DEPARTMENT OF THE INTERIOR 

UNITED STATES GEOLOGICAL SURVEY

GEORGE OTIS SMITH, DIRECTOR

BULLETIN 512

POTASH-BEARING ROCKS OF THE 

LEUCITE HILLS

SWEETWATER COUNTY 

WYOMING

BY

ALFRED R. SCHULTZ AND WHITMAN CROSS

WASHINGTON

GOVERNMENT PRINTING OFFICE 

1912

CONTENTS.

» I'ngc.

Introduction................................................................ 5

Review of earlier publications................................................ G

General character of leucite-bearing rocks...................................... 8

The rocks of the Leucite Hills.......'......................................... 9

External character. ................... --.--. -'------- -- ------------ - 9

Microscopic features...................................................... 10

Chemical composition................................................... 10

Composition of the minerals of the leucite-bearing rocks..................... 12

Potash and soda nitrates................................................. 14

Stratigraphy and geology................................................. 14

Quantity of leucite-bearing rock........................................... 16

Pilot Butte.......................................................... 16

Matthews Hill....................................................... 17

Boars Tusk......................................................... 19

Badger Teeth....................................................... 20

Cross Mesa. .................... ^.................................... 22

Osborn Mesa......................................................... 23

Hatcher Mesa........................................................ 24

Emmons Mesa....................................................... 25

Zirkel Mesa.......................................................... 25

Orenda Mesa......................................................... 27

Black Rock Mesa..................................................... 28

Steamboat Mountain................................................. 29

North Table Mesa................................................... 31

South Table Mesa................................................... 33

Table Mountain..................................................... 33

Other exposures of leucite-bearing rocks................................ 34

Summary of available leucite-bearing rock............................ 35

Transportation........................................................... 36

Status of the lands containing potash-bearing rock......................... 37

3
ILLUSTRATIONS.

Page. 

PLATE I. Map showing location of the potash-bearing rocks of the Leucite Hills,

Sweetwater County, Wyo....................................... 16

FIGURE 1. Map showing the location and topograpllic relief of Pilot Butte....... 16

2. Map showing the location and topographic relief of Boars Tusk and 

Matthews Hill................................................... 19

3. Map showing the location and topographic relief of the Badger Teeth. 21

4. Map showing the location and topographic relief of Cross and Osborn 

mesas and their relation to the lava-bowlder locality.............. 22

5. Map showing the location and topographic relief of Hatcher, Emmons,

and Zirkelmesas............................................... 26

6. Map showing the location and topographic relief of Orenda Mesa.... 27

7. Map showing the location and topograpllic relief of Black Rock Mesa. 28

8. Map showing the location and topographic relief of Steamboat Mountain............................................................ 30

9. Map showing the location and topograpllic relief of North Table and 

South Table mesas, Table Mountain, Iddings, Weed, and Hallock 

buttes, Endlich and Hague hills and their associated dikes....... 32

4
POTASH-BEARING ROCKS OF THE LEUCITE HILLS, 

SWEETWATER COUNTY, WYOMING.

By ALFEED R. SCHULTZ and WHITMAN CROSS.

INTRODUCTION.

The purpose of the present paper is to give a brief description

of the rocks in the Leucite Hills, Wyo., with an estimate of the

amount of leucite-bearing rock available and of the approximate 

amount of potash that these rocks may yield as soon as a process 

is discovered by which the potash may be dissociated from the 

rock cheaply enough for commercial use.

In view of the possibility that some such process may be 

devised, it is important to know the conditions of occurrence of 

the rocks, their areal distribution, and the amount of rock available. 

Several reduction processes for extracting potash from igneous 

rock have been patented, but thus far none has proved commercially successful. The extraction of all the potash from 

these refractory silicates involves many difficulties, and not only 

has no process yet been perfected, but in the opinion of many 

industrial chemists no promising process has even been suggested 

that can be successfully applied on a commercial scale. The extraction of all the potash from these rocks involves the extraction 

of potash from at least three minerals leucite, phlogopite, and 

sanidine. Whether or not these potash-bearing rocks will ever be 

utilized depends entirely on the technologic chemist and the industrial engineer, but the geologic and other data here presented are 

fundamental and should be at the command of anyone who intends 

to attack the economic problems of utilizing the potash or other 

valuable elements contained in the rocks. Any enterprise endeavoring to utilize these lavas for the establishment of a home source 

of potash should not overlook the fact that foreign potash now 

commands a price much in excess of the foreign cost of production, 

including all exporting and transportation charges. This wide 

margin of profit makes possible extensive reductions in the present 

prices, which might destroy all chances of success for .any competitor entering the field under present conditions. The facts 

presented in this report are not the result of new but of old work

5
6 POTASH-BEARING BOCKS OF LEUCITE HILLS, WYOMING.

and are made available to the public in this form so that all the 

authoritative data on these exceptional rocks may be readily available. The observations here recorded have been made by the 

geologists of this Survey during the last 30 years in connection with 

scientific explorations and with detailed examinations of coal land.

Practically all the potash salts of mineral origin consumed in 

American industries at the present time are imported from Germany, 

which is the only country in the world where potash mines are profitably worked. These potash salts are extensively used in the United 

States in the fertilizer industry and are also essential to many other 

industries that are vitally connected with the welfare of the American 

people. The imports of potash salts into the United States in 1910 

amounted to 1,798,391,012 pounds, valued at $11,615,134. In view 

of this enormous quantity of imported potash, costing the American 

consumers annually nearly twelve-million dollars and the amount 

may be expected to increase rapidly it behooves us to ascertain 

whether or not the United States can itself supply the demand.

Among the sources of mineral potash are the potash-rich rocks and 

minerals, such as granite, alunite, feldspar, and leucite. The potash 

feldspar minerals, orthoclase and microline (KAlSi308 or K2O.AJ203. 

6Si02 ), carry from 10 to 12 per cent, with a possible theoretical content of 16.9 per cent of potash (K20); leucite (K2AlSi4012 ) has a 

theoretical content of potash (K20) equivalent to 21.5 per cent. 

The richest leucite-bearing rock in the United States thus far studied 

and analyzed contains approximately 12 per cent of potash (K20).

The largest and best-known area of potash-rich, leucite-bearing 

rocks in the United States embraces the Leucite Hills, in the north 

half of the Rock Springs dome, Sweetwater County, Wyo. The 

exposures in the Leucite Hills area were visited by Mr. Schultz in the 

summers of 1907 and 1908, while engaged in a study of the Rock 

Springs coal field. In the present report Mr. Schultz has prepared 

the geologic and geographic descriptions and the estimates of the 

quantity of leucite rock present, and Mr. Cross is responsible only 

for the petrographic descriptions and the discussions of the chemical and mineral composition of the rocks.

REVIEW OF EARLIER PUBLICATIONS.

More than half a century ago Alexander von Humboldt published 

his unchallenged conclusion that leucite was a mineral found only in 

Europe, and even as late as 1868 the general impression prevailed 

that leucite was known as a constituent of lavas at only three European localities the Italian volcanoes about Vesuvius; the Laacher See, 

in Prussia; and the Kaiserstuhl in the Black Forest, Baden, Germany. 

In 1850 an occurrence of leucite-bearing rock was discovered by
REVIEW OF EARLIER PUBLICATIONS. 7

Loftus near Urmia, in Persia. Since then leucite has been recognized 

in many of the basalts in Saxony, Bohemia, the Thiiringerwald and 

the Rohn Mountains, in Germany, as well as in Asia, Africa, South 

America, Australia, and in many other parts of the world. It 

remained, however, for the geologists and petrographers of the 

Fortieth Parallel Survey (1867-1873) to prove the existence of 

leucite-rich rocks in North America, at the locality described in the 

present paper. The occurrences in this locality, in the Dutch Indies, 

and in Persia proved the wide distribution of leucite-bearing rocks. 

The microscopic study of the specimens collected from the Leucite 

Hills, together with a chemical analysis, proved them to be richer in 

the mineral leucite and more peculiar in their general composition 

than any of the rocks occurring in the Old World.

The leucite-rich rocks were first found in the Leucite Hills, 8$ miles 

northwest of Point of Rocks, Wyo., by S. F. Emmons, who examined 

the southern mesa and gathered specimens in 1871 while engaged in 

the work of tlie Fortieth Parallel Survey. The material thus collected was subsequently studied and described by Zirkel.1

In 1877 the most northern areas of the Leucite Hills were visited by 

F. M. Endlich,2 of the Hayden Survey. His descriptions of the lava 

localities, like those of Emmons, are very brief, being based on reconnaissance observations made before the commercial importance of 

the rocks of the region had been ascertained.

John W. Powell, former Director of the United States Geological 

Survey, in his geologic explorations of the Uinta Mountains from 

1868 to 1875, also visited the westernmost locality of the Leucite Hills 

and collected specimens from the mesa now known as Pilot Butte. 

Further than the brief statement made in a single report,3 no published data resulted from PowelTs examinations. The specimens 

collected by him were held by the United States Geological Survey 

and subsequently examined and described by Whitman Cross in connection with specimens collected by himself. Cross, with one assistant, W. B. Smith, visited the Leucite Hills late in the fall of 1884 for 

the purpose of collecting a large number of specimens of rock for 

the "educational series" then being assembled by the Geological 

Survey. The results of this examination, together with a careful 

description of the rocks, from both microscopic study and chemical 

analysis, were published by the permission of the Director of the 

Survey in the autumn of 1897. 4

1 Zirkel, Ferdinand, Microscopical petrography: Rept. U. S. Geol. Expl. 40th Par., vol. 6, 1876, pp. 

259-261.

2 Endlich, F. M., Eleventh Ann. Rept. U. S. Geol. and Geog. Survey Terr., for 1877,1879, pp. 6, 9,10, 

119,133,134, and 135; Twelfth Ann. Rept., for 1878,1883, atlas, map 3.

3 Powell, J. W., Geology of the Uinta Mountains, U. S. Geol. and Geog. Survey Terr., 1876, pp. 18-22,36. 

«Cross, Whitman, Igneous rocks of the Leucite Hills and Pilot Butte, Wyo.: Am. Jour. Sci., 4th ser., 

vol. 4, August, 1897.
8 POTASH-BEAEING ROCKS OF LEUCITE HILLS, WYOMING.

In 1896 J. F. Kemp, 1 with two assistants, visited the Leucite Hills, 

and the results of their observations were read before the Geological 

Society of America in December of the same year.

During the summer of 1902 J. F. Kemp and W. C. Knight 2 spent 

some time together studying, photographing, and collecting from the 

exposures in these hills. While thus making a detailed study of the 

different hills they discovered several exposures not previously 

observed. This was the first attempt to find and map all the distinct 

masses of these rocks and to determine their structural and stratigraphic relations.

A further study of the geologic conditions and structural features 

of the vicinity of the Leucite Hills was carried on during the seasons 

of 1907 and 1908 by the United States Geological Survey in the course 

of a detailed investigation of the coal deposits of the Rock Springs 

dome. Although the primary object of the investigation, which was 

in charge of A. R. Schultz, was the classification and valuation of the 

public coal land, much additional knowledge regarding the geology, 

structure, stratigraphy, and physiography of the area and the occurrence and distribution of the leucite-bearing rock was obtained in 

connection with the coal work. All the 22 known localities were 

visited by members of the Survey, and extensive collections of specimens were obtained from most of the exposures. Preliminary reports 3 

on the coal of the Rock Springs field have been published. The distribution and outlines of the lava exposures are shown on the maps 

accompanying these reports, but only a brief statement is made concerning the leucite rocks collectively. The specimens collected by 

members of the Geological Survey are now in the hands of Mr. Cross 

and a joint report on the occurrence and petrography of these interesting rocks is in course of preparation. A detailed report on the 

geology and stratigraphy of the Rock Springs coal field will be prepared as soon as time and the work on hand will permit.

GENERAL CHARACTER OF LEUCITE-BEARING ROCKS.

The silicate of alumina and potash to which mineralogists have 

given the name leucite is a primary constituent of several kin'ds of 

igneous rocks known in many parts of the world. While by no 

means uncommon, the leucite-bearing rocks are very much less abundant than those containing the potash feldspar called orthoclase or 

sanidine, a similar silicate of alumina and potash. This comparative 

rarity of leucite has led many petrographers to emphasize its pres1 Kemp, J. F., The Leucite Hills of Wyoming: Bull. Geol. Soc. America, vol. 8, February, 1897, pp. 169-182.

2 Kemp, J. F., and Knight, W. C., Leucite Hills of Wyoming: Bull. Geol. Soc. America, vol. 14, 1903, 

pp. 305-336.

8 Schultz, A. R., The northern part of the Rock Springs coal field, Sweetwater County, Wyo.: Bull. U. S. 

Geol. Survey No. 341, 1909, pp. 256-282; The southern part of the Rock Springs coal field, Sweetwater 

County, Wyo.: Bull. U. S. Geol. Survey No. 381, 1910, pp. 214-281; Weathering of coal in the arid region 

of the Green River basin, Sweetwater County, Wyo.: Idem, pp. 282-296.
EXTERNAL CHARACTER. ' 9

ence as a distinguishing characteristic of certain rocks by giving them 

such names, as "leucite basalt/' "leucite tephrite," and "leucitite," 

even though the rock contains but small a percentage of leucite.

Leucite rocks are specially abundant in Italy, in a long chain of 

volcanoes stretching northwestward from Vesuvius. Some of the 

lavas of this vent are particularly noted for their prominent leucite 

crystals and in most mineral collections the best specimens of leucite 

are from this source.

There are but three localities in the United States where leuciterich rocks are known. Two of these are in Montana, in the Bearpaw 

and Highwood Mountains, the rocks of which have been described by 

Weed and Pirsson. 1 None of the Montana rocks is so rich in potash 

as to possess probable value as a source of this substance, except 

under a method of extraction not applicable to potash feldspar.

The lavas of the Leucite Hills, Wyo., contain on the average a 

somewhat larger percentage of potash than any other known igneous 

rocks. A brief untechnical description of the various rock types 

found in this district follows:

THE ROCKS OF THE LEUCITE HILLS.

EXTERNAL CHARACTER.

The lavas of the Leucite Hills are all very fine grained, rather 

earthy-looking rocks, and in most of them a dark mica in small hexagonal plates is the only mineral that can be recognized by the 

unaided eye. In many of the rocks these mica plates are arranged 

in rude parallel position, causing an easy fracture, the face of every 

parting glistening with the reddish-brown mica flakes, while at right 

angles to the partings the mass is dense and only here and there can 

cross sections of the flakes be seen. Most of the mica crystals are 

but 2 or 3 millimeters in diameter.

The rocks vary in color from a dull reddish or yellowish gray to 

straw-yellow. The denser rocks are the darkest in tone and have the 

most pronounced schistose appearance. The lighter-colored varieties are usually porous in some degree, the cavities being minute and 

irregular in shape except in the pumiceous material, which is abundant in some places. No coarsely vesicular lava has been found. 

Some of the pumice is very light, with nearly round pores, and in 

places the pores are drawn out as delicate tubes.

In some of the reddish porous lava glistening cleavage surfaces of 

feldspar grains can be seen, but leucite has not been detected in it 

except with the help of the microscope.

The abundant material collected by Mr. Schultz indicates that the 

flow rocks of all the mesas and hills in this region exhibit practicaUy

1 Weed, W. H., and Pirsson, L. V., The Bearpaw Mountains of Montana: Am. Jour. Scl., 4th ser., vol. 2, 

1896, p. 147. Pirsson, L. V., Petrography and geology of the igneous rocks of the Highwood Mountains, 

Montana: Bull. U. S. Geol. Survey No. 237,1905.
10 POTASH-BEARING ROCKS OF LEUCITE HILLS, WYOMING.

the same textural varieties. As a rule the plugs or volcanic necks 

consist of dense and notably schistose rock.

The point northwest of Rock Springs known as Pilot Butte, which 

may be considered as an outlier of the Leucite Hills, is made up of a 

lava that is closely allied to those already described, but contains 

only 8 per cent of potash.

MICROSCOPIC FEATURES.

The study of thin sections under the microscope shows the denser 

form of the rock to consist principally of three minerals. The mica 

is rich reddish brown, its color varying, of course, with the thickness 

of the plates. Besides the mica there are two colorless minerals. One 

of these appears in sharply defined prisms of octagonal form, the 

properties of which show it to be a nearly iron-free pyroxene called 

diopside. The other colorless mineral is leucite, in innumerable 

round grains of minute size crowded between the mica and diopside 

crystals. The leucite is in some rocks developed in the characteristic crystal form, but more commonly it appears in droplike particles. The little grains of leucite vary ordinarily between 0.01 and 

0.05 millimeter in diameter. Aside from these three minerals there 

is a considerable amount of a very pale pinkish or colorless glass 

serving as a matrix to bind the crystals together. No other minerals 

of quantitative importance occur in the rock of this type. The 

dense, generally reddish rock consisting essentially of leucite, diopside, and mica is called wyomingite. No very similar rock is known 

from any other part of the world.

The more abundant vesicular rock has mica, diopside, and leucite of 

the same characteristics as those in the denser type, with a variable 

amount of orthoclase, the potash feldspar, which, as developed in 

lavas, is more frequently called sanidine. In some specimens examined sanidine equals leucite in amount, but no varieties have been 

seen in which leucite is less abundant than sanidine. There is no 

doubt a continuous series of rocks between that free from sanidine 

and the form richest in that mineral. The rock containing both 

leucite and sanidine in notable amount is called orendite, to distinguish it from the purely leucite type. According to Mr. Schultz's 

observations, this sanidine-bearing variety is much more abundant 

than the wyomingite. The rock of Pilot Butte, known as madupite, 

consists of phlogopite, diopside, and a glassy base which is rich in 

potash and would probably have produced much leucite had this 

lava become completely crystalline.

CHEMICAL COMPOSITION.

One partial and six complete analyses of the leucite-rich rocks 

have been made in the laboratory of the Geological Survey, and two 

less complete ones were made for the Fortieth Parallel Survey reports. 

These nine analyses, together with one of a rock from Bearpaw Peak, 

Mont., are given in the table on page 11.
CHEMICAL COMPOSITION. 11

No. 1 is an analysis made by Pawel, published in the German 

re'sume' of Zirkel's report.1

No. 2 is by R. W. Woodward and was quoted by Emmons 2 and 

Endlich.3 Nos. 1 and 2 were probably made on the same material, 

the exact locality being unknown. The only specimens collected by 

the Fortieth Parallel Survey belong to wyomingite.

No. 3 is of wyomingite from the Boars Tusk, a dark-gray variety 

of the rock richer in mica and diopside than the other kinds.

No. 4 represents rock near Fifteenmile Spring, on the northeast 

side of Zirkel Mesa. It is the typical dense reddish-brown wyomingite such as occurs in many of the mesas and hills. It is identical in appearance with the specimens of the Fortieth Parallel 

Survey collection.

No. 5 is of orendite found associated with the wyomingite of analysis 

4 at Fifteenmile Spring.

No. 6 is of orendite from the north cliff of Table Mountain, a 

light straw-yellow variety of the rock with very prominent micas. 

This is als'o a common type of the rock. Analyses 3 to 6 were made 

by W. F. Hillebrand.

No. 7 is an analysis by Chase Palmer, not previously published, of 

orendite from Hallock Butte, collected by Mr. Schultz.

No. 8 is a partial analysis by Chase Palmer of orendite from Emmons 

Mesa.

No. 9 is an analysis of madupite from Pilot Butte, by W. F. Hillebrand.

No. 10 is an analysis of "leucitite" from Bearpaw Peak, Mont., 

made by H. N. Stokes and given here for comparison.

Analyses of leucite-bearing rocks.

Silica (Si02) ...................

Titanic acid (TiO2) ............ 

Alumina ( AljOs) ...............

Lime (CaO). ...................

Potash (KsO)..................

Water (H,0).. ................ 

Phosphoric acid (P^O*) ........ 

Sulphur trioxide (80s) ........ 

Fluorine (Fl).................. 

Other constituents .............

Specific gravity. . ..............

Wyomingite.

1

56.30

i2.63 

6.92

5.08

5.63

2.21 

11.50

100.27

2

54.42

is. 37

.61

3.52

6.37

4.38

1.60 

10.73 

2.76

' 'i'.w

99.58

3

50.23 

2.27 

11.22 

3.34

1.84

7.09

5.99

1.37 

9.81 

2.65 

1.89 

.'74 

.50 

1.68

100.62 

2.779

4

53.70 

1.92 

11.16 

3.10

1.21

6.44

3.46

1.67 

11.16 

3.41 

1.75 

.06 

' .44 

.92

100.40 

2.627

Orendite.

5

54.08 

2.08 

9.49 

3.19

1.03

6.74

3.55

1.39 

11.76 

3.50 

1.35 

.29 

.49 

1.03

99.97 

2.686

6

54.17 

2.67 

10.16 

3.34

.65

6.62

4 10

1.21 

11.91 

1.53 

1.59 

.16 

.36 

1.65

100.21 

2.699

7

51.07 

2.13 

9.93 

2.72

1.19

10.31

4.87

.82 

9.92 

4.23 

1.53 

.33 "".'ei"

99.66

8

51.38 "io.'si"

1.09 

11.40

Madupite.

9

42.65 

1.64 

9.14 

6.13 

1.07 

10.89 

12.30 

.90 

. 7.99 

4.22 

1.52 

.58 

.47 

1.55

100. 11 

2.857

"Lou 

citite."

10

46.51 

.83 

11.86 

7.59 

4.39 

4.73 

7.41 

2.39 

8.71 

3.55 

.80 

Tr. 

Tr. 

.96

99.73

1 Zirkel, F., Uber diekrystallinischen Gesteine iftngs des 40ten Breitegrades in Nordwest Amerika: Ber. 

K. Sachs. Gesell. Wiss., Jan., 1877, p. 239.

a Emmons, S. F., Kept. U. S. Geol. Expl. 40th Par., vol. 2, 1877, p. 237. 

8 Endlich, F. M., Eleventh Ann. Kept. U S. Geol. and Geog. Survey Terr., for 1877,1879, p. 135.
12 POTASH-BEARING ROCKS OP LEUCITE HILLS, WYOMING.

Among the less important constituents shown by analysis of the 

rocks of the Leucite Hills are manganese, baryta, strontia, zirconia, 

and several other substances. The distribution of the main elements 

will be plain from the discussion of the chemical composition of the 

minerals.

COMPOSITION OF THE MINERALS OF THE LEUCITE-BEABING

BOCKS.

While analyzing the wyomingite and orendite Dr. Hillebrand was 

successful in separating nearly pure mica and diopside in sufficient 

amount for analysis. The leucite and sanidine particles are too small 

and too intimately intergrown with other minerals for such separation, 

but their composition must be nearly the theoretical one, for the 

crystals are fresh and pure. In the following table is given the theoretical composition of the leucite and sanidine and that found by 

Hillebrand, by analysis, of the mica and diopside. The small amount 

of soda shown by the analyses is doubtless for the most part contained 

in the leucite.

Composition of minerals of the leudte-bearing rocks.

Silica (SiOs). ...........................................

Titanic oxide (Ti02). ..................................

Baryta (BaO). .........................................

Lime (CaO).. . .........................................

Soda (Na20) ...........................................

Potash (KjO)..... .....................................

Water (H2 0)...................-.......... ---.--- ----

Fluorine (Fl) ..........................................

Less O for Fl. ..........................................

Leucite.

55.0

23.5

21.5

100.0

Sanidine.

64.7

18.4

16.9

100.0

Diopside.

50.86

S (M

1 19

1.82

17.42

23.23

.76

.42

.31

.03

99.16

Phlogopite.

2 no

12.18

.73

9 73

Qft

1.00

.20

44

10.70

2.35

2.46

.06

100. 80 

1.03

99.77

In the original description of these leucite-bearing rocks by Mr. 

Cross there may be found much more extensive discussion of the 

chemical composition of both rocks and minerals than is appropriate 

in this place. But certain things need to be pointed out as bearing 

on the availability of these rocks as sources of potash.

The analyses show the diopside to be unusually poor in iron and to 

carry but very little potash. The mica is found to be the magnesia 

and potash rich species known as phlogopite, which is rare in igneous 

rocks. Its presence here is due to the high percentage of magnesia 

and potash as compared with iron and alumina.
COMPOSITION OF MINEEALS. 13

The molecular proportions of silica, alumina, and potash in leucite 

and sanidine (orthoclase) are as follows:

SiOa

4

0

AljOs

1

1

K20

1

1

That is to say, sanidine contains 50 per cent more silica than leucite, 

expressed in number of molecules. The rarity of leucite in igneous 

rocks is explained by the laws of chemical affinity affecting igneous 

magmas, which under usual conditions favor the formation of feldspar 

rather than leucite, if there is enough silica present. Quartz and 

leucite are therefore very rarely found together. 

Knowing the composition of wyomingite and of its chief minerals,

one may calculate the approximate mineral composition. The result 

for the rock from the Boars Tusk (No. 3, p. 11) is as follows:

Approximate mineral composition of rock from Boars Tusk.

Uncombined silica............................................ 18.7

Leucite..................................................... 26.1

Noselite..................................................... 8.7

Diopside..................................................... 18.8

Phlogopite................................................... 19.9

Accessory minerals............................................ 7.8

100.0

This result is peculiar, for the free silica is more than enough to 

have formed sanidine instead of leucite, and no explanation of this 

unusual development of leucite has been found. The uncombined 

silica is mostly in the glassy base to which reference has been made. 

No quartz or tridymite the latter another form of pure silica has 

been observed in any section of wyomingite.

A similar result is obtained from the calculation of analysis 4 

(p. 11). This gives a still larger amount of uncombined silica, with 

leucite 35.7 per cent, phlogopite 22.3 per cent, and diopside only 

10.7 per cent.

The calculation of the mineral composition of orendite is more 

difficult because it contains a peculiar hornblendic mineral, the composition of which is unknown.

The potash content of wyomingite is distributed between leucite, 

phlogopite, and a glassy base, most of which must be uncombined 

silica. In orendite another portion must be contained in sanidine, 

and very possibly a small amount is in the hornblende referred to. 

 Soda appears to replace a part of .the potash in leucite, or, where 

considerable sulphur trioxide is present, the whole may be found in 

the mineral noselite, as in the Boars Tusk wyomingite.
14 POTASH-BEAEING ROCKS OF LEUCITE HILLS, WYOMING.

The extraction of the entire potash content of these rocks must 

therefore be effected by a process applicable to leucite, sanidine, and 

phlogopite at least, and probably to other minerals.

POTASH AND SODA NITRATES.

On the north side of Table Mountain, in a cleft by which the cliff 

surrounding this flat-topped hill can be easily scaled, there were 

found in 1884 some masses of a white, sugar-like substance, which 

chemical analysis proved to be nearly pure potash nitrate or niter. 

This mineral partly filled protected cavities and crevices in the cliff 

on the east side of the cleft. Its character was not recognized when 

it was found and no observations were made satisfactorily determining 

its origin, It may be of organic source but possibly is connected 

with the leucitic lavas.

An incrustation on the east face of the Boars Tusk, in protected 

cavities found in 1884, proved on analysis to be soda niter with 

small contents in potash.

These nitrates are of no economic importance, but the explanation 

of their occurrence is a matter of some scientific interest, and it is 

to be hoped that future examination of the Leucite Hills may settle 

this point.

STRATIGRAPHY AND GEOLOGY.

Structurally the Rock Springs field consists of a huge dome of 

Cretaceous and Tertiary rocks, which rises in the midst of the nearly 

horizontal rocks of the Green River Basin and partly divides the 

southern portion into two smaller basins the Bridger Basin on the 

west and the Red Desert or Washakie Basin on the east. The major 

north-south axis of the dome is approximately 90 miles long and is 

located close to the west limb of the anticline. The beds along this 

limb dip from 5° to 30° W.; those along the east limb dip from 5° to 

10° E. The minor axis is approximately 50 miles long, extending 

across the dome in a direction north of east and south of west, passing 

north of Aspen Mountain and through a point 4 miles north of Black 

Buttes, a station on the Union Pacific Railroad. Several small 

anticlines and synclines are developed upon the main dome, but for 

the most part they are unimportant.

This dome has been greatly reduced by erosion. From its crest 

have been removed all of the Tertiary and late Cretaceous ("Laramie") and most of the Montana formations. No important creeks 

or rivers flow through or rise within the Leucite Hills area. Bitter 

Creek, the largest waterway, passes south of the Leucite Hills but , 

receives the drainage from Killpecker Creek, which rises near the ' 

Boars Tusk, and also from a few gulches along the south side of the 

Leucite Hills and from the valley heading at Fifteenmile Spring. All 

the remainder of the drainage from the hills east and south of Steam-
STRATIGBAPHY AND GEOLOGY. 15

boat Mountain goes eastward and is tributary to the Great Divide 

Basin. Northwest of Steamboat Mountain the area is drained by 

Jack Morrow Creek, which flows in a northwesterly direction into the 

Sandy and thence into Green River.

Resting on or cutting through the sedimentary rocks in the 

north half of this dome are the Leucite Hills, which rise like monadnocks out of the dissected table-land, or like sentinels from the bottoms 

of the eroded valleys. The leucite-bearing rock masses of Pilot Butte 

and Steamboat Mountain are supported on Tertiary (Green River) 

beds. The Boars Tusk, Matthew Hill, Table Mountain, North Table, 

South Table, and Black Rock rest on or cut through the basal Tertiary (Wasatch) beds; others, such as Orenda Mesa and some of the 

dikes about Table Mountain, are in contact with the Wasatch and 

"Laramie" formations; all the remainder come into contact with 

various formations of Montana age. The separate or detached exposures of the Leucite Hills range from talus-covered hills, volcanic 

necks, and associated dikes, as in the Boars Tusk, Badger Teeth, 

Iddings Butte, and others, to intruded lava sheets, stocks, dikes, and 

flows with one or more cones, as in Emmons Mesa, Steamboat Mountain, Orenda Mesa, and Zirkel Mesa. Some of the mesas have been 

built up of successive flows, on top of which rise cones formed of fragmental pumice or of very cellular scoria. Some of the cones, as on 

Steamboat Mountain and one on Zirkel Mesa, are made up of solid 

lava which has welled up in the form of a huge blister. Most of the 

cones are composed of fragmental reddish rock and are remnants of 

old cinder cones whose missing segments were either destroyed during 

an eruption or have since been removed by erosion.

The volcanic activity which forced the leucite-bearing rock out 

toward the surface is certainly younger than the Green River formation, as the leucite-bearing rock at Pilot Butte and Steamboat Mountain rests as surface flows upon that formation. It appears that after 

the fresh-water beds of the Eocene had been laid down there was a 

long epoch of erosion in which the entire region was reduced to a 

peneplain or nearly level surface. This was succeeded by mild 

volcanic activity, during which the leucite-lava flows north and west 

of Rock Springs were poured out on a planed off, nearly level surface, 

formed by the truncation of the underlying rocks. This volcanic 

activity culminated in or accompanied the orographic movements 

that resulted in rapid erosion and the deposition of an extensive 

gravel sheet known as the Bishop conglomerate over the entire region 

from the Uinta Mountains northward to Bitter Creek. This gravel 

sheet is independent of the folds and faults in the underlying rocks, 

which are beveled across, entirely irrespective of either hardness or 

structure. From this gravel-covered lava-capped plain the present 

topographic features have been carved in late Quaternary time, 

almost solely by erosion.
16 POTASH-BEARING BOOKS OF LEUOITE HILLS, WYOMING. 

QUANTITY OF LETJCITE-BEABING BOCK.

No detailed account of the geologic, dynamic, and stratigraphic 

features of the leucite-bearing rocks will be given here, but a brief 

description of each occurrence will be presented and a computation 

made of the approximate acreage and tonnage of leucite-bearing rock 

in each locality and the approximate amount of potash it contains. 

A map showing the location of the potash-bearing rocks forms Plate I. 

The method of extracting the potash from the rock and its use will 

not be considered in this paper.

FIGURE 1. Map showing the location and topographic relief of Pilot Butte, T. 19 N., E. 106 W. Crossruled areas represent lava in place; stippled areas show distribution of lava fragments.

PILOT BUTTE.

Pilot Butte (fig. 1) is a curious flat-topped castle-like mound lying 

northwest of Rock Springs, in the NE. | sec. 10 and NW. £ sec. 11, 

T. 19 N., R. 106 W. of the sixth principal meridian, Wyoming. This 

flat-topped mesa rises 450 feet above the plateau country of White 

Mountain. It is a rudely circular mass with two small indentations, 

one on the east and the other on the west side of the mesa. The top 

of this mound, approximately 1,000 feet in diameter, is bounded on 

all sides by abrupt, nearly perpendicular faces and 0 slopes gently 

toward the east. The western crest lies approximately 50 feet higher 

than the crest along the east side, where the lava cap is 100 feet thick. 

On the west face the cap rock is approximately 150 feet thick and shows
U. S. GEOLOGICAL SURVEY BULLETIN 612 PLATE I

MAP SHOWING LOCATION OF THE POTASH-BEARING ROCKS OF THE LEUCITE HILLS, SWEETWATER COUNTY, WYOMING.

By Alfred R. Schultz. Shaded areas represent exposures of leucite-bearing rock.
QUANTITY OF LEUCITE-BEABING ROCK. 17

more or less distorted basaltic flow structure, suggesting proximity 

to the vent from which the lava exuded and spread out over the surface. On the southwest side of this castle-like mound occur several 

small exposures suggesting part of a dike which may be connected 

with the west end of the mesa. This dike appears to cut the nearly 

horizontal beds of the Green River formation, while the cap of the 

mesa or surface flow spreads out laterally over the same beds. Around 

this table-like mound are numerous large bowlders and much fine 

talus, which effectually conceal the contact of the Green River formation and the lava. These float pieces are restricted to a zone 

around the mesa, approximately 1,900 feet in diameter. No bowlders 

are seen outside of this narrow zonal belt. The rocks either have 

been entirely disintegrated or never extended beyond their present 

limits. A full description of the light-gray platy rock of Pilot Butte 

is given by Cross.1

The area of the cap rock in Pilot Butte is approximately 16 acres. 

One acre-foot of leucite-bearing rock, or 1 acre covered with a flow 

of lava 1 foot thick with a specific gravity of 2.8 would yield 3,798 

tons. Assuming the average thickness of the lava flow over the 

16 acres to be 100 feet (the thicker portion is restricted to the west 

end of the mesa), we find that the 16 acres would yield 6,076,800 tons, 

making the total available rock in Pilot Butte, including the bowlders, 

small dikes, and talus-covered slope not embraced in the computations 

but estimated at 3,200 tons, approximately 6,080,000 tons. Assuming that the potash (K20) content of this rock is equal to 8 per cent 

of the total mass, as given in the analysis of the rock from Pilot Butte, 

we would have 486,400 tons of potash stored in Pilot Butte.

MATTHEWS HILL.

Matthews Hill is alow rounded knoll lying in the SE. % NE. | and 

the NE. i SE. J sec. 21, T. 23 N., R. 104 W. (See fig. 2.) From a 

distance no one would suspect that this inconspicuous knoll was in 

any way connected with the lava exposures, as it rises only about 40 

feet above the sandy waste which surrounds it. Fragments of the 

lava are scattered about the base and over the slopes of the elongated 

east-west mound. Matthews Hill is undoubtedly a volcanic neck like 

the Boars Tusk but, unlike it, has suffered excessive erosion in which, 

together with the surrounding Tertiary beds (Wasatch formation), it 

has been cut down to the level of Killpecker Valley. Regarding the 

dikes associated with the volcanic neck, Kemp and Knight 2 make the 

following statement:

On the crest of the hill there is a narrow dike 60 yards in length and having a strike 

nearly northeast and southwest. This is separated from a small dike having a course

1 Cross, Whitman, Igneous rock of the Leucite Hills and Pilot Butte, Wyoming: Am. Jour. Sci., 4th ser., 

vol. 4, 1897, p. 127.

2 Kemp, J. F., and Knight, W.C., Leucite Hills of Wyoming: Bull. Geol. Soc. America, vol. 14,1903, p. 329.

22008° Bull. 512 12 2
18 POTASH-BEARING BOOKS OF LEUCITE HILLS, WYOMING.

nearly at right angles to it by 15 feet of sandstone. A short distance beyond the cross 

dike there are two other dikes having a strike of south 10° west. * * * The first 

one has a length of 22 yards and is separated by 10 feet of shale from the second, which 

extends nearly to the base of the hill. The rock from all of these dikes is mostly 

schistose, but there are occasional pieces of agglomerate, such as is found at the Boars 

Tusk and the other volcanic necks in this region. * * *

The dikes are wyomingite in an advanced stage of decomposition. The slides show 

spots of alteration, which are not infrequently distributed through them and which 

are filled with some secondary and feebly refracting mineral, probably a zeolite. 

Leucite, diops'ide, and phlogopite make up the fresher portions.

The area of the Matthews Hill volcanic neck is approximately 1£ 

acres, and its average height above the level of Killpecker Valley is 

40 feet. This neck contains roughly 228,690 tons of leucite-bearing 

rock. If we assume that the remainder of the elongated mound 

which rises above the valley bottoms and whose slopes are covered 

with leu cite rock is made up of lava, talus blocks, and associated 

dikes, we will have approximately 200,000 tons in addition to that 

estimated above, or 428,690 tons above the level of the base of the 

mound. In addition to this there is below the level of the valley the 

downward extension of the volcanic neck, about which very little is 

known. The main body of the volcanic neck may expand with 

depth, or, on the other hand, it may become much smaller. Assuming, however, that the neck continues downward with unchanged 

cross section and that the rock could be mined to a depth of 3,000 

feet, or the maximum workable depth assumed in reserving the 

better classes of coal lands at the present time, we would have 1£ 

acres yielding 3,798 tons of leucite-bearing rock per acre-foot, or 

5,697 tons for every foot of depth, making a total for the 3,000 feet 

of 17,091,000 tons. The average of eight analyses of wyomingite 

and orendite show an average potash (K20) content of 11.08 per 

cent. Assuming that the rock will average at least 10 per cent of 

potash, we have the following amount of leucite-bearing rock and 

potash stored in Matthews Hill:

Leucite-bearing rock and potash of Matthews Hill.

Leucite-bearing 

rock in tons.

428, 690

17,091,000

17, 519, 690

Potash (K2O) 

in tons.

42,869

1,709,100

1,751,969

BOARS TUSK.

The extraordinary volcanic neck known as the Boars Tusk is one 

of the most striking exposures in the region. The main mass, with its 

double spire, lies in the SE. £ SW. | sec. 16, T. 23 N., R. 104 W., near 

the middle of Killpecker Valley, just south of the shifting sand dunes.
QUANTITY OP LEUCITE-BEABING ROCK. 19

(See fig. 2.) It penetrates the basal beds of the Wasatch, but the 

contact is concealed by talus blocks. The Boars Tusk consists of 

three parts. The basal portion resembles a frustum of a very flat 

cone covered with fine talus. This frustum is approximately 100 feet 

high, and on it rests a frustum of a steeper cone composed of coarser 

talus. This frustum is approximately 100 feet high and consists of 

huge fallen bowlders from the Tusk, mixed with some finer material. 

On top of this frustum rises the main rock of the Tusk, which is the 

remnant of a plug occupying one of the conduits through which the 

potash-rich magma rose to the surface. Cross 1 states:

The mass of the column is partly a compact breccia and partly massive rock. On 

the southern and western sides is a breccia made up of the same rock type, which in 

massive form reaches to the top of the column on the east and north and is apparently 

separated from the breccia by fissures.

I Mile

FIGURE 2. Map showing the location and topographic relief of Boars Tusk and Matthews Hill, T. 23 N., 

E. 104 W. Cross-ruled areas represent lava in place; stippled areas show distribution of lava fragments.

Kemp 2 makes the following statement regarding the rock of the 

Boars Tusk:

The material of the Tusk is chiefly eruptive agglomerate and tuff, but the whole 

mass is penetrated by the north and south dike, whose width is from 30 to 50 feet and

1 Cross, Whitman, Igneous rock of the Leucite Hills and Pilot Butte, Wyoming: Am. Jour. Sci., 4th ser., 

vol. 4,1897, p. 119.

a Kemp, J. F., and Knight, W. C., Leucite Hills of Wyoming: Bull. Geol. Soc. America, vol. 14,1903, 

p. 328.
20 POTASH-BEARING ROCKS OF LEUCITE HILLS, WYOMING.

which is sheeted by the fault. The dike itself contains many inclusions and much 

resembles a hardened tuff. The bowlders of the agglomerate are partly a cellular, 

eruptive rock and partly fragments of shale and sandstone.

The amount of rock in the Boars Tusk is somewhat difficult to 

compute, as all of the contacts are concealed beneath the talus surrounding the main spire of the Tusk. The area covered by the spire 

or Tusk proper above the frustum of the upper cone is approximately 

1.6 acres. Assuming that the plug will not decrease in size from the 

base of the upper cone, or Tusk proper, down to the level of the 

vaUey, and that the exposed massive part of the Tusk is approximately equal to the volume of a cone whose base is 1.6 acres and 

whose altitude is that of the Tusk above the frustum of the upper 

cone, or 140 feet, we have available in the plug of the Boars Tusk 

approximately 1,866,384 tons of leucite-bearing rock above the 

level of Killpecker Valley. In the frustum of the cones surrounding 

the volcanic plug, which are composed largely of talus and bowlders, 

we have approximately 8,900,000 tons, on the assumption that all of 

the mass in the frustum of the cones is made up of this material. 

Assuming that the volcanic plug will have at least the same area 

below the level of Killpecker VaUey as it has where the talus-covered 

slope conceals the main volcanic plug of the Tusk, we would have 1.6 

acres yielding 3,798 tons of leucite-bearing rock per acre-foot, or 

6,076 tons for every foot in depth, making a total of 18,228,000 tons 

for a total depth of 3,000 feet. Using in our computations 10 per 

cent potash content for this rock as in other cases, we have for the 

Boars Tusk the foUowing results:

Leucite-bearing rock and potash of Boars Tusk.

Portion of frustum of cones surrounding volcanic plug above level of valley. .

Leucite-bearing rock, in 

tons. .

1,866,384

8,900,000 

18,228,000

28,994,384

Potash (K2O), 

in tons.

186, 638

890,000 

1,822,800

2,999,438

BADGER TEETH.

The Badger Teeth exposures are the remnants of an old volcanic 

neck lying in the SE. 1 NW. £ sec. 7, T. 21 N., K. 103 W. (See fig. 3.) 

They consist of five projecting toothlike masses arranged along an 

east-west line, the two largest being on the east, near the crest of 

the knoll, and the other three on the west slope. A somewhat conical platform of sandstone of Montana age rises about 65 feet above 

the bottom of Back Canyon. On this platform rises a conical mass 

of talus to a height of 75 feet, above which the two larger teeth 

project, the highest reaching an elevation of 7,023 feet, or 173 feet
QUANTITY OP LEUCITE-BEARING ROCK. 21

above the valley bottom. Regarding the material in the Badger 

Teeth, Kemp * makes the following statement:

The projecting masses consist partly of a green volcanic agglomerate and partly of 

solid eruptive rock. The mass of the two larger teeth consists of about half of each. 

Before the explosive activity which gave rise to the agglomerate there must have 

been a solid dike, because the bowlders of the agglomerate are chiefly of eruptive 

rock themselves, and the interstices are filled with tuff or mud precisely as at the 

Boars Tusk. The dike is a dense drab rock, which in places is amygdaloidal. The 

amygdules contain crystals of aragonite, which, except for the chalcedony of Steamboat Mesa and the niter observed by Dr. Cross, is the only secondary mineral we have 

observed in the amygdules. The aragonite occurs in platy crystals and in tufts of 

needles. In the field we thought the needles to be some zeolite, but they were 

kindly determined to be aragonite by Dr. Austin F. Rogers, of the department of 

mineralogy, Columbia University. The dike 

also contains many inclusions of sandstone and 

shale. * * *

The extremely limited character of the exposure brings one irresistibly to the conclusion 

that it is an elongated volcanic neck built up 

in a short fissure. * * *

The dike is wyomingite and one of the best 

examples of this rock in the hills. The leucites are large and abun'dant. The diopsides 

are also unusually large and well formed. 

The phlogopite has its own six-sided boundaries. There is abundance of a yellow glass 

present in which the other minerals are embedded. A very few stray sanidines were detected, so that it can not be said that the rock 

lacks this mineral entirely. Apatite is also 

present. The rock is practically identical with 

that at the Boars Tusk and Wortman dike.

FIGURE 3. Map showing the location and 

topographic relief of the Badger Teeth, T. 21 

N., R. 103 W. Cross-ruled areas represent 

lava in place; stippled areas show distribu- The amount of rock in the Badger tion of lava fragments.

Teeth above the sandstone platform

of Montana age is approximately equal to the volume of a cone whose 

base covers 4 acres and whose height is 75 feet, or about 379,800 tons. 

Assuming that the area of the volcanic neck below the talus cone 

remains the same as at the surface and is at least 1£ acres, we would 

have 17,461,305 tons of rock in the plug below the sandstone platform of Montana age to a depth of 3,000 feet below the bottom of the 

valley of Back Canyon.

Leucite-bearing rode and potash in the Badger Teeth.

Badger Teeth and talus cone above sandstone platform of Montana age. ..... 

Volcanic neck below sandstone platform of Montana age to a depth of 3,000

Leucitebearing rock, 

in tons.

379,800 

17,461,305

17,841,105

Potash 

(KsO), 

in tons.

37,980 

1,748,130

1,784,110

i Kemp, J. F., and Knight, W. C., Leucite Hills of Wyoming: Bull.Geol. Soc. America, vol. 14, 1903, 

pp. 326-327.
g 

O CD

PIGTJEE 4. Map showing the location and topographic relief of Cross and Osborn m

bowlder locality. Cross-ruled areas represent lava in place; stippled areas show 
QUANTITY OF LEUCITE-BEARHSTG BOCK. 23

ter of a mile south of the center of sec. 35. The longest tongue of 

lava extends toward the northwest for more than a mile and drops 

approximately 100 feet in this distance. The cone is the north half 

of an old ring whose south hah2 was destroyed at the time of eruption 

or has subsequently been eroded. It is built up of fragments of 

reddish pumice. The rock of the mesa is composed of orendite, 

leucite, sanidine, diopside, hornblende, phlogopite, and rutile. Outside of the material composing the cone, the escarpment and top "of 

the mesa appear to be made up of one flow. The entire mass of rock 

back from the cone, where there is probably a volcanic conduit, is 

made up of this surface flow and no leucite-bearing rock occurs 

beneath the capping bed.

The amount of rock in this surface flow is approximately 70,832,700 

tons and it contains about 7,083,270 tons of potash (K20). Rising 

on top of this surface lava sheet is the cone of pumice south of the 

center of section 35. The amount of rock in the cone lying above the 

surface flow may be estimated at 7,899,840 tons, containing about 

789,984 tons of potash, making a total of 78,732,540 tons of rock, or 

7,873,254 tons of potash, above the surface of the underlying sedimentary rock. No attempt is made to estimate the tonnage that 

may exist in the volcanic conduit beneath the cone through which 

the material of the mesa no doubt was derived.

OSBORN MESA.

Osborn Mesa (fig. 4) lies on the highest point of the west ridge of 

the Continental Divide south of Steamboat Mountain and reaches 

an elevation of 7,998 feet. Although a commanding mesa, it is not 

of great superficial area. The longer axis of the flow is about a quarter of a mile long and extends in a southeast-northwest direction 

along the Continental Divide. The exposure is about an eighth of a 

mile in width and is surrounded on the slope of the hill by talus 

blocks or bowlders that extend more than a quarter of a mile back from 

the vertical edge of the cap rock, which is approximately 100 feet 

thick. The source of the material composing this mesa is no doubt 

a dike or vent associated with the flow which may be concealed beneath its surface. No dike or volcanic neck was seen during the 

examination, but from the relations at the mesa and along the Continental Divide, which slopes from the mesa both to the southeast 

and the northwest, it appears that the lava was forced to the surface 

in the locality of the mesa. About 1£ miles to the northwest, on the 

Continental Divide, in the SW. i SE. £ sec. 36, T. 22 N., R. 103 W., 

occur four large bowlders, with associated fragments of smaller rock, 

lying at an elevation of about 7,700 feet, or approximately 200 feet 

lower than the base of the flow at Osborn Mesa and 100 feet higher
24 POTASH-BEARING ROCKS OF LEUCITE HILLS, WYOMING.

than the base of the lava at the east end of Cross Mesa, half a mile to 

the west. These bowlders probably represent the remnants of an 

old flow which at one time was continuous from Osborn Mesa to the 

bowlder locality and may have extended some distance toward the 

northwest. The topographic relations along this part of the divide, 

as well as the small remnants of lava and altered sandstones, suggest 

that it was at one time capped by a tongue of lava extending northwestward from Osborn Mesa much as the tongue now extends northwestward from Cross Mesa. This lava surface flow may also have 

extended northeastward and joined with the lava at Hatcher Mesa. 

The slope from Osborn Mesa northwestward along the divide to the 

four bowlders is comparable .to the slope of the lava flow on Cross 

Mesa and probably represents part of the same surface, which in 

turn may be a part of the nearly base-leveled plain upon which the 

Bishop conglomerate and the lava flows rest.

Osborn Mesa lies in the SW. J SE. J and the SE. J SW. \ sec. 6, 

T. 21 N., R. 102 W. The area of the lava cap is about 15 acres, and 

as the rock is a typical orendite, its mass is approximately 5,697,000 

tons, and it contains about 569,700 tons of potash. This computation does not take into consideration the talus blocks nor the rock 

which may occur in a dike or vent through which the lava reached 

the surface.

HATCHER MESA.

Hatcher Mesa is in the S. £ sec. 33, T. 22 N., R. 102 W., about a 

quarter of a mile south of the center of the section. (See fig. 5.) 

It is a conspicuous flat-topped hill, approximately a quarter of a 

mile in diameter, and is bounded by a high vertical scarp. The 

talus blocks scattered along the slope below the scarp extend down 

to the valley and are distributed over an area whose diameter is 

equal to about half a mile. The top of the lava cap is 7,670 feet 

above sea level, or 420 feet above the bottom of the valley. The 

thickness of the lava sheet is about 50 feet. The general appearance 

of the lava on this mesa and its nearness to Emmons Cone suggest 

that it may be the remnant of a once continuous flow extending 

from Emmons Cone, on Emmons Mesa, about a mile to the south, 

northward to Hatcher Mesa or to some point beyond.

The elevation of the base of the lava cap at Hatcher Mesa is, however, nearly 100 feet higher than the base of the lava along the northwestern part of Emmons Mesa, and as there has been no displacement 

by faulting, the source of the lava can not be Emmons Cone. It is 

more probable that it is a remnant of a surface flow that spread out 

over the surface from Osborn Mesa, 2 miles to the southwest, connecting Osborn Mesa, Hatcher Mesa, and the bowlder locality. The 

slope from Osborn Mesa to Hatcher Mesa is approximately the same
QUANTITY OF LEUCITE-BEARING ROCK. 25

as that from Osborn Mesa to the bowlder locality and is similar to 

that on Cross Mesa. It is of interest to note in this connection that 

the old surface must have sloped toward the north along the crest of 

the divide, with a corresponding slope toward the east and west on 

the two sides, as seen in the lava surfaces in Cross and Emmons 

mesas. Whether it marks the location of an earlier Continental Divide 

or only a minor irregularity on the nearly base-leveled plain is a matter 

of conjecture.

The present area of the lava-capped mesa is 27 acres, its mass 

about 5,127,300 tons, and its potash content about 512,730 tons.

EMMONS MESA.

Emmons Cone is one of the prominent landmarks in this vicinity. 

The cone lies on the northwestern part of the mesa of the same name 

and from its peculiar color may be easily distinguished from all points 

of view. The mesa from which the cone rises is a nearly flat-topped 

prominence a little oveHialf a mile in width and about 1£ miles long, 

extending in an east-west direction. The thickness of the lava cap 

is approximately 50 feet, and the surface slopes gradually toward 

the east. This mesa may at one time have been connected with 

Zirkel Mesa, from which it is now separated by a narrow gulch or 

ravine eroded into the underlying sandstone of Montana age. The 

lava of Emmons Mesa was derived from the vent at Emmons Cone; 

that of Zirkel Mesa came from one or more of the vents on it. The 

cone on Emmons Mesa rises approximately 162 feet above the top of 

the mesa, or to an elevation of 7,862 feet, and its base is approximately 

three-eighths of a mile in diameter. Emmons Mesa lies in sees. 3, 

4, 9, and 10, T. 21 N., R. 102 W., and its relation to Hatcher and 

Zirkel mesas may be seen in figure 5. The area of the lava cap is 

440 acres; it contains approximately 83,556,000 tons of rock and the 

potash content is about 8,355,600 tons. The cone that rises above 

the level of the mesa contains approximately 11,074,968 tons of 

rock, or 1,107,496 tons of potash, making a total for this mesa, 

exclusive of the bowlders surrounding the mesa and any associated 

volcanic necks or plugs, of 94,630,968 tons of rock, or 9,463,096 tons 

of potash.

ZIRKEL MESA.

Zirkel Mesa, by far the largest exposure of lava in the Leucite Hills, 

lies chiefly in the east half of T. 21 N., R. 102 W., but extends into 

the western part of T. 21 N., R. 101 W. It consists of lava flows 

with high and nearly vertical escarpments, more or less dissected and 

indented at various places about the margin. The mesa is built up 

of a complex of several flows whose material came, in part, at least, 

from separate vents. The entire mass of lava rests on rocks of
26 POTASH-BEARING ROCKS OP LEUCITE HILLS, WYOMING.

Montana age which have been cut by at least three prominent faults, 

none of which affect the lava, thereby proving that the age of the 

lava flow is later than the faulting. (See fig. 5.) The surface of the 

mesa is very irregular in some places, but in others it is nearly flat. 

From the top of the mesa rise five prominent cones, four of which 

consist of fragments of pumice, and the other, with its smaller assoa Miles

FIGURE 5. Map showing the location and topographic relief of Hatcher, Emmons, and Zirkel mesas, 

Tps. 21 and 22 N., R. 102 W. Cross-ruled areas represent lava in place; stippled areas show distribution 

of lava fragments.

ciated blisters, is made up of solid lava similar to the cones on Steamboat Mountain.

Because of the irregularity of the surface and the varying thickness 

of the flows from the several vents, it is difficult to compute the tonnage in Zirkel Mesa. No attempt will be made to estimate the 

amount of rock that may occur in the vents from which the lava 

exuded or that is distributed about the mesa in the form of talus 

and bowlder blocks. The mesa covers approximately 3,300 acres 

and the average total thickness of the flows is 75 feet. The amount
QUANTITY OF LEUCITE-BEABING EOCK.

of rock in this more nearly horizontal part of the mesa is equal to 

940,005,000 tons, with approximately 94,000,500 tons of potash. 

The irregularities on the mesa, including the cones and protuberances, 

contain approximately 102,336,276 tons of leucite-bearing rock, in 

which are stored 10,233,627 tons of potash, making a total of 1,042- 

341,276 tons of rock, or 104,234,127 tons of potash.

ORENDA MESA.

Orenda is one of the larger mesas and lies 2£ miles northeast of 

Zirkel Mesa, in sees. 19, 20, 29, and 30, T. 22 N., R. 102 W. The 

rock is orendite, named from this locality, and in some respects resembles that of Zirkel Mesa. The main trend of the exposure is north 

and south. (See fig. 6.) The rock mass'is made up of several 

irregular flows or series of flows, as is the case at Zirkel Mesa, but here 

the flows appear to have a common source or vent located more 

nearly at the center 

of the mesa. The 

cones, three in number, consist of fragmental reddish-yellow 

pumice. The south

cone is much higher 

than the two at the 

north and reaches an 

elevation of 7,560 

feet. The entire mesa 

is limited laterally by 

a high scarp, beyond 

which is found the customary zone of talus 

and broken bowlders. 

The Orenda Mesa 

araa contains approximately 369 acres. While the scarp is in general rather high, there 

are several points near the heads of little gulches where it is 

indented and the abrupt wall is comparatively low. The surface 

of part of the mesa is undulating and rises toward the cones. The 

average thickness of the flow to the base of the three cones may 

be taken as 100 feet. This thickness applied to the area gives 

approximately 140,355,600 tons of rock, or 14,035,560 tons of potash. 

Above this mass rise the three cones, which contain approximately 

9,320,584 tons of rock, or 932,058 tons of potash, making a total in 

the mesa, outside of the talus and the volcanic vents below the 

base of the lava flow, of 149,676,184 tons of leucite-bearing rock containing potash approximating 14,967,618 tons.

o >2 i Mile

FIGURE 6. Map showing the location and topographic relief of Orenda 

Mesa, T. 22 N., R. 101 W. Cross-ruled areas represent lava in place; 

stippled areas show distribution of lava fragments.
28 POTASH-BEARING ROCKS OF LEUCITE HILLS, WYOMING.

BLACK BOCK MESA.

Black Rock is the most eastern exposure of the Leucite Hills and 

lies hi sees. 13 and 24, T. 22 N., R. 101 W. It is roughly 

circular in outline, but is broken on the north side by a semicircular reentrant. The mesa rises 450 feet above the level of the 

valley on its north side and the nearly flat top has a broad eastwest depression near the center, by virtue of which the north and 

south sides of the scarp rise considerably above the average level, 

reaching a maximum height of 7,200 feet along the south crest.

The slopes are covered by talus, above which rises the nearly vertical scarp of leucite-bearing lava. This lava exhibits a suggestion of

basaltic structure, having a roughly 

columnar surface, due to a system of 

nearly vertical joints which give it 

the general appearance of an old volcanic neck or stock. Near the north 

base of the scarp the rock is soft and 

porous and in many places resembles 

a tuff. Numerous other factors suggest that this is an old neck rather 

than a surface flow, as previously 

reported. The main scarp of the mesa 

is about 100 feet high, but in places it 

extends much farther down the hillside, particularly on the northeast side, 

thus giving it a greater thickness at 

this point. The top, as seen from a 

distance, appears to be nearly horizontal, but on closer examination it is

geen £o nave a slight slope toward 

, , rni , the center oi the mesa. I he general 

appearance of the hill may be inferred

 ~ from figure 7.

Black Rock Mesa stands above the basal beds of the Wasatch 

formation, or what has been called the Black Rock coal group in 

the coal reports on this region. There is no indication of the existence of sedimentary rock underneath or in contact with the lava of 

the mesa. On the extreme south side the rock at the base is very 

scoriaceous, being composed largely of fragments of all sizes, which 

are more or less angular and are held together by a vesicular lava 

mass. Two-thirds of the way up the cliff is a 20-foot band of heavy 

massive lava, but the top is scoriaceous. At the top there is a 

fairly pronounced horizontal flow structure, layers of dense lava 

alternating with more porous layers.

0 ^Mile

FIGURE 7. Map showing the location and 

topographic relief of Black Hock Mesa, T. 22 

N., R. 101 W. Cross-ruled areas represent 

lava in place; stippled areas show distribution of lava fragments.
QUANTITY OF LEUCTTE-BEARING BOCK. 29

The area of Black Rock Mesa is about 12 acres. As this rock 

is the variety called wyomingite, its weight is approximately 3,798 

tons per acre-foot, or 45,576 tons for every foot of rock over the 

entire area. As there are at least 100 feet exposed, the amount of 

rock available is about 4,557,600 tons, containing 455,760 tons of potash. These figures do not include any rock below a plane 100 feet 

beneath the top of the mesa. The exact location and size of the volcanic conduit are not known, and an estimate made at present of the 

leucite rock available from Black Rock below the upper 100 feet is a 

mere guess. However, if this proves to be the stock of an old volcanic 

neck and retains the same dimensions to a depth of 3,000 feet below 

the surface of the valley, it will contain approximately 152,679,600 

tons of rock, or 15,267,960 tons of potash, making a total for the 

Black Rock locality of 157,237,200 tons of leucite-bearing rock, or 

15,723,720 tons of potash.

STEAMBOAT MOUNTAIN.

Steamboat Mountain is the second largest exposure in the Leucite 

Hills region, being surpassed only by Zirkel Mesa. The lava capping 

here rests on beds of Green River age. These, together with the 

underlying Wasatch formation, form the south face of the semicircular mountain which rises 1,200 feet above the sand-dune country 

to the south and more than 1,000 feet above the west limb of the 

Continental Divide.north of Table Mountain. (See fig. 8.)

The southern face of the escarpment is very regular and consists 

of a vertical semicircular cliff rising from 50 to 60 feet above the 

underlying sedimentary beds, whereas on the north side, where the 

lava is considerably thinner, it is deeply dissected by ravines that 

head near the south side of the mesa. At the base of the cliffs the 

contacts with the underlying sediments are concealed by talus, which 

forms 25° to 35° slopes. The surface of the mesa, which slopes 

gently toward the north, is very rough and irregular.

On the top of the mesa are three hills or "cones." The northern 

and lower of these is perfectly conical in outline; the other two are 

less perfect cones, being flatter and more rounded on top, but they 

are higher, reaching elevations of about 8,610 feet. Just east of 

the northern conical mass is a low mound which may be the remnant 

of a fourth cone. These cones, unlike most of those in the group, are 

not made up of fragmental pumice but consist of hard lava flows like the 

one on Zirkel Mesa and may mark the positions of vents or volcanic 

conduits above which huge blisters of lava have been built up.

Regarding the rock of Steamboat Mountain, Kemp and Knight 1 

make the foUowing statement:

The lava occurs in two distinct and easily recognizable flows, each of which is about 

30 feet thick. The contact is marked by a black scoriaceous crust on the lower sur1 Kemp, J. F., and Knight, W. C., Leucite Hills of Wyoming: Bull. Geol. Soc. America, vol. 14, 1903, 

pp. 325-326.
P _. P £L

S- m £±. «<J

c? a ® g

Hi!

s § & §

oo

£1 O £1

^. & ^

P 2. tS8 ® 8

8^3 

?.^ ~

§1

o- 2

CD S CD J"

FIGTJEE 8. Map showing the location and topographic relief of Steamboat Mountain, 

represent lava in place; stippled areas show distribution of la
QUANTITY OF LEUCITE-BEABING ROCK. 31

cisely as in some Vesuvian scorias. We have seen no similar rock anywhere in the 

hills. It has doubtless been caused by the quick chill at the underside of the flow 

The scoria may be collected along the old and partially completed road at the southwest corner of the mesa.

On the east side of the mesa no evidence of two flows was seen 

unless the presence of scoriaceous zones is to be regarded as such 

evidence. The scoriae seem, however, to be distributed irregularly 

through the lava mass. Below the lava lie 100 feet or more of brown 

sandstones and shales. At the contact and for some distance below 

it the sandstones and shales are burned or baked to a brick-red, becoming lighter as their distance from the contact increases.

Steamboat Mountain lies in sees. 8, 9, 10, 11, 15, 16, and 17, T. 23 

N., K. 102 W. The area covered by the lava flow capping the mountain is about 1,019 acres. At an earlier date no doubt the mesa 

extended farther out on the great table-land of shales belonging 

to the Green River formation that now forms the west limb of the 

Continental Divide north of Steamboat Mountain. In this connection it may be of interest to call attention to the fact that the lava 

cap on Table Mountain, 4£ miles to the southwest, is approximately 

at the same elevation as that on Steamboat Mountain, and is only a 

little more than twice as far from the southern cone of Steamboat 

Mountain as the farthest point on the northeastern tongue of lava on 

Steamboat Mountain is from the same source.

Owing to the irregularity of the surface and the variations in the 

thickness of the lava, it is somewhat difficult to estimate the tonnage 

of rock in Steamboat Mountain. Assuming, however, that the average thickness of the lava exclusive of the cones is 50 feet, for every foot 

in depth over the entire area we have 3,870,162 tons, making a total 

for 50 feet of 193,508,100 tons of leucite-bearing rock, or 19,350,810 

tons of potash. In addition to the mass of rock in the mesa, the 

material in the cones above the general level is equal to approximately 

12,573,700 tons, containing 1,257,370 tons of potash, giving a total 

amount of rock capping Steamboat Mountain of 206,181,800 tons, 

containing 20,618,180 tons of potash.

NORTH TABLE MESA.

North Table Mesa lies in the south center of sec. 36, T. 23 N., 11. 

103 W., and in the north center of sec. 1, T. 22 N., K. 103 W. (See 

fig. 9.) It is a flat-topped mesa rising to an elevation of 7,900 feet, 

or approximately 700 feet above the valleys lying on its north and 

southeast sides. The top of this mesa is at least 400 feet lower than 

the top of Table Mountain. The mesa, which covers about 80 acres, 

is rimmed by a prominent scarp ranging in height from 40 to 60 feet 

and averaging approximately 50 feet. At the base of this scarp is 

the customary highly inclined slope, such as surrounds each of the 

other mesas.

Near the west base of North Table Mesa, in the SE. \ SE. J sec. 35, 

T. 23 N., R. 103 W., there is a small dike, about 15 feet wide, which is
32- POTASH-BEARING ROCKS OF LEUCITE HILLS, WYOMING.

exposed for a distance of 50 feet. For the southwest 20 feet it 

extends in a direction N. 30° W., the rest of the dike striking N. 60° 

E., at a right angle to this portion. The outer part of this dike 

weathers into forms resembling extrusive bombs and spherulites. 

Computed in the same way as for the other localities, North Table 

Mesa contains about 15,192,000 tons of rock, in which the potash 

content approximates 1,519,200 tons.

R.I03W. R.I02W.

123 N.

T22N

T23N.

T22K

R.IQ3W. R.I02W.

JL z Miles

FIGUKE 9. Map showing the location and topographic relief of North Table and South Table mesas, Table 

Mountain, Iddings, Weed, and Hallock buttes, Endlich and Hague hills, and their associated dikes. 

Cross-ruled areas represent lava in place; stippled areas show distribution of lava fragments. /

SOUTH TABLE MESA.

About an eighth of a mile south of North Table Mesa, on its south 

slope, lies South Table. (See fig. 9.) This is the smallest flat-topped
QUANTITY OF LEUCITE-BEARING EOCK. 33

mesa in the field. The top lies approximately 250 feet lower than 

the top of North Table and is surrounded by a prominent scarp 

nearly 200 feet high. This mass is a remnant of a volcanic neck and 

exhibits a poorly developed columnar structure. The rock is dense 

and platy and is largely schistose, the planes of schistosity being 

about vertical. It resembles the material of the dikes much more 

strongly than it does the material of the surface flows. Many of its 

characteristics are similar to those observed at Black Rock, in sec. 

13, T. 22 N., R. 101 W.

The lava at South Table covers about 8 acres, and the upper 100 

feet of the intruded mass contains about 3,038,400 tons of rock and 

303,840 tons of potash. If the diameter of the volcanic neck remains 

uniform in size to a depth of 3,000 feet below the level of the valley 

the core of the volcanic neck would contain an additional amount of 

105,736,320 tons of rock, or 10,573,632 tons of potash, making a total

for South Table of 108,774,720 tons of potash-bearing magma, or 

10,877,472 tons of potash.

TABLE MOUNTAIN.

Table Mountain (fig. 9) lies in the SW. J sec. 6, T. 22 N., R. 102 W.,, 

and is the most conspicuous of all the exposures in the Leucite Hills 

locality. It has also been called North Pilot Mesa, because it is so 

conspicuous a landmark and may be seen so readily from any direction on entering this region.

The top of this mesa has an elevation of 8,300 feet, and is therefore 

as high as Steamboat Mountain. The lava cap on North Table lies 

approximately 1,300 feet above the bottom of the valley, near its east 

base. The mesa is surrounded by a vertical scarp, varying in height 

from 30 to 60 feet, with an average of about 50 feet. The topmost 

layer of the mesa is much more vesicular and porous than the lower 

part of the flow and, when seen from a distance, has a somewhat 

lighter appearance. On the north side of the mesa, at a point near 

the center, in a cavity or recess on the east side of the cleft through 

which the top may readily be gained, Dr. Cross found potassium 

nitrate in 1884.

Southeast of Table Mountain, in the SE. i SE. I sec. 6, T. 22 N., 

R. 102 W., near the base of this slope, is a dike extending N. 30° W. 

Its maximum thickness is 16 feet, but it varies greatly along the 

strike, in places pinching down to a few inches, in others expanding 

to nearly the maximum. The longest single exposure covers about 

700 feet. Many inclusions were seen in the dike, and the carbonaceous shale at the contact seems to have been baked slightly for a 

distance of 1 to 2 inches back from the igneous mass. The rock, 

weathers a light gray and is schistose in habit, the schistosity being; 

due chiefly to the parallel arrangement of the phlogopite minerals. 

22008° Bull. 512 12 3
36 POTASH-BEARING ROCKS OF LEUCITB HILLS, WYOMING.

seen at Boars Tusk, Badger Teeth, and Iddings Butte, there is considerable leucite-bearing rock in these localities that has not been 

included in the estimate. Some idea of the amount of material 

below the mesa for each conduit may be obtained by comparison 

with the amount estimated for the portions of the Boars Tusk and 

Badger Teeth lying below the level of the valley.

The figures in the above table for Pilot Butte are based on a 10 

per cent potash content, the amount assumed for all the other localities, 

whereas in the computations used in the discussion under the heading of Pilot Butte, 8 per cent potash, the result as determined by 

one analysis of this rock, was used.

TRANSPORTATION.

The most accessible routes for railroad transportation and those of 

easiest grade in the northern part of the Rock Springs field lie along 

the larger valleys or main tributaries of Bitter Creek, namely, Ninemile and Tenmile creeks, Horse Thief Canyon, Killpecker Valley, 

and its tributaries. Railroad tracks built along any of these valleys 

would become feeders to the main Union Pacific line along Bitter 

Creek and would thus afford an easy means of transportation, as 

gravity could be utilized in part in running the loaded cars from the 

mines to the nearest point on the main line.

Thus far the Union Pacific is the only railroad crossing this area, 

and all points in the northern part of the Rock Springs field are 

readily accessible from its main line. Several projected lines have 

been surveyed across the north end of the field, but no other line has 

begun active construction. The location of the Union Pacific Railroad, with its spur tracks on either side of its main line, places it in 

a position to control the future development of the entire field. The

grade along its main line is moderate, and by short branch spurs 

with easy grade similar to the branches built along Horse Thief 

Canyon to Superior, Wyo., along the west side of Baxter Basin to 

Gunn, Wyo., and up Killpecker Valley, it will be comparatively easy 

to reach any part of the field. As many of the lavas occur on high 

mesas or divides, it may be necessary, if it is ever demonstrated that 

this rock will furnish large quantities of commercially available potash and alumina, to transport the quarried rock from these high 

elevations to some point where it may be treated by a local plant or 

loaded on cars along the line of one of the railroad branches. For 

this purpose aerial tramways or ore chutes may be readily installed. 

Zirkel Mesa, the largest of the lava localities, lies only 2 miles 

from the Superior branch of the Union Pacific Railroad, but it will 

not be practicable to extend this branch to any of the exposures, 

as between Horse Thief Canyon, along which the railroad track lies, 

and Osborn, Emmons, and Zirkel mesas there rises a very abrupt
STATUS OF LANDS. 37

scarp, whose crest lies approximately halfway between the railroad 

track and the southern exposure of the leucite rock on Zirkel Mesa. 

The rise from the railroad track in Horse Thief Canyon to the crest 

of the escarpment is over 700 feet, while the surface on top of the 

escarpment is nearly level from the crest back to the mesa, the 

entire table-land sloping gently toward the north and east.

STATUS OF THE LANDS CONTAINING POTASH-BEARING BOCKS.

Prior to 1907 and 1908, when the coal examinations were made 

in the Rock Springs field, no attempt had been made to utilize the 

leucite-bearing rock in the Leucite Hills, and it was considered of 

importance only from a scientist's point of view. Since that time, 

however, conditions have somewhat changed. As yet the United 

States has developed no potash industry and is dependent entirely

on foreign countries for its supply of this valuable material, the 

imports of which in 1910 amounted to 1,798,391,012 pounds, valued 

at $11,615,134, and during the first nine months of 1911 were

I,601,659,217 pounds, valued at $11,665,367, amounting to more 

than $1,250,000 a month. At present every effort is being made 

to locate valuable potash deposits in the United States so as to 

supply, if possible, the constantly increasing demand from our own 

resources. Since the recent stimulation of interest in the possibility 

of finding potash in this country a number of companies have been 

formed for the purpose of exploiting or developing the deposits in 

various forms. It is reported that an attempt will be made to 

extract the potash (K2 0) and alumina (A12 03 ) from the rock of the 

Leucite Hills in the vicinity of Zirkel Mesa. The problem of devising 

methods to extract all or any part of the potash and alumina from 

the lavas of the Leucite Hills is one whose solution rests entirely 

with the chemical and industrial engineers. The approximate 

amount of potash and alumina these rocks contain is well known, 

and the point to be determined is merely whether the extraction 

process to be used will separate enough of the minerals at (a sufficiently low cost to make it a commercial success.

So far as known, no final patent has been granted by the United 

States to any of the lands in which the lava occurs except the odd 

sections within a distance of 20 miles of the Union Pacific main line, 

which were included in that company's original grant. The total 

number of 40-acre tracts in the Rock Springs field in which exposures 

of potash-bearing rock occur number 290, containing approximately

II,600 acres. Of this amount, 154 tracts, or 6,160 acres, still belong 

to the Government, and 136 tracts, or 5,440 acres, belong to the Union 

Pacific Railroad Co., unless that company has disposed of its title 

subsequent to receipt of final patent.
38 POTASH-BEARING ROCKS OF LEUCITE HILLS, WYOMING.

It is reported that the Union Pacific Railroad Co. has agreed to 

lease, under certain conditions and for certain royalties, the right, 

beginning September 1, 1912, to take rock for potash and its byproducts from the following-described lands, all of which lie on 

Zirkel Mesa:

T. 2-1 N., R. 101 W., sec. 19, W. £. 

T. 21 N., R. 102 W., sec. 9, NE. £;

sec. 11, all;

sec. 13, all;

sec. 15, NE. £, E. £ NW. J, N. £ SE. £.

According to the records of the General Land Office only one entry 

is on file at the present time within the lava areas of the Leucite 

Hills, namely, that in the E. | SW. I and the S. $ SE. |, sec. 12, 

T. 21 N., R. 102 W., on the northeast side of Zirkel Mesa. This 

homestead entry was made March 12, 1907, but final certificate has 

not yet been issued. Mineral claims at some of the exposures may 

have been staked out on the ground, later applied for by the discoverer, 

and legally recorded by the proper count}7- officers at Rock Springs, 

Wyo., .but thus far none of these lands have gone to patent, and 

title therefore still rests with the Government. It is to be noted 

that no provision exists in the present law which permits the withdrawal or reservation of lands from the appropriate forms of mineral 

entry for the sake of potash or, in fact, for any minerals other than 

coal, gas, oil, or phosphate.

The following table shows the location of the areas of the leucitebearing rocks by township, range, and section, and indicates what 

tracts are still part of the public domain:

Locations of leucite-rich rock on Government and Union Pacific Railroad lands.

Location.

T. 21 N., R. 101 W..... 

T. 22 N., R. 101 W.. ... 

Do.................

T.21N., R. 102 W.....

Do.................

Do.................

T.22N., R. 102 W.....

Do.................

Do.................

Name.

Zirkel Mesa ........... 

Orenda Mesa. .........

Hallock Butte Weed

Butte, Id dings 

Butte, and dikes.

Government.

Sec. 6, SW.JSW.J. ...... 

Sec. 18, W.iNE. i, NW. 

J,NW.JSW.J. 

Sec. 20, S.JSW. }........ 

Sec. 30, NE. }, N. i SW. }, 

SE.JSE. }. 

Sec.24,NW.JNE.J,N.i

NW.J. 

Sec.6, SE. JSW.J.SW. i

SE.J. 

Sec. 4, S.|. ...............

Sec.2,S.iSW.|. ........

Sec. 10, E. *, NW. J, E. i 

SW. }. 

Sec. 12, NE. \, W. \, S. * 

SE. J. 

Sec. 14, all. 

Sec.24,N.i,N.JS.J.

Sec. 18, S. i NE. J, SE. 1

NW.1,E.JSW.1,SE.J. 

Sec.18, E.iNE.J.

Union Pacific.

Sec. 19, AV. J, W. iE. *.

Sec. 19, S.JSE.}. 

Sec. 29, NW. i, NE. J SW. 

J, W.*SW. }. 

Sec. 13, S. J SW. J, SW. J

SE. J.

Sec. 3, S. J SW. i SW. J

SB.l. 

Sec.9,N.J. 

Sec. 1, SE.JSE. }.

Sec. 11, all. 

Sec. 13, all. 

Sec. 15, E. J, E. \ NW. J, 

NE. \ SW. \. 

Sec.23,N.JNE.i.

Sec. 33, E. i SW. J, W. J

SE.J. 

Sec. 17, S. J NW. J, N. J

SW. i.
STATUS OF LANDS. 39 

Locations of leucite-rich rock on Government and Union Pacific Railroad lands Contd.

Location.

T. 22 N., R. 102AV.....

Do.................

T.23N., R. 102 W.....

T. 21N., R.103W.....

Do.................

T. 22N., R.103 W.....

Do.................

Do.................

Do.................

T. 23N., R. 103W..... 

T. 23.N./R. 104 W.....

Do.................

T. 19N., R. 100W.....

Name.

Endlich Hill.. ........

Table Mountain and

dikes.

Badger Teeth.....'....

.....do................

South Table..........

North Table..........

.....do.:.............. 

Boars Tusk...........

Matthew Hill.........

Pilot Butte...........

Government.

Sec. 8, S. 4 SW. 1, SW. J

SE. J. 

Sec. 18, NE.JNE. J. 

Sec. 6, SW. i, NW. iSE.

iS.iSE.J. 

Sec. 8, SE.iSE.i. .......

Sec. 10, SW. JNE.J, 8.4 

Sec. 10, N. 4, N. 4 SW. J, 

SE.i.

Sec. 2, N.JNE. }.........

Sec. 34, N. * NE. i, SE. J

NE.i. 

Sec. 36, SW.J-SE. }.......

Sec. 36, SW. }, W. A SE. \. 

Sec. 16, E. 4 SW. £ W. 4

SE.j. 

Sec.22,SW.iNW.i,NW.

J SW. J.

Sec. 10, E. JNE.J........

Union Pacific.

Sec. 7, SE.I SE.i.

Sec. 17, NW. JNE.J, N. J 

NW. i.

Sec.9, SE.JNW.i,SW. i,

W. 4 SE.i. 

Sec. 11, NW. i SW. J. 

Sec. 15, N. i NE. J, SW. J 

NE. i, NW. i, N. J SW. 

i, SW. i SW. J, NW. J 

SE.i. 

Sec. 17, E. i NW. }. 

Sec. 7, SE.|NW. i, NE.i

SW. i.

Sec. 35, NW. } NW. i, S. 4

NW.i, SW. iSE.J.

Sec. 1, SW. i NE. J, SE. i

MW.i. 

Sec. 1. NW. i NE. i, N. JNW. J.

Sec. 21. SE.i NE.i, NE.i

SE.}. 

Sec. 11, W.J NW.j. .

 The United States Government, realizing the great present and 

the greater future need of potash as a fertilizer, has been active in 

recent years in its search for sources of this compound. Both the 

Department of the Interior and the Department of Agriculture are 

taking part in this search and all possible mineral and organic 

sources are being sought and tested. Tho Geological Survey's 

activities are confined to the possible geologic sources and are inspired by a desire to place at the service of the public the special 

training of its staff of geologists. This paper has been prepared 

in furtherance of this end and others similar in tenor will appear 

from, time to time.

o