Bulletin No. 202 Series A, Economic Geology, 18

DEPARTMENT OF THE INTERIOR

UNITED STATES GEOLOGICAL SURVEY

CHARLES D. WALCOTT, DIRECTOR

TESTS

FOR

GOLD AND SILVER IN SHALES FROM

BY

WALDEMAR LINDGREN

WASHINGTON

GOVERNMENT PRINTING OFFICE

1902

CONTENTS.

Page.

Introduction .-__----.__.--....--.--..------..--...-..-.----......--..__._._ 5

Field work .._______..____..___._....._..-.._._..-._....-._.-..--....---. 6

Location ....._____..._.......___..-.....-._.'..__.._.__._..___.___.;____. 6

Topographic features and drainage.-...__--...__-----..---..._--...__.---- 6

Geological features .................... ^........'........................... 7

Cretaceous rocks......--.....-...........-..-..--.---.----.-.-....-.- 7

Niobrara group................................................... 8

Benton group..................................................... 8

Pleistocene rocks ..-.--...-.-..-.-..-..-...-......-.-.......--....--- 9

Sampling and assaying. --.---..-...-.--.---...--....--'-----..----.-...... 9

Sampling...............____.___......___....'---...-.-......_-.....___ 9

Preparation of sample for assaying................................... 12

Methods of assay...... --...--....-.......-..-.-......--....-.-.......- 13

Results of assays ........................................^.....'...... 14

Summary and conclusions.-......-.-...---.--....-.---......----...-..--. 18

Index ................ ....-.................;........................... 21

TESTS FOR GOLD AND SILVER IN SHALES FROM 

WESTERN KANSAS.

By WALDEMAR LINDGREN.

INTRODUCTION.

The assertion, that certain clay shales of western Kansas contain 

gold and silver dates back about seven years. In 1895 a company of 

men, among them a certain H. H. Artz, sunk a shaft near- Smoky 

Hill River, in Trego County, prospecting for zinc. It is stated that 

some indications of this metal were found, but of more importance 

was the announcement that the soft clay shales encountered contained 

a notable percentage of gold. It soon became known that the same 

clay shales extended through a large part of Ellis County and were 

especially well exposed in the bluffs along Smoky Hill River in the 

southern part of that county. A great number of assays of these 

shales were made by different persons, and a large percentage of the 

samples was said to contain gold and silver. The asserted amounts 

vary considerably. Dr. 3. T. Lovewell, of Topeka, in a paper read 

before the Kansas Academy of Science," stated that he had made 

many hundreds of assays and supposed that the clay had average 

values of $2 to $3 per ton in gold and silver, the latter metal always 

accompanying the gold. One series of 100 assays gave an average of 

more than $10 per ton. Dr. Ernst Fahrig, of Philadelphia, 5 obtained 

from actual mill runs in an experimental plant an average of $2.80 

per ton. One of these runs yielded 2.6 ounces silver and $1.36 gold 

per ton, and another of them gave an aggregate value of $6.75 per ton. 

The Kansas Pioneer Gold Shale Company, advertising their stock in 

the principal papers of St. Louis, Chicago, and New York, state the 

value as $8 to $10 per ton, and compute the wealth contained in one 

acre of shales to be $5,250,000. Others, among them Prof. E. Ha worth, 

of the Kansas State University, have denied that the shales contain 

gold in notable quantities. 6'

The statements of tenor obtained by assays are usually accompanied by the explanation that the values are extremely irregular, 

different assays from the same carefully mixed pulp giving widely 

differing results.

«Topeka Serniweekly Capital, January 3,1902. 

''Kansas Daily Capital, Topeka, May 3,1902.

e Kansas Seiniweekly Capital, Topeka, June 6,1902. Mineral Resources of Kansas for 1898, 

Lawrence, Kans., 1899.

5
6 TESTS FOE GOLD AND SILVER IN KANSAS SHALES.

It was not long before mills were erected to extract the values from 

the clay shale. In 1900 a company was formed and erected a mill on 

Smoky Hill River, 14 miles west-southwest of Hays. Some kind of 

a chloridizing process was to be used, but no run was ever made, the 

superintendent and owner of the process, W. F. Miller, absenting 

himself unexpectedly before actual work had begun. In 1901 a 

smaller experimental mill was built near the works just mentioned by 

Mr. A. G. Gage, who used a variation of the cyanide process, and 

claimed to have extracted some gold during a series of short runs. 

In the spring of 1902 the Kansas Pioneer Gold Shale Companj7 built a 

mill using the same process and supposed to handle 100 tons per day. 

This mill, which is located 11 miles southwest of Hays, on Smoky 

Hill River, had just started crushing and leaching in May, 1902. 

Finally, during the same month, a company called the Fahrig Mining 

and Milling Company was organized in Topeka for the purpose of 

constructing and operating a 100-ton mill on Smoky Hill River. The 

Fahrig process consists in treating the ore with a salt of uurevealed 

composition and in precipitating the gold and silver by electrolytic 

methods.

FIELD WORK.

The investigation of the Kansas shale deposits was undertaken by 

the United States Geological Survey in May, 1902. The actual work 

in the field occupied eight days, from May 12 to May 20, and was 

carried on from Hays as a base.

LOCATION.

Although attention was first drawn to the shales in question through 

prospecting work in Trego County, all the later developments have 

taken place in Ellis County, adjoining Trego Count}7 on the east. 

Ellis is one of the west-central counties of Kansas. Its county seat, 

Hays, is located on the line of the Union Pacific Railroad, 272 miles 

west of Kansas City. Although near the western limit of the "rain 

belt," the county produces much wheat and supports a numerous and 

\vell-to-do fanning population.

TOPOGRAPHIC FEATURES AND DRAINAGE.

The region is drained by Smoky Hill River, which has its headwaters in eastern Colorado and flows through the southern part of 

Trego and Ellis counties almost due east to its junction with the 

Saline River. In Ellis County Saline River flows parallel to and 25 

miles north of Smoky Hill River. Big Creek traverses Ellis County 

diagonally, flowing southeasterly to its junction with Smoky Hill 

River. As may be expected of a stream heading in an arid country, 

Smoky Hill River sometimes runs dry. After heavy rains it rises 

rapidly and is often unfordable.

The general relief is that of a rolling, gently undulating country,
LINDOREN.] GEOLOGICAL FEATURES. 7

through which the rivers have cut well-defined though not veiy de.ep 

trenches. The elevation at Hays is 2,000 feet. Along Smoky Hill 

River south of Hays elevations range from i,9CO to 2,000 feet. 

Smooth, grassy hills rise between Big Creek and Smoky Hill River to 

2,200 and 2,300 feet, and to somewhat less elevation between Big 

Creek and the Saline. East of Hays still more gentle outlines prevail, the divide rising little more than 100 feet above the main streams. 

The highest elevations, 2,400 feet, are in the rough hills south of 

Smoky Hill River, about 20 miles west-southwest of Hays.

Smoky Hill River flows in a sandy bed rarely more than a few hundred feet in width. The gentle curves of the stream are marked by 

steep bluffs, 20 to 80 feet high, on the convex side and moderate 

slopes on the opposite, concave, side. These bluffs -are due to the 

lateral cutting of the banks by the river.

This part of Kansas' is mapped b}7 the United States Geological 

Survey on a scale of 2 miles to the inch and with a contour interval 

of 20 feet; the Hays and Ellis quadrangles embrace all points referred 

to in this paper.

GEOLOGICAL FEATURES.

The geology of this part of Kansas is described in a general way in 

Volume II of the Report of the University Geological Survey of 

Kansas. The rocks exposed are sedimentary and of Cretaceous age, 

excepting the sands and gravels along the river, which, of course, are 

of much later (Pleistocene) age. The two great divisions of the Cretaceous, the Benton and the Niobrara, cover the whole area. The 

beds of -shale and lime lie nearly horizontal but have a slight northeasterly dip.

CRETACEOUS ROCKS.

Beginning from the top, that part of the Cretaceous column with 

which we are here concerned is subdivided as follows: 6"

Section of Cretaceous rocks in ivestern Kansas.

Feet. 

f Smoky Hill chalk .................................. 300

Niobrara group....... \ Fort Hays limestone..----...---..-.--..----.-..... 50

[Septaria horizon.

fBlue Hill shale -__......_._._...._.___..__........ 100

'Uppe"r-j Ostrea shales..._---_--.__._..-.------.-..--------. 150

[Fencepost limestone ....__...._...---...._.--.-.--. 1

Benton group. - f Inoceranius horizon ............................... 5

I Flagstone ..--....--.--...--..-..-.---..... ---..-.- 10

Lower j Lincoln marble.............--.-.----.----.........- 15

I Bituminous shale..................--.....-..-----. 30

Total ...................................... 661

"The divisions here used follow the description by Prof. E. Haworth, Geol. Surv. Kansas, 

Vol. II, pp. 215-221.
8 TESTS FOR GOLD AND SILVEE IN KANSAS SHALES. [BULL.202.

Niobrara group. The upper member of this group, the Smoky 

Hill chalk, does not cover notable areas in Ellis County. The Fort 

Hays limestone, on the contrary, is exposed on the hills south of 

Hays and also to some extent on the ridge north of that town. The 

thickness is not over 50 feet. The rock is a yellowish limestone, 

easily dressed and locally used as building stone. It appears again 

south of Smoky Hill River, capping the shale in th-3 roughly eroded 

area 20 miles west-southwest of Hays.

Just below the Fort Hays limestone is a well-marked horizon, in 

which the shales contain large calcareous concretions (septaria), 

often large and containing abundant veins and crystallized masses of 

calcite of different colors ranging from white to dark brown.

Benton group. A great thickness (2^0 feet) of shales underlies the 

Fort Hays limestone. The upper 100 feet are called the Blue Hill 

shales and are fissile light-gray to dark-gray shales without fossils 

and containing only small amounts of pyrite and organic matter. 

These are exposed in the hills west and northeast of Hays. They 

also outcrop below the same limestone on the south side of Smoky 

Hill River, 18 miles west-southwest of Hays, and extend far up into 

the adjoining Trego County along the river. Samples 3, 18, and 19 

are from this horizon. The shales forming the bed rock at Hays 

probably belong in the lower part of this division. Several deep 

wells sunk 4 and 5 miles east and east-northeast of Hays penetrated 

nothing but shales to a depth of 200 to 360 feet.

The lower division, called the Ostrea shales, is 150 feet thick and 

covers a large area, especially along Smoky Hill River, from some 

point in Trego County down to a point south or a little southeasterly 

of Hays. It is a dark-gray calcareous shale, containing a little 

pyrite, finely divided and also sometimes in concretions. It also 

contains an abundance'of fossil shells, largely of Ostrea congesta; 

sharks' teeth are also often found. Narrow bands of light-gray or 

3rellowish-gray limestone part the shale at intervals of from 5 to 20 

feet. Almost the only good exposures are found along the river 

banks, on either side, according to the curves of the river. Here the 

bluffs are from 20 to 60 feet high, and if the rock is not fresh on the 

surface it takes but little work to obtain unaltered material. Near 

the top of the bluffs the shales are whitish and decomposed and 

usually covered with Pleistocene sands.

The shales are almost black when somewhat moist, but have a darkgray color when dry. They generally appear mottled by minute 

whitish specks in a darker predominating mass. The weathered outcrops are soft .and disintegrate into a clayey soil, breaking up into 

small flat fragments. When fresh the shale is quite compact, 

though breaking easily into large flat fragments 2 to 4 inches thick. 

While the upper Blue Hill shales are poor in calcite, the Ostrea 

shales effervesce readily with acids. When washed in a miner's pan,
LINDGKKN.] SAMPLING AND ASSAYING. 9

the heavy residue consists of calcite grains, a few fragments of quartz, 

and some scant, well-rounded granules of black iron ores; besides 

there is always a little extremely fine-grained pyrite. No colors of 

gold could be detected. Samples 1, 2, and 4 to 14 (see pages 10-12) 

are from the Ostrea shales.

The Lower Benton group contains much more limestone than the 

upper division. It consists of about 70 feet of alternating shales and 

limestone, as indicated in the above table. It is exposed in the 

eastern part of Ellis County, though the identification of its various 

members is not easy during a rapid traverse of the country. The 

50-foot bluffs of shale covered by limestone, on the north bank of 

Smoky Hill River, 3 miles west of Pfeifer and also at Falkenstein's 

farm on the south bank, about the same distance from the town 

mentioned, are believed to belong in this horizon. Samples 15, 16, 

and 17 are from this horizon. The Ostrea shales on Smoky Hill 

River at a point 14 miles west-southwest of Hays are 250 feet below 

the Fort Hays limestone, and must consequently be near the bottom 

of the Upper Benton. The vertical distance from here to the Dakota 

sandstones below can hardly be more than 100 feet.

PLEISTOCENE ROCKS.

To this most recent time division belong the sands and fine gravels 

.along the bottoms of Smoky Hill River and also covering the low 

shale bluffs which follow the stream. The material of this terrane is 

chiefly quartzose and the grains are remarkably well rounded. By 

washing the material in a miner's pan a heavy residue of black sand, 

probably both magnetite and ilmenite, is obtained. These grains also 

are extremely well rounded. Besides, the sand contains abundant 

grains of garnet and some epidote; fragments of topaz are also said 

to occur. A number of pans of this sand was washed near Copeland's 

road crossing, and in one a very minute color of gold was obtained.

SAMPLING A:NT> ASSAYING.

SAMPLING.

The principal gold-bearing stratum is supposed to be the Benton 

group, including the Ostrea shales and the Blue Hill shales. It is 

stated that these rocks over practically the whole of the areas in which 

they occur contain more or less gold and silver, though the metals 

may be rather irregularly distributed. Samples showing value are 

claimed to have been obtained in Trego County along Smoky Hill 

River as far westward as the Benton shales extend, all along Smoky 

Hill River in Ellis County, and also in Rush County, adjoining on 

the south.

It is claimed that values have also been found in samples collected 

near Hays; for instance, in the shales underlying the Fort Hays
10 TESTS FOE GOLD AND SILVEK IN KANSAS SHALES. [BULL. 202.

limestone 4 miles west of the town, and also in samples collected 

along Saline River, along which Fort Benton shales are also said to 

outcrop. All the mills, however, are located on Smokj7 Hill River 

south west of Hays, and from this vicinity have also been taken the 

by far largest number of assayed samples.

In order to arrive at a reliable conclusion regarding the contents of 

these shales in precious metals, the samples described below were 

carefully taken. The method used included, first, the clearing of a 

convenient exposure to a required depth so as to obtain fresh material. 

Along the river bluffs the shales are very little altered and fresh rock 

is comparatively easily found. The required thickness of shale being 

exposed (usually amounting to from 2 to 4 feet), a sample of from 20 

to 30 pounds was broken down on a square of canvas; this material 

was then reduced to pieces about the size of a walnut, or smaller,, and 

the whole amount was quartered down twice to a weight of from 3 to 5 

pounds. It was then put into quait jars and the same securely sealed. 

The following samples were taken:

Samples collected for assay.

No. Locality. Character of material.

South side of Smoky Hill River, 3| 

miles east of the line dividing Ellis 

and Trego counties. Small quarry 

located behind Miller's mill, 20 feet 

above the river. Exposure 25 feet 

high. This sample represents the 

average of 3 feet from floor of 

quarry up to the lower band of 

limestone.

Same as No. 1. This sample represents 8 feet of shale between the 

two layers of limestone. Above 

the upper limestone band the shales 

appear decomposed by surface action.

South side of Smoky Hill River. 34- 

miles northeast of the southwest 

corner of Ellis County, and about 

2| miles south of Miller's mill. The 

horizon is in the Blue Hill shales 

just below the Fort Hays limestone. The elevation is about 

2,250 feet. This sample represents 

an average thickness of 2 feet.

Mouth of gulch emptying into Smoky 

Hill River from the south, 3J miles 

west of the Ellis-Trego county line. 

This locality is about 200 feet west 

of Gage's experimental mill. The 

bluff is here 30 feet high and consists of dark-gray shale divided by 

two narrow partings of gray lime. 

The sample represents 3 feet of 

shales 3 feet above the bed of the 

gulch.

Black shale containing some pyrite 

and divided by two narrow bands 

of gray limestone.

Dark-gray shale with fossils and 

some concretions of pyrite.

Thinly laminated gray clay shale 

with no fossils and but little 

organic matter.

Dark-gray Ostrea shale with fossils 

and a little pyrite.
JJINDGREN.] SAMPLING AND ASSAYING.

Samples collected for assay Continued.

11

Locality. Character of material.

Same as No. 4, 500 feet east of Gage's 

experimental mill. From small pit 

in shales at the river level, which 

showed indication of haying been 

recently blasted. Material for experimental work in Topeka was

. reported to have been taken from 

this locality. The exposure showed 

6 feet of shale covered by 10 inches 

of gray lime; above this 6 feet of 

shale. The sample covered 3 feet 

of the lower shale.

Same as Nos. 4 and 5. 650 feet east of 

 Gage's experimental mill at base

of 30-foot bluff, the upper part 

more or less decomposed. This 

sample is an average of 2 feet close 

to river level.

Same as No. 6. Average of 3 feet, 

from 5 to 8 feet above river level.

South bank of Smoky Hill River, 11 

miles southwest of Hays and 1 mile 

west of Copeland's crossing, in 

quarry from which material was 

being extracted for reduction in 

the Pioneer Company's new mill. 

The place is less than 100 feet distant from the mill. The bluff is 

here approximately 30 feet high, 

the upper 6 feet consisting of wellwashed Pleistocene sand. Below

. this 4 to 6 feet of decomposed shale, 

below which the quarry has exposed 

fresh material. The sample is an 

average of the shale from 8 up to 10 

feet above the river.

Same as No. 8. The sample is an 

average of 2 feet, from 10 to 12 feet 

above the river level.

About 150 feet east of the Pioneer 

Company's mill. The bluff is here 

18 feet high and consists of shale 

with two or three narrow bands of 

harder limestone. The sample represents an average of 3 feet, from 5 

to 8 feet above the river.

South bank of Smoky Hill River, onefourth mile west of the Pioneer 

Company's mill. Twenty-five-foot 

bank of shale covered by 6 feet 

of sand and gravel. The sample 

Avas taken from blasted cut 2 feet 

above river level, from shale averaging 2 feet in thickness.

Fossiliferous Ostrea shales of darkgray color containing a little pyrite.

Dark-gray fossiliferous shale with a

little pyrite.

Dark-gray fossiliferous shale with 

a little pyrite.

Dark-gray clay shale, fossiliferous 

and containing a little pyrite.

Dark-gray fossiliferous shale containing a little pyrite.

Dark-gray fossiliferous shale.

Dark-gray fossiliferous shale with a 

little iron pyrites.
12 TESTS FOE GOLD AND SILVER IN KANSAS SHALES. [BULL.202. 

Samples collected for assay Continued.

No. Locality. Character of material.

13

16

17

18

19

North bank of Smoky Hill River, 10i 

miles southwest of Hays and 300 

feet east of Copeland's road crossing. The shale bluff is 30 feet high 

and contains four smaller bands of 

dark-gray lime. The sample was 

taken 4 feet across just above the 

river.

North bank of Smoky Hill River, 800 

feet west of Copeland's road crossing. Shaft 40" feet deep. 15 feet 

above the river. Filled with water. 

The sample was carefully picked 

from east side of dump.

Same as No. 13. Sample^picked from 

west side of dump.

Fifteen miles south-southeast of Hays, 

in Rush County, 3| miles westsouthwest of the town of Pfeifer. 

South side of Smoky Hill River. 1 

mile south of sharp bend; Baskel's 

farm on Shelter Creek; bluff opposite house on west side of creek, consisting of 35 feet of thin-bedded 

shale capped by 12 feet of yellowish 

limestone.

Fourteen miles south-southeast of 

Hays, in Rush County, near boundary line of Ellis, 4 miles west-soxithwest of Pfeifer. South side of 

Smoky Hill River at Falkenstein's 

farm. Bluff 15 feet high from river 

level of shale with several indistinct 

limy layers.

Same as No. 16. Average of 2 feet 

of shale about 8 feet above river 

level.

Four and one-half miles west-northwest of Hays and one-fourth mile 

south of railroad, on farm of J. C. 

West. Bluff of 50 feet of Blue Hill 

shale without lime partings, overlain by 20 feet of Fort Hays limestone. Average of 24- feet near top 

of shale, 6 feet below limestone.

X

Same as No. 18. Average of 3 feet of 

shale at foot of bluff.

Dark-gray fossiliferous shale.

Dark-gray fossiliferous shale.

Dark-gray fossiliferous shale.

Dark-gray clay shale with some fossils.

Nodules of partly decomposed iron 

pyrites in shale.

Dark-gray shale without much carbonaceous substance.

Dark-gray clay shale without fossils, and with little carbonaceous 

material.

Dark-gray clay shale.

PREPARATION OF SAMPLES FOR ASSAYING.

The 19 samples described above were sent to Washington, D. C., 

and further examined. The shale in each lot was crushed, carefully 

mixed, and quartered down until the last half of the sample amounted 

to one-half to three-fourths pound. This quantity was finally ground
LTNDOHEN.] METHODS OF ASSAY. 13

and sieved through an SO-mesh screen. From this ground material 

the assays were made.

METHODS OF ASSAY.

The fire assay, as well known, consists in smelting in crucible or 

scorifier with litharge or lead. The lead absorbs the gold and silver 

contained in the ore, and this gold and silver remains behind when 

the lead is driven oft' b}7 a process of oxidation. For small and moderate amounts of the precious metals this is the most accurate method 

known, and in skillf ul hands always gives reliable results. The claim 

that "the fire assay will not bring out the values" is well known and 

reiterated to weariness, especially in districts where higher values 

are desired than nature put in the ores. True enough, the fire assay, 

like any other analytical operation, requires intelligent care and suitable ingredients. Where there are large amounts of copper, zinc, 

tellurium, and similar elements in the ore, this assay needs particular 

attention in order to prevent losses. As in every other quantitative 

analytical process, there are sources of error in the fire assay. A very 

small quantity of gold and silver may be lost in the slag in the first 

smelting. This is generally inappreciable. But in cupelling the lead 

button there is always a certain loss of silver by absorption by the 

cupel, much less by volatilization. This loss may amount to several 

per cent in case of very poor ores and small silver beads, but is then 

generally practically negligible. The loss of gold during cupellation 

is ordinarily very much smaller than that, of silver, and practically 

nil. One often hears assertions that the proper A7 alues are not 

brought out by this assay because of the extremely fine distribution 

of the gold. This is absurd, because the chemical reaction, i. e., the 

absorption of gold and silver by the lead, takes place practically independent of the mechanical state of the precious metals. If anything, a fine division would be more favorable to their absorption by 

the lead. In the same category may be put the assertion that the 

gold in these shales is carried away in the fumes from the crucible.

When one considers that the very minute particles in a low-grade 

but paying ore, even after fine crushing, are likely to be securely 

locked up in grains of quartz or other refractory material, it becomes 

clear that the extraction of gold by chlorine, bromine, or potassium 

cyanide, which have little effect on these inclosing shells, must be 

less effective than a fusion. In a fusion with proper fluxes these 

shells are completely disintegrated, and the molten lead dissolves the 

precious metal almost entirely. The fire assay is, in fact, used in all 

cyanide and chlorination works to test ores and tailings.

This statement regarding the wet process also holds good for analytical work. Only in case the ores contain large quantities of gold 

or silver do the wet methods offer any advantage over fusion and 

cupellation. Electrolytic quantitative tests of gold and silver are
14: TESTS FOE GOLD AND SILVER IN KANSAS SHALES. [BULL.202.

known, but rarely used, a offering no advantage over other assays and 

requiring as much preliminary work in the elimination of other metals 

as do wet tests by precipitation of the gold by hydrogen sulphide, zinc, 

oxalic acid, or other means.

The accuracy of the fire assay varies, of course, with the quantity 

and character of the material, the purity of the reagents, and the skill 

of the assayer. Dr. W. F. Hillebrand, operating on Leadville rocks, 

gives 0.005 ounce per ton as the limit of accuracy for silver assays 

when 4 assay tons of material are used and extremely careful and 

painstaking work is done. 6 Using 2 assay tons in ordinary Avork, one 

ought to easily determine quantities of 0.05 ounce of silver ton, and 

0.005 ounce, or 10 cents, per ton of gold.

RESULTS OF ASSAYS.

The nineteen samples were first assayed by myself in the laboratory 

of the Survey. The general proportions of the charge were as follows : 

One A. T. c shale, 2 A. T. litharge (contents of silver, 0.005 ounce per 

ton), 2 A. T. soda, one-half A. T. borax. A layer of litharge was spread 

over the mixed charge and a layer of salt above this. Samples 1 to 8, 

inclusive, were assayed with a charge of 2 A. T. shale, and the rest of 

the fluxes were in the proportion given above. For the remaining 

numbers 1 A. T. was used. Samples 1, 3, 17,-18, and 19 were assayed 

without addition of nitrate of soda, and in case the lead button was 

too large it was .scorified down to suitable size. In the remainder of 

the samples which contained much carbon, niter was added in varying proportions to obtain a convenient button.

For the purpose of collecting the gold, in case no silver was present 

in the shale, 1.5 to 3 mg. of chemically pure silver was added to each 

assay, excepting Nos. 1 and 2. This was recovered, minus the minute 

losses chiefly caused by the absorption of the cupels. No gold was 

found in any of the samples, though in some of them minute black 

specks remained after parting the silver buttons. Some of these disappeared on ignition, while others remained, but upon examination 

with the lens failed to show the luster and color of gold.

The same samples were then assayed in the laboratory of the Survey, by Dr. E. T. Alien, who reports as follows:

I have examined nineteen samples of shale from western Kansas, collected by 

Mr. Lindgren, and find no gold in any of them.

The samples were assayed in the crucible with about 1 part soda and 2 parts of 

litharge to 1 part of the ore, and, since most of the shales contained considerable 

carbonate of calcium, from one-half to 2 parts of borax and some powdered glass 

were added to make the fusion thinly fluid. Niter was put in to oxidize the excess 

of carbonaceous matter in all but Nos. 15, 18, and 19. Two A. T. of each sample

o A. Classen, Ausgewaehlte Methoden der analytischen Chemie, Braunschweig, 1901, pp. 3, 245, 

and 254.

6Mon. U. S. Geol. Survey, Vol. XII, p. 595. 

c A.T. = Assay ton = 29.166 grams.
L1NDOJKEN.] EESULTS OF ASSAYS. 15

were taken except Nos. 7, 8, 10, and 12, where only one A. T. was used. Two or 3 

mg. of gold-free silver were added to each crucible charge to collect the gold in 

case the quantity of silver in the shale should prove insiifficient. This silver was 

recovered after ciipellation, minus a very small and nearly constant loss, which 

is always caused by absorption by the cupels, volatilization, etc. When the beads 

were parted the majority dissolved without residue. In several there remained 

one or two extremely minute, unweighable black specks. These either disappeared on ignition or else failed to develop the color and luster of gold, though 

they were examined carefully with a good lens.

In the previous work the added silver might easily have masked the 

presence of small fractions of an ounce of that metal per ton in the 

shale. Consequently, a third series of assays of the same samples 

was undertaken jointly by Dr. E. T. Alien and myself, in order to 

ascertain whether small quantities of silver were present. The laboratory and all utensils employed were kept scrupulously clean, and

we do not believe that there was any possibility of the introduction 

of gold or silver into the samples except from the litharge. The 

latter was assayed in duplicate, using 10 A. T. in each charge, with 

the following result:

Assay of litharge.

Number.

1 .....................................

s...........:.........................

Silver.

Ounce, per ton. 

0.005

0.005

. Gold.

Distinct trace in 10 A. T.

Doubtful trace in 10 A. T.

The particles remaining after parting were carefully examined by 

a microscope of high power.

The charges for the assays were in the main similar to those indicated above. Two A. T. shale were used in all of the assays except 

in 11, 15, 16, 17, 18, and 19, in which 1 A. T. was taken. The assay 

of No. 3 failed and no more material was available. About 1£ parts 

of litharge lo 1 part of shale were used. The cupellation was undertaken with particular care to guard as much as possible against losses 

from absorption and volatilization. In the cases where weighable 

buttons were obtained the quantity of silver due to the litharge was 

subtracted, and the figures given in the following table thus indicate 

the true amount of silver contained in the shale.

Of six-samples marked "repeated" in the table duplicate assays 

were made. In the duplicates the niter method was avoided and a 

charge was made as follows: One A. T. ore, 3 A. T. litharge, 2 A. T. 

soda, one-half A. T. borax. Nos. 14 and 16 were roasted and some 

argol was added to the charge.

The parting was effected in small glazed porcelain capsules and 

with very exceptional care. The residue after parting and annealing 

was examined by a petrographic microscope. In No. 5 we obtained
16 TESTS FOE GOLD AND SILVER IN" KANSAS SHALES. [BULL.202.

from 2 A. T. two flakes of gold weighing together 0.01 mg., equaling 

0.005 ounce per ton, or a value of 10 cents per ton. In No. 13 several 

very minute, unweighable flakes of gold were discovered by using 

high magnifying powers; they could not be recognized by an ordinary lens.

In nearly all of the samples after parting and ignition almost 

microscopic, unweighable black.specks were found. It was determined to subject these to more detailed examination. Under high 

magnifying power these specks appeared as angular, irregular masses 

having a dark-gray or black color and submetallic to metallic luster. 

A few of them were loose aggregates of the same substance with 

occasional glints of silvery or yellowish luster, which might possibly 

arise from included particles of gold. The appearance under the 

microscope is that of graphite. Besides this substance only a few 

particles of oxide of iron Avere noted in the residue. A number of 

the black specks collected were then subjected to the following 

chemical tests: First, evaporated with aqua regia to dryness, the 

specks were still visible and seemed unattacked. We next tried 

burning in a stream of oxygen. The operation was difficult on account 

of the minute size of the particles, but in two separate trials the 

specks disappeared upon being treated in a current of that gas. In 

conclusion, we assert that these dark particles are neither gold nor 

platinum, though we suspect that in manj^ cases they have been 

reported as traces of gold. We believe it most probable that these 

particles are graphitic carbon, contained in the silver. It will probably be objected that carbon could not without change pass through 

the oxidizing operation of cupellation. Be this as it may, the quantity of carbon obtained was certainly extremely small, and it is a

known fact that silver has a decided tendency to unite with carbon

under some conditions, as shown by Gmelin-Kraut. a

Content of gold and silver in samples of shale.

Number.

1 .....................

2.... ......................

4--...--.----....----.---.-.

5..........................

6..........................

'7..........................

8...................-..,'...

9...................".......

Silver^

Ounce per ton.

None.

0.007

0.017

0.007

0. 022

0. 037

0. 097

Gold.

Ounce per ton. 

"M"nnp

None.

"NTmip

0.005

None.

None.

None.

Total value..

Per ton.

§0. 004

.110

.004

.013

. 022

.060

oHandbuch der Chemie, Vol. Ill, pt 2.

''Although the quantities of silver have been given to the third decimal, as calculated from 

the weights of the beads, it must be understood that quantities below 0.01 or 0.02 ounce per ton 

are very'doubtful under these conditions.
LINDGREN.] EESULTS OF ASSAYS.

Content of gold and silver in samples of shale Continued.

17

Number.

10---;---- ...............

10..........................

11.1.. .......... ............

11. - - -.- 

12. ..........................

12

IS---..... ------------------

18 .. - 

14.... . _.__ _

14.... ................ ......

15 . - --_ .-

16.... .--.--...-. ---------

16... ..... ..... ......

17--.. ----------------------

18.. -.---------. ------------

19.... ......---. ..-

Silver.

Ounce per ton.

None.

0.045

0.030

Probably none.

0.030

0.087

None.

0. 072

None.

0.085

0.037

None.

0.095

Probably none.

Probably none.

Gold.

Ounce per ton. 

None.

None.

None.

None.

None.

None.

Microscopic trace.

None.

None.

None.

None.

None.

None.

None.

None.

None.

Total value.

Per ton.

$0. 027

.018

.018

.052

.043

. .051

.022

.057

For further confirmation the samples of most importance that is, 

those from the banks of Smoky Hill River, in the vicinity of the 

mills were sent to Mr. George E. Roberts, the Director of the Mint, 

who kindly had them assayed. ISTos. 1, 2, 4, 5, 6, 7, and 8 were 

assayed by Mr. W. F. Bowen, assayer of the mint bureau, and Nos. 

9, 10, 11, 12, 13, 14, and 16 were assayed by Mr. Jacob B. Eckfeldt, 

assayer of the mint in Philadelphia.

Mr. Bowen states that he used 1 A. T. ore to 1 A. T. litharge with 

necessary fluxes, and that a little niter was added. His results are as 

follows:

Assays of samples by W. F. Bowen.

\ Number.

1..... ... ...----...-.--.-..-.. ........... .

2... ......... .............. ............... .

4.-....... ...... ... -.. ......

6--..----...---.......:.... ...............

7....... ..... ....... -.. .--.-..

8........ . .... ....... .. -... --...

Silver.

Oz. per ton. 

0.30

0.20

0.15

0.30

0.15

Gold.

Oz. per ton. 

Trace.

Trace.

None.

None.

None.

0.05

Trace.

Total value."

Per ton. 

$0.18

.12

.09

1.18

.09

a Column added by W. Lindgreii.

Bull. 202 02-
18 TESTS FOR GOLD AND SILVEE IN KANSAS SHALES. [BULL.202.

At the writer's request Mr. Bowen repeated No. 7 on new material 

from the same original sample. This time he obtained 0.45 ounce 

silver and no gold; total value, 27 cents.

Mr. Eckfeldt states that he used 1 A. T. ore, 3 A. T. litharge, 2 A. T. 

soda, and -J- A. T. borax. No niter was added. His results are as 

follows:

Assays of scwnpZes by J. B. Eckfeldt.

No. Silver.

; Oz.per ton. 

9. . 0.8

10..-...:- .-.-.--_.-_.-._.-_.._-._.____ .35

11 ........................................ Trace.

is.-.-........-...............-......-;..-- .5

13.-----.-..-.--.----.-.-.--..-.-.-.-..... .4

14. ---..--_--_.--_.--._.._--_.___..__._... Trace.

16 . .2

Gold.

Oz.per ton. 

0.01

Trace.

.02

Trace.

Trace.

Total value."

Per ton.

$0.38

.21

.70

24

.12

a Column added by W. Lindgren.

As statements were made that the shales examined contained considerable quantities of zinc (from 2 to 20 per cent), and certificates 

to this effect were shown me by local chemists, it was decided to test 

a few samples for zinc and also for copper. Samples 1, 5, and 8, 

respectively, from the quarry pits of Miller's, Gage's, and the Pioneer 

Company's mills were selected and examined by Dr. E. T. Alien, of 

the United States Geological Survey. These samples showed no trace 

of zinc or copper. ,The concretions in the shale just below the Fort

Hays limestone (Septaria horizon) contain a brown carbonate of lime,

which is frequently mistaken for zinc blende/'

SUMMARY AND CONCLUSIONS.

Nineteen samples of Benton shale were collected in Ellis and Rush 

counties, Kans., chiefly along Smoky Hill River. These samples were 

taken with great care, each representing the average of a certain 

thickness of beds, in order to ascertain whether these shales contain 

gold and silver and whether, if so, they may be considered as of economic value. The majority of the samples were collected in pits and 

quarries from which material had been extracted by other parties for 

the purposes of assays or treatment in gold mills. These samples 

were first assayed for gold by myself, then by Dr. E. T. Alien. No gold 

was found in any of the samples. The silver could not be determined 

with great accuracy, for some pure silver was added in order to collect any gold that might be present, but there was certainly not more 

than a small fraction of an ounce in any one of the samples.

" E. Hawortli, Mineral Resources of Kansas for 1897.
LINDGREN.] SUMMARY AND CONCLUSIONS. 19

The same samples, except No. 3, of which sufficient material did 

not remain, were then assayed jointly by Dr. Alien and myself. 

Twelve samples showed the presence of small amounts of silver up to 

0 cents per ton in value, while in 6 no silver or only doubtful traces 

were found. No. 5 showed 10 cents of gold per ton, and No. 13 a 

trace of (gold. No gold was found in the remaining 16 samples.

Samples 1, 2, 4, 5, 6, 7, and 8 were assayed by Mr. W. F. Bowen, 

acting assayer of the mint bureau. In five of these small values of 

silver were found, ranging up to 27 cents per ton. In two of the 

samples no silver was found. One of the samples (No. 7) gave $1 

of gold per ton; this assay was repeated, and this time no gold was 

found. Traces of gold were found in three samples, and in three 

samples of the seven no gold was found.

Samples 9,10,11,12, 13,14, and 16 were then assayed by Mr. Jacob 

B. Eckfeldt, assayer of the mint in Philadelphia. In five of these 

silver Avas found, ranging up to 30 cents per ton, while two samples 

yielded only a trace. No. 12 gave 40 cents of gold per ton, and No. 9 

gave 20 cents per ton, while traces of gold were found in the remaining five samples. In all, 77 assays were made of material taken from 

the 19 samples.

The results indicate that minute quantities of silver are often contained in these shales and that some samples show the presence of 

very small quantities of gold. The same samples do not always give 

the same results when repeated, which goes to confirm the statement 

on page 5, that the metals when present are somewhat unevenly distributed through the rock. None of the samples contain silver or 

gold in economically important quantities. While, of course, it is 

impossible to say what may be contained in those parts of the shale 

beds Avhich have not been assayed, it is extremely improbable that 

this material will ever be of economic importance as a silver or 

gold ore.

INDEX.

Page. 

Alien, E. T., assays by.................... U-15

samples examined by ................. 18,19

Artz, H. H., shaft sunk by................ 5

Assays, irregularity of results of ........ 5

methods of ............................ 13-14

results of .............................. U-10

samples for, method of collecting.... 10,18

samples for, method of preparation of 12-13 

samples collected for, table showing. 10-12 

summary of............................ 18-19

Bituminous shale in western Kansas.

thickness of........................ 7

Blue Hill shales, character and outcrops of--..------.....-..-.-...-.-- 8

samples from.......................... 8

thicknessof ........................... 7

Bowen, W. P., assays by............... 17,18,19

Copper, samples tested for ............... 18

Cretaceous rocks in the region, extent

and character of ................... 7-9

section of.............................. 7

Drainage of the region, features of ...... 6-7

Eckfeldt, J. B., assays by................. 18,19

Fahrig, Ernst, assays by, results of...... 5

Fahrig Mining and Milling Company,

organization of.................... 6

Fencepost limestone in western Kansas,

thickness of........................ 7

Flagstone in western Kansas, thickness of 7 

Fort Benton group of rocks in western

Kansas............................. 7,8-9

Fort Hays limestone, character and outcrops of............................ 8

thickness of............................ 7

Gage, A. G., mill built by................. C

Geology of the region, features of........ 7-9

Page 

Gmelin-Kraut, cited....................... 16

Haworth, E., cited ........................ 18

divisions of Kansas Cretaceous by.... 7

views of................................ 5

Hillebrand, W. F., limit of accuracy for

silver assays given by............. 14

Inoceramus horizon in western Kansas,

thickness of......-.....-....---.... 10

Kansas Pioneer Gold Shale Company,

mill built by....................... 6

reference to............................ 5

Lincoln marble in western Kansas, thickness of............ .................. 7

Lovewell, J.T., cited...................... 5

Miller, W. F., reference to................ 6

Niobrara group of rocks in western Kansas....-.-......-..---..---...---.-.. 7,8

Ostrea shales, character and outcrops of. 8-9 

samples from.......................... 9

thickness of............................ 7

Pleistocene rocks in the region, character

of.-----.......--......-.---..-----. 9

Roberts, G. E., assays under direction of. 17-18 

Rocks of the region, character and outcrops of............................ 7-9

Samples for assay, method of collecting.. 10,18 

method of preparation of............. 12-13

table showing ......................... 10-12

Smoky Hill chalk, thickness of........... 7

: Smoky Hill River, course and character

j of................................... 6-7

i mills erected on....................... 6

shaft sunk near........................ 5

Topography of the region, features of... 6-7 

Trego County, shaft sunk in.............. 5

Zinc, samples tested for................... 18

21

O