/,'7 -

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Uranium in 

Carbonate Rocks 

GEOLOGICAL SURVEY PROFESSIONAL PAPER 474-A 

Prepared on behalf of the 

U.S. Atomic Energy Commission 

Uranium in 

Carbonate Rocks 

By KENNETH G. BELL 

SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY 

GEOLOGICAL SURVEY PROFESSIONAL PAPER 474-A 

Prepared on behalf of the 

U.S. Atomic Energy Commission 

A study of ore deposition and occurrence of uranium 

in carbonate environments, including analyses of 

70 samples 

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1963 
UNITED STATES DEPARTMENT OF THE INTERIOR 

STEWART L. UDALL, Secretary 

GEOLOGICAL SURVEY 

Thomas B. Nolan, Director 

For sale by the Superintendent of Documents, U.S. Government Printing Office 

Washington, D.C., 20402 
CONTENTS 

Abstract __________________________________________ _ 

Introduction ______________________________________ _ 

Objectives of the investigation _______________________ _ 

Previous investigations _____________________________ _ 

Theoretical considerations __________________________ _ 

Selection of sample materiaL ________________________ _ 

Analytical procedures ______________________________ _ 

Classification of carbonate rocks _____________________ _ 

Syngenetic uranium in carbonate rocks _______________ _ 

Epigenetic uranium deposits in carbonate rocks ________ _ 

Uranium in hydrothermal veins __________________ _ 

Efflorescent deposits of uranium minerals _________ _ 

Page 

A1 

1 

1 

1 

2 

4 

4 

5 

5 

8 

8 

9 

Page 

Epigenetic uranium deposits in carbonate rocks-Con. 

Uranium deposits in karst terrains________________ All 

Tyuya-Muyun, Fergana district, Uzbek S.S.R__ 11 

Bighorn-Pryor Mountains, Wyoming and 

Montana________________________________ 11 

Peneconcordant uranium deposits in carbonate rocks_ 12 

Uranium deposits in the Todilto Limestone, New 

Mexico__________________________________ 13 

Uranium deposits in the Sundance Formation, 

Wyoming________________________________ 17 

Summary__________________________________________ 18 

Literature cited____________________________________ 18 

TABLES 

Page 

TABLE 1. Uranium content of dolomite from the Hermosa Formation, Paradox Basin, San Juan County, Utah____________ AS 

2. Analyses of some carbonate rocks and source materials____________________________________________________ 21 

m 

SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY 

URANIUM IN CARBONATE ROCKS 

By KENNETH G. BELL 

ABSTRACT 

Carbonate rocks generally have been considered to be among 

the least uraniferous substances of the earth's crust. This 

conclusion has been based on analyses of a few samples. An 

investigation of the association of uranium with several types 

of carbonate rocks indicates that some revisions of the previous 

conclusion are necessary. Rocks that are composed almost 

wholly of carbonate minerals and that include only minute 

traces of other constituents generally contain about 0.0001 

percent (1 gram per ton), or less, of syngenetically deposited 

uranium ; they are among the least uraniferous rocks. The 

impure carbonate rocks, which form gradational series with 

many other kinds of sediments, may contain readily measurable 

quantities of syngenetically deposited uranium that is associated with the noncarbonate constituents. The quantities of 

such uranium may range from about O.OOOX to O.OOX percent 

and reach a maximum of a few tens of grams per ton. The 

phosphatic constituent in some appreciably uraniferous limestones and dolomites is thought to hold the uranium; detrital 

constituents and possibly organic matter may hold uranium in 

other carbonate rocks. Uranium is deposited epigenetically in 

carbonate rocks under a variety of circumstances, and some of 

these deposits provide rich ores. Epigenetically deposited 

uranium minerals in carbonate host rocks are found in hydrothermal veins, in efflorescent depos.its, in cavities of karst 

terrains, and as peneconcordant deposits in stratified carbonate 

rocks. The geochemical conditions that caus.e epigenetic deposition of uranium in carbona1

te rock environments, with the 

exception of those causing some efflorescent deposits, have not 

been determined. 

INTRODUCTION 

Limestones, dolomites, and other sedimentary carbonate rocks generally have been considered to be among 

the least uraniferous of all the rocks of the earth's crust, 

containing from almost none to about 4 parts per million uranium. This conclusion has been based on theoretical considerations and a few analyses of limestones 

and dolomites predominantly of marine origin. Recent 

investigations of carbonate rocks, both in the field and 

in the laboratory, have shown that, whereas most rocks 

that have carbonate minerals as major primary constituents have very little or possibly no uranium, nevertheless certain classes of these rocks may contain aboveaverage quantities of uranium. The earlier conclusion 

has been revised, and some qualifying amendments have 

been made. The investigations described below have 

not been accomplished in sufficient detail to permit complete recognition of all the geochemical relations involved, but some valid relationships have been established. 

OBJECTIVES OF THE INVESTIGATION 

The principal objectives of this investigation were to 

determine ( 1) to what extent uranimn is deposited 

syngenetically with carbonate sediments and what goochemical environments are essential for the inclusion 

or uraniferous substances with carbonate sediments and 

(2) some of the conditions under which uranium may 

be deposited epigenetically in carbonate rocks. Information leading toward attainment of these objectives 

was acquired by field examination of many carbonate 

rocks and by chemical analysis of a representative collection of these rocks and of carbonate source materials. 

PREVIOUS INVESTIGATIONS 

It was discovered during early investigations of the 

radioactivity of rocks and other terrestrial materials 

that carbonate rocks in general have very low levels of 

radioactivity. Consequently, little study has been made 

of radioactive constituents in carbonate rocks as compared with the amount of study of these constituents 

in other terrestrial materials. Because the uranium 

contents of many carbonate rocks are close to, or below, 

the threshold of analytical chemical procedures, many 

determinations by such methods are inconclusive. The 

results of some investigations have been reported in 

terms of radium contents, others as equivalent uranium 

contents-that is, actual uranium determinations were 

not accomplished. 

There are few published data pertaining to the 

uranium contents of carbonate rocks. These data are 

not accompanied by detailed descriptions or even 

descriptions of the principal characteristics of the rocks 

that were tested. Evans and Goodman (1941, table 9) 

Al 
A2 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY 

have reported uranium contents ranging from 0.30 

X 10-6 to 2.6 X 10-6 g per g of rock ( 0.00003 to 0.00026 

percent) for five samples of limestones from four 

localities. Lahner ( 1939) reported uranium contents 

ranging from 0.12 X 10-7 to 10.1 X 10-7 g per g of rock 

( 0.000012 to 0.0001 percent) for 12 carbonate rocks of 

various kinds; the sample materials were taken from 

museum specimens. Bell (1956, p. 521) reported uranium contents ranging from 0. 7 to 3.8 ppm (parts per 

million) ( 0.00007 to 0.00038 percent) for 11 typical 

marine limestones and dolomites. Baronov and others 

(EapoHoB, PoHOB, n RyHamoBa, 1956) determined 

the uranium contents of 128 composites of carbonate 

rocks made up from 5,475 samples collected from the 

Russian platform; each composite represented a tier, 

division, or system of the stratigraphic scale; ages 

ranged from the late Precambrian to Quaternary. 

The uranium contents of the composites ranged from 

1.2 to 5.4 ppm. Distinguishing cha.racteristics of the 

carbonate rocks represented in each composite are not 

given. Inasmuch as the range of values is rather high 

it is suspected that a substantial number of more or less 

phosphatic carbonate rocks were represented in the 

sample material. (See p. A5.) Some d~rminations 

of uranium contents of carbonate rocks containing 

epigenetically deposited minerals have been published, 

but inasmuch as the investigations dealt with uranium 

ores or potential ores of variable grade, the analytical 

data are not considered to be characteristic of carbonate 

rocks as a group. 

This rather meager collection of uranium determinations made on carbonate rocks indicates that, in general, 

uranium contents range from small fractions of a part 

per million to a few parts per million (probably in the 

range of <O.OOOOx to O.OOOx percent). Probably only 

syngenetically deposited uranium was present in the 

samples analyzed, but this condition cannot be taken 

for granted. The reports do not indicate whether variations in uranium contents can be attributed to depositional environments or to the kinds and amounts of 

noncarbonate constituents in these rocks. 

THEORETICAL CONSIDERATIONS 

The terms "limestone" and "dolomite" by definition 

designate sedimentary rocks composed predominantly 

of the carbonate minerals calcite and dolomite. The 

terms commonly are used to designate rocks containing 

roughly 50 percent or more by volume of carbonate 

minerals, and sometimes they are used questionably to 

designate rocks of which carbonate minerals are important constituents but constitute less than 50 percent 

of the volume. The noncarbonate constituents of different limestones and dolomites may consist of clastic 

detritus, clay minerals, iron oxides, manganese oxides, 

calcium phosphate minerals, calcium sulfate minerals, 

organic detritus, bitumens, various other organic derivatives of former plant and animal life, and many other 

substances. The carbonate-rich rocks therefore are 

parts of gradational series of which the end members 

are pure limestone or dolomite on the one hand and 

shales, siltstones, saline evaporites, and different varieties of organic-rich sedimentary rocks on the other 

hand. 

The sedimentary carbonate rocks are deposited in 

aqueous environments. The chemical conditions may 

be either oxidizing or reducing, but a much larger 

volume of carbonate sediments prdbably is deposited 

under oxidizing or slightly reducing conditions than 

under strong reducing conditions. The oxidation-reduction potential of the medium from which carbonate 

sediments are deposited has no bearing upon the deposition of alkaline-earth carbonates that constitute the bulk 

of the carbonate rocks, but it does play a major role in 

the kind and amount of syngenetically deposited chemical impurities. 

Carbonate sediments are formed by biogenic and 

chemical processes. Some reef limestones ·and coquinas 

are formed almost entirely of skeletal parts and shells 

of organisms; other limestones are composed almost 

wholly of precipitated calcium carbonate; many carbonate rocks are composed of a mixture of bioclastic 

and chemically precipitated components. The noncarbonate constituents in carbonate rocks may be deposited by any one of the sedimentary processes. 

It has been known for a long time that uranium in 

the oxidized, hexavalent or uranyl, state is highly soluble in the presence of substantial concentrations of 

carbonate or bicarbonate ions, and this property is utilized by analytical chemists in making quantitative separations of uranium from several other metallic elements 

(Fresenius and Hintz, 1895; Rodden and War£, 1950, 

p. 16, 31). It follows that in natural environments 

where the carbonate or bicarbonate ion concentration 

is high with respect to that of the uranyl ion, uranium 

should not be precipitated along with carbonate sediments. Nearly pure carbonate rocks that were deposited 

in oxidizing environments cannot be expected to contain 

appreciable quantities of syngenetically deposited 

uranium. 

Uranium in the tetravalent, or uranous, state is 

thought to form a soluble complex with the carbonate 

ion. This conclusion is based on the fact that uraninites, or pitchblendes, which contain a mixture of hexavalent and tetravalent uranium, will dissolve completely 

in some carbonate solutions, and uranium oxide (presumably uraninite) does not precipitate from all uraniferous carbonate solutions that are subjected to the 

reducing action of hydrogen sulfide. The behavior of 
URANIUM IN CARBONATE ROCKS A3 

the uranous ion in the presence of high concentrations 

of the bicarbonate and carbonate ions apparently has 

not been fully investigatE~d. 

Theoretical considerations indicate that uranium 

should not be deposited s:yngenetically with nearly pure 

carbonate rocks laid down in reducing environments. 

For example, a nearly pure limestone, even though 

characterized by a fetid odor due to hydrogen sulfide 

or sulfurous organic substances, normally cannot be 

expected to be appreciably uraniferous. 

Inasmuch as uranium has a strong tendency to remain 

in solution in the presence of high carbonate-ion concentrations and is not eoprecipitated with carbonate 

minerals, that uranium which is a syngenetic constituent of carbonate rocks must be intimately associated 

with the impurities or noncarbonate constituents of 

these rocks. Common constituents, or impurities, that 

occur in various carbonate rocks, and which are capable 

of holding small amounts of uranium, are certain heavy 

mineral resistates, sedimentary or marine apatite, 

fluorite, some kinds of organic matter, and possibly 

other less-abundant substances. 

Heavy mineral resistates may be present in impure 

carbonate rocks, especially those that contain clastic 

sediments. Zircon, sphene, igneous apatite, monazite, 

and other resistates commonly contain small amounts 

of uranium. Although these minerals contribute to the 

total uranium content of the host rock, the amount of 

the contribution generally is very small. 

Marine apatite is an important constituent of many 

marine limestones and dolomites, in fact, a completely 

gradational series exists between nearly pure carbonate 

rocks at one end and nearly pure phosphate rocks at 

the other end. The uranium content of primary marine apatite characteristically ranges from 0.005 to 0.02 

percent; phosphatic sediments that have been reworked 

in marine environments may have uranium contents 

ranging from 0.005 to 0.1 percent; it is thought that 

this uranium substitutes for calcium in the apatite 

structure, and it has been shown that uranium can be 

secondarily leached from or introduced into the apatite 

structure (Altschuler and others, 1958). If it is assumed that all the phosphate content of carbonate rocks 

is in the form of apatite, then the quantity of this 

mineral commonly is more than adequate to account 

for all the uranium. Some carbonate rocks contain 

substantial amounts of phosphatic fossils that hold 

small quantities of uranium. This uranium probably 

was introduced into the shells and skeletons after death 

of the organisms and is not strictly syngenetic, but for 

the purpose of this discussion it is considered to be so. 

Some fluorite, particularly the purple varieties, may 

contain small quantities of uranium. Most fluorite in 

sedimentary carbonate rocks probably is an epigenetic 

constituent, but small grains of this mineral are found 

in some limestones that are not metamorphosed and 

show no evidence of alteration or introduction of material by hydrothermal or other solutions. 

Organic matter is an important constituent of many 

sedimentary carbonate rocks. Again there are gradational series ranging from nearly pure carbonate rocks 

to nearly pure organic rocks. The hexavalent uranyl 

ion and the tetravalent uranous ion are known to form 

complexes with many organic substances, and several 

such combinations are utilized in analytical chemistry 

(Rodden and Warf, 1950, p. 11, 13). Undoubtedly 

many other organo-uranium combinations exist that 

have not been fully investigated or that are unrecognized. A part of the syngenetic uranium in some carbonate rocks probably is attached to organic matter. 

Inasmuch as the precise composition and identity of 

organic matter in sedimentary rocks are little-investigated subjects, only general statements can be mltde 

about the association of uranium with organic matter. 

Some forms of humic matter have a high capacity for 

taking up uranium (Szalay, 1957; Manskaya and others 

(MaHcRaH, .I(p03AOBa, n EMeJI:bHHOBa, 1956) ; Vine 

and others, 1958), but the precise composition and character of the organo-uranium combination are unknown. 

Many organic acids, some of which occur in nature in 

small or minute quantities, can form uranium salts. 

Hydrocarbons that are major constitutents of petroleums, asphalts, and most native bitumens apparently 

have no capacity for taking up uranium (Bell, 1960b), 

but some of the organic acids that are very minor constituents of petroliferous substances may readily form 

uranium salts. Some organic-rich carbonate rocks contain above-average quantities of uranium. 

This discussion of theoretical considerations so far 

has dealt primarily with syngenetic deposition of 

uranium in carbonate rocks. Epigenetic deposition of 

uranium in carbonate rocks is known to occur under a 

variety of widely differing conditions, hut no complete 

explanation for the origin of some epigenetic uranium 

deposits in carbonate rocks can ibe provided at this time. 

Solutions that transport uranium are likely to be 

either appreciably acid or alkaline rather than neutral. 

Uraniferous acid solutions can be of hydrothermal 

origin or can form from ground water in the zone of 

oxidation where sulfide minerals become oxidized. 

Acid solutions that flow through substantial amounts of 

carbonate rocks become neutralized, or they even may 

become slightly alkaline. Some uranium may be deposited as the pH changes. Alkaline carbonate-rich 

solutions readily transport uranium, and it is evident 

that the minerals of many uraniferous hydrothermal 

veins were deposited from such solutions. Some of 

these veins are found in carbonate rocks. The condi-
A4 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY 

tions that cause deposition of both uranium and carbonate minerals are not fully understood. Very few 

paragenetic studies of such deposits have been made; 

additional thorough studies are needed to provide more 

information on the order of deposition and the influence of wallrock and to furnish clues concerning the 

precise chemical and physical conditions that existed 

at time of deposition. 

The conditions that cause deposition of uranium in 

hydrothermal deposits undoubtedly are physically and 

chemically complex. It is possible to write chemical 

equations, based on experiments made at room temperature and approximately atmospheric pressure, 

that might represent reactions occurring during the 

depositional processes, but one does not have complete 

assurance that these reactions always occur in the range 

of physical and chemical environments that exist 

during genesis of hydrothermal deposits. The effects 

of temperature and pressure on the solubility relations 

between various ions in the ore-forming fluids, and 

on phase relations of the solid and dissolved portions 

of the reacting constituents are virtually unknown to 

the geologist. The same statement can be made concerning most epigenetic deposition of uranium in sedimentary rocks under conditions other than 

hydrothermal. 

SELECTION OF SAMPLE MATERIAL 

During this investigation, 70 samples of sedimentary 

carbonate rocks and carbonate source materials were 

collected and analyzed to determine their contents of 

uranium and principal constituents. In addition, 

eight samples obtained from well cuttings were checked 

for uranium contents only; the small size of these samples precluded determinations of other constituents. 

Most of the samples that were collected and analyzed 

represent carbonate rocks in which the uranium contents are probably wholly syngenetic. These rocks 

contain very small quantities of uranium and no visible 

or identifiable uranium-bearing minerals except possibly some clastic resistates and sedimentary marine 

apatite. A few carbonate rocks containing uranium 

minerals of undoubted epigenetic origin were sampled 

primarily for determination of their phosphate and 

fluoride contents; samples of such rocks having wide 

ranges of uranium contents can be selected at will because the epigenetic minerals usually are readily visible 

and identifiable, and it was thought that the possible 

presence of fluorides and phosphates that might have 

been associated with the uranium mineralization would 

be of greater interest. 

The number of samples analyzed was limited by the 

available capacity of the laboratory for this work. 

The sampling seems very sparse in relation to the al· 

most infinite variety of carbonate rocks. An attempt 

was made to get a wide coverage of carbonate rocks of 

varying compositions that were deposited in different 

environments. The collection includes marine and nonmarine rocks, calcitic and magnesian limestones, dolomites, marls, marlstones, fetid and nonfetid rocks, 

calcareous shells, and predominantly carbonate rocks 

having as impurities substantial amounts of phosphate 

minerals, clastic detritus, clays, iron oxides, and organic 

matter. 

The rock samples were taken from individual beds 

or from vertical sections a few inches thick because 

the character and composition of sedimentary carbonate rocks commonly change abruptly within short vertical distances, even from stratum to stratum within 

some thinly bedded series. The purpose of this selectivity was to limit each sample, insofar as practicable, 

to a unit representing a single depositional environment. About 50 pounds of rock was taken from most 

of rf:Jhe units sampled; the original sample was broken 

into small fragments and by successive quartering was 

reduced to approximately a 2-pound sample. The latter was pulverized in a grinder equipped with ceramic 

plates and then was further reduced by quartering to 

about 100 grams of material which was sent to the 

laboratory for analysis. 

ANALYTICAL PROCEDURES 

All the sample material collected during this investigation was analyzed in the Geological Survey Laboratory at Denver, Colo. The constituents th81t were determined are: uranium, acid-insoluble matter, calcium as 

calcium oxide, magnesium as magnesium oxide, total 

R20 8, iron as ferric oxide, phosphorous as phosphoric 

pentoxide, and fluorine. The results of the analyses 

are tabulated in ta;ble 2. 

Total uranium in the samples was determined by the 

ethyl acetate extraction-fluorimetric method. Details 

of the procedure are described by Grimaldi and others 

(1954). 

Acid-insoluble matter was determined as follows : 

To 2 g of the sample was added 50 ml of 1 : 1 hydrochloric acid; and the mixture was heated to a boil on a hot 

plate. The sample was then digested 1 hour on a steam 

bath, 50 ml of hot water was added, and the sample 

was filtered through tared sintered glass crucibles and 

washed with 1-percent hydrochloric acid. The crucibles and insoluble matter were dried at 105°0 and 

weighed. 

Acid-soluble calcium oxide and magnesium oxide 

were determined by titration with versene (Shapiro 

and Brannock, 1956). 

R20 8 was determined by ammonium hydroxide precipitation from an aqua regia solution. 
UR~ ~ CARBONATE ROCKS A5 

Total iron was determined colorimetr~cally with 

o-phenanthroline ( Cuttitta, 1952). 

Total phosphate was determined by the volumetric 

method of the Association of Official Agricultural 

Chemists (1950, p. 8-10). 

Total fluorine was determined colorimetrically by the 

method of Icken and Blank (1953) :following distillation by the method of vVillard and Winter ( 1933). 

An approximate mineral composition was calculated 

:for all samples in order to make a rough check of material balances and to assure that no important constituent was overlooked. All phosphate was assumed to 

be in the :form of apatite, (CaF)Ca4 (P04 }s; all fluorine not accounted :for in apatite was assumed to be in 

fluorite (CaF2); all calcium in excess of that assumed 

to be in apatite and fluorite was assumed to be in calcium carbonate ( CaC03) ; all magnesium was considered to be in magnesium carbonate (MgC03) ; uranium was assumed to be in the :form of the oxide, U30s; 

the percentages of insoluble matter and R20 3 were used 

as determined. The sun1mation of these assumed constituents is 100 ± 3 percent :for most of the samples. 

Deficiencies greater than 3 percent :for a :few samples 

reasonably can be accounted :for by constituents such 

as manganese oxides or earbonate, sulfide minerals, organic matter, silicate minerals, and other minor constituents known to be in the rocks. 

A petrographic examination of the rocks was made 

:for the purpose of observing textural features and 

identifying the principal noncarbonate constituents. 

The observations are included in table 2. 

CLASSIFICATION OF CARBONATE ROCKS 

The carbonate rocks and source materials sampled 

and analyzed during this investigation are divided into 

18 categories. The division is based in part upon welldefined characteristics and in part is arbitrary. This 

classification, used in the discussion and in presenting 

analytical data in table 2, is simply one possible method 

of classifying these rocks; obviously many classification schemes can be devised. 

The principal point of interest in this discussion is 

tJhe uranium content of carbonate rocks; 'therefore, they 

are divided into two ma;jor categories, those containing 

only syngenetically deposited uranium, and those containing epigenetically deposited ·uranium. Further 

subdivisions are based on combinations of the :following :features : ( 1) marine versus nonmarine origin, ( 2) 

unmetamorphosed versus metamorphosed rocks, ( 3) 

principal carbonate constituent, that is, calcitic limestones composed predominantly of calcite and containing less than 4 percent magnesium carbonate, magnesian limestones containing more than 4 percent and less 

686494-63-2 

than 30 percent magnesium carbonate, and dolomite 

which is arbitrarily considered to include all the rocks 

containing more than 30 percent magnesium carbonate, 

and ( 4) :fetid versus non:fetid rocks. Carbonate-bearing concretions, tufas, and shells of organisms are 

placed in separate categories. . The separation of fetid 

:from non:fetid rocks was made because some of the :fetid 

rocks may have been deposited in reducing environments that commonly are thought to be conducive to the 

precipitation of uranium. 

SYNGENETIC URANIUM IN CARBONATE ROCKS 

Minute quantities of uranium can be deposited syngenetically with carbonate sediments by at least :four 

mechanisms: 

1. Uranium can be a minor constituent of some substances that may be coprecipitated with carbonate 

sediments; an example is calcium fluophosphate, or 

marine apatite, in which a small quantity of uranium can substitute :for calcium. 

2. Uranium may be adsorbed on clay, gelatinous silica, 

and some :forms of organic matter that are deposited simultaneously with the ca,rbonate sediments. 

3. Uranium may become incorporated in the sediments 

shortly after deposition and, while the sediments 

still are in contact with the aqueous medium :from 

which deposition occurred, by base, exchange; an 

example of this mechanism is the increase of uranium in marine apatites that remain in contact 

with ocean water (Altschuler and others, 1958). 

4. Uranium can be a minor constituent of some heavy 

mineral resistates that are present in clastic detritus deposited with some impure carbonate sediments. 

It is essential to notice that uranium deposited by these 

mechanisms is contained in impurities adventitiously 

deposited with carbonate sediments. No primary uranium carbonate minerals are known to be deposited 

syngenetically with carbonate sediments. 

The analytical data presented in table 2 indicate 

that the most characteristic :feature of carbonate rocks 

containing only syngenetic uranium is the generally 

very low content of this element, which in most of the 

samples ranges from less than 1 ppm ( <0.0001 percent) to about 4 ppm ( 0.0004 percent). Among 51 

samples of carbonate rocks in which the uranium content is thought to be wholly syngenetic, 15 samples had 

uranium contents of less than 1 ppm, and 10 samples 

had uranium contents of 1 ppm. These 25 samples include marine and nonmarine rocks, calcitic limestones, 

magnesian limestones, dolomites, :fetid and non:fetid 

rocks, and metamorphosed and unmetamorphosed 
A6 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY 

rocks. The rocks in this group were deposited under a 

wide variety of sedimentary conditions. 

The most significant feature of this group of samples 

is that it includes most of the nearly pure carbonate 

rocks that were analyzed (examples: Upper part of the 

Burlington Limestone, I-A, No. 260486; upper part of 

the Madison Limestone, I-A, Nos. 260492 and 260493; 

Franklin Limestone, I-E, No. 249713, and I-B, 

No. 249714; Niagara Group, I-G, Nos. 249702 and 

249703; dolomites from the Stockbridge Limestone, 

I-I, Nos. 249704 and 260487). The group includes 

several fetid rocks (examples: Pinery Limestone 

Member of the Bell Canyon Formation, I -C, 

No. 260483; Edwards Limestone, I-D, No. 260448; 

Hueco Limestone, I-D, No. 260488; limestone bed in 

Pierre Shale, I-D, No. 249717). The group also includes some carbonate rocks that contain a few percent 

of impurities in the form of acid insoluble matter, iron 

and aluminum oxides, and probably other minor constituents (examples: St. Louis Limestone, I-A, 

No. 249711; Sinbad Limestone Member of Moenkopi 

Formation, I-A, No. 260542; limestone from Maysville Group, I-A, No. 249710; limestone from Chaffee 

Formation, I-D, No. 260457; Pony Express Limestone 

Member of \Vanakah Formation, I-J, No. 260479). 

Only one conclusion can be drawn from this assemblage 

of data, that is, uranium is not syngenetically deposited 

in significant quantities with most carbonate rocks. 

This conclusion is in accordance with the theoretical 

consideration that uranium compounds, under most 

circumstances, are not deposited from solutions in 

which carbonate, or bicarbonate, or carbonate and bicarbonate ion concentrations are high with respect to those 

of various uranium ions. 

The fact that the fetid rocks do not contain significant quantities of uranium merits a brief comment. If 

the sediments that constitute these rocks had been deposited from sulfurous waters where reducing conditions prevailed, they might be expected to contain 

greater quantities of uranium than nonfetid rocks 

having otherwise identical compositions. The quantities of uranium would be dependent upon rates 

of sedimentation and availability of uranium in 

the aqueous medium. Rapid sedimentation generally 

would result in low uranium contents. Sediments 

oftentimes may be deposited on the ocean bottom or a 

lake bottom under oxidizing conditions and, after a 

particular layer becomes buried at a slight depth, 

putrefaction of a small content of organic matter 

creates a sulfurous reducing environment. The available uranium is limited to the minute quantity present 

in the connate water and, consequently, the sediment 

cannot become appreciably enriched with the element. 

No attempt was 1nade during this study to determine 

whether the fetid character of the rocks was acquired 

contemporaneously with deposition or by subsequent 

alteration of primary sediments. 

The trubulated data indicate that, when substantial 

quantities of phosphate are present in carbonate rocks 

as an impurity, the uranium contents may be considerably increased. For example, the limestone sample 

from the Uinta Formation (I-F, No. 260490) contained 

0.28 percent P20 5 and 0.021 percent uranium, a dolomite 

sample from the IGttatinny Limestone (I-I, No. 

249706) contained 0.40 percent P205 and 0.0020 percent 

uranium, and a sample from the !iilton Dolomite (I-I, 

No. 249708) contained 3.06 percent P205 and 0.0030 

percent uranium. The sample of limestone from the 

Uinta Formation, which is of nonmarine origin, was 

taken from a bed about 4 inches thick; this sample contained a small quantity of organic matter of undetermined character that probably holds some of the 

uranium. The IGttatinny Limestone and Milton 

Dolomite are of marine origin and have thick, slightly 

phosphatic beds that can be traced for considerable 

distances. There is no constant ratio between the 

phosphate and uranium contents of carbonate rocks. 

Some of the most phosphatic samples collected during 

this investigation, such as one from the Bigby Limestone (I-A, No. 260445) that contained 2.85 percent 

P20 5 and one from the Hermitage Limestone (I-B, 

No. 260446) that contained 6.87 percent P205, contained 

only slightly more uranium than the general run of 

nonphosphatic rocks, that is, 0.0002 and 0.0004 percent 

respectively. 

Four samples of slightly phosphatic and uraniferous 

limestone containing a substantial amount of organic 

matter (III-A, Nos. W66873, W67241, W67247, and 

W90218) from the Bear River Formation of Cretaceous 

age, Fall River area, Bonneville County, Idaho, (collected by J. D. Vine of the Geological Survey) have 

been analyzed, and the results are included in table 2. 

These limestone samples contained about 1 percent P205 

and 0.01 to 0.024 percent uranium. The phosphateuranium ratios are unusually high, and some of the 

uranium probably is associated with the organic 

matter. The Fall River locality has not been examined 

by the author, and it cannot be stated definitely whether 

all the uranium in this limestone is syngenetic or 

whether some of it may represent a late enrichment. 

For this reason these samples are not listed with those 

believed to contain only syngenetic urani urn. 

A lack of correlation between phosphate and uranium 

in apatites and phosphorites has been noted by several 

investigators (Hebert, 1947; Davidson and Atkin, 

1953; Altschuler and others, 1958). Recent investigations by Altschuler and others (1958) indicate that 

uranium probably enters the apatite structure in iso-
URANIUM IN CARBONATE ROCKS A7 

morphous substitution for calcium, and the substitution 

can take place as the mineral is formed and at any time 

thereafter when ocean water, ground waters, or other 

aqueous solutions make uranium available. The phosphatic constituents of carbonate rocks probably are 

predominantly forms of apatite, fluorapatite, and carbonate-apatite. The introduction of uranium into 

lacustrine and marine limestones and dolomites most 

likely occurs between the time the sediment is deposited 

on the bottom and its burial by the next suceeding layer. 

The quantity of uranium that can be introduced is dependent upon its concentration in the water and the 

length of time the sediment remains unburied. These 

conditions are conducive to highly variable 

uranium-phosphate ratios, particularly when the rate 

of sedimentation fluctuates. 

None of the samples listed in table 2 as containing 

only syngenetically deposited uranium contained megascopically visible fluorite although a few of them contained a few hundredths of a' percent of fluorine in 

excess of that which would be held in fluorapatite if all 

the phosphate constituent exists in this mineral. (Examples: Bigby Limestone, I-A, No. 260445; Hermitage 

Limestone, I-A, No. 260446; Mahogany oil shale bed 

(of economic usage) in the Parachute Creek Member 

of the Green River Formation, I-F, No. 260464; marlstone from the Green River Formation, I-K, No. 

260485). The maxim urn uranium content of these 

samples was 0.0004 percent, and it cannot definitely be 

associated with any particular constituent. The Salem 

Limestone ( Spergen Limestone of former usage) locally 

contains scattered small crystals of purple fluorite. The 

two samples of this rock, I-A, No. 249720, and I-D, No. 

260463, that were selected for analyses did not contain 

any visible fluorite and contained only 0.0004 and 

0.0003 percent uranium respectively. During wet 

periods, thin effiorescent films of a carnotite-type mineral, which apparently is a transient substance here, 

appear on some joint surfaces and parts of quarry faces 

in this rock (J\fuilenburg and Keller, 1950; Gott and 

others, 1952, p. 34). 

Uranium, in many places, is associated with various 

native organic substances that, in general, have not been 

precisely identified. There is substantial evidence that 

uranium tends to associate with humic-type organic 

substances (Vine and others, 1958; M·anskaya and 

others (MancEaa, Jipos.n;oBa, :n: EMeJibaHoBa, 1956)) 

and shuns sapropelic-type organic substances, including 

petroleum hydrocarbons (Bell, 1960b) and sapropelic 

solids. Different carbonate rocks contain a wide variety 

of native organic substances as impurities. 

Several of the samples of carbonate rocks analyzed 

during this investigation contained readily noticeable 

quantities of organic matter. A sample of dark-gray 

fetid Madison Limestone (I-C, No. 260450) that contained many fossil brachiopods contained 0.0004 percent uranium. A sample from the Sinbad Limestone 

Member of the Moenkopi Formation (I-A, No. 260452) 

that contained about 2 or 3 percent of heavy petroliferous residue and a sample of dolomite from the Niagara 

(I-G, No. 249703) that contained enough residual 

petroliferous matter to give the rock a dark brown color 

contained 0.0001 and less than 0.0001 percent uranium, 

respectively. These determinations confirm the earlier 

observations that petroliferous substances are not carriers of significant quantities of uranium (Unkovskaya, 

1940; Bell, 1960b). Two samples of metamorphosed 

Franklin Limestone (I-E, No. 249713, and I-B, No. 

249714) that contained abundant flakes of graphite both 

contained less than 0.0001 percent uranium. A sample 

of madstone from the Mahogany oil shale bed in the 

Parachute Creek Member of the Green River Formation 

(I-F, No. 260464) that contained at least 25 percent 

kerogen contained only 0.0004 percent uranium. This 

determination supports the observation that sapropelic 

substances are not carriers of significant quantities of 

uranium. The samples that were analyzed did not indicate any tendency for uranium to concentrate in the 

organic-rich carbonate rocks. 

During the course of investigating the distribution of 

uranium in salt-pan deposits (Bell, 1960a), several samples of drill cuttings from the Hermosa Formation of 

the Paradox basin, southeastern Utah, were checked 

for uranium contents. This collection included seven 

samples of dolomite. The small amounts of material 

that were available permitted only uranium determinations to be made. A few thin beds of slightly uraniferous black shale (maximum uranium content was 0.0057 

percent) are interspersed in the dolomite. The dolomite 

samples contained no megascopically visible shaly 

material. All the samples were oil stained and emitted 

an odor of crude petroleum when crushed. The analytical data are listed in table 1. No unusual concentrations of uranium are indicated, and it is thought 

that the slight traces of uranium were deposited syngenetically with the carbonate sediments. 

A few conclusions can be drawn from the preceding 

discussion and from the analytical data presented in 

table 2: Uranium is an insignificant syngenetic constituent of rocks composed almost wholly of carbonate 

minerals and of only traces of phosphates, fluorides, 

and organic substances of humic origin. The uranium 

contents of these rocks reasonably can be considered to 

range from 0 to 0.0001 percent ( 1 gram per ton). 

The almost pure carbonate rocks are end members 

of gradational series with many other kinds of sedimentary rocks. As the proportions of noncarbonate 

constituents increase, the uranium contents likewise 
A8 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY 

TABLE 1.-Uraniumcontent of dolomite/rom the Hermosa Formation, Paradox basin, San Juan County, Utah 

[Analysts: C. G. Angelo, J.P. Schuch, and E. J. Fennelly] 

Sample Description 

252225 ____ ----- Dolomite ___ --- __ --------------- 252226 ______________ do ________________________ _ 

252227 ______________ do ________________________ _ 

252228 _ _ _ _ _ _ _ _ _ Dolomite and anhydrite ____ ---- __ 252248_ _ _ _ _ _ _ __ Dolomite ________ ---- ___ -------- 252253 ______________ do ________________________ _ 252256 ______________ do ________________________ _ 

Source of samples: 

Uranium 

(percent) 

0.0004 

• 0011 

. 0003 

. 0003 

. 0002 

. 0001 

. 0005 

Nos. 252225, 252226, 252227, 252228 from Shell Oil Co. 1 North Boundary Butte 

well, CSW~NE~ sec. 33, T. 42 S., R. 22 E., San Juan County, Utah, at depths of 4,221 ft 6 in, 4,622 ft, 4,623 ft, and 4,625 ft, respectively. 

No. 252248 from Superior Oil Co. 1-28 Navajo well, CNW~NW~ sec. 28, T. 

41 S., R. 26 E., San Juan County, Utah, at depth of 6,073 to 6,074 ft. 

No 252253 from Shell Oil Co. 1 Desert Creek well, SW+4SE~NW34 sec. 2, T. 42 S., R. 23 E., San Juan County, Utah, at depth of 5,128 ft 6 in. 

No. 252256 from Reynolds Metal Co. 1 Hatch well, sec. 4, T. 39 S., R. 24 E., 

San Juan County, Utah, at depth of 5,799 to 5,800 ft. 

may increase appreciably. The presence of phosphate, 

presumably as calcium phosphate in some form of 

apatite, commonly has a significant effect on uranium 

content. Many phosphatic carbonate rocks contain 

quantities of uranium that are n1easurable by routine 

chemical methods (in excess of 0.0001 percent or 1 gram 

per ton). This uranium probably substitutes for calcium in the apatite structure, and the quantities of 

uranium in such rocks are dependent upon environments existing at times of sedimentation and upon subsequent geological histories. There is no consistent 

ratio between the uranium and the phosphate contents 

in these rocks; in fact, some phosphatic limestones are 

almost devoid of uranium, and the quantities of uranium 

in other phosphatic limestones may reach a few tens of 

grams per ton. The uranium in carbonate rocks containing substantial amounts of detrital sediments is 

most likely to be in uraniferous heavy mineral 

resistates. The association of uranium with organicrich carbonate rocks has not been thoroughly investigated. Available data indicate that carbonate rocks 

containing sapropelic derivatives such as kerogen and 

petroleum hydrocarbons are not enriched in uranium. 

It is pointed out in the discussion of epigenetic uranium 

deposits in carbonate rocks that some of these rocks 

which contain rich uranium deposits are strongly fetid. 

Analyses of several fetid limestone and dolomite 

samples show that these rocks, as a group, are not at 

all enriched with syngenetically deposited uranium. 

Finally, no useful result can come from any attempt 

to establish average uranium contents of comparatively 

impure carbonate rocks on the basis of available data. 

The uranium contents of these rocks are associated with 

the noncarbonate constituents rather than the carbonates, and, to have any meaning at all, average uranium 

contents should be expressed in relation to quantities 

of specific impurities in the carbonate rocks; sufficient 

analytical data to justify such expressions have not 

been assembled. 

EPIGENETIC URANIUM DEPOSITS IN 

CARBONATE ROCKS 

Uranium is deposited epigenetically in carbonate 

rocks under a wide variety of circumstances. In the 

discussion that follows these deposits are divided into 

four types : ( 1) hydrothermal veins, ( 2) effiorescent deposits, ( 3) deposits in karst terrains, and ( 4) peneconcordant deposits. The term hydrothermal vein should 

need no explanation. The effiorescent deposits form 

at or near the earth's surface by evaporation of uraniferous solutions. Many minerals can be deposited in 

caves, solution channels, and other cavities in the carbonate rocks of karst terrains; uranium minerals are 

included in this group. The peneconcordant deposits 

are formed in permeable sedimentary rocks. Epigenetic uranium deposits may originate from hydrothermal processes, from supergene enrichment processes, 

may be effiorescent, or even may form as results of combinations of these processes. 

URANIUM IN HYDROTHERMAL VEINS 

Large uraninite-bearing veins of hydrothermal origin cut across sedimentary carbonate rocks in the Shinkolobwe district, Republic of Congo (Thoreau and du 

Trieu de Terdonck, 1933, 1936; Bain, 1950; Derriks 

and Vaes, 1956), and in the Lake Athabaska region, 

Saskatchewan, Canada (Alcock, 1936, p. 36; Christie 

and Kesten, 1949; Bowie, 1955; Robinson, 1955). Uranium-bearing veins have been discovered in carbonate 

rocks at several localities in Central Asia; the uranium 

minerals near the surface are mainly carnotite and 

tyuyamunite and are accompanied in different deposits 

by barite, sulfide minerals, and secondary copper minerals. Available descriptions hint that the primary 

mineralization in some of these deposits may have been 

hydrothermal. Such deposits at Kan-sai in the 

Tadzhik S.S.R. are described by Arapov (ApanoB, 

1936); deposits at Tyuya-Muyun in the Uzbek 

S.S.R. are described by Alexandrov (AJieRcaH;o;poB, 

1922), Pavlenko (IIaBJieHKO, 1933), and Betekhtin 

(BeTexTHH, 1946); deposits at Agalyk in the Uzbek 

S.S.R. are described by Gorbunov (rop6yHoB, 1935) 

and Gotman croTlvraH, 1937); and deposits at Taboshar in the Tadzhik S.S.R. are described by Vol'fson 

(BoJin<f>coH, 1940). 

The uraninite-bearing hydrothermal veins at Shinkolobwe are enclosed by dolomite in which there are 

some schist, sandstone, and siliceous beds. The structure, mineralogy, and geological history of these deposits are complex. The deposits have been deeply 

weathered, and above the present ground-water table 
URANITUl4 ~ CARBONATE ROCKS A9 

the secondary ores, which have been largely mined out, 

consist of a great variety of secondary uranium minerals and oxidation products of primary sulfide and 

selenide minerals. Descriptions of the deposits by 

Thoreau and du Trieu de Terdonck (1933) and Derriks and Vaes (1956) indicate that a large proportion 

of the carbonate constituents in the oxidized zone has 

been removed, apparently by weathering processes. 

Below the water table, in the unoxidized zone, uraninite is the only uranium mineral, and carbonate minerals, both in the veins and in the wallrock, are intact. 

The mineralization process apparently included at 

least two phases of vein carbonate mineral deposition, 

one preceding and one following uraninite deposition 

(Derriks and Vaes, 1956, p. 127). Several sulfide minerals, those of nickel and cobalt being most abundant 

and including iron, molybdenum, and copper sulfides, 

were deposited after the uraninite. Descriptions of 

the deposits indicate that uraninite replaces some of 

the earlier carbonate minerals, and, in turn, is replaced 

by later carbonate minerals; uraninite and sulfide minerals tend to be concentrated in separate veins. 

Uraninite-bearing veins in the Lake Athabaska region, Saskatchewan, Canada, are enclosed in a sequence 

of Precambrian rocks that includes gneisses, chlorite 

schists, diabases, basalts, quartzites, conglomerates, and 

dolomites. The vein materials consist principally of 

carbonate and sulfide rninerals and lesser amounts of 

uraninite and other minerals. Uraninite-bearing parts 

of the veins occur within all the rocks of the region, but 

published descriptions soem to indicate that the quantities of uraninite are least where dolomite forms the 

wallrock. About 40 percent of the uraninite occurs as 

colloform masses, 5 percent as dusty or sooty powder, 

and most of the remainder as massive pitchblende or 

uraninite (Robinson, 1955, p. 61). 

There is little inforn1ation available to the author 

about the uraniferous veins of Central Asia. The obtainable literature reports only the presence of secondary uranium minerals in these deposits; this indicates that the descriptions probably apply to oxidized 

zones. Some of the veins in the Tyuya-Muyun locality 

originally may have consisted of minerals of hydrothermal origin. The hydrothermal activity could have 

been associated with nearby igneous intrusions according to Pavlenko (IIaBJieHRo, 1933) and S'himkin 

(1949). Arapov (Apa1roB, 1936) has described uraniferous deposits within limestone, which in places has 

been converted to skarn, along the contact with a 

granodiorite batholith in the vicinity of Kan-sai. 

Other uranium deposits within limestones and near 

contacts with igneous intrusive rocks that are situated 

near Agalyk in the Uzbek S.S.R. have been described by Gorbunov crop6yHOB, 1934)' Zil'bermintz 

(3nJII>6epMHHD;, 1935), and Zil'bermintz and Samoilo 

(3HJII>6epMHHD; H CaMOti:Jio, 1935). 

Slightly uraniferous apatite and traces of a powdery 

yellow uranium mineral have been found in a fault 

zone in the Kittatinny Limestone at the Mulligan 

quarry, Clinton, N.J. The traces of secondary yellow 

uranium mineral may have been derived from the apatite or may be a slight supergene enrichment of uranium 

leached from the carbonate rock itself or from formations that formerly overlay the Kittatinny hut have 

been eroded from the locality. The rock exposed in the 

Mulligan quarry is dolomite or has the chemical composition of dolomite. Two samples (I-I, Nos. 249706 

and 249707) taken from the quarry contained 0.0020 

and 0.0006 percent uranium respectively; sample 

249706 was taken from a bed of slightly phosphatic rock 

approximately 10 feet thick. 

In summary, it is pointed out that, although carbonate rocks would seem on the basis of theoretical considerations to provide unfavorable environments for 

the deposition of uranium minerals from hydrothermal 

solutions, such deposits do exist and some furnish rich 

ores. This situation indicates a gap in our knowledge 

of the chemical behavior of uranium. Carbonate gangue 

minerals are abundant in the known deposits. 

At Shinkolobwe, uraninite veins are enclosed in predominantly carbonate rocks; on the other hand, in the 

Lake Athabaska region carbonate rocks form a small 

part of the stratified sequence, and the richest parts of 

the uraninite-bearing veins are adjacent to siliceous 

rocks. An interesting observation has been made by 

Derriks and Vaes (1956, p. 106) in describing the Shinkolobwe deposits. They state, "The uraninite is always 

crystalline. We have never observed at Shinkolobwe 

the colloform type which occurs at Great Bear Lake and 

St. J oachimstal." The following question arises: Is 

uraninite deposited in a carbonate rock environment 

likely to be crystalline and that deposited in a silicate 

rock environment likely to be colloform ~ 

EFFLORESCENT DEPOSITS OF URANIUM MINERALS 

Superficial deposits of efflorescent epigenetic uranium 

minerals are found in some places on walls of solution 

cavities 'and open fractures and even on surfaces of outcrops of all kinds of rocks. Tyuyamunite, carnotite, 

uranophane, bayleyite, and schroeckingerite are the 

most common constituents of such deposits, but other 

secondary uranium minerals may be deposited. The 

distribution of uranium minerals is generally erratic 

and commonly is so sparse that the minerals are barely 

visible. Such deposits are fairly common in semiarid 

regions and are rather uncommon elsewhere. The 

uranium minerals in some deposits are associated with 

substantial amounts of chalcedony and (or) opal and 
AlO SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY 

in other deposits with secondary calcite or with nonuraniferous efflorescent minerals. All these substances 

are deposited because the solutions that transport them 

evaporate. A change of pH as the solutions enter a 

carbonate rock environment probably is a secondary 

factor causing deposition. 

The largest efflorescent deposits that have been found 

in carbonate rocks in the United States are in the Miller 

Hill area of Carbon County, Wyo. Here they are small 

uranium deposits on and within a few feet of outcrops 

of a thin lenticular lacustrine algal limestone bed in 

theN orth Park ( ~) Formation of Pliocene ( ~) age. The 

limestone is more resistant to erosion than the so.ft sandstone above it. The limestone is exposed in small cliffs 

and on benches ranging from a few feet to a few hundred feet in width behind the cliff's. The only visible 

uranium mineral is uranophane that is spottily distributed in fractured and brecciated parts of the limestone. 

This mineral apparently does not occur in the rock ·along 

the cliff faces; it is most abundant in a zone of variable 

width on the benches extending from the margin of the 

overlying sandy sediments towards the cliff's. 

Slightly uraniferous chalcedony and opal, mostly 

dark gray to black, have been deposited in fractures, 

vugs, and solution cavities in the limestone. These minerals, which have a greater distribution than the uranophane, definitely are epigenetic constituents of the 

rock. The chalcedony and opal were deposited from 

ground-water solutions carrying both silica and uranium. A part of the silica seems to have been deposited 

as a result of evaporation, but reactions between silicarich solutions and the carbonate rock may have caused 

a substantial part of the deposition of silica. 

The uranophane in this limestone seems to be a strictly 

efflorescent mineral. It has been found only in the 

upper part of the limestone bed where it crops out or 

is covered with a thin soil mantle; it has not been found 

on cliff faces because it can be readily leached in such 

places. U ranophane evidently is being formed by 

evaporation of uraniferous ground-water solutions, and 

capillary action is instrumental in bringing the solutions toward ground surface. U ranophane is a rather 

soluble uranium mineral; it is more soluble than carnotite and tyuyamunite. There is probably a slow, but 

continuous, movement of uranium across the limestone 

benches; uraniferous ground water draining from the 

more elevated terrain behind the benches evaporates 

from the porous limestone exposed along the benches; 

through the medium of successive resolution and redeposition, the uranium moves toward the cliff faces and 

finally is carried a way in the surface drainage. U ranium that becomes incorporated in uranophane is not 

leached from chalcedony and opal. 

Uranium deposits in the Miller Hill area also have 

been described briefly by Love ( 1953) and by Vine and 

Prichard (1959) who suggest that the uranium was 

leached from tuffaceous beds in the upper part of the 

North Park ( ~) Formation and transported to sites of 

deposition by ground water. 

Small pockets of ore-grade material are found in the 

Miller Hill area. The deposits discovered up to 1958 

ranged from a few hundred pounds to possibly a ton 

of ore-grade rock. The small size of these deposits, 

and an erratic distribution of the uranium mineral make 

them unfa.vorable for profitable exploitation. 

U ranophane is locally rather abundant in the uppermost part of the Todilto Limestone, Grants district, 

McKinley County, N.Mex., but not in sufficient quantity to constitute ore. It has been deposited in vugs, 

solution cavities, and along open fractures. This 

uranophane seems to be in the form of efflorescent 

deposits. 

Similar deposits found in carbonate rocks elsewhere 

in the United States produce interesting specimens but 

not ores. Such minor deposits in the Hueco and 

Edwards Limestones of west Texas are described by 

Eargle (1956). Carnotite and tyuyamunite form thin 

films on fracture surfaces and walls of cavities in these 

limestones and on surfaces of boulders ·and pebbles in 

the alluvial mantle. The uranium probably has been 

leached from thin clay and shale beds in the limestone 

formations by ground and surface waters. Yell ow 

secondary uranium minerals occur in cavities and fractures in limestone beds of Mississippian and Pliocene( ~) 

age in the vicinity of Clarkdale and Jerome, Ariz. 

Minor deposits of uranium minerals occur in the limestone facies of the Hermosa Formation, Gypsum Valley 

area, San Miguel County, Colo. Stephens (1954) has 

described briefly minor deposits of secondary uranium 

minerals in cherty limestone of the Browns Park ( ~) 

Formation of Miocene(~) age in the Saratoga area, 

Carbon County, Wyo.; these deposits are similar to 

those in the Miller Hill area. Isachsen and others (1955, 

p. 129) mention the presence of copper-uranium mineral 

concentrations in the uppermost parts of the Kaibab 

Limestone of Permian age near Williams, Ariz. 

Thin films of carnotite coat fracture surfaces and 

cavities in dolomite wallrock of hydrothermal fluorspar 

pipes in the Thomas Range district, Utah (Thurston 

and others, 1954, p. 5 and 29') . The fluorite in these 

deposits is slightly uraniferous, and near-surface weathering probably has released some uranium that has been 

redeposited in carnotite. 

Yell ow coatings of carnotite, or a carnotite-type 

mineral sporadically appear on rock faces of quarries 

in the Salem Limestone ( Spergen Limestone of former 

usage) near Ste. Genevieve, Mo. The limestone itself 
URANIUM IN CARBONATE ROCKS All 

does not seem to contain unusually large amounts of 

uranium; the two samples (I-A, No. 249720 and I-D, 

No. 260463) analyzed during this investigation contained 0.0004 and 0.0003 percent uranium, respectively. 

A few thin seams of dark-gray to black clays and shales 

are interspersed among the limestone strata. A sample 

of shale collected by G. B. Gott, U.S. Geological Survey, 

contained 0.48 percent uranium oxide as U30 8• Ura-· 

nium probably is being leached from the clays and 

shales by ground waters and is being deposited in 

carnotite where these waters evaporate from rock 

surfaces. 

URANIUM DEPOSITS IN KARST TERRAINS 

Rich deposits of secondary uranium minerals are 

found in caves, solution channels, and fractures in 

carbonate rocks of karst terrains at Tyuya-Muyun, 

Fergana district, Uzbek S.S.R., U.S.S.R., and in the 

Pryor Mountains-Bighorn Mountains area of Montana 

and Wyoming. According to Alexandrov (AJieRca-H 

m>OB, 1922), the Tyuya-Muyun deposits have been 

known for several centuries and were worked sporadically by the Chinese for the copper minerals that they 

also contain. The deposits in the Pryor and Bighorn 

Mountains were discovered in 1955. 

TYUYA·MUYUN, FERGANA DISTRICT, UZBEK S.S.R. 

The ore deposits for which the Tyuya-Muyun 

locality is especially noted consist mainly of incrustations of calcite, barite, and several secondary uranium, 

vanadium, and copper minerals that partly or wholly 

fill a series of caves, solution channels, and fractures 

in metamorphosed limestones of Paleozoic age. The 

deposits are in the northern foothills of the Alai Range, 

and according to Pavlenko ( llaBJieHRO, 1933) they are 

close to an area where a series of younger volcanic rocks 

have been erupted upon a sedimentary terrain. The 

-ores have been mined to depths exceeding 175 meters. 

The incrustations locally reach a thickness of 1.5 meters 

and consist of successive layers that vary in number, 

thickness, and to some extent in order of deposition 

from one cavity to another; the general sequence of 

mineral layers, in order of deposition as stated by 

Betekhtin (BeTexTHH, 1946) , is as follows : ( 1) calcite interspersed with thin argillaceous-carbonaceous 

bands, (2) coarse-grained calcite with tyuyamunite, 

turanite (5 CuO .v, 0 5 • 2H20), and other minerals, (3) 

barite, both red and honey yellow and red quartz, ( 4) 

barite breccia cemented with younger barite and carbonate minerals, and ( 5) dense calcite and earthy red 

clays. 

The Tyuya-Muyan deposit, as described by Fersman 

(<DepcMaH, 1928), is in the midst of a vein field. According to Shimkin ( 1949), at least 5 barite veins 

containing uranium, vanadium, and copper minerals, 

and at least 30 pure barite veins are known in the 

locality. No report that describes completely the 

possible origin and emplacement of the uraniferous 

ores has been available to the author. No direct association between the uraniferous barite veins and the 

fillings of the karst cavities has been demonstrated. 

Pavlenko (llaBJieHRo, 1933) has proposed the following general sequence of mineral deposition within 

the cavities: (1) a thermal ore process which was 

dependent upon solidification of diabase rocks and 

during which calcite and then calcite and ore minerals 

were deposited, ( 2) a thermal barite process during 

which barite was deposited, (3) a typical first "karst" 

process during which banded crusts were deposited, and 

( 4) a second "karst" process during which previously 

deposited barite was reworked and quartz and then 

aluminous sediments were deposited. Pavlenko's conclusions and the presence of many barite veins containing metallic constituents suggest that the uranium may 

be of hydrothermal origin. No published reports 

available to the author stated that primary uranium 

minerals, such as uraninite, have been found in the 

locality. Unsubstantiated reports indicate that uraninita has been found in deep mines of the locality. 

BIGHORN-PRYOR MOUNTAINS, WYOMING AND MONTANA 

A karst terrain that was formed in the upper part of 

the Madison Limestone of Mississippian age during 

Late Mississippian or Early Pennsylvanian time is now 

exposed on the westward-facing slopes of the Pryor 

Mountains of south-central Montana and the northern 

part of the Bighorn Range of north-central Wyoming. 

Some of the caves and solution channels formed during 

the main karst-forming stage subsequently have become partly or wholly filled with an assortment of 

debris, and some of this debris is mineralized with 

tyuyamunite. 

The materials within individual caves and solution 

channels may include blocks of limestone that have 

fallen from the backs and walls, chert nodules and 

other insoluble residue from the limestone, clay, silt, 

and sand washed in from the surface of the ground or 

from rocks that formerly overlay the Madison, and in 

some caves large quantities of siliceous sinter. Some 

of the fine-grained sediments are stratified and indurated and form masses of siltstone or sandstone. 

The rubble in some of the caves is unconsolidated, and 

in other caves it is cemented by siliceous sinter or by 

secondary calcite. 

The uranium deposits are restricted to the rubble, 

sinter, and sediments within the caves and to scaly 

crusts on the walls of caves, solution channels, and 

fractures. Tyuyamunite is the only uranium mineral 
A12 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY 

that has been identified from these deposits. Tyuyamunite occurs in powdery form dispersed in silt and 

siliceous sinter, as powdery films on secondary calcite, 

as scaly crusts on walls of cavities and caverns, and as 

films and scaly crusts on limestone rubble and chert 

nodules. Some caves in the area have not been mineralized. The controlling factors of the mineralization 

process have not been determined. The deposits range 

from insignificant accumulations of tyuyamunite within 

a single small opening to those occupying series of connected caves, channels, and fractures extending over 

distances of several hundred feet horizontally and to a 

known depth of 175 feet. The quantity of uranium in 

the mineralized material ranges from mere traces to 

several percent and tends to be erratically distributed. 

The uranium was introduced into the cave fillings 

from some source outside of the limestone. Although 

cave walls may be coated with highly uraniferous incrustations, limestone an inch or so back from the incrustations generally is nonuraniferous except along 

surfaces of connected fractures and solution cavities. 

This observation was checked by uranium determinations on two samples of limestone broken from the walls 

of heavily mineralized caves, one at Big Pryor Mountain in Montana and the other at the Little Mountain 

locality near the north end of the Bighorn Mountains 

in Wyoming. The two samples (I-A, Nos. 260492 and 

260493) contained less than 0.0001 percent uranium. 

The source of the uranium has not been determined. 

The two most likely methods of emplacement seem to 

be: (1) the deposits are supergene enrichments of 

uranium leached from formations that are younger than 

the Madison Limestone and which formerly covered 

the area, and (2) the tyuyamunite is the oxidized 

residue of hydrothermal deposits. 

The principal point in favor of the supergene enrichment hypothesis is the presence, in the Mesozoic and 

Tertiary rocks of the region, of several formations containing an abundance of arkosic and tuffaceous material. The most uraniferous of these sediments are in 

the Tertiary section. An obstacle to strict supergene 

enrichment is the presence of several more or less impervious mudstone, clay, and shale formations and 

strata distributed throughout the sedimentary sequence. 

Shale and clay beds in the Amsden Formation of Pennsylvanian age that directly overlies the Madison would 

seem to prevent a normal type of supergene enrichment. It is possible that as the present Madison surface was exposed through erosion, surface and ground 

waters carrying uranium leached from surrounding 

terrain may have deposited it in the cave and solution 

channels in the limestone. 

Evidence supporting a possible hydrothermal origin 

for the uranium likewise is meager. Very few features 

that might be attributed to hydrothermal activity 

were seen by the author while examining several dozen 

prospects. Fluorite and barite are common, although 

minor, constituents of the material filling fractures and 

caves of the Big Pryor Mountain locality; these minerals were not observed in the limestone wallrock. 

Several hundred pounds of massive pyrite within a 

fracture zone was exposed in a prospect in the Little 

Mountain locality. Secondary calcite, commonly in 

the form of dog-tooth spar, occurs in many of the deposits and is very abundant in the Little Mountain locality. Siliceous sinter partly fills some caves and has 

been deposited in large quantities along some fracture 

zones in the Big Pryor Mountain locality ; it is either 

a minor constituent or does not occur in deposits of the 

Little Mountain locality. Most of the limestone in the 

upper part of the Madison is very pure, and the effects 

of hydrothermal solutions upon it would be mainly 

solution and redeposition of calcite. No sulfide minerals or oxidation products of sulfide minerals except 

pyrite, limonite, and possibly other iron oxides have 

been observed. 

The problem of the genesis of uranium ores in karst 

terrains of the Madison Limestone probably cannot be 

solved until exploration has progressed to depths below 

the zone of oxidation. Disappearance of the uranium 

mineral with increasing depth will be a point in favor 

of supergene enrichment. The presence of primary 

uranium and sulfide minerals at deeper levels will favor 

the hydrothermal hypothesis. The physical characteristics of some of these ores, especially those occurring 

in silt-filled caves, are, in general, similar to many sandstone uranium ores from the Colorado Plateau region. 

The bulk of the tyuyamunite in all the deposits is within 

siliceous cave and fracture fillings, and the mineralized 

zones tend to end abruptly on or very close to the limestone walls. Uraniferous solutions prdbably entered 

the channels and caves where a slight reaction with the 

carbonate wallrocks changed the pH enough to cause 

precipitation of a uranium mineral. 

PENECONCORDANT URANIUM DEPOSITS IN 

CARBONATE ROCKS 

The largest and richest uranium deposits in carbonate 

rocks within the United States are of the type called 

peneconcordant by Finch (1959). These deposits are 

"tabular, lenticular, or irregularly shaped masses of 

widely differing size that are, in general, concordant to 

the gross sedimentary structures of the enclosing rock 

burt th'3Jt, in detail, cut across sedim·entary structures. 

This local discordance is a diagnostic characteristic 

indicating that the deposits are epigenetic rather than 

syngenetic." The uranium deposits in limestone beds 

of the Todilto Limestone of Late Jurassic age in north-
URANIUM IN CARBONATE ROCKS A13 

western New Mexico definitely can be placed in this 

category. Some small uranium deposits in limestone 

lenses at the base of the Sundance Formation of Late 

Jurassic age in Wyoming have similar characteristics. 

All these deposits in limestones have physical features 

like those of most uranium deposits in sandstones of 

the Colorado Plateau region. 

URANIUM DEPOSITS IN THE TODILTO LIMESTONE, 

NEW MEXICO 

A few large and several small uraniun1 deposits have 

been discovered in limestone beds of the nonmarine 

Todilto Limestone in the Grants district, Mcl{inley and 

Valencia Counties, N. Mex. Other small deposits in 

this formation have been discovered in the Laguna district, Valencia County; in the Sanostee area, Apache 

and San Juan Counties; and in the Rio Cebolla and 

Arroyo del Agua areas, Rio Arriba County. Only the 

Grants district has produced a substantial amount of 

ore. 

The Todilto was deposited in a nearly elliptical basin 

about 300 miles long in an east-west direction and 100 

miles wide (Rapaport and others, 1952, p. 23). The 

formation consists of two members. The lower Inember is a sequence of supposedly fresh- to brackish-water 

beds of limy shale, silty limestone, and lilnestone that 

reaches a maximum thickness of about 40 feet. The 

upper member, of considerably smaller areal extent . . ' consists mainly of gypsum and anhydrite that was deposited in the basin sink; it attains a thickness of at 

least 95 feet in the northern part of the Lucero uplift 

near Laguna (Rapaport and others, 1952, p. '23). The 

Todilto rests upon the nonuraniferous Entrada 

Sandstone. 

The Summerville Formation, Bluff Sandstone 1\lor- . ' r1son Formation, all of Late Jurassic age, and the 

Dakota Sandstone of Early ( ? ) and Late Cretaceous 

age overlie the Todilto in the order given in the Grants 

di~trict.. The . Summerville and Dakota are weakly 

m1nerahzed with uranium in a few places. Some of 

the largest known uranium deposits in the United 

States are in the Morrison Formation of the Ambrosia 

Lake district a few miles northwest of the Grants district; a large ore body has been mined out of the Morrison Formation at Poison Canyon on the north edge 

of the Grants district. 

It is desirable to point out some features that characterize the limestone member of the Todilto and which 

possibly influenced the deposition of uranium because 

substantial uranium deposits are uncommon in limestones. The Grants district is described in some detail 

because the largest known deposits are in this district 

and because outcrops and mining operations have provided excellent exposures. 

686494-63-3 

The limestone member of the Todilto in the Grants 

district is a part of the southern rim of the San Juan 

Basin and is on the north flank of the Zuni uplift. 

The upper gypsiferous member is absent in this locality. 

The limestone is underlain, apparently conformably, by 

the Entrada Sandstone, and these formations are exposed on low southward-facing cliffs that form the 

steep slope of a dissected cuesta about 15 miles long 

and a half a mile to about 2 miles wide. The back 

slope of the cuesta is a gentle dip slope formed on the 

upper part of the Todilto; its surface is made somewhat 

irregular by minor structural features and variable 

thicknesses of residual soil and alluvium. The Todilto 

passes under younger formations that are exposed on 

southward-facing cliffs several hundred feet high and 

which form the main part of the southern rim of the 

San Juan Basin. 

The limestone ranges in thickness from about 18 to 

about 30 feet. Much of it is thinly bedded and tends 

to split along bedding planes. Several thin units can 

be recognized, but only three persist throughout most 

of the district. These are a basal, or near basal, very 

fine grained dense limestone; a middle unit of very 

thinly bedded fine-grained crinkly lin1estone; and an 

upper unit of coarse-grained recrystallized limestone, 

which in most places is rather coarsely crinkled. 

These three principal units are separated locally from 

one another and fron1 the underlying Entrada Sandstone and the overlying Summerville Formation by lenticular, thinly laminated shaly and silty beds that range 

fron1 a feather edge to about a foot in thickness· other 

lenticular shaly and silty beds are interspersed ~ithin the 1nain lin1estone units. These partings vary in 

thickness and number from place to place. 

The Grants district probably lies along, or close to, 

the strand line of the upper gypsiferous member of the 

Todilto where thin layers of gypsum or anhydrite formerly were interspersed with limestone beds or where 

a 1nixture of calcium sulfate and calcium carbonate 

was deposited. Subsequently, anhydrite, where that 

was the primary sulfate mineral, was hydrated to 

gypsum, and the attendant swelling helped produce the 

crinkly features of the upper unit of the limestone 

member. The gypsum along the strand line eventually 

was leached .from the rock. Results of the leaching 

were formatiOn of a porous texture, completion of 

crinkling of the thinly laminated limestone, and erratic 

recrystallization of the calcite constituent. 

The limestone is strongly fetid. It has a brownish 

color except in places where it has been recrystallized, 

and there the colors are usually white and light shades 

of pink, yellow, and gray; locally the presence of hematite is the cause of a red color. It generally has been 
A14 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY 

assumed that the odor and brown color are due priInarily to a small amount of petroliferous substance. 

Attempts to extract organic matter from several 

samples of limestone collected in the Grants district 

have been unsuccessful. Several kinds of organic solvents were used in the experiments. It is concluded 

that this rock is not now petroliferous, and that it probably never has been petroliferous. The limy sediments 

undoubtedly contained significant amounts of organic 

matter as they were being deposited, and the traces 

that remain give the rock its brown color. The exact 

nature of the organic matter cannot be stated. The 

only fossils that have been recognized in the Todilto 

are remains of ostracodes (Swain, 1946), and the author has found remains of small fishes. The scarcity 

of readily recognizable fossil forms suggests that most 

of the organic matter likely was derived from minute 

organisms of which plankton might have been the principal members. The organic matter, brown color, and 

fetid odor have been eliminated from some of the 

thoroughly recrystallized rock. 

The sediments that formed the limestone member of 

the Todilto were composed principally of chemically 

precipitated carbonates, 1ninor amounts of clay- and 

silt-size detritus, and traces of organic matter. The 

analyses reported in table 2 (II-C, Nos. 260469-260477) 

show that the rock is a normal high-calcium limestone 

containing approximately 1 percent of magnesium carbonate. It contains less than 0.01 percent P 20 5 and 

variable a1nounts of acid-soluble R20s ranging from 

about 0.8 to about 3.8 percent. Most of the limestone 

contains less than 10 percent of clastic sediments, but 

some lenses are mar lstone and calcareous siltstone, and 

some thin stringers are composed almost wholly of detrital quartz and feldspars. 

The limestone is mostly very thinly stratified and 

consists of alternating layers of dense finely crystalline 

calcite and calcite mixed with silt. The silty layers generally are thinner than the dense calcite layers, but they 

evidently have been quite permeable because epigenetic 

minerals locally have been deposited in them and have 

given the rock a banded appearance. 

The calcareous sediments consisted of very fine 

grained material that was deposited in an aqueous environment, and they probably were subjected to considerable compaction before lithification occurred. 

Layers of dense material inhibited vertical movement 

of water and solutions; hence, the main flow was laterally along bedding planes and through relatively 

·more permeable silty lenses. This condition has had 

a readily noticeable effect on the deposition of epigenetic minerals. Secondarily induced permeability in the 

limestone resulting from leaching of calcium sulfate 

minerals and development of vertical fractures has 

been an important factor in redistribution of secondary 

uranium minerals. 

Four types of deformation have affected the Todilto 

Limestone in the Grants district. The first is tectonic 

folding that has produced broad, slightly undulating 

structures in all the formations of the area ; these folds 

are a mile or more wide and have closures of only a 

few tens of feet and axes that trend approximately 

northward. The second type of deformation is smallscale folding that is almost wholly confined within the 

limestone beds and has affected adjacent formations in 

only a few scattered places; these folds probably were 

caused by hydration of calcium sulfate and su~sequent 

leaching of this material. These folds range from a 

few inches to some 30 or 40 feet in width, but most are 

less than 10 feet in width; they range from a few feet 

to a few hundred feet in length and have closures of 

a few inches up to 5 or 6 feet; the numbers of these folds 

vary greatly from place to place, the limestone in some 

localities being almost devoid of them and in other 

localities being tightly crumpled by closely spaced series of such folds. The third type of deformation consists of northward- and northeastward-trending fault 

zones that cross the district; there is but little vertical 

displacement along these faults; the amount of horizontal displacement has not been determined. Finally, 

the entire section was tilted as the present regional 

structures of the San Juan Basin and Zuni uplift 

formed. 

An interesting feature of the Grants district is the 

recrystallized character of much of the uppermost few 

feet of the limestone. The results of this alteration 

vary considerably from place to place. The limestone, 

where altered, generally has been more or less recrystallized to depths of about 5 feet below its upper surface, but locally it is recrystallized to depths of as much 

as 10 to 12 feet below the upper surface. The rock in 

the latter places is coarsely crystalline, vuggy, and is 

streaked with hematite stain. The cause of this recrystallization has not been determined. It may have been 

caused by warm water, of undetermined origin, moving 

through porous strata and along fractures. Recrystallized limestone has considerably greater areal distribution than rock enriched with uranium minerals 

and fluorite. 

Ore bodies mined or discovered in the Grants district 

up to 1960 tend to be clustered along zones of major 

faults. These fractures are unmineralized except for 

minor amounts of secondarily redistributed uranium 

minerals. The primary uranium mineralization occurred mainly in the small anticlinal structures within 

the limestone adjacent to fault zones; this feature suggests a structural control. What role, if any, was 

played by the major fractures is not clear. The masses 
URANIUM IN CARBONATE ROCKS A15 

of primary or "black" ore, of which uraninite is the 

important constituent, are mostly small and range from 

insignificant pods to bodies about 30 feet wide, 200 x 300 

feet long, and about 3 feet thick. At some places two 

or more bodies of primary ore, in adjacent small anticlines, can be mined from the same pit, particularly if 

the intervening rock has been heavily mineralized with 

secondary uranium minerals. The uraninite in some 

ore bodies has been altered almost completely to secondary uranium minerals. Secondary minerals are 

likely to be redistributed along fracture surfaces, in 

vugs, and in solution cavities for substantial distances 

from sites of the primary deposition. The redistributed yellow secondary minerals are especially conspicuous in the upper, crinkly layers of the limestone. Ore 

bodies of predominantly secondary uranium minerals 

tend to be irregulary rounded rather than elongate. 

Several epigenetic minerals, and some that possibly 

are authigenic, occur in the mineralized parts of the 

limestone. There are two categories of these minerals, 

those that are primary, and those that are alteration 

products of the primary minerals. In the primary category are pyrite, fluorite, uraninite, barite, some calcite, 

and probably hematite. It seems unlikely that all these 

minerals were deposited during the same phase of mineralization. The alteration products of the primary 

epigenetic minerals include carnotite, tyuyamunite, 

uranophane, and limonite. Redistributed calcite is 

abundant. Small, probably authigenetic manganesebearing nodules, possibly composed predominantly of 

psilomelane ( ~), are widely, though not abundantly, 

distributed in the limestone. These nodular masses 

rarely exceed an eighth of an inch in diameter. There 

is no evidence to indicate that any of these minerals 

are mainly syngenetic except for some fine-grained 

pyrite in parts of the limestone that are otherwise unmineralized. None of the minerals listed above is confined to any particular stratum, and none is even 

approximately uniformly distributed within a particular stratum. The bulk of the primary minerals are 

concentrated in zones of former bedding-plane porosity 

and generally are further controlled by the small anti-

· clinal structures; the banded appearance of rock so 

mineralized commonly does not extend more than a few 

feet from the flanks of the folds. The secondary minerals, particularly those of uranium, in most places 

have been redistributed beyond the limits of the primary deposits and are concentrated mainly in fractures. 

The primary uranium mineral, uraninite, is preserved 

mainly in the fine-grained dense limestone of the lower 

units. Ore in lots of a few tons containing several 

percent uranium can be handpicked from places where 

uraninite is especially abundant. The limestone generally has been recrystallized to the point where stratification features are obscure or eliminated; the uraninite 

occurs as small grains, irregular masses, and small 

stringers that show some indication of following the 

former stratification but also in many places cut across 

it; lenticular masses of nearly pure uraninite about half 

an inch thick and a few inches long that obviously _replace the limestone are found in this rich ore. Small 

grains and nodular masses of uraninite definitely follow 

bedding planes and give the rock a somewhat discontinuous banded appearance around the flanks of rich 

ore bodies and in places where there has been relatively 

little primary uranium mineralization as well as little 

or no recrystallization of the limestone. This feature 

indicates that bedding plane permeability exerted considerable control over localization of uraniferous solutions. No direct association between uraninite and 

organic matter has been observed. 

Fluorite is rather widespread in the Grants district 

and locally attains concentrations ranging from a trace 

to possibly 5 percent. It occurs as minute grains and 

as aggregates of microscopic grains. Some of the 

fluorite is purple, some is colorless, and some of the 

aggregates consist of mixtures of purple and colorless 

grains. Although some of the fluorite is uraniferous, it 

does not seem to be associated directly with uraninite. 

Some aggregates of fluorite grains have cores of uranophane, a peculiar feruture that cannot now be explained. 

Fluorite-rich parts of the limestone are not characteristically mineralized with uraninite, in fact, some fluorite-rich rock seems to be devoid of uraninite. Some 

of the richest concentrations of fluorite occur in the 

small anticlinal structures, particularly those adjacent 

to major fractures. In those parts of the limestone that 

are not extensively recrystallized, fluorite, like uraninite, follows the stratification, and some of the rock is 

conspicuously banded. No conclusive evidence has been 

found indicating that fluorite and uraninite belong to 

the same period of mineralization. It is possible that 

the two minerals were deposited at different times from 

unrelated solutions. 

Hematite, or some other reddish iron oxide, is a conspicuous constituent of some of the mineralized limestone. Most of this mineral is extremely fine grained 

and tends to color the rock a dull red. It probably does 

not amount, at the most, to more than 1 percent of the 

rock. Hematite also has a tendency to follow bedding 

planes and is more likely to accompany uraninite than 

is fluorite, but hematite and fluorite are not always 

found together in mineralized zones devoid of uraninite. 

Known uranium deposits in the Todilto Limestone 

outside of the Grants district are small and are distributed along the margins of the San Juan Basin or 

at points within the basin sink where the upper gyp-
A16 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY 

siferous member is missing. Only secondary uranimn 

minerals have been found in these deposits. 

Although the source of the uranium in the Todilto 

Limestone has been a subject of much speculation by 

many geologists, no completely satisfactory answer has 

been found. The author believes that the uranium in 

the limestone was derived from the same source as that 

which furnished the uranium in the overlying sandstone 

formations and that it was deposited at the same time. 

When the origin of uranium deposits in sandstones is 

determined, it is expected that the deposits in the 

Todilto Limestone also will be explained. 

Limestones generally are not favorable host rocks 

for uranium deposits; therefore, some unusual conditions had to exist to cause deposition of uraninite in the 

Todilto. This limestone probably contains no significant amount of syngenetic uranium. The validity of 

this statement cannot be established completely on the 

basis of analyses of samples collected in the Grants 

district. All the rock seems to contain redistributed 

uranium in the form of secondary minerals. All the 

samples collected by the author contained visible traces 

of yellow minerals even though considerable effort was 

expended to obtain rock free from such constituents. 

Even so, it should be noted that samples 260469 and 

260471 contained only 0.0005 and 0.0006 percent uranium, respectively (table 1, II-C). The analyses of 

nine samples also show that the Todilto is almost nonphosphatic, the maximum quantity of P 20 5 being only 

0.08 percent. It already has been pointed out in the 

discussion of syngenetic uranium in carbonate rocks 

that only those carbonate rocks that have a few tenths 

of 1 percent or more of P 20 5 are likely to contain syngenetic uranium in quantities exceeding about 0.0004 

percent. It is concluded that the possibility that a 

minor amount of syngenetic uranium in the Todilto 

could have been concentrated and redeposited is nil. 

The uraninite, as well as fluorite, hematite, and some 

other less abundant minerals, are distributed in the 

limestone in a manner indicative of epigenetic 

deposition. 

The ore-forming solutions responsible for deposition 

of uranium in the sandstone units overlying the Todilto 

fluids, structural features for entrapment of the fluids, 

and chemical environments causing precipitation of ore 

minerals. Within the Todilto, structural features are 

readily visible, and the availability of ore-forming 

fluids can be easily explained, but the precise nature 

of the chemical environment in which the uranium 

was precipitated cannot be fully explained. 

The ore-forming solutions responsible for deposition 

of uranium in the sandstone units overlying the Todilto 

Limestone in the area also must have deposited the 

uranium in the Todilto; no evidence has been uncovered 

to the contrary, and there is no evidence of more than 

one period of primary uranium mineralization in the 

area. It is reasonable to assume that uraniferous solutions migrated through several permeable strata of the 

local section and that, wherever structural and chemical conditions were favorable uranium was deposited. 

Structural features in the Todilto that trapped oreforming fluids were mainly the small folds that are 

confined to the limestone itself. Generally the overlying Summerville Formation, composed mostly of 

shales and mudstones, had formed an impervious ca.p 

over the limestone. Ore-forming solutions may have 

flowed along fractures in the limestone to some extent, 

but the major movement was controlled by stratification 

features and was along thin permeable beds that average only a small fraction of an inch in thickness. This 

circumstance is indicated by the predominant deposition of uraninite, fluorite, and hematite along bedding 

planes. Bedding-plane permeability seems to have been 

an inherent feature of the lower units of the Todilto 

in the Grants district. 

The geochemical environment that existed as the 

uraninite was deposited is not fully understood. The 

pH of the mineralizing solutions must have been nearly 

neutral or slightly alkaline. Large masses of the liinestone have been almost completely recrystallized, but 

are not characteristically mineralized with uraninite. 

Those parts of the limestone that contain the uraninite 

show relatively little recrystallization and only minor 

extraction of the carbonate constituent; this condition 

would not exist if the mineralizing solutions had been 

acid. Even moderately acid mineralizing solutions 

would have dissolved substantial amounts of the limestone; conversely, strongly alkaline solutions, or solutions nearly saturated with carbonate ions, probably 

would not have permitted replacement of calcite 

by uraninite. It is concluded that recrystallization of 

the limestone was not an essential feature of the mineralizing process and that the fact that uraninite occurs 

in some of the least recrystallized parts of the limestone is indicative of nearly neutral or moderately alkaline solutions. 

The environment was undoubtedly reducing and sul--

furous as uraninite was being deposited. The uranium 

ores of the Ambrosia Lake district are characterized 

by an abundance of very fine grained iron sulfides that 

are dispersed throughout the mineralized parts of the 

rock. Iron sulfides also are present in ores of the 

Todilto Limestone, althought not so abundantly. The 

limestone itself is a fetid rock. 

The state of the uranium as it was introduced into 

the limestone is a subject that can only be speculated 

upon. Some, and possibly all, of the uranium may 

have existed in the uranyl form, most likely as a uranyl 
URANIT~ ~ CARBONATE ROCKS A17 

carbonate complex. The sulfide ion readily reduces the 

uranyl ion under some conditions, and it probably was 

the reducing agent in the Todilto Limestone. 

Phase relations that exist with varying temperatures 

and pressures in complex solutions containing uranyl, 

uranous, sulfide, and carbonate ions, and which may 

be in contact with solid phases of uranium oxides, are 

virtually unknown. The presence of uraninite in the 

Todilto Limestone seems to indicate that reduction of 

uranyl uranium by sulfide ions may occur in a carbonate environment, but the concentrations of reacting 

constituents, and the Eh and pH of the solutions, cannot be stated from present know ledge. The only alternative is that uranium might be transported in the 

uranous state and be deposited by some process that 

cannot be explained on the basis of present knowledge. 

URANIUM DEPOSITS IN THE SUNDANCE FORMATION, 

WYOMING 

Some small, low-grade uranium deposits are found 

in lenticular limestone beds at the base of the Sundance 

Formation in Wyoming. These deposits have some 

features similar to those of deposits in the Todilto 

Limestone and therefore are classed as peneconcordant. 

The largest known deposits in the Sundance Formation are in sec. 3, T. 44 N., R. 83 W., in Johnson 

County. This locality is on the east flank of the Bighorn Mountains and 3!bout 2 miles southwest of the 

abandoned Mayoworth post office. The formations exposed in the vicinity of the uranium deposits are the 

Chugwater, Sundance, and Morrison. The upper part 

of the Chugwater, of Triassic and Permian age, consists 

of a thick section of massive to cross bedded fine-grained 

red sandstone. The Sundance Formation, of Jurassic 

age, consists of a hasal lenticular limestone having a 

maximum thickness of about 20 feet that is overlain 

by beds of nonglauconitic sandstone and shale approximately 200 feet thick and an upper sequence of glauconitic shale and sandstone about 150 feet thick; all 

these units contain marine fossils. The Morrison 

Formation, of Jurassic age, consists of shale and sandstone. The only uraniferous material that has been 

found in these formations in this locality, other than 

the deposits in the limestone, is fossil dinosaur bone in 

the Morrison Formation (Love, 1954, p. 3) . 

The formations at the Mayoworth locality strike approximately N. 30° W. and dip 12° to 15° NE. The 

largest exposure of the limestone at the base of the Sundance Formation is within an area of several acres on a 

northeastward-facing dip slope in the SW% sec. 3. 

This limestone bed feathers out within distances of 

about a mile to the northwest and southeast. 

The limestone consists predominantly of calcitic 

oolites cemented with calcite. It is mostly dull grayish 

brown, hut in places it is reddish because of local abundance of iron oxides. The freshly broken rock is 

strongly fetid. The limestone contains no recognizable 

organic matter, and organic solvents extract no material from it. Chemically the rock is a calcitic 

nonphosphatic limestone (table 2, II-B, No. 249721). 

Metatyuyamunite is irregularly distributed within 

the limestone, some forming coatings on fracture surfaces and some replacing, or partly replacing, oolites 

and calcite cement. These two modes of deposition do 

not everywhere occur together; consequently, the most 

richly mineralized parts of the limestone are small 

pockets where the two occur together. The uranium 

content of the rock generally is substantially less than 

0.1 percent except for a few small pockets. A petrographic description of the rock has been presented by 

Guilinger and Theobald (1957). 

Inasmuch as most of the metatyuyamunite on fracture surfaces obviously is redistributed, it seems that 

the primary uranium deposition involved replacement 

of the oolites and calcite cement. Whether metatyuyamunite is the primary uranium mineral or an alteration product of some previously existing mineral is 

unknown. No structural control of deposition has 'been 

observed, perhaps because observations have been restricted to the upper surface of the limestone and to a 

few prospect pits not exceeding 5 feet in depth. 

The source of the uranium in the limestone is a subject for speculation. The author has observed no features that indicate syngenetic deposition of the uranium. 

The limestone can be considered to be nonphosphatic 

(table 2, II-B, No. 249721 contained less than 0.05 

percent P 20 5) and is a type not likely to contain aboveaverage quantities of syngenetic uranium. The uranium probably was carried into an originally porous 

limestone by ground-water solutions and was precipitated in the reducing environment of the fetid rock. 

There is no apparent source of uraniferous solutions in 

the immediate vicinity. No other appreciable concentrations of uranium minerals are known to exist for 

considerable distances around the Mayoworth locality. 

There are no intrusive igneous rocks or hot-spring deposits nearby that could point to possible hydrothermal 

solutions. The uranium may have been leached from 

other rocks of the region and concentrated in the limestone. Love (1954) has suggested that it might have 

been leached from volcanic ash in the White River 

Formation of Oligocene age, which was deposited unconformably upon the upturned edges of the Jurassic 

formaJtions but which subsequently was eroded from the 

area. 

The uranium probably was deposited epigenetically 

in the limestone. If uraniferous solutions entered the 

limestone and a reducing environment was encountered, 
A18 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY 

it is reasonable to assume that the primary mineral was 

uraninite; because the known deposits are within 5 

feet of the surface of the ground where oxidation is 

complete, no trace of uraninite has been found. 

SUMMARY 

Uranium deposits can be formed epigenetically in 

carbonate rocks by several mechanisms. Some of these 

mechanisms produce deposits that furnish interesting 

mineralogical specimens but generally do not provide 

ores; most of the effiorescent deposits belong in this 

category. Other mechanisms have produced a few deposits that have been mined profitably primarily for 

their uranium contents alone; examples of these deposits are the hydrothermal veins at Shinkolobwe, Republic of Congo, the peneconcordant deposits in the 

Todilto Limestone in New Mexico, and deposits in the 

karst terrains of the Pryor Mountains in Montana and 

the Bighorn Range in Wyoming. 

Carbonate rocks are less favorable host rocks for 

epigenetic uranium deposits than are clastic sedimentary rocks, metamorphosed clastic sedimentary rocks, 

and igneous rocks. Carbonate rocks that contain significant epigenetic uranium deposits are in the so-called 

uranium provinces of the earth, and even in these 

regions the deposits generally seem to be restricted to a 

single carbonate rock formation. 

The exact physical and chemical conditions that 

cause primary deposition of uranium in carbonate rocks 

are virtually unknown. U raninite seems to be the only 

primary uranium mineral deposited in the hydrothermal veins. TyuJ.amunite, uranophane, uraniferous 

fluorite, and possibly other minerals may be deposited 

as primary constituents in some of the other types of 

deposits, but this point has not been established 

definitely. It cannot be stated that the same chemical 

conditions existed during mineralization of deposits 

having different physical characteristics. The fact 

that uraninite can be deposited in carbonate rocks, and 

apparently from solutions rich in carbonate, or bicarbonate, or carbonate and bicarbonate ions, seems to be 

puzzling, but this circumstance merely points out a gap 

in our knowledge of the chemical behavior of uranium. 

Only a few favorability criteria can be suggested that 

might aid in the discovery of epigenetic uranium deposits in carbonate rocks. The known significant deposits are in uranium provinces, and this circumstance 

would seem to define favorable regions. Uraniferous 

hydrothermal veins in carbonate rocks are most likely 

to be found in districts where similar veins occur in 

other types of rocks. Uranium deposits in karst terrains are most likely to exist where there has been 

deep-seated hydrothermal activity; a less favorwble 

criterion is the presence, or former presence, of tuffaceous or arkosic sediments that could have furnished 

uranium for supergene enrichment. The only known 

peneconcordant deposits are in fetid limestones. 

LITERATURE CITED 

Alcock, F. J., 1936, Geology of the Lake Athabaska region, 

Saskatchewan: Canada Geol. Survey Mem. 196, 41 p. 

Alexandrov, S., 1922, Tyuya Muyun Radium expedition of 

1922: Mining Journal [Moscow] no. 10-12, p. 415-416. 

(AJieRCaH;o;poB, C., 1922, TroH-MyroHcRaH pa;o;HeBaJI :mcne-

;IJ;HIJ;HH 1922. r.: I'opHI:.I:H: jKypHaJI, I'o;o; 98, BLinycR 10-12, 

CTp. 415-416.) 

Altschuler, Z. S., Clarke, R. S., Jr., and Young, E. S., 1958, 

The geochemistry of uranium in apatite and phosphorite: 

U.S. Geol. Survey Prof. Paper 314-D, p. 45-90. 

Arapov, Yu. A., 1936, Mineralogy and geochemistry of the Kansai 

ore deposit, in Tadjik-Pamir expedition of 1934, Reports 

of the expedition, No. 49: Acad. Sci. (U.S.S.R.), 104 p. 

(AparroB, IO. A., 1936, MHHepaJiorHJI H reOXHMHH RaHca:H:-

Koro MecTopom;o;eHHH: Ta;o;mHRCRo-IIaMHpcRaH 9Rcne-

;IJ;HD;HH 1934 r., Tpy;o;LI 9Rcrre;o;Hn;HH, BLirrycR 49, ARa;o;eMHH 

HayR C.C.C.P.) 

Association of Official Agricultural Chemists, 1950, Official 

methods of analysis, 7th ed., 910 p. 

Bain, G. W., 1950, Geology of the fissionable materials: Econ. 

Geology, v. 45, p. 273-323. 

Baronov, D. I., Ronov, A. B., and Kunashova, K. G., 1956, 

On the geochemistry of dispersed thorium and uranium in 

clays and carbonate rocks of the Russian Platform: Geochemistry [Moscow] 1956, no. 3, p. 3-8. (BapoHOB, B. n., 

PoHoB, A. B., H RyHamoBa, R. I'., 1956, R reoXHMHH 

pacceRHHOrO TOpHH H ypaHa B rJIHHaX H Rap60HaTHhlX 

nopo;o;ax pyccRo:H: nJiaTcilopMLI: I'eoxHMHH 1956, BLinyCR 

3, CTp. 3-8.) 

Bell, K. G., 1956, Uranium in precipitates and evaporites, in 

United Nations, Geology of uranium and thorium: Internat. 

Conf. on the Peaceful Uses of Atomic Energy Proc., Geneva 

1955, v. 6, p. 520-524. 

---1960a, Deposition of uranium in salt-pan basins: U.S. 

Geol. Survey Prof. Paper 354-G, p. 161-169. 

---1960b, Uranium in petroleum and rock asphalt: U.S. 

Geol. Survey Prof. Paper 356-B, p. 45-65. 

Betekhtin, A. G., 1946, Deposits of radioactive metals; Uranium 

and radium, in Tatarinova, P. M., and Betekhtin, A. G., 

eds., Course in useful mineral deposits: Moscow-Leningrad, 

p. 233-238. (BeTeXTHH, A. I'., 1946, MecTopom;o;eHHH 

pa;o;HoaRTHBHLIX MeTaJioB; YpaH n pa;o;H:H:: B Rypc MecTopom;o;eHHii noJieBHDIX HCROnaeMLix; IIo;o; pe;o;aRn;ne:H: II. M. 

TaTapHHoBa H A. I'. BeTeXTHHa, CTp. 233-238.) 

Bowie, S. H. U., 1955, Thucholite and hisingerite-pitchblende 

complexes from Nicholson mine, Saskatchewan, Canada: 

Great Britain Geol. Survey Bull. 10, p. 45-55. 

Christie, A. M., and Kesten, S. N., 1949, Goldfields and Martin 

Lake map areas, Saskatchewan (Preliminary account) : 

Canada Geol. Survey Paper 49-17. 

Cuttitta, Frank, 1952, The colorimetric determination of total 

iron with o-phenanthroline: A spectrophotometric study: 

U.S. Geol. Survey TEI-223, issued by U.S. Atomic Energy 

Comm. Tech. Inf. Service, Oak Ridge, Tenn., 25 p. 

Davidson, C. F., and Atkin, D., 1953, On the occurrence of 

uranium in phosphate rock: Internat. Geol. Cong., 19th, 

Algiers 1952, Comptes rendus, sec. 11, p. 13-31. 
URANIUM IN CARBONATE ROCKS A19 

Derriks, J. J., and Vaes, J. F., 1956, The Shinkolobwe uranium 

deposit: Current status of our geological and metallogenic 

knowledge, in United Nations, Geology of uranium and 

thorium: Internat. Conf. on the Peaceful Uses of Atomic 

Energy Proc., Geneva 1955, v. 6, p. 94-128. 

Eargle, D. H., 1956, Some uranium occurrences in West Texas: 

Texas Univ., Bur. Econ. Geology, Rept. Inv. 27, 23 p. 

Evans, R. D., and Goodman, Clark, 1941, Radioactivity of 

rocks: Geol. Soc. America Bull., v. 52, p. 459-490. 

Fersman, A. E., 1928, The uranium-vanadium mine in Turkestan, 

in All Union Geol. Cong., 3d, Tashkent 1928, Guidebook of 

the excursions: no. 1, Paper 22, Geol. Comm. Publication, 

Leningrad. (<DepcMaH, A. E., 1928, 'YpaHo BaHap;n:eBI:.Iit 

pyp;HHR TroH-MyroH B TypReCTaHe: BcecoiOSHhlfi reoJiorn:qeCimit C:&eap;, m TamReHT 1928, IlyTeBO)l;HMeJIL 

eRCRypcn:it: BI:.IrrycR 1, No. 22, llap;aHHe reoJiorn:qecRoro 

RoMn:TeTa, JleHn:Hrpap;, 1928.) 

Finch, W. 1., 1959, Peneconcordant uranium deposit-a proposed term: Econ. Geology, v. 54, p. 944-946. 

Fresenius, R., and Hintz, E., 1895, Bestimmung des Urans in 

Phosphorsaure und Arsensaure enthaltenden Erzen: 

Zeitschr. Anal. Chemie, v. 34, p. 437-439. 

Gorbunov, N. P., 1935, Tadjik-Pamir Expedition of 1934, in 

Tadjik-Pamir Expedition of 1934: Acad. Sci. (U.S.S.R.), 

p. 5-36. (rop6yHoB, H. II., 1935, Tap;mn:cRcRo IlaMn:pcRaH 

aRcrrep;n:~n:H 1934 r. : B Tap;mn:RCRO IlaMn:pcRa.JI e~tcrrep;n:~n:H 

1934 r., CTp. 5-36, ARap;eMn:H HayR C.C.C.P.) 

Gotman, Ya. D., 1937, Petrography and mineralogy of the 

Agalyk uranium and vanadium deposit (Middle Asia): 

Acad. Sci. (U.S.S.R.) Bull., Geol. Ser. 1937, p. 291-311. 

(roTMaH, JI. ,I(., 1937, IleTporpaqmH n MHHepaJiorn:H 

AraJII:.IRCRoro ypaHo-BaHap;n:eBoro MecTopomp;eHHH (CpeAHHH Aan:H): llaBeCTHSI A~tap;eMn:H HayR C.C.C.P., 1937, 

CepnH reoJiorn:qecRaH, CTp. 291-311.) 

Gott, G. B., Wyant, D. G., and Beroni, E. P., 1952, Uranium in 

black shales, lignites, and limestones in the United States, 

in Selected papers on uranium deposits in the United States: 

U.S. Geol. Survey Circ. 220, p. 31-35. 

Grimaldi, F. S., May, 1., Fletcher, M. H., and Titcomb, J., 

compilers, 1954, Collected papers on methods of analysis 

for uranium and thorium: U.S. Geol. Survey Bull. 1006, 

184 p. 

Guilinger, R. R., and Theobald, P. K., 1957, Uranium deposits in oolitic limestone near Mayoworth, Johnson 

County, Wyoming: U.S. Geol. Survey BulL 1030-K, p. 

335-342. 

Hebert, Claude, 1947, Contribution a l'etude de la chimie des 

phosphates de calcium: Annales des Mines Mem., v. 136, 

no. 4, 93 p. 

Icken, J. M., and Blank, B. M., 1953, Determination of fluorides. 

Spectrophotometric adaption of method of Association of 

Official Agricultural Chemists: Anal. Chemistry, v. 25, p. 

1741-1742. 

Isachsen, Y. W., Mitcham, T. W., and Wood, H. B., 1955, Age 

and sedimentary environments of uranium host rocks, 

Colorado Plateau: Econ. Geology, v. 50, p. 127-134. 

Lahner, llse, 1939, Uran- und Thoriumbestimmungen an Kalken 

und Dolomiten und die Frage des radioaktiven Gleichgewichtes in diesen Gesteinen: Akad. Wiss. Wien, Math.-

Naturwiss. Kl., Sitzungsber., sec. 2, v. 148, p. 149-162. 

Love, J. D., 1953, Preliminary report on uranium deposits in the 

Miller Hill area, Carbon County, Wyoming: U.S. Geol. 

Survey Circ. 278, 10 p. 

Love, J. D., 1954, Uranium in the Mayoworth area, Johnson 

County, Wyoming-A preliminary report: U.S. Geol. Survey 

Circ. 358, 7 p. 

Manskaya, S. M., Drozdova, T. V., and Emel'ianova, M. P., 

1956, Uranium binding by humic acids and melanoidines: 

Geochemistry (Moscow), 1956, no. 4, p. 10-23. (MaHCRaH, 

C. M., ,I(poap;oBa, T. B., H EMeJI:&HHOBa, M. II., 1956, 

CBHSI:.IBaHn:e ypaHa ryMHHOBLIMH RHCJIOTaMH u MeJiaHonp;n:HaMn:: reoxn:MHH 1956, BI:.IrrycR 4, CTp. 10-23.) 

Muilenburg, G. A., and Keller, W. D., 1950, Carnotite and 

radioactive shale in Missouri: Am. Mineralogist, v. 35, 

p. 323-324. 

Pavlenko, D. M., 1933, New data on the geology and genesis of 

the Tyuya-Muyun deposits in Uzbekistan: Problems of 

Soviet Geology, v. 4, no. 10, p. 123-142. (IIaBJieHRo, 

,I(. M., 1933, HoB:&Ie p;aHHI:.Ie o reoJiornn: n: reHeance MecTopomp;eHHH TroH MyroH B ¥a6e~tn:cTaHe: Ilpo6JieMI:.I. 

CoBeTcRoit reoJiorn:n:, ToM 4, BI:.IrrycR 10, CTp. 123-142.) 

Rapaport, 1., Hadfield, J. P., and Olson, R. H., 1952, Jurassic 

rocks of the Zuni uplift, New Mexico: U.S. Atomic Energy 

Comm. RM0-642, issued by U.S. Atomic Energy Comm. 

Tech. Inf. Service, Oak Ridge, Tenn., 47 p. 

Robinson, S. C., 1955, Mineralogy of uranium deposits, Goldfields, Saskatchewan: Canada Geol. Survey Bull. 31, 128 p. 

Rodden, C. J., and Warf, J. C., 1950, Uranium, in Rodden, C. J., 

ed., Analytical chemistry of the Manhattan Project: Nat. 

Nuclear Energy Ser., div. 8, v. 1, p. 3-159, McGraw-Hill 

Book Co., Inc., New York. 

Shapiro, Leonard, and Brannock, W. W., 1956, Rapid analysis 

of silicate rocks: U.S. Geol. Survey Bull. 1036-C, p. 19-56. 

Shimkin, D. B., 1949, Uranium deposits in the U.S.S.R.: Science, 

v. 109, p. 58-60. 

Stephens, J. G., 1954, Uranium in limestone: Saratoga area, 

Carbon County, Wyoming, in Geologic investigations of 

radioactive deposits-Semiannual progress report, June 1 

to Nov. 30, 1954: U.S. Geol. Survey TEI-490, p. 131-132, 

issued by U.S. Atomic Energy Comm. Tech. Inf. Service, 

Oak Ridge, Tenn. 

Swain, Fredrick, 1946, Middle Mesozoic nonmarine ostracoda 

from Brazil and New Mexico: Jour. Paleontology, v. 20, 

p. 543-555. 

Szalay, A., 1957, The role of humus in the geochemical enrichment of U in coal and other bioliths: Acta Phys. Acad. Sci. 

Hungaricae, v. 8, pts. 1-2, p. 25-36. 

Thoreau, J., and du Trieu de Terdonck, R., 1933, Le gite d'uranium de Shinkolobwe-Kasola (Katanga) : Memoires de 

l'lnstitut Colonial Beige, v. 1, pt. 8. 

---1936, Concentrations uraniferes du Katanga (Congo 

Belge): Internat. Geol. Cong., 16th, Washington 1933, 

v. 2, p. 1099-1101. 

Thurston, W. R., Staatz, M. H., Cox, D. C., and others, 1954, 

Fluorspar deposits of Utah: U.S. Geol. Survey Bull. 1005, 

53 p. 

Unkovskaya, V., 1940, Determination de faibles quantities 

d'uranium par le procede de fluorescence: A cad. Sci. 

(U.S.S.R.), Comptes rendus, v. 29, p. 380-383. 

Vine, J. D., and Prichard, G. E., 1959, Geology and uranium 

occurrences in the Miller Hill area, Carbon County, 

Wyoming: U.S. Geol. Survey Bull. 1074-F, p. 201-238. 

Vine, J. D., Swanson, V. E., and Bell, K. G., 1958, The role of 

humic acids in the geochemistry of uranium, in United 

Nations, Survey of raw material resources: Internat. Conf. 

on Peaceful Uses of Atomic Energy Proc., Geneva 1958, 

v. 2, p. 187-191. 
A20 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY 

Vol'fson, F. I., 1940, The principal features of the metallogeny 

in the West Tian-Shan: Acad. Sci (U.S.S.R.) Bull., Geol. 

Ser., no. 3, p. 65-83. (BoJIL!f>coH, <D. H., 1940, OcHOBHLie 

't!epTLI MeTaJIJioreHHH saHa;n;Horo THH-illaHH: HsBeCTHH 

ARa;n;eMHH HayR C.C.C.P., CepHH reoJIOrH't!eCRaH, BLmycR 

3, CTp. 65-83.) 

Willard, H. H., and Winter, 0. B., 1933, Volumetric method for 

determination of fluorine: Indus. and Eng. Chemistry, Anal. 

Ed., v. 5, p. 7-10. 

Zil'bermintz, V. A., 1935, The uranium-vanadium deposit near 

Samarkand, in Tadjik-Pamir Expedition of 1934: Acad. 

Sci. (U.S.S.R.), p. 197-205. (3HJIL6epMnHn;, B. A., 1935, 

YpaHo-BaHa;n;HeBoe MecTopom;n;eHne 6JIH3 CaMapRaH;o;a: 

B Ta)l;mHRCRo-llaMnpcRaH ::mcrre;n;nn;nH 1934 r., CTp. 

197-205, ARa)l;eMBH HayR C.C.C.P.) 

Zil'bermintz, V. A., and Samoilo, M. V., 1935, Material on the 

mineralogy of Karatyube Mountain (Zerayshan Range), 

in Geology of the Zeravshan-Gissar system; Petrography 

and Mineralogy: Acad. Sci. (U.S.S.R.), p. 217-242. 

(3nJIL6epMHHn;, B. A., H CaMo:iiJio, M. B., 1935, MaTepnaJII>I 

R MBHepaJiornu rop RapaTio6e (3epaBmaHCRHH Xpe6eT): 

B R reOJIOrHB 3epaBmaHCRO rnccapCROH CHCTeMLI; lleTporpa!f>HH H MHHepaJiorHH: Ta;n;muRCRo-IlaMHpcRaH sRcrre-

;n;nn;nH 1933, Tpy;n;LI ::mcrre;n;Hn;Hu, BLirrycR 29, CTp. 217-242, 

ARa)l;eMHH HayR, C.C.C.P.) 
TABLE 2.-Analyses in percent of some carbonate rocks and source materials 

[Analysts: R. P. Cox, E. J. Fennelly, D. L. Ferguson, W. D. Goss, Claude Huffman, H. H. Lipp, E. C. Mallory, Wayne Mountjoy, W. W. Niles, L. F. Rader, D. L. Schafer, J.P. Schuch, and D. L. Skinner] 

Chemical composition Approximate mineral composition 

La bora- ~ ~ 0 

tory Source Age Locality .c 

9: .c .s & Remarks sample .§:g &}~ Ql ~ "'..., 0 0 

l~ l'<i ·~E 0 0 0 "' 'Cj s 0 ~ r;; 0 ~ 0 bl) "' 0 ~~ 0 bl) "' ~ ~ "' Ql p:; p 0:1 

~ s 0:1 -< 0 1'r; l'<i -< 0 0 ~ 8 

I. ROCKS AND SOURCE MATERIALS CONTAINING ONLY SYNGENETIC URANIUM 

A. Marine limestones-no significant metamorphism, nonfetid 

. Burlington Early Missis- Road cut, U.S. 0.1 55.4 <0.5 0.15 0.030 0.02 ------- <0.0001 0.1 98.87 <1.05 0.05 ------- 0.15 99.1+ Light-gray medium-grained lime- Limestone. sip pian. Highway 60, stone. Contains a few fossil east bank brachiopods and fragments of James River, crinoid stems. Composed of Galloway, calcite and traces of very fine Mo. grained clay-size material. Madison Lime- Mississippian. Open pit, Tri- <.1 55.3 <.5 .13 .020 <.01 ------- <.0001 <.1 98.75 <1.05 <.02 ------- .13 98.9+ Buff fine-grained dense limestone. stone, pacer claims, Contains poorly preserved micro- T. 58N., R. fossils. Composed of minute 94 W. Big- calcite grains (about 35 percent) horn County, in a matrix of extremely fine Wyo. grained calcite. Calcite is the 2 

2 

only mineral that can be identi-

. Washita Group_ Cretaceous ____ Top of Kings 1.2 54.1 .6 .42 <.01 .0003 1.2 96.60 1.26 

fied under the microscope • .121 ------- <.02 ------- .42 99.5 Buff fine-grained dense limestone, 

:y~~~~~h~ Contains some small macro- fossils and many microfossils. east of Composed of an extremely fine McCamey, grained matrix of calcite in which Tex. there are scattered small grains and stringers of clear colorless 

2 

secondary calcite, some replacing fossils, and a few minute quartz 

Mississippian. Sec. 4, T. 9 S., 2.5 .02 .020 <.01 <.0001 grains. . Madison Lime- 53.4 .6 ------- 2.5 95.36 1.26 <.02 ------- .02 99.1+ Buff fine-grained dense limestone. stone. R. 27 E., Car- Composed of an extremely fine- bon County, grained calcite matrix in which Mont. there are small grains of calcite 

Salem Lime- Late Missis- Upper bench 1. 75 53.2 <1.0 .20 .11 <.05 .0004 1. 75 95.00 <2.09 <.12 .20 97.0+ 

and minute grains of quartz. ------- ------- Gray medium-grained oolitic lime- stone. sip pian. Busson's stone cemented with calcite. ~uarry, Ste. Microfossils are abundant, many enevieve, with aggregates of minute quartz Mo. grains or cryptocrystalline silica 

in the interior parts. There are a few minute grains of detrital 

2 

2 

. St. Louis Lime- Late Missis- Abandoned 3.47 53.2 <1.0 1. 30 .82 .05 <.0001 3.47 94.89 <2.09 quartz. ------- .12 ------- 1.30 99.8+ Dark-gray fine-grained fossiliferous stone, sip pian. quarry, N~ limestone. Composed of calcite sec. 34, T. 3 S., grains, macrofossils, microfossils, R. 4 E., near and oolites(?). Many of the Corydon, Ind. fossils are composed of crypto- crystalline silica. There are some small aggregates of fine-grained clay-size material and many 

Sinbad Lime- Early Triassic. sw~~ sec. 6, T. 4.1 52.7 .8 1.4 .81 .12 0.005 ,0001 4.1 93.84 1.67 

minute pyrite granules. .28 ------- 1.4 101.3 Dark-gray fine-grained dense lime- stone Member 21 S., R. 13 E., stone, Composed chiefly of of Moenkopi Grand Conn- extremely fine grained calcite; Formation. ty, Utah. minor constituents are fine2 

grained detrital quartz (about 2 

percent), pyrite and other opaque minerals, and traces of petrolif-

. Maysville Road cut, U.S. erous residue • Late Ordo- 4.55 52.1 1.1 2.11 .88 .13 .021 <.0001 4.55 92.71 2.30 .31 0.02 2.11 102.0 Gray medium-grained fossiliferous Group, vician. Highway60, limestone, Rock is about 25 5 miles west of percent fossils. Composed of Frankfort, fine-grained calcite, minor quan- Ky. titles of detrital quartz, clay, phosphatic material, and a very minute auantitv of nvrite. 

~ 

i 

!21 

~ 

~ 0 

~ 

~ 

!;:d 

0 

c 

~ '(Jl 

~ ..-
La boratory 

sample 

Source Age 

2 60444 •••• Nicholas Lime- Middle Ordo- stone. Mem- vi clan. 

ber of Cyn- thiana Formation. 

30447---- Catheys Lime- _____ do _________ 

stone. 

2 30445 ____ Bigby Lime- _____ do _________ 

stone. 

2' 30451. ___ Belden Forma- Pennsyl- tion. vanian. 

2 30446 •• -- Hermitage For- Middle Ordomation. vician. 

2 30480.--- Twin Creek Middle and 

Limestone. Late Jurassic. 

249718.- ·- Leadville Mississippian. Limestone. 

249705 .••• Stockbridge _____ Cambrian and 

Limestone Ordovician. 

TABLE 2.-A.nalyses, in percent, of some carbonate rocks and source materials-Continued 

Chemical composition Approximate mineral composition 

..9:l ..9:l -g 

Locality ,.Q 

0 ,.Q ~ .s ::l 

~~ 31 ~~ J 

-~~ f;:<; 

-~5 0 0 0 

0 0 "' ~s 0 ~ r:: 0 0 bll 03 0 ~~ 0 bll 03 03 ::;?1 ~ Q) 

~ p 03 ::;?1 s 03 ...:: 0 f;:<; f;:<; ...:: 0 0 ~ 

I. ROCKS AND SOURCE MATERIALS CONTAINING ONLY SYNGENETIC URANIUM-Continued 

A. Marine limestones-no significant metamorphism, nonfetid-Continued 

Abandoned 5.6 51. 1 <.5 2. 3 0.90 0.07 

quarry 2 miles 

0.007 0.0002 5. 6 91.09 <1.05 0.16 ------- 2.3 

east of Carlisle, Ky. 

Road cut, U.S. 4. 9 50.3 1.5 2.2 .54 .59 

Highway31, 

2 miles north 

.064 .0002 4. 9 88.41 3.14 1. 40 0.02 2.2 

of Columbia, 

Tenn. 

___ •• do ___________ 2.2 52.3 . 7 5.2 .20 2.85 .39 .0002 2.2 86.32 1. 46 6. 75 . 29 5.2 

West slope of 11.9 47.0 .6 4.0 . 74 .13 

Vail Pass, 

Eagle 

.016 .0006 11.9 83.62 1. 25 . 31 .01 4.0 

County, 

Colo. 

Road cut, U.S. 24.3 34.0 1.2 13.7 .50 6.87 .71 .0004 24.3 44.35 2. 51 16.26 .20 13.7 Highway31, 

2 miles north 

of Columbia, 

Tenn. 

Road cut, U.s. 32.2 33.6 1.2 8.3 .19 .12 .056 .0004 32.2 59.62 2.51 .28 .09 8.3 

Highway 40, 

Parleys Canyon, Utah. 

B. Marine Limestone-metamorphosed, completely recrystallized, nonfetid 

Abandoned 0.03 56.1 <1.0 0.18 0.08 <0.05 

Strauss ------- 0.0003 0.03 100.17 <2.09 <0.12 ------- 0.18 

quarry, Marble, Colo. 

Quarry at Far- nams, Mass. . 75 56.0 <I.O .30 .11 <.05 ------- .0002 . 75 100.00 <2.09 <.12 ------- .30 

-.5 

0 

E-t 

99.2+ 

100.1 

102.2 

101.1 

101.3 

103.0 

100.4+ 

101.1+ 

Remarks 

Gray fine-grained fossiliferous lime- stone. Rock is about 5 percent fossils. Composed of finegrained calcite, minor quantities of detrital quartz, clay, phosphat- ic material, and a very minute 

quantity of pyrite. Fine-grained, mottled gray and 

brown, fossiliferous limestone. 

Composed chiefly of irregular- sized calcite grains, phosphatized microfossils (2 to 3 percent), small quantities of detrital quartz and clay, and scattered minute 

granules of pyrite. Macrofossils are composed of calcite. 

Medium-grained mottled gray and 

brown limestone. Composed chiefly of calcite. Many phos- phatized microfossils (3 to 4 per- cent), detrital quartz (about 1 

percent), a few minute pyrite granules, and specks of iron oxide. 

Dark-gray fine-grained fossiliferous 

limestone. Composed chiefly of 

calcite. Many microfossilsf some phosphatized. Some smal gran- ules of phosphatic material are interstitial to calcite grains. There are very small quantities of detrital quartz, minute pyrite granules, and a black opaque mineral. Bulk of insoluble mat- ter seems to be finely divided 

clay. 

Dark-gray fine-grained arenaceous limestone. A few fossil brachiopods; many microfossils, most of 

which are phosphatized. Composed of calcite matrix, about 15 

percent recognizable phosphatic material, 10 percent detrital 

quartz, 2 percent detrital feldspar, come clay, and a few 

minute pyrite granules. Gray fine-grained argillaceous lime· stone. Slaty cleavage. Only recognizable constituents are minute grains of quartz, musco- vite(?), and pyrite. Almost 

opaque in thin section. 

arof 

ana 

> 

~ 

~ ~ t:rJ 

~ 

(") 

~ ~ 1-4 

t:C 

I 

00 

8 

0 

G') 

t:rJ 

~ 

~ G') 

t:rJ 

0 

1:"1 

0 

~ 
249714 •••• Franklin Lime- Precambrian __ Abandoned 1.59 stone. quarry at McAfee, N.J. 

26049L •• Leadville Lime- Mississippian Quarry at .3 stone. Garfield, Colo. 

249716__ __ Hermosa Forma- Middle Penn- Bank of Yule 4.07 

tion. sylvanian. Creek, Marble, 

Colo. 

260450 •••• Hueco Lime Permian ______ Abandoned road 1.5 stone. cut, U.S. Highway 62, 1 mile west of Hueco 

Inn, Hudspeth County, Tex. 

260478 ••.• Madison Lime- Mississippian .• Center Ell.! sec. .5 stone. 14, T. 3 S., R. 

7 E., Wasatch 

County, Utah. 

26048L ••• Unknown _______ ---------------- Road cut, U.S. 2. 9 

Highway 50, 

40.2 miles east of Eureka, 

I Nev. 

I 260483 ____ Pinery Lime- Permian •••••• Outcrop on south 1.5 stone Mem- side of U.S. 

ber of Bell Highway 62, 1 

Canyon For- mile east Salt 

mation. Flat, Tex. 

260448 __ __1 Edwards Lime- I Early Creta- stone. ceous. I South slope King Moun- I 1.8 

tain, 2 miles 

northeast of 

McCamey, 

Tex. 

I 

~60488 __ __1 Hueco Lime- Permian ______ Road cut, U.S. I 4.0 stone. Highway62, 

Hueco Gap. Hudspeth 

County, Tex. 

54.5 <1.0 .22 .16 <.05 ------- <.0001 1. 59 97.32 <2.09 <.12 -------

53.5 1.7 ------ ------- <.Ol ------- .0003 .3 95.53 3. 55 <.02 -------

53.4 1.0 .55 .23 .06 0.017 .0004 4.07 95.19 2.09 .14 0.02 

C. Marine Limestone-no significant metamorphism, fetid 

54.3 0.5 0.29 0.055 <0.01 ------- 0. 0002 1. 5 96.96 1. 05 <0.02 -------

53.2 1. 7 .14 .030 <.01 ------- .0004 .5 95.00 3. 56 <.02 -------

53.4 .7 . 70 .14 .20 0.030 .0001 2. 9 94.87 1.46 .47 0.02 

53.4 <.5 .42 .18 .07 .018 .0001 1.5 95.18 <1.05 .17 .02 

D. Marine magnesian limestone-no significant metamorphism, fetid 

148.sl 4.511.1 I o. 54 I o. 02 '-------1 o. 0001 I 1.8 I 87.09 I 9.41 I 0. 05 , _______ , 

1 49.4 1 3.1 1 .42 I .030 I <.01 1-------1 <.0001 I 4.0 I 88.21 1 6.48 I <.o2 1-------1 

.22 

-------

.55 

0.29 

.14 

o. 70 

.42 

1.1 

99. 1 + White very coarse-grained lime- stone. Composed of coarse cal99.4+ 

102.0 

99.8+ 

98.7+ 

100.4 

97.3+ 

I 99.50 

cite crystals, a few grains of 

quartz and graphite, aggregates of epidote, and pyrite granules. Gray medium-grained limestone. 

Contains traces of graphitic carbon, minute pyrite granules, and granules of colorless zoisite(?) or epidote(?). Gray fine-grained limestone. Contains minute grains of quartz, colorless zoisite(?) or epidote(?), and tiny granules of pyrite and 

graphitic carbon. 

Light-tan fine-grained dense lime- stone. Contains about 45 percent poorly preserved microfossils, a few aggregates of cryptocrystal- line silica, and specks of powdery iron oxide probably formed by alteration of pyrite. Dark grayish-brown fine-graine limestone. Composed chiefly of 

very fine grained calcite enclosing scattered large crystals of calcite, a few small aggregates of crypto- crystalline silica, and traces of 

clay. Rock contains scattered 

macrofossils and microfossils~ 

Color probably is due to organic matter. 

Light-brown fine-grained dense 

limestone containing small chert 

nodules. Sample analyzed con- tained no chert nodules. Composed chiefly of fine-grained calcite and a small amount of detrital 

quartz and feldspar, and scattered 

tiny specks of iron oxide probably formed by alteration of piirite. Brown fine-grained dense ime- stone. Composed chiefly of very fine grained calcite and scattered 

small grains of colorless calcite, a few tiny grains of detrital 

quartz, small aggregates of cryp- tocrystalline silica, and minute 

~fi~~J:'t~nules; microfossils are 

Light-tan fine-grained dense lime- stone containing small chert 

nodules. Composed chiefly of 

very fine grained calcite and tiny grains of detrital quartz, aggregates of cryptocrystalline silica, 

and specks of iron oxide. Rock 

is partly stained brownish, pos- sibly by organic matter. There are a few microfossils. 

.42 I 99.1+ Light-brown fine-grained lime- stone. Composed chiefly of finegrained calcite and scattered 

larger grains; microfossils are abundant; some seem to be 

phosphatized and others are composed partly of cryptocrystal- line silica. Specks of iron oxide, 

probably formed from pyrite, 1 I are abundant. 

0 

~ ~ 

z 

&; 

~ 

ttl 

0 

tz:j 

~ 

!;)j 

0 

c 

p:j 

Ul 

> 

~ 

~ 
La boratory 

sample 

Source Age 

I 

260452 •••• Sinbad Lime- stone Mem- Early Triassic. 

berofMoenkopi Formation. 

260457---- Chaffee Forma- Late 

tion. Devonian. 

260463 •••• Salem Lime- Late Missis- stone. sippian. 

249718 ____ Pierre Shale _____ Late Creta- ceo us. 

260458 ____ Carmel Forma- Middle and 

tion. Late Jurassic. 

149713 •••• Franklin Precambrian 

Limestone. 

T.A.BLE 2.-A.nalyses, in percent, of some ca.rbonate rocks and source materials-Continued 

Chemical composition Approximate mineral composition 

C!) $ d :a Locality .a 0 .g ~ 

g~ ~ '6~ <e ~ .s~ 0 0 0 

~~ 0 0 0 "' 0 ~~ 0 0 r;:;- ~ 0 ·sa bO Qil bO Qil Qil 

~ ~ C!) p:: o3 ~ 8 o3 

~ 0 ~ ~ p ~ 0 0 ~ - -

I. ROCKS AND SOURCE MATERIALS CONTAINING ONLY SYNGENETIC URANIUM-Continued 

D. Marine magnesian limestone-no significant metamorphism, fetid-Continued 

SWH sec. 6, T. 

21 S., R. 13 E., 

Grand Conn6.2 49.0 2.2 2.1 0.84 0.04 0.011 0.0002 6.2 87.39 4.60 0.09 0.02 2.1 

ty, Utah. 

Road cut, U.S. 11.4 38.2 9.0 2.3 .44 .06 .025 .0001 11.4 68.05 18.83 .14 .04 2.3 

Highway6-

24, east end of 

Glenwood 

Canyon, Garfield County, Colo. 

Middle bench, 

Busson's 

18.1 33.2 8.8 4.3 1.24 .05 .048 .0003 18.1 59.05 18.41 .12 .09 4.3 

~uarry, Ste. 

enevieve, 

Mo. 

Road cut U.S. 17.8 38.9 3.5 5.59 2.45 .65 .037 .0001 17.8 67.95 7.32 1. 54 ------- 5.59 

Highway40, 

· 5 miles west of 

Kremmling, 

Colo. 

Northeast end 27.6 35.8 2.5 4. 7 . 75 .12 .025 .0002 27.6 63.62 5.23 .28 .03 4. 7 ot San Rafael 

Swell, Emery County, 

Utah. 

-- ----------------------- ------

E. Marine magnesian limestone-metamorphosed, completely recrystallized, nonfetid 

Abandoned 0.17 51.8 3.3 0.45 0.26 <0.05 ------- <o. ooo1 0.17 92.50 6.90 <0.12 ------- 0.45 

quarry at Franklin, 

N.J. 

-- -------

Remarks 

'd 

0 

8 

100.4 Gray medium-grained asphaltic limestone having many small 

cavities; petroleum stained. 

Composed of fine-grained calcite 

and coarser grained secondary calcite lining cavities. Small 

detrital quartz grains are abundant. Rock contains about 0.3 

percent pyrite and many microfossils, a few of which are phos- phatized. 100.7 Dark-gray fine-grained dense lime- stone. Composed of an ex- tremely fine grained matrix in 

which there are many small 

calcite grains and detrital quartz grains. Scattered granules and 

small stringers of pyrite con- stitute about 0.1 percent of the 

rock. There are a few macro- fossils. 

100.1 Gray fine-grained argillaceous lime- stone. Composed chiefly of very fine grained carbonate minerals 

and substantial amounts of 

detrital quartz and clay; small 

blebs and stringers of an opaque black substance probably are carbonized organic residue. 

100.2 

Rock contains a few tiny granules of pyrite. Gray fine-grained argillaceous lime- stone. Composed of an ex- tremely fine grained, almost 

opaque matrix, 2 to 3 percent detrital quartz and feldspar, 2 

to 3 percent phosphatic material, 

abundant shreds and blebs of 

black opaque material that is 

probably an organic residue, and 

many granules and tiny veinlets 

of pyrite. 101.5 Grayish-brown fine-grained dense 

limestone. Contains about li 

percent detrital quartz and feld· 

spar and a considerable amount of clay and iron oxide. 

100.0+ White, very coarse grained lime- stone. Composed of large grains of carbonate minerals and a few 

:flakes of graphite and phlogopite 

- ------------- ----

> 

~ 

~ ~ 

~ ~ 

c 

~ 

~ 

~ 1-4 

0 

z 

U2 

1-3 

0 

C) 

l?=.l 

~ 

~ C) 

l?=.l 

0 

t"4 

0 

~ 
2· 60490 1 ___ Uinta Forma- Eocene ________ Near Parlette 

tion. gilsonite 

mine, Uintah 

County, 

Utah. 

50464.--- Mahogany oil . ____ do _________ NW~ sec.20, shale bed of T.10 S., R. 

Parachute 25 E., Uintah 

Creek. County, Member of Utah. 

2 

Green River 

Formation. 

~-------

i9702 ____ Niagara Group .. Middle Silur- Quarry at ian. Genoa, Ohio. 2 

2 <19703. ___ _____ do ___________ _____ dO----·--·- _____ do ________ •• _ 

2 <19712._ .. Little Falls Late Cam- Abandoned 

Dolomite. brian. quarry at Canajoharie, 

N.Y. 

~- -

<19715 ____ Fremont Lime- Late Ordovi· Sec. 24 and 25, stone. cian. T.48N., R. 

5 E., Saguache County, Colo. 

2 

l9717 ---- Leadville Lime- Mississippian_ Strauss quarr~, 

stone. Marble, Coo. 

2· 

i9704 ____ Stockbridge Cambrian and Quarry at Limestone. Ordovician. Farnams, 

Mass. 

2 

2 <10487 ---- __ ... do._------·- _____ do.------- Abandoned 

quarry at Ashley Falls, 

Mass. 

69706..-- Kittatinny Late Cam- Mulligan 

Limestone. brian and quarry, ClinOrdovician. ton, N.J. 

29707 .. __ _____ do __ ------·- _ ____ do. _______ _____ do __ --··----

See footnote at end of table. 

F. Nonmarine magnesium limestone-no significant metamorphism, nonfetid 

9.4 40.2 3.6 3. 5 1. 90 0.28 0.054 0.021 9.4 71.07 7. 53 

55.0 14.8 6. 7 7. 6 2.41 .09 .11 .0004 55.0 25.89 14.01 

-~ -- - --

G. Dolomite-no significant metamorphism, nonfetid 

0.23 31.1 22.3 0.21 0.10 <0.05 ------- 0. 0001 0.23 55.54 46.65 

.45 31.0 21.1 .19 .07 <.05 ------- <.0001 .45 55.36 44.14 

5. 72 29.5 19.8 1.43 .69 <.05 ------- <.0001 5. 72 52.68 41.42 

- - - ~ 

H. Dolomite-no significant metamorphism, fetid 

0.43 30.6 22.4 0.33 0.20 <0.05 ------- 0.0004 0.43 54.64 46.86 

I. Dolomite-metamorphosed, completely recrystallized, nonfetid 

0.56 31.1 20.6 0.82 0. 72 <0.05 ------- <0.0001 0.56 55.54 43.09 

2.05 30.7 20.2 .48 .28 <.05 ------- <.0001 2.05 54.82 42.25 

3.5 32.7 17.4 .93 .18 .02 ------- <.0001 3.5 58.34 36.40 

8.59 28.4 19.4 2.64 .36 .40 0.05 .0020 8.59 49.72 40.58 

9.85 27.7 18.9 2.69 .67 .05 ------- .0006 9.85 49.34 39.54 

0.66 0.04 3. 5 92.20 

.21 .25 7. 6 103.0 

----- ---- --· -~- --

<0.12 ------- 0.21 102.6+ 

<.12 ----·-- .19 100.1+ 

<.12 ------- 1.43 101.3+ 

---------- --

<0.12 ------- 0.33 102.3+ 

<0.12 ------- 0.82 100.0+ 

<.12 ------- .48 99.6+ 

.05 ------- .93 99.2 

.95 0.03 2.64 102.5 

.12 ------- 2.69 101.5 

Brown, extremely fine grained limestone containing small quan- titles of organic matter{ manga- nese oxide(?), detrlta quartz and feldspar, and analcite(?). 

Dark-brown madstone containing at least 25 percent kerogenous organic matter. Rock is mostly too fine grained and opaque to permit identification of constitu- ents. It contains at least 5 per- cent analcite in visible grains, 1 to 2 percent pyrite, and scattered 

small grains of detrital quartz. 

--

White medium-grained dolomite. 

No recognizable constituent 

other than dolomite. 

Brown fine-grained dolomite. No 

recognizable constituent other 

than dolomite. Rock is petro- leum stained. 

Grayish-brown fine-grained dolo· 

mite. Contains a small quantity of detrital quartz, small aggregates of cryptocrystalline silica, 

and minute granules of a pyro- bitumen generally called 

anthraxolite. 

------ - - -

Grayish-brown fine-grained dolomite. No recognizable constitu- ent other than dolomite. Rock 

is slightly stained by a brown 

substance. 

Light-gray fine-grained dolomite. 

Contains a few tiny aggregates and stringers of cryptocrystalline silica and minute pyrite grains. Light-gray fine-grained dolomite. 

Contains about 1 to 13-i percent 

quartz and a few minute musco- vite$ains. 

White medium-grained dolomite. 

Contains about 1 to 13-i percent tremolite, a few small quartz grains, and some minute musco- vite fiakes. 

Gray fine-grained dense dolomite. 

Contains a few small quartz grains and tiny quartz veinlets 

and minute granules of an iron 

mineral. 

Dark-gray fine-grained dense dolomite. Contains a few small 

quartz grains and tiny veinlets 

filled with c;g-artz pyrite, and 

graphitic car on(?). There are many ver~ minute pyrite gran- ules distri uted throughout the 

rock. 

c::f 

~ 

~ 

!2l 

~ t:J:j 

~ 

~ 

~ 

~ 

~ 
La boratory 

sample 

Source Age 

- ---

249708 .••. Milton Dolo- Late Cammite. brian. 

249709 •• -- _____ do._-------- ••••• do._------

. - - ---

260482---- Flagstaff Lime- Late Pale- stone. ocene and 

early 

Eocene(?). 

260465 ____ Fresh-water Modem _______ 

marl. 

260479 ____ Pony Express Late Jurassic .. Limestone 

Member of 

Wanakah 

formation. 

-- -- -

260485 ____ Green River Eocene ________ 

Formation. 

260456 ____ Tufa ____________ Recent ________ 

- ---

TABLE 2.-A.nalyses, in percent, of some carbonate rocks and source materials-Continued 

Chemical composition Approximate mineral composition 

.s:l .s:l d 

Locality .0 0 .0 il-l .El .El<ll OJ.< ~ ~~ o; 

.s! ~ ~~ 0 0 0 

~Ill 0 0 <ll ~.!3 

0 0 ~ r:: 0 Ill 0 "'<D 0 ·as bO 'C)'d bO Ill Ill 

~ ~ <D ~ Ill 

~ s Ill 

-< 0 ~ ~ p -< 0 0 ~ 

- -----

I. ROCKS AND SOURCE MATERIALS CONTAINING ONLY SYNGENETIC URANIUM-Continued 

I. Dolomite-metamorphosed, completely recrystallized, nonfetid-Continued 

Outcrop on east 13.80 28.4 17.1 4.80 1. 06 3.06 .29 .0030 13.80 43.50 35.77 7.24 .04 4.80 

side of U.S. 

Highway7, 

south of 

Milton, Vt. 

_____ do._-------- 22.45 24.0 15.8 3.46 1.16 . 70 .078 .0014 22.45 41.18 33.05 1. 66 .03 3.46 

1. Nonmarine limestone-not metamorPhosed, nonfetid 

Abandoned 1.4 53.9 <0.5 0. 62 0.16 0.05 0.008 0. 0001 1.4 96.12 <1.05 0.12 0.008 0. 62 

Bird's Eye 

quarry, sec. 30, 

T.10 S.bR. 4 

E., Uta 

County, 

Utah. 

Lake bottom, 1~ 2.8 52.2 .5 1.0 .11 .03 .005 <.0001 2. 8 93.11 1. 05 .07 .004 1. 0 

miles south 

of Charlo, 

New Brunswick, Canada. 

Abandoned 5.0 51.1 . 5 .91 .19 .02 ------- .0001 5.0 91.20 1.05 .05 ------- .91 

quarryl Sawpit, Coo. 

--------~--- ------

K. Nonmarine magnesian limestone-not metamorPhosed, nonfetid 

SW!4 sec. 14Er 16.8 29.1 10.8 3. 7 1.00 0.17 0.085 <0.0001 16.8 51.37 22.59 0. 40 0.15 3. 7 

lOS., R.6 ., Utah County, Utah. 

'i 

0 

~ 

105.13 

101.8 

98.3+ 

98.0 

98.2 

95.0 

-~-----

L. Calcareous tufa from uraniferous district-not metamorPhosed, nonfetid 

S~i sec. 24, T. 30 7.2 49.7 1.6 0.68 0.03 0.12 0.050 0.0004 7.2 88.36 3.35 0.28 0.08 0. 68 100.0 

N.,R.90W. 

Fremont 

County, Wyo. 

- -

Remarks 

Gray tine-grained siliceous dolomite. Contains about 10 per-

~1n: %~~~ a~d 6l~~~t s~E:r:~! that seems to be an organicresi- due; phosphatic constituent 

probably is mixed with this re- sidual substance. Extremely tine 

grained pyrite is dispersed throughout the rock. (R20s probably includes some (P04)-B,) 

Gray tine-grained siliceous dolomite. Composed chiefly of 

cloudy carbonate mineral and 

about 10 percent quartz and 

cryptocrystalline silica. Some of 

the cloudiness seems to be due to clay-size detritus. Contains a few minute pyrite granules. 

Light-brown, extremely tine 

grained dense limestone. Only constituent that can be identifled is calcite. 

Buff unconsolidated marl currently being deposited. Composed chiefly of extremely fine grained calcium carbonate and a small 

quantity of clay and silt. 

Very dark gray, extremely tine 

grained dense limestone; con- tains about 3 percent detrital 

quartz, some detrital feldspar, and minute granules of pyrite. 

Buff, extremely fine grained marl· stone. Mostly too fine grained for identification of constituents. 

Contains a tew tiny grains of a carbonate mineral, quartz, and 

pyrite. 

---

Buff fine-grained deposit of extinc1 

spring. Composed chiefly o calcite and contains about 3 per· cent quartz and cryptocrystallinE silica, traces of organic matter, 

limonite, and some clay. 

> t..:> 

Oo) 

~ ~ t_:fj 

l;:lj 

c 

~ ~ 

~ 1-4 

~ UJ 

8 

0 

~ t_:fj 

~ 

~ 0 

tot 

0 

~ 
260489 ____ Land snail. _____ Modem _______ Sec. 29, T. 6 S., 0.1 55.0 

R.4 E., Utah 

County, 

Utah. 

260468---- Barnacle ________ _____ do. ________ Falmouth, <.1 54.0 

Mass. 

260467---- Clam, tivela _____ do _________ Lions Head, <.1 53.2 

atultorum. Santa Barbara County, 

Calif. 

260489 ____ Blue mussel, Modern _______ 

mytilua edulia. 

Hull, Mass •.••.• .2 50.0 

260484 2 ___ Tansill Forma- Permian.----- SE~ sec. 21, T. 0.05 55.0 

tion. 22 S., R. 25 

E., Eddy 

County, 

N.Mex. 

-~-

24g721 ____ Sundance For- Late Jurassic .• Sec.3, T. 44 5.11 52.8 

mation. N., R.83W., 

Johnson 

County, 

Wyo. 

260469 ____ Todilto Lime- Late Jurassic .• NW~ sec. 31, 4.7 53.2 stone. T.13 N., R.9 

W., McKinley County, 

N.Mex. 

260470 •••• _____ do ______ ----- • •.•• do _________ •.••• dO----------- 2. 7 52.7 

260471 ____ _____ do ___________ ••••• do _________ ••••• do ________ --- 10.6 46.9 

260472 ____ _____ do ___________ _____ do _________ _____ do ___________ 8.2 49.1 

See footnote at end of table. 

M. Shells ot Modern organisms 

<0.5 0.09 0.011 0.02 ------- <.0001 0.1 98.16 

<.5 .11 .020 <.01 ------- <.0001 <.1 96.43 

<.5 .11 .013 <.o1 -------- <.0001 <.1 95.00 

<.5 .42 .020 .06 .006 <.0001 .2 89.12 

D. ROCKS CONTAINING EPIGENETIC URANIUM 

A. Marine limestone-not metamorphosed, nonfetid 

<0.5 0.34 0.14 0.05 0.010 0.0054 0.5 98.09 

B. Marine limestone-not metamorphosed, fetid 

<1.0 0.86 0.44 <0.05 ------- 0.055 5.11 94.28 

C. Nonmarine limestone-not metamorphosed, fetid 

0.5 0.89 0.13 0.04 0.020 0.0005 4. 7 94.87 

<.5 . 78 .16 .02 ------- .031 2.7 94.05 

.8 2.8 .35 .06 .024 ,0006 10.6 83.55 

.5 1.3 .25 .08 .018 .0032 8.2 87.46 

<1.05 0.05 ------· 0.09 

<1.05 >.02 ------- .11 

<1.05 >.02 ------- .11 

<1.05 .14 .002 .42 

<1.05 0.12 0.01 0.34 

<2.09 <0.12 ------- 0.86 

1. 05 0.09 0.03 0.89 

<1.05 .05 ------- . 78 

1.67 .14 .04 2.8 

1.05 .18 .02 1. 3 

98.4+ 

96.5+ 

95.1+ 

89.7+ 

99.1+ 

100.2+ 

101.6 

97.6 

98.8 

98.2 

Includes small amount of chitin. 

Snails lived on a terrain of Flagstaff Limestone. 

Shells contained small amount of 

organic matter. Includes a small quantity of chitin 

and other organic matter. 

Includes some chitin and other 

organic matter. 

Brownish-gray fine-grained vnggy limestone. Vugs are lined with 

secondary calcite. Small specks 

and stains of reddish-brown iron 

oxide are distributed throughout the rock. Traces of a powdery yellow mineral, probably tyuya- munite, occur on some vug walls. 

Mottled reddish-brown and gray 

oolitic limestone containing about 0.2 percent metatyuyamu- nita on fracture surfaces and 

irregularly distributed through- out the rock, about 4 percent detrital quartz and feldspar, 1 

percent cryptocrystalline silica, 

and stains of reddish-brown iron 

oxide. 

Brownish-gray fine-grained dense 

limestone. Contains about 3.5 

percent detrital quartz and feldspar, a few minute specks of iron 

oxide, and traces of tyuyamunite on fracture surfaces. 

Brownish-gray fine-grained dense 

limestone. Contains about 2 

percent detrital q.uartz and feldspar, traces of rron oxide and 

tyuyamunite. 

Light brownish-gray fine-grained thin-bedded silty limestone. 

Contains about 10 percent 

detrital quartz and feldspar, a few minute granules of iron oxide 

and pyrite, and thin films of 

tyuyamunite. 

Brownish-gray fine-grained dense 

limestone. Contains about 7 

percent detrital quartz and feldspar, and a few specks of reddishbrown iron oxide. There are traces of tyuyamunite on fracture 

surfaces. 

~ 

i 

z 

f; 

~ 0 

~ 

~ 

~ 

0 

~ 

> 1::..:> 

-.J 
TABLE 2.-.A.nalyses, in percent, ot some carbonate rocks and source materials-Continued 

Chemical composition Approximate mineral composition 

La bora-

~ $ 0 

tory Source Age Locality 0 ,Q 

:::l e 

sample 5l~ ~ '¢"' .,:::l ~ 

.S-<-> 1":>:1 

~E 0 0 0 

.c,~ 0 0 "' 0 ~ r;: 0 ·s S 0 bO «l 0 ~.§ 0 bO «l «l 

~ ~ ct> 

~ «l 

-< 0 1":>:1 1":>:1 p -< 0 ~ s 0 "' ~ -

II. ROCKS CONTAINING EPIGENETIC URANIUM-Continued 

C. Nonmarine limestone-not metamorphosed, fetid-Continued 

260473 ____ Todilto Forma- Late Jurassic •. NW}-4 sec. 31, 15.5 44.9 0.5 2.1 0.22 0.07 0.025 0.023 15.5 79.98 1.05 .16 0.04 2.1 

tion. T.13N.KR.9 

W.,Mc inley County, 

N.Mex. 

260474 ____ _____ do •• _ •• _____ _____ do _________ _____ do ___________ 16.1 45.4 . 4 1.9 .14 .04 .009 .0039 16.1 80.98 .84 .09 .01 1.9 

260476.--- ___ •• do ___________ _____ do _________ ____ .do ___________ 1. 5 56.1 <.5 .88 .10 .08 .85 .45 1.5 97.78 <1.05 .18 1. 73 .88 

260475 ____ _____ do ___________ _____ do _________ __ ••• do _______ ---- 1.5 53.7 <.5 .93 .45 .04 .048 .033 1.5 95.70 <1.05 .09 .09 .93 

260477---- _____ do ___________ _____ do _________ Sec. 2\i T. 13 10.2 46.6 <.5 3.8 . 51 .06 .067 1.19 10.2 82.91 <1.05 .14 .13 3. 8 

N., .9W., 

McKinley 

County, 

N.Mex. 

.. ------------ -- --~~----------------~~--~-----------

III. ROCKS IN WHICH THE GENETIC CHARACTER OF THE URANIUM WAS NOT DETERMINED 

A. Brackish water limestone-not metamorphosed, fetid 

W668733 __ Bear River Early Creta- Sec. 4, T. 1 S., 10.9 46.5 0. 7 3.1 0. 93 0.86 0.15 0.024 10.9 80.80 1. 46 2.04 0.15 3.1 

Formation. ceo us. R.42 E., 

Bonneville 

County, 

Idaho. W902183 __ _____ do.--··----- _ ••••• do ________ ______ do __________ 11.0 46.5 . 6 4.1 .86 1.35 .17 .012 11.0 79.73 1.26 3.20 .10 4.1 

W672473 __ _____ do _____ ------ ••••• do _________ _____ do ___________ 12.6 45.8 .5 4.8 1.1 . 91 .12 .011 12.6 79.55 1.05 2.15 .08 4.8 

<d 

~ 

98.8 

99.9 

102.0+ 

98.3+ 

97.2+ 

98.5 

99.4 

100.2 

Remarks 

Brownish-gray fine-grained dense 

limestone. Contains about 15 

percent detrital quartz and feldspar, a few specks of reddishbrown iron oxide and pyrite granules. There are traces of 

tyuyamunite on fracture surfaces. 

Brownish-gray fine-grained dense 

limestone. Contains about 15 

percent detrital quartz and feldspar and a few specks of iron 

oxides. There is tyuyamunite on fracture surfaces. 

Light brownish-gray fine-grained dense limestone. Contains about 

1 percent detrital quartz, many tiny fluorite grains, and traces of 

tyuyamunite. 

Recrystallized limestone that is 

bleached and partly stained by iron oxides. The altered equtva· lent of sample 260469. Contains 

about 1 percent quartz in rounded 

and corroded reams, small aggregates of pow ery tyuyamunite, and iron oxide stains. 

Brownish-gray fine-grained dense 

limestone spotted and streaked 

with red iron oxide and uranlnite. 

Contains about 8 percent detrital 

quartz and feldspar. Mineral· 

ized parts consist of a mixture of 

extremely fine grained reddishbrown substance (hematite?) 

and uraninite interstitial to, and 

replacing, calcite, and abundant 

minute pyrite granules. 

Gray fine-grained limestone con- taining a substantial quantity of organic matter. 

Dark-gray thinly laminated lime· stone with thin coaly partings. Contains about 10 percent or· ganic matter, 0.5 percent pyrite, and a few quartz grains. Phos· 

phatic constituent probably is 

mixed with the dark coaly sub- stance. 

Gray fine-grained limestone con- taining a substantial quantity of organic matter. 

> tV 

00 

~ 

~ ~ 

c 

~ ~ 

; 

I 

Ul 

1-3 

0 

~ 

~ 

~ 0 

t:z:.l 

0 

s 

~ 
W67241 a __ Bear River Early Creta- Sec. 4, T.1 S., Formation. ceo us. R.42E., 

BonnevUle 

County, 

Idaho. 

260454 ____ Mancos Shale ___ Late Creta- Road cut, U.S. ceo us. Highway40, 

1 mile west of 

Steamboat 

Springs, Colo. 

260455 ____ Monterey Shale_ Miocene_----- Road cut, U.S. 

Highway 101, 

2 miles north 

of Shell 

Beach, San 

Luis Obispo County, Calif. 

-- ---- ------- --'-

1 Collected by E. P. Baroni. a Collected by A. P. Pierce and J, W. Mytton. a Collected by James D. Vine. 

36.7 

20.6 

24.4 

30.9 .9 9.4 4.0 .34 .08 .022 36.7 54.26 1. 88 .80 .10 9.4 103.1 Gray fine-grained argillaceous lime- stone with a substantial quantity of organic matter. 

B. Carbonate concretions in marine shales-not metamorphosed, nonfetid 

41.0 1.1 5. 8 1. 66 0.10 o. 016 0. 0001 20.6 72.98 2. 30 0.24 0.01 5. 8 101.9 Gray fine-grained concretion in 

shale. Consists chiefly of very fine grained calcite, about 15 

percent clay, 5 percent detrital 

quartz, a small quantity of or- ganic matter, and a few pyrite granules. 

19.5 14.2 6.2 2.25 .20 .047 .0005 24.4 43.00 29.70 .48 .06 6.2 103.8 Brownish-gray fine-grained con- cretion in shale. Consists chiefly of extremely fine grained material 

in which no minerals can be 

recognized, and contains about 

15 percent detrital quartz and 

feldspars, a few granules of 

pyrite, and a trace of organic matter. 

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