59.78% Ca3(PO4)2.
Limestone.
No. 9—
6 y2 ' — Overburden.
4' — Phosphate rock, 65.25%Ca,(PO4)2.
Limestone.
No. 10—
iy2' — Overburden.
21/2' — Phosphate rock, 71.88% Ca3(PO4)2.
Limestone.
No. 11—
6' to 7' — Overburden.
2'-7"— Phosphate rock, 72.86% Ca3(PO4)2.
Limestone.
No. 12—
12' to 13' — Overburden.
5 '-7"— Phosphate rock, 72.85% Ca3(PO4)2.
Limestone.
No. 20. R. S. Stark quarry, east side Versailles-Midway pike, 3%
miles southwest of Midway, Ky.
2'-4' Overburden.
2' Phosphate rock, 66.48% Ca3(PO4)2.
Limestone.
No. 22. R. S. Stark quarry, east side Versailles-Midway pike, 3^
miles southwest of Midway, Ky.
5' Overburden.
4' Phosphate rock, 58.55% Ca3(P04)?.
Limestone.
No. 23. Clinton M. Hawkins farm, 3 miles southwest of Midway, or
y2 mile south of Wallace, Woodford County.
1' 6" Overburden.
1' 6" Phosphate rock, 59.88% Ca3(PO4)2.
Limestone.
23
No. 100. S. C. McKinnivan estate, 1 mile southeast of Wallace.
10' Clay overburden with chert.
1' Phosphate. rock, containing 17.79% Ca^PO,),.
Limestone.
No. 104. S. C. McKinnivan estate, 1^4 miles southwest of No. 100.
7'..... .Clay.
2' 1" Low grade phosphate rock.
6' 3" Phosphate rock, lower part of which is brown phos-
phate muck.
Limestone.
Analyses-
No. 104. 2' 1" layer. 31.86% Ca:i(P04),.
No. 104A. Highest grade material in drilling. 53.47% C'a:t
(PO,),.
No. 104B. Muck from lower part of drilling. 49.04% Ca3(PO4):,.
No. 101. Will Steele's estate, south side Frankfort and Lexington pike,
114 miles southeast of Wallace.
1' 10" Clay.
0-8" Phosphatic Clay.
3' 9" Phosphate rock, 48.46% Ca3(PO4),.
Limestone.
No 102. Will Steele's estate, 14 mile south of No. 101.
3' 4" Clay.
10' 4" Phosphate rock, 48.06% Ca,(PO4),.
Limestone.
A grab hand sample selected from the core drilled showed 48.18%
Ca3(Po4)2.
No. 103. Will Steele's estate, ^ mile west of No. 101.
4' 5" Clay.
2' 2" Phosphatic clay and low grade f Upper 2' 2", 53.47%
phosphate Ca3(P04)3.
5" Phosphate rock I Lower 5", 65.16%
Limestone. Ca3(P04),.
No. 105. R. S. Stark estate, 1% miles southeast of Wallace, north of
Frankfort and Lexington pike.
2' 7" Clay.
2' Phosphate rock containg sand and clay, becoming clay
at base, 31.49% Ca3(PO4)2.
2' 11" Clay.
Limestone.
No. 106. R. S. Stark estate, % mile north of No. 105.
6' 5" Clay.
No phosphate rock.
Limestone.
No. 107. R. S. Stark estate, % mile northwest of No. 105.
4" 6" Phosphate rock 5 Upper half' 42'92% Ca'(PO')"
Limestone. <Lower hal(' 23'80%
24
No. 108. Estate of the late Mrs. Margaret Murray, 1% miles southeast
of Wallace and north of Frankfort and Lexington pike.
9' Clay.
7' 8" Phosphate rock.
2' Clay and some phosphate.
Limestone.
Three different grades of phosphate rock came from this drilling
containing 31.47%, 41.46%, and 63.87% Ca.CPOJ,, the latter from a
2' 10" layer overlying the 2' clay bed.
No. 109. Estate of the late Mrs. Margaret Murray, % mile northwest
of No. 108.
2' 10" Clay.
1' 5" Chert.
1' 10" Clay and chert.
3' 6" Phosphate rock.
Limestone.
Two different grades of phosphate rock came from the hole, con-
taining 54.48% and 54.06% of Ca3(PO4),.
No. 110. Estate of the late Mrs. Margaret Murray, 1% miles east of
Wallace, near corner of farm.
11' 4" Clay.
4' Low grade phosphate rock.
Limestone.
Two different grades of phosphate rock came from the hole, con-
taining 21.30% and 30.40% Ca,(PO4)2.
No. 111. Estate of the late Mrs. Margaret Murray, 580 feet south of
No. 110.
3' 5" Clay.
2' Phosphate rock.
Limestone.
Three different grades of phosphate rock came from the hole, con-
taining 20.30%, 37.62%, and 20.43% Ca3(PO4)2.
No. 112. Henry L. Martin estate, % mile east of Wallace, north of
Frankfort-Lexington pike.
8' 9" Clay.
2' 9" Phosphate clay.
3' 2" Phosphate sand, 50.30% Ca3(P04)2.
3' 9" Sand and plate rock, 60.87% Ca3(PO4)2.
Limestone.
No. 114. H. L. Martin, Jr. estate, % mile south of house.
1' 11" Clay with phosphate rock at base.
4" Phosphate rock, 25.78% Ca3(PO4)2.
Limestone.
No. 115. Gate to H. L. Martin, Jr. estate, l1/^ miles southwest of Mid-
way.
12' 8" Clay.
4' 2" Phosphate rock, 37.43% Ca3(PO4)2.
Limestone.
25
No. 116. H. L. Martin, Jr. estate.
5' 11" Clay.
3' 1" Phosphatic sand, 35.16% Ca3(PO4)2.
3' 9" Clay and phosphate rock, 44.30% Ca3(PO4)2.
3' 1" Phosphate sand and plate rock, 56.50% Ca3(PO4)2.
Limestone.
No. 118B. H. L. Martin, Jr. estate, % mile south, 15° E. from the rail-
road crossing.
2' 7" Clay.
11" Phosphate rock, 56.19% Ca3(PO.4)2.
Limestone.
No. 119. H. L. Martin, Jr. estate.
6' 2" Clay.
2' 1" Phosphate rock, 43.53% Ca3(PO4)2.
Limestone.
No. 120. H. L. Martin, Jr. estate, N. 10° E. from the house.
WT 11" Phosphate rock ...... \ Upper 3' °"' 28'92% <*•<«>.),.
Limestone. 1 Lower 4' U* 40'62% Ca<
No. 121. H. L. Martin, Jr. estate.
5' 1" Clay.
3" Phosphate rock, 40.19% Ca3(PO4),.
Limestone.
No. 122. H. L. Martin, Jr. estate, % mile northeast of No. 121.
4' 4" Clay.
3' 5" Phosphate rock, 50.20% Ca3(P04)2.
Limestone.
No. 123. H. L. Martin, Jr. estate, % mile southeast of house.
o' Q" Clav
3- 3" Phosphate rock ....... \ U<">er r £ 31'06%
Limestone. I Lower r 10 ' 22'20% Ca»<PO'>"
No. 124. H. L. Martin, Jr. estate, east of Versailles and Midway pike,
about % mile southwest of Midway.
8' 6" Clay.
6' 3" Phosphate rock; lower 4' 7" gave 34.38% Ca3(P04)2.
Limestone.
No. 125. H. L. Martin, Jr. estate.
5' 9" Clay.
2" Phosphate rock, 24.36% Ca3(P04)2.
Limestone.
No. 126. James J. Nugent, just northeast of Wallace crossroads.
7' 5" Clay.
11' 9" Phosphate rock.
Limestone.
The three grades of phosphate rock from this drilling ran as fol-
lows: Phosphate sand 8", 31.96%; phosphatic clay 3' 2", 43.34%; and
phosphate rock, T 2", 54.25% Ca3(PO4)2.
26
No. 127. Nugent Bros, estate, y2 mile south of Wallace crossroads.
8' ...Clay.
V 3" Phosphate rock ........ .( U™er 4' 10"' 45'00% Ca.(PO.),.
Limestone. ( Lower 3' 5"' 65'92% Ca»<PO<),.
No. 128. A. T. Harris estate, 1% miles southeast of Wallace.
4' 5" Clay.
1' .............. Phosphate rock, 47.32% Ca3(PO4)2.
Limestone.
No. 129. A. T. Harris estate.
3' 7" Clay.
1' 3" Phosphate rock, 58.86% Ca3(P04)2.
Limestone.
No. 130. A. T. Harris estate, just west of house.
8' ...... 3""" Phosphate rock ...... \ V™er S' 7"' 40'61% Cas(PO<);.
Limestone. I Lower 4' 8"' 64'74% Ca,<PO.),.
No. 131. A. T. Harris estate, % mile west of house.
' 6' .............. Clay.
2' 5" Phosphate rock, 39.21% Ca3(PO4)2.
Limestone.
No. 132. E. L. Lillard estate, 2y2 miles southeast of Midway near South
Elkhorn Creek.
4' ........ Clay.
........
4' 9" Phosphate rock ..... < Upper 2' r'> 45'13% CMPOJ,
Limestone. ( Lower 2' 8"' 36'27% Ca,,(PO4)=.
No. 133. E. L. Lillard estate, % mile west of No. 132.
7' 6" Clay.
4' 2" Phosphatic clay, 24.56% Ca3(PO4)2.
3' 2" Phosphatic sand and plate rock, 36.78% Ca3(P04)2.
3' 3" Phosphatic sand and plate rock, 48.34% Ca3(P04)2.
Limestone.
No. 134. E. L. Lillard estate, % mile northwest of No. 133.
3' 4" Clay.
5' 2" Phosphate rock, 33.11% Ca3(P04)2.
Limestone.
No. 136. E. L. Lillard estate, 3 miles southeast of Midway.
3' 6" Clay.
3" Phosphate rock, 52.23% Ca3(PO4)2.
Limestone.
No 138. E. L. Lillard estate, % mile west of Zion's Hill near South
Fork of Elkhorn.
3' .............. Clay.
1' 4" Phosphate rock, 39.82% Ca3(P04)2.
5' .............. Phosphatic clay, 15.82% Ca3(P04)2.
Limestone.
27
No. 137. J. B. Sellers estate, 2 miles southeast of Midway near high-
way.
8' Clay.
......
6' 2" Phosphate rock ...... ( V™*r V 5"' 48'67% Cas(PO4)2.
Limestone. \ Lower 4' 9"' 37'69% Ca»(PO4)2.
No 144. R. S. Stark estate, just east of Versailles-Midway pike, iy2
miles southwest of Wallace, opposite old quarry.
8' 1" Clay.
14' 4" Phosphate rock, 50.77% Ca3(PO4),.
Limestone.
No. 145. R. S. Stark estate, 25 feet west of hole No. 144.
3' 5" Clay.
V 2" Phosphate rock, 71.64% Ca3(PO4)a.
Limestone.
No. 146. R. S. Stark estate, l1^ miles south of Wallace, near Southern
R. R.
5' 7" Clay.
1' 5" Low grade phosphatic material, 41.32% Ca,(PO4)o.
Limestone.
No. 147. R. S. Stark estate, % mile southeast of No. 146.
1' 10" Clay.
2' 8" Phosphate rock, 57.06% Ca:((P04)2.
1' 6" Clay and chert.
4' 2" Clay.
Limestone.
No. 148. R. S. Stark estate, y2 mile northeast of No. 147.
2' 2" Clay.
3' 3" Phosphate rock, 53.10% Ca3(P04)2.
8' ........ Dark brown clay, 29.50% Ca^PO,),.
Limestone.
No. 150. Lister Witherspoon, iy2 miles southwest of Wallace and west
of Versailles-Midway pike.
4' 5" Clay.
3' 1" Containing some phosphatic sand merging into clay
at base, 23.26% Ca3(P04)2.
Limestone.
No. 156. Lister Witherspoon estate, rear of residence.
5' 6" Clay.
1' 4" Phosphate sand and clay; this and the 2' 1" layer be-
low gave 16.11% Ca3(P04)2.
11" Cherty material passing into clay gumbo.
2' 1" Phosphate rock and clay.
Limestone.
No. 151. McBrayer Moore estate, 1 mile southwest of Wallace.
6' 10" Clay.
No phosphate rock.
Limestone.
28
No. 152. George McLeod estate, 2% miles southwest of Wallace.
2' 5" Clay.
8" Containing some phosphate sand, no analyses.
Limestone.
No. 155. George McLeod estate, in front of house near sink hole.
15' 4" Clay.
2' 3" Phosphate sand, 33.55% Ca3(P04)2.
Limestone.
No. 159. Estate of Thomas Dunlap, 3 miles S. B. of Wallace, north side
of Frankfort and Lexington pike.
2' 2" Clay.
1' 4" Phosphate muck, 33.09% Ca3(P04)2.
Limestone.
A sample of phosphate rock collected from a 3' 6" bed exposed in
excavating a barite vein near gate to farm gave 52.49% Ca. (PO4)2.
No. 161. Estate of Wm. A. Dunlap, 2V, miles S. E. of Wallace, near
South Elkhorn Creek.
1' 11" Clay, the lower part of which contains phosphate rock
fragments.
1' 6" Clay and some fragments of high grade phosphate rock.
1' 11" Phosphate muck, probably low grade, 35.45% Ca:;(PO4)2.
Limestone.
No. 162. Estate of Wm. A. Dunlap, 2 miles east of Wallace.
3' 10" Clay.
1' 7" Fine phosphate sand.
3' 4" Phosphate muck and phosphate sand, 42.01% Ca.CPOJo.
4' 5" Low grade clay.
Limestone.
District West of Midway.
No. 142. Estate of Mrs. Chas. Nuckols, 1% miles northwest of Midway.
4' 10" clay.
1' 6" Phosphate rock.
Limestone.
The two grades of phosphate rock from this hole gave 52.43% and
48.16% Ca3(P04)2.
No. 143. Estate of Mrs. Chas. Nuckols, 14 mile north of No. 142.
8' 8" Clay.
4' Phosphate and clay, rather low grade, 37.56% Ca;.(P04)2.
2' 2" Phosphate sand, 51.13% Ca3(P04)2.
Limestone.
The two grades of phosphate rock from this hole gave 37.56% and
51.13% Ca.,(P04)2.
No. 139. E. L. Davis estate, Rookwood Station, on L. & N. R. R., 1%
miles N. W. of Midway.
2' 2" Clay.
V 10" Phosphate rock, 40.35% Ca3(P04)2.
Limestone.
29
No. 140. E. L. Davis estate, % mile N. E. of No. 139, on railroad.
5' 3" Clay.
4' 3" Phosphate rock and sand, 64.30% Ca3(PO4),.
10" Clay and plate rock, 37.90% Ca3(PO4)2.
1' 8" Clay.
Limestone.
No. 141. E, L. Davis estate, on L. & N. R. R., in small sink y2 mile
S. W. of No. 139.
11' .Clay.
4' 8" Phosphate rock j U^er *'' 35'21% Ca3(P04)2.
Limestone. ( Lower 6"> 56'41% Ca3(P04),
No. 163. Chas. Thomas estate, 2y2 miles N. W. of Midway.
11' 11" Clay.
1' 4" Black muck.
2' 2" Sandy phosphate, carries 38.22% Ca3(PO4),.
2' Black muck, carries 50.75% Ca:;(PO4)2.
1' 8" Fine black muck and sand.
Limestone.
No. 164. Chas. Thomas estate, y2 mile S. W. of No. 163.
4' 5" Clay.
1' 9" Phosphate rock, carries 46.37% Ca3(Po4),.
Limestone.
No. 166. Chas. Thomas estate, north of Leestown pike, *4 mile S. W.
of No. 165.
11' 2" Clay.
1' 7" Low grade phosphate, carries 32.20% Ca3(P04),.
4' 6" Clay with a few inches of phosphate sand.
Limestone.
No. 169. On the south side of the highway, between the highway and
the L. & N. Railroad, y2 mile east of Spring Station.
7' 9" Clay.
5' 4" Phosphate rock, carries 43.14% Ca3(PO4),.
Limestone.
No. 170. Estate of Mrs. Harry Wise, just north of house, % mile N. E.
of Spring Station.
3' 5" Clay.
2' 5" Containing disseminated phosphate muck, carries
58.12% Ca3(P04)2.
Limestone.
No. 171. Estate of Mrs. Harry Wise, % mile northeast of No. 170.
5' 4" Clay.
4' Phosphate muck, carries 31.37% Ca3(PO4)2.
Limestone.
No. 172. Estate of Dr. Samuel A. Blackburn, % mile northeast of
Spring Station.
10' 3" Clay.
1' 7" Phosphate rock, carries 38% Ca3(PO4)2.
Limestone.
30
No. 173. South side of Leestown pike, 3 miles northwest of Midway.
10' 4" Overburden.
5' 9" Low grade phosphate muck and clay; lower part con-
tains 31.78% Ca3(P04)2.
Limestone.
No. 174. Estate of Mrs. Annie Slack, 2y2 miles northwest of Midway,
south side Lexington pike.
4' 2" Clay.
3' 5" Phosphate rock, upper 2' 8", contains 44.15% Ca3(PO4)2.
Limestone.
Frankfort District.
No. 175. Estate of Judge E. C. O'Rear, 3y2 miles east of Frankfort.
5' Clay.
1' 9" Low grade phosphate rock, contains 45.41% Ca3(PO4),.
Limestone.
Note. — A hand sample of phosphate chips collected at the gate to
the estate of Judge E. C. O'Rear gave 70.65% Ca3(PO4),.
Several drill holes put down on different parts of the estate were
found to contain no phosphate rock.
No. 182. Estate of Judge T. H. Painter, 6 miles N. E. of Frankfort,
north of South Elkhorn Creek.
2' Clay.
1' 8" Phosphate rock 5Upper 8" contained 32-42% Ca3(PO4),.
Limestone. (Lower V contained 43.67% Ca3(P04)2.
No. 188. Estate of Judge T. H. Painter, 5% miles east of Frankfkort,
just north of the South Fork of Elkhorn Creek.
2' 2" Clay.
2' 7" Phosphate rock, carries 53.98% Ca3(PO4)2.
Limestone.
Several drill holes put down on different parts of the estate were
found to contain no phosphate rock.
iiul'n.,',
Forks of Elkhorn District.
No. 191. Estate of South Trimble.
Scattering fragments of phosphate rock in this drill hole yielded
56.79% Ca3(PO4),.
A few other drill holes on this estate gave no phosphate rock.
No. 192. Estate of George Hannon, 5% miles N. E. of Frankfort, near
gate at entrance to estate.
5' 9" Clay.
1' 10" Fine phosphate sand and rock, containing 41.86%
Ca3(P04)2.
Limestone.
31
Lexington District.
No. 13. J. B. Haggin estate (Elmendorf) : Quarry on estate, %-%
mile east of Maysville pike.
3' Overburden.
2' 6" Phosphate rock, 51.40% Ca:i(PO4)2.
Limestone.
No. 27, 28, 29. Southern Railway (Louisville & Lexington line) near
Cahill place, iy2 miles west of Lexington.
4' Overburden (clay and soil).
3' 6" Massive phosphate rock.
3' 9" Clay.
Limestone.
No. 27. Top 4' of soil less than 2% Ca3(P04)2. This indicates in a
general way what may be expected in the top soil of this
region.
No. 28. Chip from the 3' 6" bed: 53.15% Ca3(P04)a.
No. 29. Sample of the 3' 9" bed which may be considered phosphatic
clay. 16.44% Ca3(PO4)2.
No. 33. James P. Headley estate, east side Russell Cave pike, just
outside Lexington city limits.
8' Overburden (clay and soil).
5' Phosphate rock, 35.14% Ca:1(PO4),.
Limestone.
No. 34. Station No. 11, near Hulett's, interurban railway, between
Nicholasville and Lexington, Ky.
5' Overburden.
3' Chiefly maganese and iron oxide concretions. Less
than 1% Caa(PO4)2.
10' Clay.
5' Massive phosphate rock, upper 4 feet carries 30.98%
Ca3(PO4)2.
No. 40. R. W. Higgins quarry, 1V2 miles northwest of Greendale,
Fayette County.
1' Overburden.
3' Phosphate rock, 29.79% Ca3(P04)2.
Limestone.
No. 218. Estate of Judge Jas. H. Mulligan, N. E. of Lexington, between
L. & N. R. R. and Russell Cave pike.
5' 10" Clay.
1' 3" Phosphate rock, containing 49.18% Ca3(P04),.
Limestone.
No. 218A. Estate of Judge Jas. H. Mulligan, W. of No. 218, but E. of
railroad.
8' 2" Clay.
4' 3" Phosphate rock, containing 45.06% Ca3(PO4)2.
Limestone.
32
No. 219. Estate of Judge Jas. H. Mulligan, E. of point where Russell
Cave pike crosses L. & N. R. R.
4' 3" Clay.
1' 5" Phosphate rock, containing 39.91% Ca:,(PO4),.
Limestone.
No. 194. Just east of Mentelle Park, Lexington. (No analysis.)
1' 4" Phosphate sand.
Limestone.
(Note: Overburden has been scraped away here to obtain clay
for brick.)
No. 195. 20 feet. E. of No. 194.
5' 3" Clay.
2' Phosphate rock, containing 31.44% Ca;,(PO4),.
Limestone.
No. 193. 25 feet E. of No. 195.
2' 10" Clay.
5' 6" Phosphate rock, containing 30.04% Ca3(P04)2.
Limestone, overlain by a thin layer of worthless yellow-
clay.
No. 197. 25 feet E. of No. 196. (No analysis.)
3' 3" Overburden.
4' 11" Phosphate sand and clay.
1' Clay.
Limestone.
No. 198. Estate of H. G. McDowell, southeast of Lexington on the
Richmond pike.
8' 7" Clay.
7' 1" Phosphate rock, lowest 5 ft., carried 48.64% Ca3(PO4),.
Limestone.
No. 199. Estate of J. D. Clark, 3y2 miles N. W. of Lexington.
No phosphate.
No. 200 Estate of J. D. Clark, % mile S. E. of No. 199.
4' 4" Clay overburden with some disseminated phosphatic
sand near base.
8' 11" Phosphate muck, containing 37.56% Ca:!(PO4)v,
Limestone.
No. 201. Estate of J. D. Clark, % mile N. W. of house.
6' 10" Overburden.
8' 6" Phosphate sand, muck, and some phosphate rock,
containing 30.93% Ca3(PO4)2.
Limestone.
No. 202. Estate of J. W. Coleman. N. of Lexington, between Newtown
and Russell Cave pikes.
4' 7" Clay.
2' 2" Phosphate sand, carries 22.78% Ca:i(PO4),.
2' 3" Barren Clay.
Limestone.
33
No 203. Estate of J. W. Coleman, N. of Lexington, between Newtown
and Russell Cave pikes.
4' 2" Clay.
2' 8" Phosphate sand and lump rock, carries 49.25%
Ca,(P04)2.
Limestone.
No. 204. Estate of Ernest Erdman, N. of Lexington and E. of New-
town pike. (No sample.)
1' 5" Clay.
l'-2' 6" A mixture of clay and phosphate rock fragments.
Limestone.
No. 206. Estate of P. P. Bradley, N. of Lexington and E. of Newtown
pike. (No sample.)
1' 3" Clay.
1' 1" Phosphate rock in scattering fragments.
1' 3" Clay.
Limestone.
No. 207. Estate of P. P. Bradley.
4' Clay.
9" Some phosphate rock.
3' 11" Barren clay.
1' 4" Phosphate rock, containing 45.13% Caa(POJ2.
Limestone.
No. 208. Estate of P. P. Bradley.
5' 10" Overburden.
4' 8" Phosphate rock, containing 48.51% Ca:i(PO4),.
Limestone.
No. 211. Estate of Capt. J. D. Yarrington, between Maysville and
Russell Cave pikes.
5' 1" Clay.
7" Containing some phosphate rock, containing 45.74%
Ca3(P04)2.
Limestone.
No. 212. Estate of Capt. J. D. Yarrington.
6' 10" Clay.
2' Low grade phosphate rock, carrying 20.54% Ca3(P04)o.
5' 6" Clay with 1' phosphate rock at base.
Limestone.
No. 213. Mr. Easton estate, N. E. of Lexington, W. of Maysville pike.
2' Clay.
2' 8" Phosphatic sand, containing less than 5% P2O5.
2' 2" Clay mixed with a little phosphate.
Limestone.
No 214. Estate of Judge George B. Kinkead, N. E. of Lexington, just
E. of Russell Cave pike.
3' 8" Clay.
4" Fine lump rock, containing 40.79% Ca3(P04)2.
Limestone.
34
No. 214A. Estate of Judge George B. Kinkead, about 50 feet further
south on the hillside from No. 214.
2' 5" Clay.
1' 6" Phosphate rock (no sample).
Limestone.
No. 214A. Estate of Mrs. Martha Withers, northeast outskirts of Lex-
ington.
2' 2" Clay.
2' 1" Containing phosphate in lower 1-2', with 34.11%
Cas(P04)2.
Limestone.
No. 216. On the Russell Cave Pike, N. 80° W. of Mrs. Martha Withers'
estate.
5' 6" Clay.
7" Phosphate rock, no analysis.
Limestone.
No. 217. Estate of Mrs. Martha Withers, E. side of the estate near
Maysville pike.
2' 1" Clay.
1' 4" Phosphate rock.
(Note: Struck water in this hole and did not get to bottom. No
sample.)
No. 217A. Estate of Mrs. Martha Withers, nearer the Maysville pike.
1' 10" Clay.
9" Phosphate rock, carrying 24.31% Ca3(PO4)2.
Limestone.
No. 221. Estate of H. Gibson heirs, S. W. of Lexington.
17' 3" Clay.
Limestone.
(Note: About 15' black muck in the lower part of the hole. Low-
est 3-5' contained 21.06% Ca3(P04)2.
No. 223. A. M. Miller estate, rear of house, South Limestone Street,
Lexington.
6' 7" Reddish brown clay.
4' 3" Phosphate sand and clay, 30.93% Ca3(PO4)2.
7" Clay chiefly, but with some phosphate sand.
2' 4" Barren clay.
Limestone.
No 224. Estate of A. M. Miller, S. W. of No. 223.
6' 3" Clay.
6' 4" Chiefly clay, with some phosphate sand, no analysis.
1' 2" Phosphate sand.
Limestone.
No. 226. Kentucky Agricultural Experiment Station grounds.
5' 7" Clay.
7" Disseminated phosphate sand with heavy chert.
4|" Variegated clay and rotten chert.
Limestone.
(Note: No sample. No phosphate rock.)
35
No. 227. Kentucky Agricultural Experiment Station grounds, % mile
S. W. of No. 226 along the road.
6' 1" Clay.
8" Phosphate sand.
4' 4" Low grade phosphate sand and clay.
2' 2" Barren clay.
9" Phosphatic muck and yellow clay, containing 35.10%
Ca3(P04)2.
1' 8" Yellow drab clay.
2' 9£" Clay and heavy chert.
Limestone.
No. 228. Estate of Joe C. Van Meter, S. of Lexington, and W. of Tates
Creek pike.
8' 4" Clay.
Limestone.
No phosphate rock.
No. 229. Estate of Joe C. Van Meter, S. of Lexington and W. of Tates
Creek pike.
5' 11" Clay.
8' Iron manganese concretions.
Limestone.
Two characteristics stand out above all the others
in the sections given above, these are the great varia-
tion in thickness and composition of the phosphate rock.
This is characteristic of the entire brown rock phosphate
area. To obtain a better idea of the composition of the
different grades of rock it would have been desirable to
wash each sample as drilled, thereby separating muck>
sand, and lump rock. This is done in practice in prepar-
ing the mined rock for market for conversion to acid
phosphate. It could not be done by the writer in the
field without much inconvenience. Tha analyses of the
hand specimens of lump or plate rock throw some light
on what might be expected from the lump rock in the
sections, and where the specimens were collected and their
analyses compared with a few of those of the lump rock
itself selected from the drillings, the results show fairly
close agreement.
LOCALITIES TO BE PROSPECTED.
It must not be inferred that all the promising locali-
ties in the blue grass region have been examined and
prospected, for such is not the case. The co-operative
36
work earned on by the United States and Kentucky
Geological Surveys was limited by the available funds,
and it is known that prospecting by private parties has
been carried on in otjier areas and which without doubt
has yielded results which may be as promising or much
more so than those obtained in this investigation. In a
cut on the Louisville and Nashville Railroad, within the
town of Versailles, beyond the iron bridge one-eighth
of a mile west of the concrete highway bridge, samples
were collected from probably the Woodburn member
since colmnwuia halli was observed. Of three samples
collected one gave 27.14 per cent., another (No. 25) gave
73.30 per cent., and a third yielded 20.84 per cent, cal-
cium phosphate. The selected chips in sample No. 25
indicate what the lump rock may run in this region.
South of Versailles, on the west side of the Nicholas-
ville pike, on the farm of Ball brothers, chips were noted
in abundance on parts of the farm, especially in the
rear of a group of small cabins. The samples collected
here gave a 79.49 per cent, calcium phosphate. To the
northwest of Versailles, where the Midway pike leaves
the trolley line, a sample collected near the Fishback
place yielded 76.23 per cent, calcium phosphate. Other
analyses of selected samples not included in the tables
above are given below. It should be remembered that
these are selected hand samples of chips which represent
lump rock alone and not the run of a drill hole or pit.
SELECTED SPECIMENS OF PHOSPHATE CHIPS.
Wallace District.
Per Cent, of
Phosphate of Lime.
Ca3(P04),.
No. 47 61.53
No. 48 .. 76.12
No. 49 .. 64.03
No. 50 12.37
No. 51 80.67
No. 52 77.47
No. 56 77.64
No. 47. R. S. Stark estate, 1% miles south of Wallace, at side of
private roa<J through farm. Taken from the bottom of a post hole.
No. 48. Locality same as No. 47. Selected chips from a pile of
phosphate rock thrown out in excavating.
37
No. 49. Mrs. M. Murray's estate. Sample collected from the bottom
of an old prospect pit just west of the house, 1% miles east of Wallace.
No. 50. Mrs. M. Murray's estate, iy2 miles east of Wallace. Chips
collected from surface. Thrown out in making an excavation in the
northeast corner of the farm near road.
No. 51. Thomas Dunlap estate, 2y2 miles southeast of Wallace,
near South Elkhorn Creek, in rear of house and barn; south hillside of
a small branch shown on the map.
No. 52. William Steele farm, about 2 miles southeast of Wallace.
Chips thrown out in digging an old phosphate pit.
No. 56. E. L. Lillard farm. Fragments collected % mile north-
east of the main gate at the entrance to the mansion.
SELECTED SPECIMENS OF PHOSPHATE CHIPS.
Lexington District.
Per Cent, of
Phosphate of Lime.
Ca.(P04),.
No. 1 48.59
No. 15 71.91
No. 32 71.14
No. 41 57.25
No. 42 73.34
No. 1. Brown lump rock, cut in the Louisville Southern Railway
near the Cahill farm, 2 miles northwest of Lexington, between the
Frankfort and Versailles pikes.
No. 15. Main Street, Lexington. Fragments of supposed phos-
phate rock from a sewer excavation nearly opposite Kaufman's cloth-
ing store.
No. 32. Rear of the plant of the Lexington Power Company, just
west of North Limestone Street about a mile from the center of the
city.
No. 41. On the Lexington-Richmond turnpike within the city
limits, at the end of East Main Street, about 100 yards east of Mentelle
Park.
No. 42. About 1 mile south 20° east of Ashland, former home of
Henry Clay. The material was selected from that thrown out in ex-
cavating for a pumping station.
SELECTED SPECIMENS OF PHOSPHATE CHIPS.
Georgetown District.
Per Cent, of
Phosphate of Lime.
Ca3(P04)2.
No. 18 48.97
No. 43 70.26
38
No. 18. L. V. Harkness estate (Walnut Hall), about ll/2 miles due
north of Lexington. Massive type of phosphate rock.
No. 43. Fred S. Crunbaugh estate, near North Elkhorn Creek,
about 2y2 to 3 miles east of Georgetown, Scott County.
SELECTED SPECIMENS OF PHOSPHATE CHIPS.
Forks of Elkhorn District.
Per Cent, of
Phosphate of Lime.
Ca3(P04)2.
No. 44 72.98
No. 44. G. L. Hannen farm, 4^ miles east of Frankfort, south
side of the pike, at the side of the lane going into the farmhouse.
SELECTED SPECIMENS OF PHOSPHATE CHIPS.
Pine Grove Station, Clark County.
Per Cent, of
Phosphate of Lime.
Ca3(P04)2.
No. 53 71.50
No. 54 40.88
No. 53. Sample overlying limestone a few hundred feet east of
Pine Grove Station and on the opposite side of the railroad.
No. 54. Material from place above the limestone a few paces
east of where the surface chips constituting No. 53 were collected.
It follows from the analyses of hand samples col-
lected in various localities where systematic prospect-
ing with the drill was not carried on, that several areas
will bear further close examination. Northwest of Ver-
sailles between the Midway pike and the trolley line to
the west of it, the type of topography is a promising
index and the region seems to have undergone the deep
weathering necessary to the development of the phos-
phate rock deposits. All the low flat hills in this region
are comprised in part in the geologic horizon of the phos-
phate rock and the latter should not be too deep for
profitable mining, provided it proves to be of sufficiently
high grade. This is a region which should be closely pros-
pected, for example in the neighborhood of the George
Fishback and the Senator Camden places.
39
According to Professor Miller, good phosphate rock
should be found on both sides of the Elkhorn Creek, that
is between the Lexington-Georgetown pike on the east
and the Lexington-Frankfort pike on the west. But little
is known of any phosphate occurrences in this general
area north of the Leestown pike.
The region around Hulett's, on the trolley line be-
tween Lexington and Nicholasville, is one which so far
as known has never been thoroughly or even superficially
prospected. It might prove to be worth going over to
make; sure that no important phosphate rock deposits
are overlooked.
Other localities where prospecting might yield re-
sults are in the vicinity of the Forks of Elkhorn, Frank-
Jin County; near Georgetown, Scott County, and in the
vicinity of Danville, Boyle County. The analysis of a
smnple found near Pine Grove Station, Clark County,
given above is also of interest. The region about Done-
rail, Fayette County, is also worth attention. In a study
like that carried on by the writer, it was impossible to
prospect over every promising region, and only careful
work, will reveal the possibilities of the different sec-
tions of the blue grass region.
METHODS OF PROSPECTING.
In beginning this investigation rock hand samples
were selected at natural or artificial exposures. It was
soon found that such samples mean little or nothing in
arriving at an adequate idep as to the real commercial
character of the deposits. For this reason systematic
prospecting with the drill was undertaken. The closeness
with which the latter was carried on may be observed
from the map. It will be appreciated that in a
government investigation prospecting could not be
cai'ried on as closely as it would have been by private
parties planning to determine tonnage in restricted areas
with the view of operating. The methods employed under
similar conditions in Tennessee are outlined further on.
From the methods employed in Kentucky and the close-
ness with which the wrork was done, a good idea is ob-
tained, where the best deposits may be expected and
where further development work ought to be carried on.
Even with the most up-to-date methods of prospecting,
40
perfectly representative samples are difficult to get. It
is doubtful whether, owing to the difficulty of properly
apportioning the lump and muck rock, the content in
calcium phosphate of the material can be represented
in any hand sample.
In the Wallace area many hand samples were collect-
ed and more than 50 holes were drilled. In but compara-
tively few of the holes was no phosphate found at all.
The limestone, however, outcrops very near the surface
in places and leaves no room for any deposits to form,
or if it ever was present, it lias been removed by erosion.
Toward the creek bottoms generally no deposits were
encountered and approaching the hilltops or 900-foot
contour, the overburden grows heavy and the deposits
thin. The richest deposits were found generally between
840 and 860 feet in elevation. The sections given above
for the individual farms show the great variation in the
thickness, character, and position of the phosphate rock
encountered.
The methods employed in this investigation for
prospecting for phosphate rock in central Kentucky
were in part those commonly employed in the brown
phosphate rock fields of Tennessee. Only drilling with
augers was employed in Kentucky. Prospecting, of
course, could not be carried on so extensively as by
private parties. Prospecting on an extensive scale is
expensive, and can only be done by those companies or
land owners who plan to ascertain definitely the work-
ability or non-workability of a given area. It is carried
on in different ways, or by a combination of different
methods.
One of the common methods of prospecting for
brown rock, which may be employed in general tor all
soft and easily penetrated sedimentary deposits, where
the overburden is also soft and not too thick, is by means
of an ordinary 4-inch earth auger handled by two men.
Three-quarter-inch pipe, in convenient lengths, may be
screwed together as the auger descends to furnish the
necessarv additional length of pipe. The auger is pro-
vided with a T-handle to make it easv to bring the re-
quired pressure to bear. Where it is difficult to penetrate
the formation, as where much chert is present, a 4-iuch
post hole digger may be used. This is merely a hollow
41
form of drill or cylinder about 10 or 12 inches long, pro-
vided with a slit. Samples are removed with comparative
rapidity with these two tools, and the auger or digger
is easily emptied after their load of material has been
loosened by a cheap screwdriver. The work is carried
on quite rapidly and the sample representing the phos-
phate bed is next treated as described.
The entire sample was spread on a piece of oil cloth
and thoroughly mixed in the usual way. It was then
quartered and the two opposite quarters discarded. This
treatment was repeated until a final small portion was ob-
tained which was in turn sampled by selecting portions
from it here and there. The final sample, which was about
four pounds in weight, was then sacked and sent to the
laboratory. In certain cases where the original drill
sample was very large, more than one sample may have
been selected and where the material from a drill hole
consisted of definite layers of lump rock, sand, and muck,
the attempt was made to secure representative samples
of each of these different varieties.
In ordinary blanket deposits it is the custom in
Tennessee to sink the drill holes about 200 feet apart in
squares ; but in rim, collar, or hat band deposits the holes
are spaced 200 feet apart throughout the length of the
deposit and from 50 to 200 feet apart on their short
axes.
In conjunction with drill holes, test pits have to be
sunk where the prospecting is done with proper care.
A pit is dug every 400 feet to obtain samples for re-
covery or washing tests. Such samples are much better
than those obtained by drilling for they represent what
may be expected from actual mining operations. By
washing such material, the quantity of lump rock, sand,
and muck may be measured and their composition or
content in bone phosphate may be determined. The re-
covered products are dried, weighed, and analyzed sep-
aratelv and the percentages of recovery calculated.
Konwing the weight of a cubic foot of the material in
the ground, the percentage of recovery may be converted
into such convenient terms as an acre foot of recoverable
material, that is the quantity recoverable per acre per
each foot of depth (43,560 cubic feet).
It is estimated that the cost of prospecting averages
42
7 to T1/^ cents per foot of hole with augers, or $1.50 to
$2.00 per acre for average conditions.
Especial care is required to determine the average
thickness of most areas where the rock is known to lie
in cutters. The phosphate rock may constitute from 30
to 50 per cent, of the total volume below the top of the
limestone table.
The samples from prospecting are prepared for
analyses by washing in an ordinary wash tub. The sand
is saved by decantation and the lump is separated by
the aid of a hose and an eight-inch slotted screen. The
recovered products are dried, weighed, and analyzed
separately. Tonnages are calculated on the basis of a
recovery of 1,000 long tons of dry rock per acre foot for
high grade deposits, but for average grades this will
be more nearly 850 tons per acre foot. For more accurate
work the percentages of recovery should be used as de-
termined in the laboratory, allowing 15 to 20 per cent,
in actual mining and treatment.*
METHOD OF COLLECTING SAMPLES.
In collecting the samples without the drill, for ex-
ample in the old workings at Wallace, the face of the
workings was carefully exposed with pick and shovel,
and a space was cleared of debris at the base of the
exposures to be sampled. About 5 pounds of rock were
picked off from each foot of section exposed, care being
taken to procure adequate representation of lump, sand,
and fine muck. The larger fragments wTere then broken
to the size of a walnut and all the grades wrere then
mixed, quartered, and the opposite quarters discarded.
This operation was repeated until the two remaining
quarters were of the proper size for analysis and ex-
amination. Similar methods were employed with the
cores of phosphate rock obtained in drilling.
THE LOCAL QUARRY INDUSTRY AS A GUIDE TO
PROSPECTING.
Natural exposures are comparatively rare in this
part of Kentucky, but many small quarries have been
opened in this region which are in most cases located
*Fisrures are taken from Barr, James A., Tenn. Phosphate Practice.,
Amn. Inst., Min. Engrs., Bull. 93, Sept., 1914, pp. 2397-2413.
43
near the public highways where they are rarely missed
by the geologist. There is a reason tor this. The estates
which border the main public pikes have stone fences
and the material entering- into their construction has
cjme from a neighborhood quarry. To save transport-
in,;;1 the stone long distances the quarry is usually located
near the highway. An examination of the soil overlying
the limestone in these quarries may often furnish a safe
index of the presence or absence of phosphate in a local-
ity. It is a criterion, however, which has to be used with
care, but the writer found it a help in indicating the
possible presence or absence of phosphate in different
localities. The difficulty with such an index is the rela-
tive scarcity of quarries, and it becomes a sound basis of
judgment only as the number of quarries increases.
TUP: COMPOSITION OF TJIK PHOSPHATE ROCK.
The material collected from the drillings shows
great variation in content of calcium phosphate. From
the method of collecting the samples it is to be expected
that the analyses would run low. In the Wallace district,
of the total number of analyses made of materials col-
lected from drillings, about 35 per cent, showed a con-
tent of 50 per cent, or more of calcium phosphate. Less
than 10 pei- cent, of the total showed i content between
(>() and 70 per cent, and but 5 per cent, of the total
showed more than 70 per cent. The latter material was
for the most part collected from well exposed sections in
the old workings of the Central Kentucky Phosphate
CYmpany, near Wallace. The remaining 65 per cent, con-
tained less than 50 per cent, calcium phosphate, the great
buik of the material having from 30 to 50 per cent.
The number of drillings made in the other districts
was not very large, not large enough to base close esti-
mates on. The results obtained are outlined below. In
the area between Midway and Spring Station, where
prospecting was carried on, about 25 per cent, of the
samples obtained in drilling contained between 50 and
60 per cent, calcium phosphate, and about 5 per cent, be-
tween 60 and 70 per cent. The remaining 70 per cent,
contained less than 50 per cent, calcium phosphate.
The great bulk of the material collected from drill-
ings in the vicinity of Lexington contained less than 50
44
per cent., wliicli is likewise true for the Forks of Elk-
horn district. The reader may reach his own general
conclusions from a study of the analyses given above,
bearing in mind that all the sections and analyses num-
bered 100 and more refer to drill records and the samples
obtained from them. In the case of selected specimens
from old excavations or natural exposures, the results
are given elsewhere. They indicate that the washed lump
rock, which is virtually what most of the latter material
represents, contains more than 70 per cent, calcium phos-
phate in many localities and one sample collected from the
Thomas Dunlap farm, 21/-> miles southeast of Wallace,
near South Elkhorn Creek, gave 80.67 per cent, calcium
phosphate. This high content in bone phosphate does
not appear to be wholly unique, for in a table comprising
6 analyses Waggaman* states that hard, brown, heavy
plates of phosphate rock collected on the Slack farm, 3
miles northwest of Midway, contained 81.08 per cent,
calcium phosphate. Foerstet likewise reports a sample
running 82.37 per cent, calcium phosphate from the same
farm. It is probable that the two samples were collected
from the same pit. Foerste likewise reports a sample
from the Lister Wither spoon farm, near the Versailles-
Midway pike, which contained 80.80 per cent, calcium
phosphate.
Thus it appears that while occasional occurrences
of lump rock are found containing more than 80 per cent
calcium phosphate and although rock in workable quan-
tities will be found running up to present commercial re-
quirements, that is containing 70 per cent, and more BPL,
it is quite safe to affirm that the bulk of Kentucky phos-
phate rock will be found to contain less than 70 per cent.
BPL. This means that in the most promising areas the
reek will have to be carefully washed and cheaply worked
by the most modern, labor-saving devices to bring it up
to present commercial standards so that it may be able
to compare with Tennessee rock. Without doubt much
of the Kentucky rock of low or intermediate grade must
wait for cheap chemical or electrical processes of con-
centration.
*Wa,^«aman, W. H. A report on the natural phosphate of Tennessee,
Kentucky and Arkansas. U. S. Dept. of Agriculture, Bureau of Soils,
Bull. 81, p. L'5, 1912.
fKentucky Oeol. Survey, Series TV., Vol. I., Pt. I., 1913, pp. 431-439.
45
ORIGIN.
SOURCE OF THE PHOSPHATE. — The phosphate was de-
posited originally on the floor of a shallow sea. Some of
it may have been chemically precipitated directly from
solution, and some may have come from phosphate se-
creting- organisms which flourished in the water of the
Ordovician sea. The phosphate probably came from
both these sources. Such organisms exist at the present
time and some of them have been shown to have shells
consisting largely or almost wholly of calcium phosphate.
F. AV. Clarke and AY. C. "Wheeler* have shown that
the element phosphorus occurs in abundance in the shells
of certain brachiopods, crustaceans and alcyonarians.
Certain worm tubes are also notably phosphatic- The
exact original nature of the phosphates is not known
since there is not enough basic material present to have
formed the normal tricalcium phosphate. Ultimately it
reaches this form in the sediments. Some of the phos-
plmtic alcyonarian corals contain from 7.95 to 13.35 per
cent, calcium phosphate. Certain of the brachiopods, es-
pecially the lingulas and glottidias, are highly phos-
phatic, containing from 74.73 to 91.74 per cent, calcium
phosphate, and some of the phosphate present is repre-
sented as a magnesian salt. The analyses of crustaceans
given show a range of 6.57 to 27.44 per cent, calcium
phosphate, with an exceptional analysis of a shrimp
shell showing 49.46 per cent, calcium phosphate. Some
worm tubes show as much as 20.72 per cent, calcium phos-
phate.
These results are interesting not only quantita-
tively, but qualitatively as well. Without doubt even
minute quantities of calcium phosphate in the shells of
animals have an important geologic and economic signi-
ficance since in connection with the formation of all our
phosphate deposits and other economic minerals as well,
the factors of time and process of mechanical concentra-
tion are highly important. Even with only minute quan-
tities of calcium phosphate originally present, slow pro-
cesses of concentration acting over long periods of time
produce important results.
ORIGINAL MODE or OCCURRENCE. — The original phos-
phatic material as now seen in nature, that is the phos-
*U. S. Geol. Survey Professional Paper Xo. 102, 1917, p. 50.
46
phatic material as originally deposited, occurs in definite
bands in the limestone mixed with calcium carbonate.
There is little question that these highly phosphatic
bands are original and that they were laid down alter-
nately with bands of limestone containing, to be sure,
some phosphate, but essentially less phosphatic than the
intervening layers. The illustrations taken in the Mt.
Pleasant, Tennessee, brown rock field, in the Wallace,
and other localities in Kentucky (see Plates VII. and
VIII.) illustrate this alternate banding. Typical cross
bedding of the phosphate and calcium carbonate layers
was also observed at the Wallace workings. The abund-
ance of the cyclora casts not infrequently gives the rock
an oolitic and almost botryoidal appearance, but the little
rounded particles are not necessarily true oolites, and
they are usually not. The alternating rich and lean phos-
phate layers thicken and thin and pinch out abruptly—
in a word they have all the characteristics of a normal
cross bedded, sedimentary rock deposited where there
was some current action.
Many samples were collected showing the marked
difference in the phosphate content between these alter-
nating layers and in a specific case which may be taken
for illustration, a sample of the purest phase of the lime-
stone in a given ledge yielded less than 1 per cent, cal-
cium phosphate, whereas the phosphate lasers inter-
bedded with it yielded 72.21 per cent, calcium phosphate.
That is, of course, an extreme difference and it is quite
likely that all the transitional compositions may be
found in these layers, from pure limestone at the one
end to the very highest grade phosphate at the other.
In the bands or layers which are notably phosphatic,
a certain minute fossil — a coiled gastropod of the genus
cyclora — is markedly abundant. In some specimens the
casts of the interior of these shells are so numerous as
to give hand specimens an oolitic appearance. Whether
the shells of these small organisms were originally
phosphatic cannot be stated with certainty. The fact
that the exterior shells have dissolved and left only casts
of the interior tends to indicate that the exterior shells
were calcareous. Their abundance and structure
rendered them admirable receptacles for the finely di-
vided and perhaps almost impalpable calcium phosphate
47
deposited on the floor of the Ordovician sea which hard-
ened in the shapes of the interior of the shells in which
forms they are now found. The mechanical role which
these minute organisms played in the concentration of
calcium phosphate was apparently a very important one.
Whether the chemical role was of any importance can-
not be stated, nor may it ever be known. Clarke and
Wheeler's results do not indicate that the gastropod
tests which they examined are important carriers of cal-
cium phosphate. It may even be true that the occurrence
of the phosphate at certain horizons may be due to
mechanical concentration effected by the abundance of
these coiled gastropods, they having served as natural
receptacles for it. Large organisms — the brachiopods—
likewise acted mechanically as receptacles for the finely
divided phosphate and the illustration shows the cast of
the interior of a brachiopod — rafenisquina alternata—
collected by A. M. Miller near Versailles, Woodford
County, Kentucky. The shell itself has been replaced by
silica, a portion of which still remains as the white patch
in the illustration, (Plate XI.) The cast of the interior
has been formed by calcium phosphate which forms the
mass of the specimen.
THE METHOD OF CONCENTRATION. — The evidence re-
veals that a great deal of calcareous material was de-
posited with the phosphate and that the latter, as it now
occurs, is the result of leaching the calcareous parts of
the originally phosphatic limestone. Some of the phos-
phate as now observed may have been originally quite
rich and some of the leaching may have occurred while
the deposits were yet exposed to current action on the
ocean floor. This, however, is pure speculation. It is
known that as a result of subaerial leaching the dissem-
inated phosphate has been concentrated as the calcar-
eous parts have dissolved away, and there has resulted
a fjur grade phosphate deposit from what was a low
grade material. In other wonls, the brown phosphate
rock deposit of Kentucky, as it occurs today, rer^e^ents
a clear case of secondary concentration or enrichment.
Several factors have played parts in the leaching or
dissolving of the calcium carbonate deposited with the
phosphate. It is presumed that the solution took place
by conversion of the normally insoluble lime carbonate
48
to the soluble bicarbonate according to the chemical re-
action. H2C03+CaC03=CaH2(C03)2. The carbon diox-
ide was furnished by percolating- meteoric waters.
Thus the first factor is a position near enough to the
surface to be brought into contact with surface waters.
In describing the stratigraphy of the phosphate area,
the Brannon member was stated to underlie the richest
phosphate horizon in central Kentucky. It was there
described as a firm, hard limestone, a good water bearer
with its outcrop marked by springs. It is the limestone
occurring in the numerous sinks of this region.
The overlying member, the Woodburn, which carries
the phosphate principally, is granular, thin bedded, and
likewise contains sinks. In other words it is of a char-
acter to readily weather and dissolve away. This com-
bination of an underlying more or less impervious
stratum and an overlying granular limestone is an ad-
vantageous one for the rapid accumulation of phosphate
and no doubt was an important factor in the segregation
of the phosphate deposits. Thus the character of the
associated sediments may be considered the second im-
portant factor in the rapidity with which the phosphate
rock may concentrate.
Two other factors have helped the leaching process,
namely, the laminated character of the limestones and
associated phosphate layers already referred to, ^ and
the joint planes which are characteristic of these lime-
stones, as they are of most rocks. The leaching of the
calcareous portions begins along the joint planes between
the laminae, especially along those planes between the
limestone and the phosphate bands, which afford easy
means of attack. As the leaching progresses the solu-
tion cavities along the joint pianos grow wider and
deeper and ultimate in the "cutters" which have been
already described. The undissolved masses of limestone
remaining between the cutters are called " horses." The
cutters have, as would be expected from the theory
ascribed for their formation, very definite courses— too
great a regularity to admit that their formation has
been largely fortuitous. In the vicinity of Wallace the
courses of the cutters were between north 8° west and
north 25° west. In Mt. Pleasant, Tennessee, where much
better opportunities exist to observe this phase of phos-
49
]>liate occurrence, the trends of the cutters follow quite
definite directions also.
The limestones not only are leached from above and
on the sides of the horses (cutters), but solution takes
place laterally, or along' the limestone and phosphate
laminae, so that actual projecting ledges or umbrella
rr.eks form on the sides of the horses. Sometimes leach-
in tv proceeds to the point where limestone masses actual-
ly become completely detached through solution and lie
amid the deposits of the phosphate rock.
The irregularities of the underlying rock surface
and the manner in which the phosphate settles down on
it, has given rise to the undulations which occur in the
phosphate rock deposits. These phenomena are well
bi ought out in the illustrations. The intervening clay
layers associated with the phosphate rock represent the
original beds of non-phosphatic clay bearing limestone.
This material weathers to a product commonly referred
to as muck.
Disseminated phosphate sand is associated with
plate, lump or hard rock and with the muck. Most of
this disseminated sand without doubt represents orig-
inally disseminated phosphate rock scattered throughout
the (deposits and which has become concentrated through
the leaching of the limestone. Most of the sand is sim-
ply Cyclora casts composed of phosphate, again illustrat-
ing the important mechanical role played by these minute
organisms in the concentration of this valuable ferti-
lizer. The term sand is not a good one from the view
point of origin, for though most of the little fragments
are rounded as fragments of such casts would be ex-
pected to be, the rounded shapes are not due to mechani-
cal attrition, but are original.
Some very interesting observations on Kentucky
rock have been made by Arthur M. Miller.* Miller be-
lieves in an original segregation of the phosphate de-
posits, that is, a segregation at the time they formed on
the ocean floor. He says, "this original segregation of
the phosphate has in no case, however, given deposits
rich enough to be commercially valuable. The latter de-
posits have resulted from the weathering of the deposits
of the first concentration. Though concentrated as the
>Ky. Geol. Survey, Series IV., Vol. I., Pt. I., 1913, pp. 327-328.
50
result of weathering, we do not believe that the facts of
occurrence warrant the explanation that in weathering
the 'carbonate of calcium has been dissolved out leaving
the phosphate of lime behind' — that in other words it
is simply a residual deposit due to the leaching out of
a more soluble constituent.
"Were the latter the case it should be possible
to find many instances of deposits of unleached phos-
phate where the amount of phosphate in the same volume
of deposit equals that which we do now find in the
weathered commercial deposits. The same amount of
phosphate should be there plus the original amount of
carbonate of lime1; but in no instance is this the case.
On the contrary, all the facts point to an actual con-
centration of the phosphate into less volume as the re-
sult of a process of replacement. "We have here the
same phenomenon as is illustrated by certain iron ore de-
posits. Water with iron in solution is checked in its
downward descent by meeting relatively impervious
stratum. Vnder these conditions the saturated stratum
(commonly a limestone) immediately above the relative-
ly impervious stratum is altered by replacement; iron
replaces calcium, the latter being finally carried away in
the form of bicarbonate by the water.
"So in the case of concentrated phosphate of lime
deposits: insoluble tricalcium phosphate acted upon by
organic acids in the superficial layers of rock waste has
its phosphorus rendered soluble ('available'). Entering
into solution in the form of phosphoric acid, it passes
downward to the lower 'rottenstone' and bed rock layers.
Here the phosphorus 'reverts' to its original tricalcium
phosphate condition, replacing the non-phosphatic or
relatively non-phosphatic limestone.
"The final theoretical reaction is expressed by the
following equation: Ca. H4 (POJ.,+2 Ca. CO,=(PO4)2+
2H,O+2C(),."
This theory of the formation of Kentucky phosphate
rests on the solubility of calcium phosphate. Without
any doubt this compound in its natural state is sumcient-
ly soluble to bring about important accumulations over
long periods of time, due to replacement, and possibly
replacement has been an important factor. As pointed
out above, in practically unaltered specimens of the phos-
51
pliatic layers interbedded with limestone, the rich phos-
phatic layers are present. These were collected by the
writer and analyses made in the survey laboratories
showed more than 70 per cent, in calcium phosphate.
Foerste* also reports mi weathered limestone near Ver-
sailles from the Woodburn member carrying 55.5 per
cent, calcium phosphate, overlain by rock containing
only 9.39 per cent, of the same ingredient. Thus to the
writer the idea of replacement is not an absolutely nec-
essary factor in accounting for the concentration of the
phosphate rock. He is willing to admit that replacement
may have played a part, but feels that the explanation
that has been given, and by which other writers have
explained the formation of the Tennessee phosphate de-
posits, will apply to the Kentucky field.
THE BROWN PHOSPHATE ROCK INDUSTRY.
GENERAL CONDITIONS.
The Kentucky phosphate field is practically a virgin
field. From its study and a comparison of it with the
Tennessee field, the writer feels that local conditions are
similar and the problem of working the Kentucky de-
posits must be along much the same lines as in Tennes-
see. For this reason it is thought that a brief descrip-
tion of the mining methods employed in the Mt. Pleasant,
Tennessee, field will prove of interest here.
There has been going on for some time in the Mt.
Pleasant phosphate field and without doubt in other
parts of the Tennessee brown rock phosphate areas, a
change that will result in leaving very little or no wasted
phosphate rock in the ground. Some phosphate is going
into the waste ponds, but the time will without doubt
come when all this material will be reworked, and even
now some companies are working or planning to work
these old tailings. Modern mining and milling methods
of the last decade have revolutionized the brown rock
phosphate industry, and incidentally are conserving this
valuable fertilizer material. They are in striking con-
trast with the crude and wasteful methods formerly em-
ployed. When phosphate was first mined in Tennessee
it is safe to say that at least half of the good material
such, for example, as is now being worked was thrown
*Loc. Cit., p. 381.
52
away. A great deal of this cannot in the nature of things
be recovered, for in the course of time it has become
so thoroughly mixed with clay and in places so covered
with overburden as to make its recovery at a profit im-
possible. The lessons learned in Tennessee no doubt will
be of value in working the brown phosphate deposits in
central Kentucky.
The object, of course, in preparing phosphate for
market is to remove as much of the clay, chert, and
limestone as possible from it. It is not possible to re-
move all these impurities, especially in the case of clay
and sand. There is no sharp division between the finest
phosphate sand and clay and it would obviously be
wasteful to carry the process of obtaining fine phosphate
sand beyond the point where the cost would offset the
value of the phosphate obtained. This is one of the prac-
tical considerations connected with the modern conserva-
tion of phosphate rock which perhaps has not always
been given just and deserved consideration. These prac-
tical difficulties have resulted in the loss of much fine phos-
phate along with the silica sand and clay. Owing to the
similarity of finely divided phosphate and silica sand in
specific gravity, no mechanical process has been de-
veloped to effect a further saving. As the problem now
stands the general development of some concentration
process is required to effect a further recovery of low
grade phosphate both in Tennessee and Florida, where
the consumers are demanding a high grade product.
The point beyond which it is not practicable to carry
preparatory treatment is not fixed and standards vary
from time to time and probably at a given time among
individuals or corporations. Thus in the phosphate min-
ing industry as practiced in Tennessee in the early nine-
ties, rock was discarded which has a high value today,
and the former apparent lapses from the highest stand-
ards have in the course of time proven to be not lapses at
all, but simply necessities imposed by trade conditions
of the time. In other words the phosphate once discard-
ed is now being used. The open cut or surface methods
of mining brown rock as practiced in the Tennessee field,
and which will be the methods employed in the Ken-
tucky field, are peculiar in this respect and the gen-
53
eralizatious made do not cover many other classes of
mining- and certainly will not apply to underground min-
ing- in general.
GRADES OF COMMEIKTAL IJKOWX PHOSPHATE ROCK.
Most of the brown phosphate rock from the Mt.
Pleasant, Tennessee, field is shipped in three grades,
namely, those containing 72, 75, and 78 per cent, of cal-
cium phosphate. The percentage of iron and aluminum
oxides ("I and A") remaining in the washed product
has an important hearing on the value of the rock. The
usual guarantees are given below. .For each per cent,
in excess of the guaranty, '2 per cent, of calcium phos-
phate. (BPL) is deducted'.
Table of Guarantees C-howir.g the Relation Between Phosphate: and
ii on rnci Alurrunn CcnLeni.
Fe_O.;+Al,O:;
BPL T and A
Per cent. Per cent.
70 6.5
72 5.5
75 5.0
76 4.1
78 to 80 4.0
Five to five and a half per cent, iron oxide and
alumina is the usual maximum allowed and that is usual-
ly referred to as "I and A" in the trade and in com-
mercial analyses. At one time only rock of 78 per cent.
grade was shipped from the Mt. Pleasant field and rock
of this grade is still known as ' ( export rock. ' ' The guar-
anteed content in phosphate of lime, "bone phosphate"
or "BPL" as it is commonly referred to in the trade,
next fell to 75 per cent., and at the present time many
of the companies are finding it difficult to ship this grade
exclusively, and the life of the 75 per cent, rock is limited.
Every per cent, of iron oxide and alumina less than the
5 per cent., is regarded as equivalent to an additional 2
per cent, of calcium phosphate, for it is considered that
in the subsequent treatment of the phosphate in the man-
ufacture of fertilizers the harmful effect of 1 per cent,
of iron oxide and alumina offsets the good effect of 2
per cent, of calcium phosphate. If much more than 5 per
54
cent, of iron oxide and alumina are present the superphos-
phate tends to become gummy and farmers find it difficult
to drill it into the land.
A few samples of Kentucky phosphate rock were se-
lected for analysis for their content in iron, alumina,
and fluorine, in addition to their content in phosphate of
lime. The results of these analyses are given below. The
content in iron and alumina shown are too high to come
within the normal commercial requirements of the pres-
ent time and indicate, as pointed out in other places in
this paper, that the bulk of the Kentucky phosphate rock
will no doubt have to wait for the general introduction of
cheap chemical or other processes of concentration be-
fore it is able to compete with the high grade phosphate
rock from the other eastern states.
Analyses of Kentucky Phosphate Rock.
(W. C. Wheeler and R. M. Kamm, Analysts.)
Ca3(PO4), ALO3 Fe,O:; F.
No. 108B 63.87 5.29 2.09 1.38
No. 112A 60.87 4.35 3.50 1.02
No. 120 28.92 7.46 5.29 0.70
No. 126B 54.25 4.63 1.42 1.18
No. 133 24.56 10.66 6.62 0.85
No. 141 35.21 5.21 5.29 0.92
No. 143 37.56 2.50 6.05 0.95
No. 108B. Mrs. M. Murray farm, 1% miles southeast of Wallace,
and north of Frankfort and Lexington pike.
No. 112A. Henry L. Martin estate, % mile east of Wallace, and
north of Frankfort-Lexington pike.
No. 120. H. L. Martin, Jr. estate, l1/^ miles southeast of Midway.
No. 126B. James J. Nugent, in orchard just northeast of Wallace
crossroads.
No. 133. E. L. Lillard estate, 2ys miles southeast of Midway, near
South Elkhorn Creek.
No. 141. E. L. Davis estate, along the Louisville and Nashville
Railroad in small sink, 1% miles northwest of Midway.
No. 143. Mrs. Charles Nuckols estate, 1% miles northwest of
Midway.
PREPARATION OF PHOSPHATE ROCK FOR MARKET.
There are many stages to be considered under the
head of preparation of phosphate rock for market, but
they may all be subdivided into 3 major operations as
55
follows: (1) removal of overburden; (2) mining; and
(3) milling, in which is included drying. The present
methods of utilizing and thus preserving from loss the
brown phosphate rock supplies, especially in the Mt.
Pleasant field, are included under the above headings
and therefore will be described in connection with them
insofar as this can be done.
REMOVAL OP OVERBURDEN.
The overburden of the brown rock phosphate de-
posits in the Mt. Pleasant, Tennessee, field varies from
one foot upwards. Usually it is less than 20 feet, but a
thickness of 30 feet is known but is excessive in those
places where mining has been in progress. The methods
of removal of overburden are diverse. Under exceptional
conditions the old time crude and expensive hand
methods have to be resorted to, but in most places, es-
pecially where virgin ground is being opened up and
where conditions are comparable with what may be
expected in Kentucky, operations are conducted in the
most up-to-date fashion, as the illustrations (Plates
XII. to XVI.) show. Where the overburden is not very
thick or hard it may be simply pried up and removed
with scrapers (Plate XII. ), or it may be loosened with
dynamite and then removed with scrapers. A favorite
method of getting rid of the overburden, used especially
in ground that is being reworked, is to first "hog" or
undercut it, pry it off with bars, and then scrape or
carry it away. The drag line excavator (Plate XIV.)
and the steam shovel (Plate XV.) are types of up-to-
date machinery used to remove overburden in the Ten-
nessee field. The hydraulic method (Plate XVI.) is
also used and this would do well in the vicinity of Elk-
horn Creek, Kentucky. Both the overburden and the
rock beds are removed by this last named method, which
is simplicity itself in action and which requires a mini-
mum of labor in operation, namely one man to handle
the hydraulic gun and two to keep the sluices clear. Of
course this last named method can only be used where
there is an abundant water supply.
Occasionally narrow benches are stripped by hand
methods. The dirt is more or less undermined by the re-
moval of the underlying rock and the bank caved over
56
into the previously mined outbench by prying with under
rods from above. In the case of deposits stripped by
scraper outfits, (Plate XII.) the outfits are such as are
used in ordinary railroad work and consist usually of
ordinary and five wheeled scrapers with a hook team
extra and a plow team. This work is usually contracted
at 141/2 cents per cubic yard. The major portion of the
stripping is now done by class 14 Bucyrus Drag Line
Excavators mounting a 70-foot boom with a iy2 yard
bucket. (Plate XIV.) This machine is adapted to the
removal of overburden that does not average more than
15 feet in thickness. With more than this depth the pits
become too narrow at the bottom.
In Hickman County, Tennessee, where the over-
burden averages 30 feet, a class 24 drag line machine
has been used. This has a 100-foot boom and a 3V> yard
bucket.
In general it cannot be said that the workability of
a bed is regulated by the depth of overburden. There are
other factors entering into the problem. If the phos-
phate bed is a very thick one, the overburden may be
quite thick and still may be removed and the operation
be a profitable one. On the other hand, if the bed is
very thin but exceedingly high grade, it may still pay
to remove what appears to be an excessively thick over-
burden.
COSTS OF REMOVAL OF OVERBURDEN.
The cost of operating the class 14 machines is as
follows :
Cost of Operating Class 14 Bucyrus Drag Line Excavator.
Per Shirt.
1 runner ($150 per month) $6.00
1 fireman 2.50
1 teamster 1.75
1 ground man 1.50
1 foreman 3.00
1 team (owned by company) 3.00
Coal, 2 tons at $2.40 4.80
Cable wear 5.00
Repairs, oil, and supplies 3.00
6% interest on $13,000; 250 shifts 3.20
10% depreciation .. 5.20
$38.95
57
The above items of expense are for a machine hav-
ing caterpillar traction for moving. If a timber and
roller machine is used an extra ground man is required.
The capacity averages 1,000 cubic yards per 10-hour
shift, though often .1,300 to 1,400 yards are dug under
favorable conditions. While the larger size machines
average more in yardage, the operating costs also in-
crease so that the cost per yard is nearly the same.
In those mines where hydraulic stripping is used
owing to the excessive depth of overburden, or where
mining conditions require it, the cost of removal amounts
to about 7 cents per cubic yard. At two mines in Tennes-
see where this method is employed the bank is cut down
by a hydraulic monitor, using a 2 o.r 2~\t> inch tip. The
water pressure usually needed is 150 to 175 pounds per
square inch. The water flows back from the face carry-
ing from 10 to 20 per cent, solids into a pump well..
From the sum}) the Avater and overburden are pumped
to the waste ponds by an 8-inch direct connected motor
driven centrifugal pump. The pump requires from 1,500
to 2,000 gallons of water per minute for full capacity
with a 75 horse power motor.
METHODS OF MINING.
Much of the mining in the Mt. Pleasant, Tennessee,
field has been done by hand on account of the method
of occurrence of the brown rock. The steam shovel has
not proved successful because it is unable to discrim-
inate between the grades of ore mined, with the result
that much clay and flint get into the product and has
to be removed subsequently. The cantilever adjunct to
mining which is employed at one mine in the Mt. Pleas-
ant, Tennessee, field is unique. The hydraulic method of
mining is used at two plants and has many advantages
as pointed out under the preceding topic. These me-
chanical, methods of mining and removing overburden
which have cheapened operating costs, have played the
major part in conserving Tennessee brown phosphate
rock and without doubt will be the means whereby Ken-
tucky rock may hope to take its place on the market.
As hydraulicking is practiced in Tennessee, the
limestone horses often get in the way and have to be
blasted out. But this is not difficult, owing to the loose
or platy character of the phosphatic limestone associated
58
with the brown rock deposits. In addition to the hy-
draulic method which may be employed only in certain
favorable locations, hand mining is also employed, es-
pecially where the ground is being reworked. Where
hand mining is practiced the ore is usually screened on
the spot where the miner is at work. The fine material
passes through the screen and is saved and washed, and
the coarse rock which is left is hauled away and dried
by burning on ricks of wood in the open (see Plate XVII),
thus saving rehandling in the mill. The lump rock, as
mined, usually contains from 20 to 21 per cent of
moisture and drying it in this way reduces the moisture
to 1 per cent, or less. In certain places where mining with
the hydraulic giant is not practicable or where the giant
fails to get all the rock, hand mining has to be resorted
to.
WORKING CUTTERS.
The term "cutters" has been explained and the fact
that the phosphate rock in them was left unmined in the
early days of brown rock mining has been pointed out.
The development of cutters, which took place along orig-
inal joint plains, varies greatly within the restricted Mt.
Pleasant field and may be expected to vary much in the
Kentucky field. In some places in Tennessee they are of
large size and some were observed 30 to 35 feet wide
and as much as 20 to 25 feet deep (Plate XVIII.), averag-
ing probably 18 to 20 feet. In these abnormally wide
and deep cutters, it is not uncommon to have small lime-
stone horses. Some of the cutters, on the other hand,
are so narrow that the phosphate rock in them can be
removed only with difficulty. (Plate XIX.)
Hand methods of mining have to be employed almost
exclusively to remove phosphate rock from these cutters
owing to the peculiar method of its occurrence. (Plates
XVIII. and XIX.) Hydraulic methods have been employ-
ed in places. Owing to the depth of the cutters the work
has been done in benches of convenient height for the
miners, (Plate XVIII.) The ore is picked out and shoveled
from bench to bench and finally into wagons, in which it
is hauled to the mills. Mining the deep cutters is usually
carried on in fair weather and when the roads are good.
In working over virgin ground at the present time the
rock in the cutters is readily and cheaply obtained by
59
the cantilever method. (Plate XIII.) The material from
the shallow cutters is picked out and screened on the
tines of a phosphate fork or on a small, movable, 1-inch
mesh screen. The coarse rock is dried or burned on
ricks of wood (Plate XVII.), and the muck is taken to the
mill where it is washed. The old cutters containing phos-
phate rock are located by hand prospecting with a long-
sharp steel rod.
THE COST OF MINING PHOSPHATE ROCK.
The cost of mining phosphate rock depends on sev-
eral factors, chief among which is the depth and expense
connected with the removal of the overburden. It will
be of interest to note here average costs in the most im-
portant phosphate producing states. In South Carolina
during the past ten years, as much as 22 feet of over-
burden have been profitably removed and river rock has
been dredged from a depth of 52 feet, including a cover
of 16 feet of sand and muck. In Florida, where a higher
grade rock is produced, it is profitable to mine rock hav-
ing an overburden of greater depth than 20 feet — the
average maximum in South Carolina. According to data
furnished by various companies to the Federal Trade
Commission* the cost of mining Florida land pebble, in-
cluding washing, drying, etc., ranges from about $1.65
to $2.50 per gross ton, not including amortization of in-
vestment or royalties in case the mining is done on that
basis. The cost of mining Tennessee brown rock ranges
from about $2.75 to $3.14 per gross ton and these are
the figures of greatest interest in connection with the
Kentucky field. The cost of mining rock in South Caro-
lina is considerably higher. The following figures were
taken from the average costs of a Tennessee mine during
six months of good mining weather :f
Per ton cents.
Mining $0.64
Transportation and team expense 0.23
Washing 0.46
Drying 0.47
Shipping and track expense 0.09
Total per long ton of dry rock $1.89
*Rept. on the fertilizer industry, 1916, p. 101.
fBarr, James A. Tenn. Phosphate Products. Bull. No. 93, Am. Inst.
Min. Engrs., Sept., 1914, p. 2410.
60
The work of mining- is chiefly done by contract, the
price being 25 cents per tram when one handling only
is required. Where two casts are required 35 to 40 cents
per tram is paid. The miners keep the track up to the
mining face.
WASHING AND DRYING.
The washing processes whereby the mined brown
phosphate rock is treed from clay, chert, and limestone
are elaborate and the mills in which the work is done are
for the most part large and modern. These modern wash-
ing plants which have done so much to make the mining
of low grade brown rock profitable, and which, therefore,
are playing such an important role in the conservation
of this class of phosphate rock, have practically all been
installed during the past 10 or 15 years. The principles
of the washing process are identical throughout but the
details of manipulation differ at different plants. The
phosphate rock as mined is brought to the washer either
in wagons or by tram. Where hydraulic mining is prac-
ticed it goes to the plant through a flume. The material
mixed with water is delivered into a hopper at the top
of the mill and the subsequent operations for the most
part are conducted by gravity. From the hopper the rock
passes through a toothed revolving crusher and then
into log washers. From the washers it passes to a
cylindrical or conical screen with circular perforations.
The coarse or lump rock which fails to pass through the
screen passes on to a picking belt where limestone and
chert fragments and clay balls are removed. The ma-
terial then goes to the wet storage sheds or piles to be
later dried. The fine material may go through a settler
or clarifier provided with riffles, or through several set-
tling tanks in succession in which the sand settles out.
The clay and sand not caught in the process goes to the
waste ponds. The above description briefly outlines the
fundamentals of the washing process as carried out at
most of the' plants handling brown rock phosphate in the
Mt. Pleasant, Tennessee, field, but, of course, as has been
mentioned, details are widely divergent.
The clay and the phosphate sand which pass to
the waste ponds are of great interest in the problem of
conservation. When the material reaches the waste pond
61
the coarse sand settles out first and naturally nearest
the_ end of the waste pipe or flume. This material is the
highest in calcium prosphate. It is planned to work ma-
terial of this character at one of the plants near Mt.
Pleasant, and already at another the old tailing dumps
are being worked. At this plant much attention has been
paid to the process of separating the clay and phosphate
sand. There is a washer at this particlar plant which
differs from any other in this field and is most throuogh
in its action. The clay resulting from the action of this
washer was observed in the waste pond. It has been in
suspension for a long time and material taken and
nibbed between the fingers appeared of almost impalpa-
ble fineness. Some of the phosphate sand from this wash-
ing process is so fine in texture that it sifts through
the meshes of the sacks in which it is shipped. It has
been suggested that material from such waste1 ponds
might be used in its present form on farm lands, but this
lias been found impracticable as it will not bear the cost
of transportation, but the high phosphate content in cer-
tain of the samples collected from such waste ponds is
noteworthy.
Drying is accomplished in two very different ways
which arc representative of the old and new methods
employed in the Tennessee brown phosphate1 field. At
nearly all the large plants modern rotating' cylindrical
dryers, similar to rotary cement kilns, are in use, but
the rock is fed both at the hot and cold ends. It would
seem that the latter method would be the more efficient.
There is generally some special cause when the old
fashioned method of drying1 on wood ricks is employed
and where it is in use it generally saves extra additional
handling or haulage. Drying* generally reduces the
moisture present from 20 or 21 per cent to 1 or 2 per
cent.
CONSERVATION OF FINES.
In drying1 phosphate rock large quantities of ma-
teiial in finely divided form is lost by being carried out
of the fiue, owing to the powerful drafts employed, es-
pecially in the modern types of dryers. At many of the
plants steps have been taken to save this material. This
is accomplished by means of bends in the flue, or by
62
hoods or baffles. The analysis of the fine material caught
and saved at some of the plants indicates that it is well
worth saving.
THE PHOSPHATE INDTSTKV AT WALLACE,
KENTUCKY.
The phosphate deposits on certain farms near
Wallace at the time of the writer's visit were under lease
by the Central Kentucky Phosphate Company. Since
then (June, 1915) they have changed hands and are now
being worked by the United Phosphate1 and Chemical
Company which, it is understood, is a subsidiary of the
Charleston, South Carolina, Mining and Manufacturing
Company. Since work started at Wallace some few years
ago it has been carried on intermittently and there have
been many shut downs lasting for short or long periods.
The total tonnage removed from the Wallace workings
has been small and in all has not amounted to more than
a few thousand tons (1,500 to 2,000 tons). Since the writer
visited the plant in June, 1915, it has been added to con-
siderably, and it is expected to resume operations on a
larger scale than ever early in 1917. In the early part
of this year, the Hawkins farm, which adjoins that on
which the old workings are located, has been acquired
and it is planned to work out to the Steele and Murray
farms which are nearby and under lease.
The overburden at the Wallace workings varies
from a fraction of a foot to 5 or 6 feet in thickness. It
occasionally reaches 10 feet. Due to its thinness, it may
be removed directly by scrapers, after it is first plowed
up or loosened with pick and shovel.
After the removel of the overburden, the phosphate
rock is usually removed with pick and shovel, loaded by
hand en to wagons, and hauled to the mill. The deposit
at Wallace normally ranges from 3 to 5 feet in thickness.
The extremes of thickness are 1 foot and 10 feet. When
the ore is of the maximum thickness it proved too costly
to remove it all according to the methods employed in
this field.
Electric power is used at the mill. The ore at the
mill is shoveled on to a belt which feeds it to a revolving
cylindrical dryer 40 feet long and 5 feet in diameter.
This is fed with coal which is burned under a forced
63
draft. The ore in the dryer travels forward and down-
ward to the hotter end. From the dryer it falls into a
pit through which passes an endless bucket conveyor,
which carries it to .a horizontal screen conveyor. The
latter in turn transfers it to a hopper through which it
falls on to burrs or grinders. Before falling on to the
burrs, the lump rock is screened, only those fragments
which are % inch or less in diameter going into the
crushers. The screen is a cylindrical affair containing
V-2 inch holes. All the lump rock passes over the screen
to a conveyor and goes to a loading bin to be wheeled on
to cars later, or it may be clmted directly on to cars.
The material which has passed through the crushers
is further ground to phosphate flour and conveyed by
elevators to its own bin. The ground rock is bagged in
paper bags of 100 or 200 pounds each, and shipped in
this form for direct application to the soil.
The old company whose methods are described above
has a spur built to its plant from a short branch line of
the Southern Railway running between Georgetown and
Versailles, Kentucky. The new company proposes to
grade tracks to those farms it proposes to work.
TRANSPORTATION FACILITIES.
The Wallace area and the area to the west of Mid-
way are admirably located with respect to railroad trans-
portation. The main line of the Louisville and Nashville
Railway between Lexington and Louisville, passes
through Midway and the phosphate area to the west be-
tween Midway and Spring Station. A branch of the
Southern Railway between Versailles and Georgetown
passes through the heart of the Wallace area, and the
topography or lay of the land about Wallace is such that
spur tracks may be built where needed at a minimum of
expense. The railroad requirements, therefore, could
hardly be improved upon.
The Kentucky deposits are also well located from
the viewpoint of distribution to the north in Ohio, and
northwest in Indiana and Illinois, where more and more
raw ground rock is coming into use. The freight rates
from Midway to Louisville, Cincinnati, and Cleveland
are in each case less than from Mt. Pleasant, Wales Sta-
tion, and Nashville, Tennessee, and this difference in
64
freight rates may compensate for a lesser content in
calcium phosphate in the Kentucky rock, and where com-
position and other conditions are equal, result in a de-
mand for the latter.
The following table is of interest in this connection:
Freight Rates From Mines in Kentucky and Tennessee to Important
Near By Markets.
Destination. Location of Mines. Freight Rates.
[Midway, Ky. .. $1.60
Cincinnati, Ohio Mount Peasant, Tenn. .. 2.50
Wales Station, Tenn. .. 2.50
[Nashville, Tenn 1.80
fMidway, Ky 1.60
Louisville, Ky.... . J Mount Pleasant> Tenn 2.25
A Wales Station, Tenn 2.25
Nashville, Tenn. 1.55
\_
fMidway, Ky 3.22
I Mount Pleasant, Tenn 3.80
Cleveland, Ohio J TTT .
Wales Station, Tenn 3.80
Nashville, Tenn. . 3.12
RAW ROCK PHOSPHATE.
Finely ground rock phosphate, sometimes called
"floats," is used to a considerable extent by farmers,
particularly in the middle west, as a source of phos-
phorus. It is often lower in phosphate of lime and con-
sequently higher in iron and alumina than rock used
for acidulating purposes. In the raw condition, the iron
and alumina, if in the form of phosphate, are advan-
tageous according to certain scientists who have ex-
perimented with these phosphates, because they have been
found to supply a favorable medium for the germination
of seeds. Floats are applied directly in turning under
crops, or are mixed with barnyard manure on the theory
that the phosphoric acid is liberated and rendered avail-
able by the action of the weak organic acids generated
during the decomposition of the manure.
The future of the Kentucky phosphate field as a
source of raw ground rock ought to be good. The use
65
of this material in the states to the north and west is
becoming increasingly popular. The advantages in
freight i ates as compared with the nearest competing
field in similar rock, the quality and other factors being
equal, is important, as is also the additional fact that
a high content in iron and alumina in the raw rock is
not considered sncli a drawback as in rock which is
acidulated in making acid phosphate for mixed fertil-
izers. Floats have been shipped in the past from the
Kentucky field when operations have been in progress
in that locality.
PIIOSPHATir LIMESTONE AS A SOTKCE OF
PHOSPHATE.
Directly below the phosphate rock horizon occurs
the phosphatic limestone from which the brown rock
itself has been derived. This is often platy in structure,
the plates of highly phosphatic material alternating
with the nearly pure calcareous layers. This platy or
laminated structure is original and throws light on the
occurrences of the brown rock itself which also occurs
in plates separated by layers of muck, clay, and sand,
the former corresponding to original layers of phos-
phatic limestone, and the latter to the intermediate clay
and less phosphatic limestone layers. There must be an
enormous tonnage of this phosphatic limestone scattered
throughout the phosphatic rock area of the blue grass
region of Kentucky. A long period of time must elapse
before any attention will be given to this comparatively
low grade material as a source of phosphate, but it
would be hazardous to say that this will never be done.
Analyses of these limestones, some of which are in a
leached and some in a partially leached condition, oc-
curring in horses between cutters contained as much as
70 per cent, calcium phosphate, and Foerste reports
unaltered phosphatic limestone in the Woodburn mem-
ber at Versailles containing 55.5 per cent, calcium phos-
phate.* In Tennessee some of this phosphatic limestone
whose analyses the writer is acquainted with averages
more than 42 per cent, in calcium phosphate. The car-
bonate and the phosphate of calcium mixture in this
material has considerable value as a fertilizer when ap-
*Kv. Geol. Survey, Series IV., Vol. I, Part I, 1913, p. 386.
66
plied directly to the land in finely pulverized form, and
although it is difficult to predict how or when such ma-
terial will be utilized, it seems fairly certain that it will
prove of value at some future time.
THE FUTURE OF LOW OR INTERMEDIATE GRADE
PHOSPHATE ROCK.
GENERAL REMARKS.
There is associated with all phosphate rock deposits
considerable rock which is not up to present commercial
requirements in content of calcium phosphate. There is
also being produced in connection with the prepara-
tion of commercial phosphate rock for market a great
deal of low grade material. To bring these classes of
material up to commercial grade, that is to a grade con-
taining 70 per cent, or more calcium phosphate, various
chemical methods have been used. The time will un-
doubtedly come when these chemical methods will find
much more extended application than at present, and
when this time arrives it will result in the utilization of
a great deal of phosphate rock now consigned to waste
ponds and dumps, and also much which will not bear the
present cost of mining. Such methods are of more than
ordinary interest in connection with the Kentucky field.
The large quantities of by-product sulphuric acid which
will become available in increasing quantity as time goes
on as the result of the elimination of the smelter smoke
nuisance, is an important element in the situation. Im-
mense quantities of such acid has in the past been avail-
able in southeastern Tennessee, and is potentially avail-
able at the smelters in the vicinity of our western phos-
phate field. Indeed the chemical method of concentrating
phosphate and thus enabling it to be transported long
distances may well be worked out in connection with the
high grade rock that the western phosphate field is able
to produce, and it will also be the means of conserving
the enormous quantity of low grade phosphate rock in
the Kentucky and other eastern fields.
67
CHEMISTRY OF PROCESS.
Phosphate rock is marketed now as such, and in
the form of acid phosphate, including in the latter term
ordinary super and donble-acid phosphate, the latter con-
taining two to three times as much soluble phosphoric
acid as ordinary super-phosphate.
Before the discovery of the extensive high grade
deposits of phosphate rock in this country aiul abroad,
the manufacture of the concentrated grades of soluble
phosphate was in fairly common practice. The large
supplies of high grade phosphate rock have rendered this
unnecessary, though in Europe and in parts of the
United States this practice is reported to be still in use.
The basic reaction involved in the preparation of
soluble acid phosphate takes place when ordinary rock
phosphate Oa,(P()4), is treated with sulphuric acid.
In simple form, the reaction that takes place may be
represented thus :
(1) Ca,(P04),+3H,$04=2H,P04+3CaS04.
(2) 4H:5P04+Ca,(P04)^3CaH4(P04)2.
Eeduced to one equation, this is as follows :
Ca3(P04)2+2H2S04=CaH4(P04)2+2CaS04.
In the presence of water, which has been omitted
from the above equations in order to simplify them, the
calcium sulphate would be changed into gypsum by ab-
stracting water from the mass. The last reaction is the
one desired by the manufacturers.
To utilize low grade rock and tailings, and to make
concentrated phosphatic fertilizers, the phosphoric acid
produced by the first reaction is evaporated in pans until
it contains about 45 per cent, phosphoric anhydride. It
is then treated with a fresh supply of phosphate rock,
when the following reaction ensues:
Ca3(P04)2+4H,PO4=3CaH4(P04)2.
It will be observed, therefore, that ordinary super-
phosphate is largely a mixture of soluble calcium phos-
phate and gypsum, while the double acid phosphate con-
tains little or no calcium sulphate, or dehydrater, and
thus has to be artificially dried. Either the phosphoric
acid itself, the double phosphate, or such compounds as
potassium or ammonium phosphate, might be shipped
from our western field, since they are highly concen-
trated products.
68
EXPERIMENTAL WORK IN THE WEST.
CHEMICAL METHODS.
With reference to the results accomplished to date
in the west toward the production of a high grade phos-
phate product which may be shipped to eastern markets,
the following is of interest:*
The first effort, having in view the production of
a high grade phosphate product which would stand the
cost of shipment to eastern markets, was instituted by
the Mountain Copper Company, at Martinez, California.
This company for many years has been producing and
marketing locally a super-phosphate, and some years
ago endeavored to produce a high grade product. The
possibility of making a high grade phosphate product
has also been considered and discussed by the technical
staff of the American Smelting and Refining Company
in connection with their acid plant at Garfield, Utah.
At Anaconda during the past two years a consistent
and elaborate investigation with a high grade phosphate
product in view has been made. The desire has been to
obtain an outlet for the waste sulphur dioxide gas of the
smelter through the production and utilization of sul-
phuric acid. The investigation was started on a small
scale in the laboratory, and is now advanced to the point
where a unit of 500 pounds of phosphate rock per day
capacity is being operated. Stated briefly, the results
obtained up to the present time are as follows :
Decomposition of the phosphate rock containing
from 30 to 33 per cent. P205 has been effected by grind-
ing with dilute sulphuric acid, agitation with acid, or
treatment with acid in a "den," as in the manufacture
of ordinary super-phosphate. The best recoveries have
been made by using the "den" decomposition followed
by leaching.
The rock is first treated with nearly the theoretical
amount of sulphuric acid in a "den" to take care of the
lime. The mixture ' ' sets ' ' after a few minutes stirring
and usually is allowed to stand covered for 16 hours at
about 40° C. The mixture is then leached with solutions
from previous teachings containing about 6 per cent,
sulphuric acid. The material filters quite satisfactorily
^Communicated by A. E. Wells of the Mine Experiment Station of
the Bureau of Mines at Salt Lake City, Utah.
69
when the sulphuric acid content of the leaching solution
is properly maintained, and the resulting1 solution may
contain as high as 20 per cent. PL,O-. The extraction is
about 90 per cent of the P203 in the rock.
In one line of investigation the solutions were evap-
orated to about 45 per cent. P20.-,, at which concentration
some calcium sulphate was deposited. This phosphoric
acid solution was then added to more phosphate rock,
the amount of rock used being about 80 per cent, of that
theoretically required to combine with the phosphoric
acid, according to the reaction: Ca:,(PO4)2+4HoPOi—
3CaH4(P04)o. The mixtiue \vas alio\v< d t;> stand for sev-
eral hours and then dried. A. <h. v ,grindable product con-
taining about 50 per cent, available I'M)- was obtained.
Another line of investigation has aimed to produce
a high grade phosphoric acid liquor or even glacial phos-
phoric acid. The solutions from the leaching mentioned
above have been evaporated on steam baths to the point
where they contain (J2 per cent. P^O-. As stated above,
calcium sulphate begins to deposit when the concentra-
tion reaches about 40 per cent. P20r>, and continues to
deposit as the concentration increases. In the laboratory
all evaporations were effected in lead or glass, as the
dilute solutions corroded iron rapidly. In some long-time
evaporations, a glacial acid, a mixture of pyro and meta
phosphoric acM resulted, containing as much as 70 to
80 per cent. P20n.
Experiments are in progress in connection with the
work now being conducted on the 500-pound unit, to detor-
mino the possibility of evaporation in a tower such as is
used in sulphuric acid concentration. At the Bureau of
Mines experiment station in Salt Lake City, tests are
in progress to determine whether the solution can be
evaporated to a dry P?0r> powder by spraying the dilute
or partially evaporated solutions into a stream of hot
gases and precipitating the dehydrated acid by electrical
profvrvta+ion methods. The evaporation problem still
remains the most serious one in the production of a high
grade phosphoric acid liquor or of glacial phosphoric
ac?d. Due to the hvgrosconic pror>erties of the glacial
acid, and the necessitv of shipping it in sealed, iron con-
tainers, it is believed that it will be most feasible to
70
prepare a 60 to 65 per cent. P205 solution to be shipped
in tank cars.
The possibility of substituting this phosphoric acid
solution for sulphuric acid in the recovery of ammonia at
the by-product coke plants with the production of am-
monium phosphate, is being investigated. No data from
this investigation are yet available.
Though it is true that the grade of rock on which
work has been done contains fairly high percentages of
phosphoric acid, theie is in MOM tana, witliin a distance
of 30 miles of the Anaconda smelter, large deposits of
phosphate rock which will average only about 23 per
cent, P20r,, and in time it is likely that these deposits
will be of considerable value. At the present time the
phosphoric acid solutions from this grade of rock con-
tain so much iron and alumina that it has been felt that
it would be much better to work out the problem with
the use of the higher grade rock, of which a great deal is
present and can be easily mined in southern Idaho and
northern Utah.
ELECTRICAL METHODS.
An interesting and recent development in the utili-
zation of low grade phosphate rock is in the production
of phosphoric acid and its derivatives, ammonium phos-
phate and double super-phosphate, by utilization of the
electric furnace. Sulphuric acid is here replaced by
silica, coke, and electric energy, and with very cheap
electric energy, the resulting product may be produced
considerably cheaper and in a much more available form
than by the present methods. The fertilizers- produced
with the aid of electric energy, fixed nitrogen and avail-
able phosphoric acid, go hand in hand with cheap water
power.
Ross, Carothers, and Merz* have recently summar-
ized the results of certain experiments in the use of the
Cottrell precipitator in recovering phosphoric acid evolv-
ed in the volatilization method of treating phosphate
rock by ignition with coke and silica in an electric
furnace. "A current of air which was passed over the
*Ross, W. H., Carothers, J. N., Mf-r?, A. R. T'-p use of the Cottrell
precipitator in recovering- the phosphoric acid evolved in the volatiliza-
tion method of treating" phosnhate rock. Journal of Industrial and
Engineering- Chemistry, Vol. IX., No. 1, January 1, 1917, pp. 26-31.
71
charge in the furnace served the double purpose of
oxidizing the fumes of phosphorus to phosphorus pentox-
ide and of carrying the latter to the precipitator. In one
series of experiments the fumes from the furnace before
entering- the precipitator were passed through a tower
provided Avith baffle plates which had the effect of cool-
ing- down the gases to about ordinary temperature. Tn
a second series of experiments the tower was cut out and
the fumes passed almost directly into the precipitator
at a temperature above 100° C. In each case the phos-
phorus pentoxide, which takes up water from the current
of air passing through the furnace and also from the
moisture driven off from the charge, is precipitated in
the form of a solution of phosphoric acid. When the
precipitation is made at temperatures about 100°, or
above, the concentration of the acid is greater than that
collected at a lower temperature, but by reducing the flow
of air through the furnace, acid of high concentration
may also be obtained with low temperature precipita-
tion.
44 The advanutages of this method of collecting the
phosphoric acid over the scrubbing tower method now
in use4 are as follows:
"1. The equipment required is simple in construc-
tion and automatic in operation.
"2. The simplicity of the construction of the pre-
cipitating pipes decreases the difficulties arising from the
corrosive action of the phosphoric and hydrofluoric acids
evolved from the phosphate rock.
"3. In this way there may be recovered phosphoric
acid of a high degree of purity suited for direct use with-
out further purification in those industries where a rela-
tively pure acid is required.
"4. A more concentrated acid can be obtained in
this way than is possible to prepare directly by any
other commercial process, and when this acid is used in
the preparation of concentrated fertilizers, such as
mono-ammonium phosphate, a dry product may be ob-
tained directly without the necessity of evaporating so-
lutions, or of drying the resultant product.
"This is the first time that the Cottrell precipitator
has been used for the precipitation of a product which
72
has been purposely volatilized with a view to its recovery
in this way."
The fertilizer division of the Bureau of Soils has
given considerable attention to the preparation of con-
centrated fertilizers and a paper recently prepared by
William H. Ross and Albert R. Merz* gives a general ac-
count of some methods which may prove to be applicable
in their preparation. The one which concerns this paper
more especially relates to the preparation of phosphoric
acid together with potassium and ammonium phosphates.
Practically the entire output of fertilizers in the
United States is consumed east of the Mississippi river,
and more than four-fifths of this consumption is in the
states bordering on the Atlantic Ocean and the Gulf of
Mexico. Our natural resources in phosphate rock, how-
ever, occur in overwhelming preponderance in the far
west.f
"A serious problem presents itself in bringing these
raw materials or products derived from them to the
region of consumption, as the distances are great and the
only means of transportation available, that by rail, is
expensive. A partial solution of this problem is found
in the production of concentrated fertilizers, whereby
the ratio of the cost of transportation to the value of the
material shipped is considerably diminished.
"The simplest of these commercial fertilizers in
chemical constitution is phosphoric acid. The processes
which have been used commercially for the preparation
of this acid may be conveniently divided into two classes,
as follows: (1) Processes which involve treatment of
the rock with a mineral acid such as sulphuric acid ; and
(2) processes in which the phosphorus is evolved from
the rock by ignition with silica and coke and its subse-
quent conversion into phosphoric acid through oxidation
and absorption of the anhydride in some form of scrub-
bing tower. With the volatilization method it has been
found possible to prepare an acid of greater concentra-
tion than it is possible to obtain directly in any process
of the first group, but even in this process when the
*Ross, W. H., and Merz, A. R. The preparation of concentrated
fertilizers: The American Fertilizer. Vol. 45, No. 8, October 14, 1916, pp.
32-35.
fSee paper by Phalen, W. C. The conservation of phosphate rock in
the United States: Trans. Am. Inst. Min. Engrs., Bull. 119, November,
1916, pp. 1901-1934.
73
scrubbing tower method of recovering the phosphoric
acid is used it is impractical to obtain an acid of greater
strength than about 50 per cent, phosphorus pentoxide
and evaporation must be resorted to for further concen-
tration. However, if the scrubbing tower be replaced by
a Cottrell prccipitator, no difficulty is found in securing
phosphoric acid which contains upward of 95.0 per cent,
phosphoric acid. A high grade phosphate rock of 75
per cent tricalciuin phosphate has 34.4 per cent. P^,
whereas a 95.0 per cent, phosphoric acid solution con-
tains 68.8 per cent P205. Therefore we have produced a
fertilizer material twice as concentrated as high grade
rock or over four times as concentrated as 16 per cent,
super-phosphate and having all the P^O-, in the so-called
available form. It may be interesting to note that this
is the first time that the Cottrell precipitator has been
used for llie precipitation of a product which has been
purposely volatilized with a view to its recovery in this
way. A detailed description of the experiments con-
ducted with the precipitator and the advantages of its
application are given in the paper referred to above.
"The phosphoric acid which is produced by this
procedure may be shipped directly in suitable containers
to the region of fertilizer consumption, there to be used
in the preparation of mixed fertilizers. This is now
actually being considered by a western concern which
contemplates shipping phosphoric acid that has been ex-
tracted from western phosphates by the sulphuric acid
method and concentrated by evaporation."
The studies made by Ross and Mcrz also include the
direct preparation of salts in which the phosphoric acid
was combined with a fertilizer base such as potassium
and ammonium to produce the corresponding potassium
(KoP04) and ammonium phosphate ((NH4)3P04).
Methods of producing a concentrated fertilizer contain-
ing all three fertilizer elements, that is nitrogen, potash,
and phosphorus, are also outlined.
THE FUTURE OUTLOOK FOP, THE KENTUCKY
PHOSPHATE FIELD.
From what has been stated with reference to the
Kentucky phosphate field, it is evident that rock of high
grade has been found in different places in the blue grass
74
region of central Kentucky, and without doubt many
more workable deposits will be found as the entire region
is systematically and carefully prospected according to
the methods usually employed in this work and outlined
in this paper.
A somewhat restricted district in the vicinity of
Wallace, a few miles south, southeast and southwest of
Midway, Woodford County, is the only one of prom-
inence within which phosphate rock is found to occur to
any great extent. Between Midway and Spring Station,
along the Louisville and Nashville Railroad, and on cer-
tain farms to the north of the railroad, is another area
where phosphate rock has been found in some quantity.
The limits of these areas have not been very accurately
determined, but enough drilling has been done to indicate
that very important deposits of phosphate rock should
be expected to be found locally. When it is remembered
that brown rock phosphate may run from 600 to 1,000
tons per acre per foot of thickness, small areas may
prove of great importance if the phosphate deposits in
them are thick enough and of good quality.
Outside of the Wallace area and that to the west of
Midway, phosphate rock is known to occur in and around
Lexington, Fayette County, in the vicinity of George-
town, Scott County, near the Forks of Elkhorn, Franklin
county, near Versailles, Woodford County, and near Pine
Grove Station, Clark County.
The material collected from the drillings made in
this field shows great variation in content of calcium
phosphate, and the sections themselves also show great
irregularity in the thickness of the phosphate bed. In the
Wallace district, of the total number of analyses made
of materials collected from drillings, about one-third
showed a content of 50 per cent, or more of calcium phos-
phate. Less than 10 per cent, of the total showed a con-
tent between 60 and 70 per cent., and but 5 per cent, of
the total showed more than 70 per cent. The latter ma-
terial was, for the most part, collected from well exposed
sections in the old workings of the Central Kentucky
Phosphate Company, near Wallace. The remaining: 65
ppr cent, contained less than 50 per cent, calcium phos-
phate, and the great bulk of the material carried from
30 to 50 per cent. The other localities in which prospect-
75
ing" was carried on showed approximately similar re-
sults.
Occasional occurrences of lump rock were found in
this area, containing more than 80 per cent, calcium
phosphate, and although rock in workable quantity may
be found running up to and above present commercial
requirements, that is, containing 70 per cent, and more
calcium phosphate, it is quite safe to affirm that the bulk
of Kentucky rock will be found to contain less than 70
per cent. BPL. This means that in the most promising
areas the rock will have to be carefully washed and
cheaply worked by the most modern, labor saving de-
vices, to bring it up to present commercial standards
so that it will be able to compete in the open market with
Tennessee rock. Without doubt, much of the Kentucky
rock of low or intermediate grade must wait for cheap
chemical or electrical processes of concentration. Some
of the very latest developments in these processes are
described^ in this paper.
The Kentucky phosphate field is practically a virgin
field. From its study and a comparison of it with the
Tennessee field, it is felt that local conditions are sim-
ilar and the problem of working the Kentucky phosphate
deposits must be along much the same lines as in Ten-
nessee. For this reason, brief descriptions of the tech-
nology of the mining and preparation of phosphate rock
for market as practiced in the Mt. Pleasant district of
Tennessee are given.
The advantages of the Kentucky field with respect
to transportation rates to markets in the north and west
are pointed out. Though the Kentucky field has an ad-
vantage in freight rates to important fertilizer markets
in Ohio, Indiana and Illinois, this has not led to the es-
tablishment of any important industry in the State thus
far. The Tennessee field, the pioneer, has enjoyed the
advantages usually accruing to the first in the field. The
Tennessee rock, on the average, is a higher grade rock
than the Kentucky, which gives the former certain ad-
vantages, until effective concentration methods, either
mechanical, chemical, or both, are introduced in the Ken-
tucky field.
The lands on which the Kentucky rock phosphate
has been found are very fertile, in fact are the most
76
fertile in the blue grass region. Consequently they
possess high values for farm and grazing purposes, and
are worth at least $200 per acre for these purposes alone.
The extent to which the Kentucky field will be developed
depends not only on what may underlie the land, but on
the attitude assumed by the farmers who own it. Whether
it is considered more valuable for farming purposes than
for the phosphate deposits which underlie it in places, re-
mains to be seen, assuming, of course, that exact knowl-
edge with regard to its mineral wealth becomes better
known as time goes on. It is certain that after mining
operations have been conducted it will cost much to
bring the land into condition for farming, if this can be
done at all. In this connection, however, it is of interest
to point out that in Tennessee, whore hydraulic mining
is practiced in one locality, the rock is mined out in a
small area and the overburden from that next to it is
washed into the area which has been mined out. The
resultant topography is level and may be farmed over
again, a most important consideration where the land is
as valuable as in the Kentucky Blue Grass region. Ac-
cording to this method of removing overburden, the land
is conserved for farming purposes for future genera-
tions and greatly improved at the same time, for a part
of the phosphate rock and sand formerly below the sub-
soil is thoroughly incorporated into the top soil, and the
fertilizer value of the phosphate rock thus rendered
available in time.
Many extensive deposits of low grade Kentucky
rock may be expected to become profitable in the future,
as methods for their practical utilization are solved, and
as the supply of high grade rock in other eastern states
shall have become exhausted.
BIBLIOGRAPHY OF PUBLICATIONS RELATING TO PHOSPHATE
ROCK.
BAKU. JAMES A., Tennessee phosphate practice: Trans. Am. Inst. Min.
Engrs., Bull. 93, Sept., 1914, pp. 2397-2413.
- The use of low grade phosphate: Trans. Am. Inst. Min. Engrs.,
Bull. 110, Feb., 1916, pp. 243-245.
Bi.AcivWKi.DEK, ELIOT, Phosphate deposits east of Ogden, Utah: U. S.
Geol. Survey, Bull. 430, pp. 536-551, 1910.
- A reconnaissance of the phosphate deposits in western Wyom-
ing: U. S. Geol. Survey Bull. 470, pp. 452-481, 1911.
C n ATARI). T. M., Phosphate chemistry as it concerns the miner: Trans.
Am. Inst. Min. Engrs., Vol. XXL, pp. 160-175, 1893.
DARTOX. N. H., and SIEKEXTIIAL. C. E., Geology and mineral resources
of the Laramie Basin, Wyo.; a preliminary report: U. S. Geol.
Survey Bull. 364, pp. 81, 1909.
ECKEL, E. C., Recently discovered extension of Tennessee white-phos-
phate field: U. S. Geol. Survey Mineral Resources, 1900 pp. 812-813,
1901.
- Utilization of iron and steel slags: U. S. Geol. Survey Bull. 213,
pp. 221-231, 1903.
- The white phosphates of Decatur County, Tenn.: U. S. Geol.
Survey Bull. 213, pp. 424-425, 1903.
Ei.iminGK. G. H., A preliminary sketch of the phosphates of Florida: Am.
Inst. Min. Eng. Trans., Vol. 21, pp. 196-231, 1893.
FOKHSTK. A. E., The phosphate deposits in the upper Trenton lime-
stones of Central Kentucky: Ky. Geol. Survey, Series IV., Vol. I.,
Part I., 1913, pp. 391-439.
GALE, H. S., Rock phosphate near Melrose, Mont.: U. S. Geol. Survey
Bull. 470, pp. 440-451, 1911.
GALE, H. S., and RICIIAKMH, R. W., Preliminary report on the phosphate
deposits in southeastern Idaho and adjacent parts of Wyoming
and Utah: U. S. Geol. Survey Bull. 430, pp. 457-535, 1910.
GARDNER. JAMES H., Rock phosphate in Kentucky: Mines and Minerals,
November, 1912, pp. 207-209.
GIRTY, G. H., The fauna of the phosphate beds of the Park City formation
of Idaho, Utah, and Wyoming: U. S. Geol. Survey Bull. 436, 82 pp.,
1910.
HAYES, C. W., The Tennessee phosphates: U. S. Geol. Survey, Sixteenth
Ann. Rept., pt. 4, pp. 610-630, 1895; Seventeenth Ann. Rept., pt. 2,
pp. 519-550, 1896.
— The white phosphates of Tennessee: Am. Inst. Min. Eng. Trans.,
Vol. 25, pp. 19-28, 1896.
78
- A brief reconnaissance of the Tennessee phosphate field: U. S.
Geol. Survey, Twentieth Ann. Kept., pt. 6, continued, pp. 633-638,
1899.
- The geological relations of the Tennessee brown phosphates:
Science, Vol. 12, p. 1005, 1900.
- Tennessee white phosphate: U. S. Geol. Survey, Twenty-first
Ann. Kept., pt. 3, pp. 473-485, 1901.
- Origin and extent of the Tennessee white phosphates: U. S.
Geol. Survey Bull. 213, pp. 418-423, 1903.
HOOK, J. S., The brown and blue phosphate rock deposits of South Cen-
tral Tennessee: The Resources of Tennessee, Vol. IV., No. 2, April,
1914, pp. 51-83.
- The white phosphates of Tennessee: The Resources of Tennes-
see, Vol. V., No. 1, January, 1915, pp. 23-33.
IHLSENG, M. C., A phosphate prospect in Pennsylvania: U. S. Geol. Sur-
vey, Seventeenth Ann. Rept., pt. 3, continued, pp. 955-957, 1896.
MATSOX, G. C., The phosphate deposits of Florida: U. S. Geol. Survey
Bull. 604, pp. 101, 17 pis., 1915.
MANSFIELD, G. R., A reconnaissance for phosphate in the Salt River
Range, Wyo.: U. S. Geol. Survey Bull. 620, pp. 331-349, 1915.
MAYNAKD, T. POOLK, White rock phosphates of Decatur County, Tennes-
see: The Resources of Tennessee, Vol. III., No. 3, July, 1913, pp.
161-169.
MEMMINGEU, C. G., Commercial development of the Tennessee ph6s-
phates: U. S. Geol. Survey, Sixteenth Ann. Rept., pt. 4, pp. 631-635,
1895.
MILLER, A. M., The association of the gastropod genus cyclora with
phosphate of lime deposits: Am. Geologist, Vol. XVII., Feb., 1896,
pp. 74-76.
- Safford on Tennessee phosphate: Am. Geologist, Feb., 1894,
Vol. XIII., No. 2, pp. 107-109.
MOSES, O. A., The phosphate deposits of South Carolina: U. S. Geol.
Survey Mineral Resources, 1882, pp. 504-521, 1883.
PARDEE, J. T., Some further discoveries of rock phosphate in Montana:
U. S. Geol. Survey Bull. 530, pp. 285-291, 1913.
PEXROSE, R. A. F., Nature and origin of deposits of phosphate lime: U.
S. Geol. Survey Bull. 46, 143 pp., 1888.
PIIALEX, W. C., Phosphate rock: U. S. Geol. Survey Mineral Resources,
1912, pt. 2, pp. 855-876, 1913; idem., 1913, pt. 2, pp. 273-289, 1914;
idem., 1914, pt. 2, pp. 41-56, 1915.
— The conservation of phosphate rock in the United States: Trans.
Am. Inst. Min. Engrs. Bull., No. 119, Nov., 1916, pp. 1901-1913.
PURDUE, A. H., Developed phosphate deposits of northern Arkansas:
U. S. Geol. Survey Bull. 315, pp. 463-473, 1907.
RICHARDS, R. W., and MAXSFIELD, G. R., Preliminary report on a por-
tion of the Idaho phosphate reserve: U. S. Geol. Survey Bull. 470,
'pp. 371-439, 1911.
79
RICHARDS, R. W., and MANSFIELD, G. R., Geology of the phosphate de-
posits northeast of Georgetown, Idaho: U. S. Geol. Survey Bull. 577,
76 pp., 14 pis., 1914.
ROGERS, G. S., The phosphate deposits of South Carolina: U. S. Geol.
Survey Bull. 580, pp. 183-220, 1914.
Sc iiri/rz, A. R., Geology and geography of a portion of Lincoln County,
Wyo.: U. S. Geol. Survey Bull. 543, pp. 131-134, 1914.
ScHUJ/rz, A. R., and RICHARDS, R. W., A geologic reconnaissance in
southeastern Idaho: U. S. Geol. Survey Bull. 530, pp. 267-281, 1913.
SMITH, G. O., and others, The classification of the public lands: U. S.
Geol. Survey Bull. 537, pp. 123-134, 1913.
STOXE. R. W. and BOXIXK, C. A., The Elliston phosphate field, Montana:
U. S. Geol. Survey Bull. 580, pp. 373-383, 1914.
STOSK, G. W., Phosphorus ore at Mount Holly Springs, Pa.: U. S. Geol.
Survey Bull. 315, pp. 474-483, 1907.
- Phosphorus: U. S. Geol. Survey Mineral Resources, 1906, pp.
1084-1090, 1907.
- Phosphate deposits in southwestern Virginia: U. S. Geol. Survey
Bull. 540, pp. 383-396, 1914.
STI-JWS, W. C., Phosphates of Alabama: U. S. Geol. Survey Mineral Re-
sources, 1883-84, pp. 794-803, 1885.
VAX HORX, F. B., The phosphate deposits of the United States: U. S.
Geol. Survey Bull. 394, pp. 157-171, 1909.
- Phosphate rock: U. S. Geol. Survey Mineral Resources, 1911, pt.
2, pp. 877-888, 1912.
WAGGAMAX, W. H., A review of the phosphate fields of Florida: U. S.
Dept. of Agriculture, Bureau of Soils, Bull. 76, 1911.
- A report on the phosphate fields of South Carolina: Bull, of the
Dept. of Agriculture, No. 18, 1^13.
WAGGAMAX, W. H., and FRY, W. H., Phosphate rock and methods pro-
posed for its utilization as a fertilizer: U. S. Dept. of Agriculture,
Bull. 312, 1915.
WKEKS, F. B., Phosphate deposits in the Western United States: U. S.
Geol. Survey Bull. 340, pp. 441-447, 1908.
WEEKS, F. B., and FERRIER, W. F., Phosphate deposits in western United
States: U. S. Geol. Survey Bull. 315, pp. 449-462, 1907.
WILBER. F. A., Greensand marls in the United States: U. S. Geol. Sur-
vey Mineral Resources, 1882, pp. 522-526, 1883.
80
Plate I.
View of Brannon cherty limestone with upper contorted limestone
layer and overlying phosphate rock debris. Cut on Queen & Crescent
Route near Virginia Avenue bridge, Lexington, Ky.
Plate II.
View showing irregular bedding in the Brannon cherty limestone
near Virginia Avenue bridge, Lexington, Ky.
Plate III.
Crushed zone in limestone in the Brannon member. East side of
Versailles-Frankfort pike, about 3 miles north of Versailles, Woodford
County, Ky.
Plate IV.
Old McMeekin limestone quarry, Newtown pike, 3 miles north of
Lexington, Ky. In this quarry Dr. R. Peter first noted the association
of cyclora and phosphate rock.
Plate V.
Arching of phosphate rock over limestone horse. Note the band-
ing in the phosphate rock and also in the limestone. United Phosphate
and Chemical Co., near Wallace, Ky.
Plate VI.
Arching of phosphate rock beds over underlying limestone.
United Phosphate and Chemical Company, near Wallace, Ky.
Plate VII.
Limestone with interlaminated phosphatic layers. Type of rock
from which phosphate deposits are derived. Quarry on Haggin estate,
east, of Maysville pike, 7 miles northeast of Lexington, Kentucky.
Plate VIII.
Alternating layers of limestone and phosphatic material, Mt. Pleasant,
Tenn.
Plate IX.
View in old phosphate workings showing "cutters" and limestone
"horses." Near Wallace, Ky.
Plate X.
Arching of phosphate rock over limestone horses. Near
Mt. Pleasant, Tenn.
Plate XI.
Rafinesquina alternata from near Versailles, Woodford County, Ky.
The shell has been replaced by SiO2 and Ca3 (PO4)2 has infiltrated
and formed a cast of the interior of the shell.
Plate XII.
Removing overburden with scrapers. Near Scotts Mill, Maury County,
Tenn.
Plate XIII.
Distant view of a cantilever, showing an open pit in part worked
out, Mt. Pleasant, Tenn. Note the method of disposing of overburden;
limestone horses, cutters, and phosphate rock curving over horses.
Plate XIV.
A typical drag line excavator at work stripping overburden.
Mt. Pleasant, Tenn.
Plate XV.
A steam shovel removing overburden, Mt. Pleasant, Tenn.
Plate XVI.
Mining phosphate rock with hydraulic gun, near Mt. Pleasant, Term.
Overburden is also removed by this method.
Plate XVII.
Drying phosphate rock by burning in open kilns, Mt. Plea-sant, Tenn.
Plate XVIII.
A deep and wide cutter. Shows the method of removing phosphate
rock by hand from deep cutters. Mt. Pleasant, Tenn.
Plate XIX.
A very narrow cutter from which it is difficult to remove the phosphate,
rock, Mt. Pleasant, Tenn.
$he phosp
ceTitrai~~K
ate rocks of
.376
0
UNIVERSITY OF CALIFORNIA LIBRARY
Live Music Archive
Librivox Free Audio
Metropolitan Museum
Cleveland Museum of Art
Internet Arcade
Console Living Room
Books to Borrow
Open Library
TV News
Understanding 9/11