Strategic and Critical Minerals in the 

Midcontinent Region, United States

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Strategic and Critical Minerals in the 

Midcontinent Region, United States

Edited by WARREN C. DAY and DIANE E. LANE

A. Geology and Mineral Paragenesis of the Pea Ridge 

Iron Ore Mine, Washington County, Missouri-Origin of the 

Rare-Earth-Element- and Gold-Bearing Breccia Pipes

By LAURENCE M. NUELLE, WARREN C. DAY, GARY B. SIDDER, and 

CHERYLM. SEEGER

B. Some Mineralogical and Geochemical Aspects of Middle and Upper 

Pennsylvanian Marine Black Shales in Part of the Midcontinent Region

By GEORGE A. DESBOROUGH, JOSEPH R. HATCH, and JOEL S. 

LEVENTHAL

C. Mineralogical and Geochemical Analysis of the Metal- and Organic-Rich 

Grassy Creek Shale of the New Albany Group (Upper Devonian and 

Lower Mississippian) in Hardin County, Southern Illinois

By GEORGE A. DESBOROUGH

Chapters A, B, and C are issued as a single volume and are not available separately

U.S. GEOLOGICAL SURVEY BULLETIN 1989-A-C
U.S. DEPARTMENT OF THE INTERIOR 

MANUEL LUJAN, JR., Secretary

U.S. GEOLOGICAL SURVEY 

Dallas L. Peck, Director

Any use of trade, product, or firm names in this publication is for descriptive 

purposes only and does not imply endorsement by the U.S. Government.

UNITED STATES GOVERNMENT PRINTING OFFICE: 1992

For sale by the

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Library of Congress Cataloging-in-Publication Data

Strategic and critical minerals in the midcontinent region, United States / edited 

by Warren C. Day and Diane E. Lane.

p. cm. (U.S.Ceological Survey bulletin ; 1989-A-C)

Includes bibliographical references.

Supt. of Docs, no.: I 19.3:1989

1. Ore-deposits Middle West. 2. Strategic materials Middle 

West. 3. Midcontinent Strategic and Critical Minerals Project (U.S.). I. Lane, 

Diane E. II. Series. 

TN23.4.S77 1992

553'.0977 dc20 91-33983

CIP
Chapter A

Geology and Mineral Paragenesis of the 

Pea Ridge Iron Ore Mine, 

Washington County, Missouri 

Origin of the Rare-Earth-Element- and 

Gold-Bearing Breccia Pipes

By LAURENCE M. NUELLE, WARREN C. DAY, 

GARY B. SIDDER, and CHERYL M. SEEGER

U.S. GEOLOGICAL SURVEY BULLETIN 1989

STRATEGIC AND CRITICAL MINERALS IN THE MIDCONTINENT REGION, 

UNITED STATES

WARREN C. DAY and DIANE E. LANE, Editors
CONTENTS

Abstract Al 

Introduction Al 

Geologic setting A2 

Geology of the deposit A2

Amphibole-quartz zone A3 

Magnetite zone A3

Massive magnetite A3 

Magnetite-cemented heterolithic breccia A3 

Pseudobreccia A3 

Specular hematite zone A4 

Silicified zone AS 

Mafic dikes A6 

Aplite dikes A6 

Banded rock A6 

REE-bearing breccia pipes A6

Mineralogy and chemistry A7 

Structure A8

Genesis of the REE-bearing breccia pipes A8 

Summary A10 

Acknowledgments A10 

References cited A10

FIGURES

Al. Geologic map of the Middle Proterozoic St. Francois terrane, southeastern

Missouri, showing locations of eight known magnetite and hematite

deposits A2 

A2. Diagram showing paragenesis of major and minor minerals in the Pea Ridge

mine A4

A3. Geologic map of the 2,275-ft level, Pea Ridge mine AS 

A4. Diagram showing paragenetic sequence of the rock types in the Pea Ridge

mine AS 

A5. Plot of abundances of rare-earth elements in breccia pipes in the Pea Ridge

mine A9

TABLE

Al. Analyses for rare-earth-elements, uranium, thorium, and gold in REE-bearing 

breccia pipes, Pea Ridge mine AS

IV Contents
STRATEGIC AND CRITICAL MINERALS IN THE MIDCONTINENT REGION, UNITED STATES

Geology and Mineral Paragenesis of the Pea Ridge Iron 

Ore Mine, Washington County, Missouri Origin of the 

Rare-Earth-Element- and Gold-Bearing Breccia Pipes

By Laurence M. Nuelle1 , Warren C. Day, Gary B. Sidder, andCheryl M. Seeger 1

Abstract

Breccia pipes containing rare-earth elements (REE) and 

gold are a potentially significant economic target in the Pea 

Ridge iron ore mine, Washington County, Missouri. The Pea 

Ridge deposit is one of eight known volcanic-hosted iron ore 

deposits in the Middle Proterozoic St. Francois terrane that are 

similar to the Olympic Dam type of deposits of Australia. The 

iron orebody is steeply dipping and tabular shaped, and it cuts 

across the host rhyolite. The footwall of the deposit is zoned 

from the massive apatite-bearing magnetite core outward to 

heterolithic breccia, pseudobreccia, a specular hematite zone, 

and an extensive silicified zone. The hanging wall is zoned 

from the massive magnetite core outward to heterolithic 

breccia, pseudobreccia, and an amphibole skarn zone. The 

REE-rich breccia pipes cut through the various rock types along 

the footwall at or near contacts. They are typically about 60 m 

long and 15 m wide, and they extend at least 120 m vertically. 

The pipes consist of fragments of rhyolite host rock and zones 

of massive magnetite, specular hematite, and silicified rocks 

supported in a matrix of rock flour, barite, feldspar, monazite, 

apatite, chlorite, xenotime, and, locally, gold. Total REE oxide 

content of samples of the groundmass material, which are not 

diluted with lithic fragments, average about 20 weight percent. 

Grades from working faces in the mine are lower, averaging 

about 12 weight percent. Gold distribution is erratic, but 

concentrations are as high as 371 parts per million.

The Pea Ridge iron deposit represents an intrusion-type 

deposit in which the magnetite orebody sloped upward into 

the host rhyolite and created the various breccia zones around 

the margins of the deposit. The REE-bearing breccia pipes 

probably formed from late-stage magmatic-hydrothermal 

fluids that evolved from the main magnetite orebody. Sanidine 

phenocrysts (or xenocrysts) in the breccia pipes confirm a 

magmatic component for their origin. The magmatic-hydroManuscript approved for publication August 5, 1991. 

'Missouri Department of Natural Resources, Rolla, MO 65401.

thermal fluids underwent second boiling and decompression 

and caused crystallization and release of a volatile phase. 

Fluid-inclusion evidence of boiling includes a mixed population of vapor-rich fluid inclusions coexisting with liquid-rich 

inclusions in quartz from the REE-bearing breccia pipes. The 

concomitant volume increase associated with boiling released 

significant mechanical energy and caused fracturing and brecciation of the wallrock. The REE-bearing fluid and crystal 

mixture streamed upward along zones of weakness (faults 

and contacts), entrained and milled wallrock fragments, and 

formed the breccia pipes.

The REE- and, locally, gold-bearing breccia pipes associated with the Pea Ridge iron deposit are attractive targets in the 

midcontinent of the United States for exploration of large 

deposits of iron, copper, REE, gold, and uranium similar to the 

Olympic Dam deposit in Australia.

INTRODUCTION

This study of the Pea Ridge mine is part of a 5-year 

cooperative effort between the Missouri Department of 

Natural Resources-Geology and Land Survey and the U.S. 

Geological Survey (USGS) under the USGS Midcontinent 

Strategic and Critical Minerals Project. One of the overall 

goals of the cooperative effort is to provide a genetic and 

predictive model for the possible occurrence of iron, copper, 

REE, and gold deposits in the midcontinent region that may 

be similar to the Olympic Dam deposit of Australia 

(Oreskes and Einaudi, 1990). Initial work centered on the 

Pea Ridge deposit inasmuch as it offers the most complete 

lateral and vertical view of this deposit type in the midcontinent region. This report presents observations and hypotheses generated from our mine mapping program. Traverses 

that cross lithologic contacts and structural features in the 

mine were selected in order to establish paragenetic 

relationships and to serve as a base for geochemical and 

petrographic studies.

Pea Ridge Iron Ore Mine, Missouri A1
GEOLOGIC SETTING

Middle Proterozoic rocks of the St. Francois terrane, 

which includes rhyolitic ash-flow tuffs, lava flows, and 

coeval granitic plutons, host Missouri's Precambrian iron 

ore deposits. Zircon crystals from the granite bodies have 

yielded U-Pb isotopic ages of 1,480-1,450 Ma (Bickford, 

1988). Kisvarsanyi (1980, 1981) recognized three types of 

granitic rocks in the St. Francois terrane: subvolcanic 

massifs, ring intrusions, and central plutons (fig. Al). The 

subvolcanic massifs, which are intrusive equivalents of 

coeval rhyolitic rocks, are epizonal biotite granite having 

granophyric and rapakivi textures and containing perthitic 

alkali feldspar; biotite is the characteristic mafic mineral. 

Magnetite is a ubiquitous accessory mineral. Ring intrusions, which include intermediate- to high-silica amphibole 

granite, biotite-hornblende granite, adamellite, and syenite, 

were emplaced in ring fractures related to caldera collapse 

and cauldron subsidence. In contrast, central plutons of 

high-silica, two-mica granite were emplaced in resurgent 

cauldrons. The central plutons have distinct accessory 

minerals, such as fluorite, topaz, allanite, monazite, garnet, 

and cassiterite, and a characteristic trace-element suite that 

includes elevated abundances of Sn, W, Nb, Y, Be, Li, Rb, 

Ba, and F. The central plutons have a unique negative 

magnetic anomaly signature (Kisvarsanyi, 1984; Kisvarsanyi and Kisvarsanyi, 1989). Most authors agree that the 

magmas were generated from melting of previously 

accreted crustal material (Nelson and DePaolo, 1985). 

Kisvarsanyi (1975) proposed that the St. Francois terrane 

formed in an anorogenic extensional tectonic setting (failed 

cratonic rift environment), whereas Patchett and Ruiz 

(1989) suggested that these rocks are not anorogenic, but 

formed during orogenic-accretionary processes associated 

with the early stages of the Grenville Orogeny.

The St. Francois terrane hosts eight known magnetite 

and hematite deposits (fig. Al), which together constitute an 

iron metallogenic province (Kisvarsanyi and Proctor, 1967; 

Snyder, 1969). The iron deposits occur as both intrusive and 

replacement bodies within volcanic rocks of the terrane. The 

deposits may be genetically related to the host anorogenic 

rhyolite rocks, as suggested by Day and others (1989) for 

the Pea Ridge deposit.

The southeastern Missouri iron metallogenic province 

contains reserves estimated at nearly 1 billion tonnes of iron 

ore (Arundale and Martin, 1970). Iron ore has been continuously produced from the province since 1815, except for 

one year during the Great Depression. Until 1963, Precambrian hematite deposits were the major source of iron 

ore in Missouri; since the opening of the Pea Ridge mine in 

1964, all iron ore production has been from subsurface 

Precambrian magnetite deposits. The Pilot Knob underground mine opened in 1967 and produced slightly more 

than 9.8 million tonnes of usable iron ore before closing in 

1980. Since 1980, the Pea Ridge mine has been the State's

0 10 20 KILOMETERS

A 

o

EXPLANATION

Granite central pluton 

Trachyte porphyry ring intrusion 

Granite porphyry ring intrusion 

Subvolcanic granite massif 

Rhyolitic volcanic rocks

Active underground mine 

Inactive mine 

Undeveloped deposit 

Town 

Contact

Figure A1. Geologic map of the Middle Proterozoic St. 

Francois terrane, southeastern Missouri, showing locations of 

eight known magnetite and hematite deposits (modified after 

Kisvarsanyi, 1981).

only iron ore producer, and it is the only remaining 

underground iron mine in the nation. To date, about 41.6 

million tonnes of usable iron ore have been produced from 

the Pea Ridge mine.

GEOLOGY OF THE DEPOSIT

The Pea Ridge magnetite-apatite deposit is a tabular 

body that is discordant to bedding of the rhyolitic host 

rocks. The orebody strikes roughly N. 55° E. and dips

A2 Strategic and Critical Minerals, Midcontinent Region, U.S.
75°-90° SE. (Husman, 1989). Xenotime from a quartz vein 

that cuts the iron ore yielded a U-Pb age of 1.46 Ga (W.R. 

Van Schmus, University of Kansas, written commun., 

1988), which is a minimum age for the deposit; this age is 

within the age range of 1.45-1.48 Ga for the St. Francois 

terrane as reported by Bickford and Mose (1975) and 

Bickford (1988).

Rocks of the Pea Ridge deposit are divided into four 

zones: (1) the amphibole-quartz zone; (2) the magnetite 

zone, which is made up of massive magnetite, magnetitecemented heterolithic breccia, and pseudobreccia; (3) the 

specular hematite zone; and (4) the silicified zone. Other 

rock types include magnetite veins, quartz veins, aplite 

dikes, mafic dikes, and a unique banded rock. REE-bearing 

breccia pipes cut rocks of the footwall. Figures A2 and A4 

present the paragenetic relationships in the deposit, and 

figure A3 is a geologic map of the 2,275-ft level.

Amphibole-Quartz Zone

The amphibole-quartz zone occurs in both the 

hanging wall and footwall of the deposit. It consists of 

massive, coarse-grained actinolite (blades as much as 5 cm 

long) and interstitial apatite, magnetite, pyrite, chalcopyrite, 

and calcite. Quartz is present as both interstitial grains and 

as massive pods 1-50 cm in diameter. From the eastern edge 

of the deposit westward, the amphibole-quartz zone thins in 

the hanging wall from massive amphibole-quartz rock into 

host rock in which fractures are filled with amphibole and 

have silicified walls (Emery, 1968). Locally, contacts grade 

into host rhyolite wallrock, which exhibits incipient stages 

of amphibole replacement. Farther from the contact, veins 

of magnetite cut massive actinolite. The footwall zone is 

less brecciated and contains fewer quartz pods than the 

amphibole-quartz zone in the hanging wall.

This zone represents a skarn alteration front that 

preceded the emplacement of the magnetite orebody. The 

protolith of the amphibole-quartz zone is the host rhyolite. 

Metasomatic replacement of the protolith has partially 

destroyed obvious textural or chemical evidence of the 

original rock type. Relict textures of rhyolitic wallrock have 

been noted in amphibole-quartz fragments along the 

hanging wall (J.R. Husman, The Doe Run Company, oral 

commun., 1990).

Magnetite Zone

In previous reports, the magnetite and rhyolite 

porphyry breccia zones (Emery, 1968) and the magnetite 

and brecciated wallrock-magnetite zones (Nuelle and 

others, 1989) were treated separately. However, further 

mapping and documentation of temporal relations have 

shown that the massive magnetite orebody and magnetitebearing breccias were contemporaneous and that it is useful 

to treat the magnetite orebody as a zone composed of 

subzones of massive magnetite, magnetite-cemented heterolithic breccia, and pseudobreccia.

Massive Magnetite

Ore faces in the massive magnetite contain as much 

as 65 volume percent magnetite, with average grades 

ranging from 47 to 55 percent magnetic iron (Emery, 1968). 

The texture varies from massive and shiny ore having 

subconchoidal fracture to finely crystalline and granular. 

Some ore has a porphyritic texture in which magnetite (or 

martite after magnetite) and hematite megacrysts are in a 

massive, fine-grained magnetite groundmass. Gangue 

minerals in the magnetite ore are predominantly apatite, 

quartz, pyrite, and monazite, and minor ferroactinolite, 

biotite, chlorite (after biotite), fluorite, barite, grunerite, and 

talc (fig. A2). The gangue forms interstitial intergrowths, 

net-textured veinlets, and pods within the massive magnetite ore.

Magnetite-Cemented Heterolithic Breccia

This breccia is characterized by fragments of host 

rhyolite, chloritized rhyolite, and rock from the amphibolequartz zone in a matrix of massive magnetite and (or) 

hematite. It occurs discontinuously along the margins of the 

orebody, but is particularly well developed along the 

hanging wall (fig. A3).

The breccia was formed in a manner similar to an 

intrusion breccia as described by Laznicka (1988). In situ 

exfoliation of wallrock fragments, filling of the planes of the 

exfoliated sheets with magnetite, and the presence of 

wallrock schlieren suggest that the magnetite ore fluid had 

Theological properties similar to an intrusive magma.

Pseudobreccia

Laznicka (1988) described one variety of pseudobreccia as being formed by replacement of host rock, which 

results in a breccialike appearance; the rock fragments are 

not produced by physical abrasion, nor are they displaced or 

rotated. The term "pseudobreccia," as used here, is defined 

as host rhyolite that has been partially to totally replaced by 

magnetite and (or) hematite along fractures and has a 

breccialike appearance. The fragments do not appear to 

have been rotated or mechanically fragmented.

The pseudobreccia has a sharp contact with the 

magnetite orebody. Along its outer margins, the pseudobreccia grades inward from iron oxide-cemented crackle 

breccia to iron oxide-cemented mosaic breccia, and then 

into rubble breccia near the magnetite orebody. Roundness 

and metasomatic alteration of the rhyolite fragments 

increases towards the orebody.

Pea Ridge Iron Ore Mine, Missouri A3
TIME

Old Young

Quartz

Actinolite

Magnetite

Hematite

Pyrite

Chalcopyrite

Apatite

Monazite

Xenotime

Biotite

Chlorite

Epidote

Muscovite/sericite

Potassium feldspar

Fluorite

Barite

Tourmaline

Rutile

Calcite

Grunerite

Talc

Anhydrite

Amphibolequartz zoneMagnetite 

zone

 

 

 

 

Magnetite 

veins

?

Specular 

hematite 

zone

Silicified 

zone

 

 - -

_ _ _

 

Quartz 

veins

 

 

REE-bearing 

breccia pipes

__ 

 

 - -

Quartz 

veins

 

 

Figure A2. Paragenesis of major and minor minerals in the Pea Ridge mine, Washington County, Mo. Solid line, major 

deposition; dashed line, minor deposition.

Specular Hematite Zone

The specular hematite (specularite) zone separates the 

silicified zone from the magnetite orebody along the footwall, and rhyolite host rock from the orebody along the 

eastern edge of the deposit (fig. A3). The width of the zone 

varies, and it thins with depth (Husman, 1989). Contacts 

between the specular hematite zone and the magnetite

orebody are commonly gradational, and the hematite contains irregularly distributed patches and areas of magnetite. 

However, the contacts are sharp locally. The specularite is 

finely to coarsely crystalline, generally platy, compact, and 

massive. Most of the specularite is an alteration product of 

magnetite.

Mapping documents that the specular hematite zone 

in part formed along fault zones and that the width of the

A4 Strategic and Critical Minerals, Midcontinent Region, U.S.
N148000

N147000

8t°f

E95000______________ 

EXPLANATION

REE-bearing breccia pipe

Silicified zone

Specular hematite zone

Magnetite - cemented heterolithic breccia

Magnetite zone

Amphibole-quartz zone

Rhyolitic volcanic rocks

Contact Dashed where inferred

Observed fault Dashed where inferred;

bar and ball on downthrown side,

arrow indicates dip direction 

Aplite dike 

Mafic dike

E96000 E97000

1675 porphyry

1825 porphyry

2275 porphyry

X-11 fault 

V-12pipe

0 1000 2000 FEET 

0 25 50 METERS

Unnamed 

porphyry

Figure A3. Geologic map of the 2,275-ft level, Pea Ridge mine, Washington County, Mo. (modified after Hussman, 1989).

zone varies proportionally with the width of the fault zones. 

The specularite is locally sheared and foliated parallel to the 

orientation of post-ore faults.

Silicified Zone

Silicified wallrock is extensively developed in the 

footwall (fig. A3). Horizontal underground drilling of the 

footwall northward away from the orebody on the 2,275-ft 

level penetrated 120 m of Silicified rock without exiting the 

zone, and surface drill holes more than 400 m north of the

TIMEAmphibole-quartz zone « 

Magnetite zone 

Specular-hematite zone 

Silicified zone 

Quartz veins

REE-bearing breccia pipes 

Mafic dikes 

Aplite dikes

Figure A4. Paragenetic sequence of the rock types in the 

Pea Ridge mine, Washington County, Mo.

Pea Ridge Iron Ore Mine, Missouri A5
orebody intersected silicified volcanic rock. The silicified 

zone is characterized by massive, white to light-gray quartz 

that replaced the host rhyolite wallrock to varying extents; 

areas that are greater than 75 percent quartz are not 

uncommon. Potassic alteration associated with siliciflcation 

included the addition of potassium feldspar to the wallrock. 

Potassium feldspar flooding converted the grayish or 

reddish-brown volcanic rocks to bright moderate-reddishorange rock. Locally, quartz and potassium feldspar form 

pegmatitic pods and veins. Accessory minerals in the 

silicified zone include fluorite, muscovite, biotite, tourmaline, chlorite after biotite, epidote, calcite, barite, rutile, 

pyrite, and chalcopyrite. In addition, Husman (1989) noted 

monazite, apatite, and topaz.

The silicified zone is a product of both open-space 

filling and replacement. An increase in the number of 

fractures from the wallrock into the silicified zone suggests 

that stockwork fracture systems may have controlled 

siliciflcation. On the 2,275-ft level, along the X-ll drift, 

siliciflcation is associated with a high-angle fault. Sericite 

along fractures and fragment surfaces shows that sericitization accompanied silicification. The silicified zone grades 

into areas of fracture-fill quartz veins. Silicification also 

extends several meters into the specular hematite zone. 

Younger sets of quartz veins cut both the zone and the 

adjacent wallrock. Relict breccia textures in the silicified 

zone suggest that brecciated zones were conduits that were 

later rehealed by silica (Seeger and others, 1989).

Mafic Dikes

Mafic dikes cut across the host rhyolite, the magnetite 

orebody, and the silicified zone. Contact with the REEbearing breccia pipes was not observed. The temporal 

relationship between the mafic and aplite dikes is ambiguous (fig. A4). Emery (1968) observed mafic dikes that are 

cut by aplite dikes. However, our mapping indicates that a 

mafic dike also cuts an aplite dike.

The dikes are black to dark greenish gray and have a 

greasy luster. They range in thickness from less than 1 cm 

to more than 3 m and occur in two fracture systems. One 

fracture system strikes N. 60° E. and dips 60°-80° SE., 

whereas the other strikes N. 85° W. and dips 60°-80° SW. 

(Emery, 1968).

Pervasive chloride alteration partially obscures the 

original composition of the dikes. However, major and 

trace-element data indicate that the dikes are tholeiitic basalt 

(W.C. Day, unpub. data, 1990). These dikes are similar to 

those emplaced throughout the St. Francois terrane during 

the waning stages of rhyolitic volcanism (Bickford, 1988).

Aplite Dikes

Aplite dikes cut the host rhyolite and the magnetite 

orebody. Contacts with the REE-bearing breccia pipes are 

not exposed, and their relative ages are therefore unknown. 

The mutually crosscutting relation between the aplite dikes 

and rocks of the silicified zone indicates that their emplacement was coeval (fig. A4).

The dikes have variable dips, and they fill fractures 

that strike N. 25° W. (Emery, 1968). They consist of 

potassium feldspar and quartz with minor to trace amounts 

of biotite, and they have a fine-grained, equigranular (aplitic) to pegmatitic texture. Some dikes grade into quartz 

veins near their terminations. Some dikes have traces of 

disseminated molybdenite.

The aplite dikes are alaskitic and are high in SiO2 

(72.0-74.7 weight percent and K2O (6.7-9.8 weight percent). Geochemical modelling of the trace-element abundances demonstrates that the aplite dikes and the host 

rhyolite are cogenetic (Day and others, 1989). The crosscutting relations of the aplite dikes with the host rhyolite, 

the magnetite orebody, and the silicified zone indicate that 

the magnetite ore was emplaced during the regional Middle 

Proterozoic igneous activity in the St. Francois terrane.

Banded Rock

Banded rock is a relatively rare rock type in the Pea 

Ridge deposit. It consists of alternating bands of light-gray 

and dark-gray minerals. The light-gray bands consist of 

igneous rock fragments, quartz, and potassium feldspar; the 

dark bands are martite and chlorite. The bands may represent altered horizons in a bedded volcaniclastic sediment. 

Beds range in thickness from 1 or 2 mm to several 

centimeters and exhibit ripple marks and graded beds 

(Marikos and others, 1989a). The banded rock occurs along 

the footwall near the contact between the specularite and 

silicified wallrock. Locally, it has a penetrative fabric, as 

defined by mineral lineations, and has been deformed by a 

drag fold along a fault zone (ADE drift, 2,275-ft level; 

fig. A3). The rock grades into specularite, which suggests 

that it was part of the host rock sequence that was replaced 

by magnetite (converted later to martite) during orebody 

emplacement. The protolith was probably a water-laid 

pyroclastic airfall tuff deposited as a volcaniclastic intraflow sediment.

REE-Bearing Breccia Pipes

Four REE-bearing breccia pipes have been delineated 

along the footwall and eastern edge of the 2,275-ft level of 

the orebody (fig. A3). The pipes are at or near the contacts 

between the major Hthologic zones. The contacts with

A6 Strategic and Critical Minerals, Midcontinent Region, U.S.
rhyolite and rocks of the silicified zone are abrupt and 

commonly sheeted; those with the specular hematite zone 

are irregular and embayed. Locally, apophyses of breccia 

pipes intrude adjacent rocks along fractures.

The pipes dip steeply (>60°) and are elongate to ovoid 

in plan view. They range in length from several meters to as 

much as 60 m and have widths as much as 15 rn. Their 

maximum vertical extents are not known, but the X-13 pipe 

(fig. A3) extends from the 2,675-ft sublevel to at least the 

2,275-ft level, a distance of about 120 m.

The breccia pipes contain fragments of rhyolite, 

magnetite-hematite ore, and rock of the silicified zone in a 

groundmass predominantly composed of rock flour, feldspar, chlorite, barite, apatite, monazite, quartz, and calcite 

(fig. A2). The rock-flour consists of milled volcanic wallrock and disaggregated specularite grains. The volcanic 

rock fragments grade in size from rock-flour to about 0.5 m 

in diameter. They are reddened, due to potassium feldspar 

alteration, and have subrounded to angular edges and 

moderate to high sphericity. The specularite fragments 

reach several meters in length, are angular, and have low 

sphericity. Where specularite fragments are prevalent, they 

form a tight-fitting, fragment-supported breccia having 

angular voids between fragments. Where wallrock fragments predominate, they are irregularly distributed and are 

matrix supported.

Most of the breccia pipe material may have been well 

indurated. For example, the X-ll pipe (fig. A3) has a 

particularly hard, fine-grained matrix. Other pipes are now 

friable because of the coarseness and excellent cleavage of 

potassium feldspar and barite and post-emplacement brecciation.

Geopetal structures within void spaces in one of the 

REE-bearing breccia pipes indicate that the magnetite 

deposit has not been tilted significantly since emplacement 

of the breccia pipes. The geopetal structure on the 2,440-ft 

level is characterized by horizontally bedded, granulated 

rock particles that fill the bottom part of the vug and calcite 

that fills the upper part of the vug.

The relative age of the REE-bearing breccia pipes is 

poorly constrained. Rhyolite wallrocks, magnetite ore, and 

rocks of the silicified zone occur as fragments within the 

pipes. Thus, the breccia pipes were emplaced after formation of the silicified zone. Aplite dikes cut across rocks of 

the silicified zone; however, relations between the aplite 

dikes and the breccia pipes have not been observed.

The absolute age of the REE-bearing breccia pipes 

can be estimated from a U-Pb date on a xenotime crystal in 

a quartz vein that is cut by a breccia pipe. The xenotime 

yielded a date of 1.46 Ga (W.R. Van Schmus, written 

commun., 1988). It occurs both in quartz veins cut by the 

REE-bearing breccia pipes and in the pipes themselves 

(fig. A2). Therefore, formation of the REE- bearing breccia 

pipes was about 1.46 Ga.

Mineralogy and Chemistry

Barite, potassium feldspar, chlorite, monazite, apatite, 

quartz, and calcite are the most abundant minerals in the 

pipes; biotite, fluorite, tourmaline, chalcopyrite, and pyrite 

are accessory minerals. Marikos and others (1989b) 

reported anhydrite in some pipes. Barite occurs as massive 

cement and open-space fill; crystals range from 1 mm to as 

much as 50 cm long. Sanidine and orthoclase are present as 

fractured and broken euhedral phenocrysts (or xenocrysts) 

that are as much as 2 cm in diameter. Apatite forms 

subhedral to euhedral crystals that range in size from 0.5 to 

1.0 cm. Quartz forms both rounded and embayed phenocrysts (or xenocrysts) and secondary overgrowths as cement 

within the groundmass. Areas of broken barite and potassium feldspar record a post-cementation brecciation event.

REE-bearing minerals in the breccia pipes include 

monazite, xenotime, and rare bastnaesite and britholite(?). 

Monazite and xenotime occur as 0.5- to 1.0-mm-long 

crystals in aggregates having a granular texture, as radial 

crystal aggregates, as acicular crystals that replaced wallrock microfragments, and less commonly as irregular 

crystals that fill cracks in barite and potassium feldspar.

Swarms of barite and calcite veins and radioactive 

zones serve as exploration guides to blind pipes. Barite and 

calcite vein swarms and crackle breccias adjacent to pipes 

represent extensions of pipe mineralization. The radioactivity results from thorium and uranium associated with 

the REE-bearing minerals. The breccia groundmass contains notable amounts of thorium and uranium, averaging 

3,321 ppm (parts per million) and 189 ppm, respectively 

(table Al). The thorium-uranium ratio is about 19, whereas 

the normal crustal ratio is about 4 (Rose and others, 1979).

The breccia pipe groundmass has variable concentrations of the REE. Data listed in table Al represent grab 

samples of groundmass material, and as such do not 

represent average ore grades of the breccia pipes. Total REE 

oxide concentrations of our samples range from 4.9 to 37.8 

weight percent, averaging 20.3 weight percent. In contrast, 

ore grades determined from bulk samples range from 7 to 25 

weight percent and average about 12 weight percent (C.W. 

Whitten, U.S. Bureau of Mines, oral commun., 1990). The 

REE-bearing breccias are enriched in the light REE, having 

a pronounced negative europium anomaly (fig. A5).

Gold is erratically distributed in the breccia pipes. 

Husman (1989) reported that gold occurs as electrum and 

sylvanite. Gold concentrations uncommonly exceed 1 ppm, 

but assays of drill core and chip samples are as high as 

371 ppm (Husman, 1989). Our samples have yielded gold 

values of less than 6 ppb (parts per billion) (table Al). The 

extremely high concentrations may be due to the "nugget 

effect," where atypically large grains of gold give a higher 

assay value than the average for the pipe.

Pea Ridge Iron Ore Mine, Missouri A7
Table A1 . Analyses for rare-earth elements (REE), uranium, thorium, and gold in REE-bearing breccia pipes, Pea Ridge 

mine, Washington County, Mo.

[The REE were determined by the ICP-MS method as outlined by Lichte and others (1987). Uranium and thorium were determined by 

delayed neutron activation analysis (McKown and Millard, 1987) and gold by graphite furnace (Meier, 1980). <, less than; -, insufficient 

number of samples above detection limit to calculate meaningful value]

Element Sample No.

(mine level)

PR-21

(2,370 ft)

PR-71

(2,370 ft)

PR-72

(2,370 ft)

PR-168

(2,370 ft)

PR-33C

(2,440 ft)

PR-33D

(2,440 ft)

PR-32

(2,475 ft)

PR-126

(2,675 ft)

PR-127

(2,675 ft)

Average Standard

deviation

Parts per million

La

Ce

Pr

Nd

Sm

Eu

Gd

Tb

Dy

Ho

Er

Tm

Yb

U

Th

34,000

34,000

5,400

18,000

2,800

420

1,900

360

2,100

400

1,200

190

1,500

297

4,400

35,000

56,000

5,500

19,000

2,900

380

1,600

320

1,700

300

830

140

990

135

1,940

22,000

33,000

3,200

12,000

2,100

270

1,700

270

1,500

270

760

110

760

192

804

35,000

58,000

5,800

20,000

2,900

360

1,800

350

2,200

450

1,400

240

1,800

94

6,160

52,000

60,000

8,900

31,000

4,300

580

2,500

340

1,400

170

310

32

160

354

10,100

18,000

29,000

2,800

9,700

1,500

230

1,200

240

1,700

370

1,200

200

1,600

284

2,710

5,700

9,500

850

3,100

450

51

460

68

410

86

240

33

210

23

227

14,000

22,000

2,100

7,600

1,200

150

860

150

870

170

530

91

670

199

1,950

12,000

20,000

1,900

6,700

1,000

130

680

110

630

110

340

53

390

121

1,600

25300

35,722

4,050

14,122

2,128

286

1,411

245

1,390

258

757

121

898

189

3,321

13,863

17,242

2391

8,175

1,140

156

622

104

594

124

409

72

580

101

2,948

Weight percent

RE2O3t* 23.9 29.2 18.2 30.5 37.8 15.8 4.9 11.8 103 203 10.2

Parts per billion

Au 6 <2 <2 2 <4 <4 <4 <2 2 - -

*Sum of rare earth oxides.

Structure

Faults are a common feature in the mine and appear to 

have occurred throughout the history of the deposit. Two 

styles of deformation are present in the deposit. One 

occurred at the transition between the ductile and brittle 

deformation regimes, whereas the other was under conditions of brittle deformation. In the former, penetrative fabric 

defined by mineral lineations, mullions, foliations, and 

elongation of pseudobreccia fragments is parallel to and 

within the fault planes. These faults commonly dip at low 

angles (45° to 60°). Also, on the 2,675-ft sublevel pseudobreccia fragments are elongated within a fault plane. The 

ductile-brittle deformation resulted from a transpressional 

event that affected the host rhyolite, magnetite ore, banded 

rocks, and mafic dikes.

Brittle deformation is recorded by high-angle faults 

that produced angular fault breccias and clayey fault gouge 

along fault planes. An example is the fault on the X-l 1 drift 

of the 2,275-ft level (fig. A3), where a high-angle reverse 

fault roughly parallels the iron ore-wallrock contact. Specular hematite was drag folded and developed foliation 

parallel to the fault plane.

GENESIS OF THE REE-BEARING 

BRECCIA PIPES

The REE-bearing breccia pipes are similar to 

magmatic-hydrothermal breccias related to porphyry-type 

deposits (Sillitoe, 1985). However, they are not entirely 

analogous due to the disparity between the two types of ore 

systems (one is a high-grade magnetite body, whereas the 

other is a porphyry copper deposit having a low metal 

content). Nonetheless, the geochemical character and the 

intimate spatial relation of the REE-bearing breccia pipes 

with the magnetite ore system implies a genetic link 

between the two.

Magmatic-hydrothermal breccias are commonly associated with subvolcanic ore deposits. The breccias are a 

result of fluids that exsolve from water-saturated magmas 

in subvolcanic or plutonic environments. The exsolved 

fluids undergo second boiling and decompression as they 

cool. Burnham (1979, 1985) quantified the process of 

second boiling as the exsolution of a vapor phase from a 

water-saturated melt, with the reaction: H2O-saturated melt 

= crystals + vapor. The violent rapid expulsion of fluid from 

magma and the increase of volume due to the expansion and

A8 Strategic and Critical Minerals, Midcontinent Region, U.S.
1,000,000

100,000

LLJ

cr

Q

o

§o

10,000

1,000

100

EXPLANATION

Sample No. See table 1 

O PR-21

 PR-71 

D PR-72

 PR-168 

A PR-33C 

A PR-33D 

V PR-32 

T PR-126 

+ PR-127

La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb

Figure AS. Plot of abundances of rare-earth elements in breccia pipes in the Pea Ridge mine, Washington County, Mo. 

Abundances normalized to Cl chondrite values of Evensen and others (1978).

subsequent decompression of the vapor phase release 

sufficient mechanical energy to generate steep tensile 

fractures in the wallrocks, or reopen existing faults and 

fractures, and further widen them by hydraulic fracturing of 

their walls (Burnham, 1985; Sillitoe, 1985). Upward 

streaming of the magmatic-hydrothermal fluid and vapor 

results in mixing and milling of fragments, production of 

rock-flour matrix, and varying degrees of upward transport 

of material (Sillitoe, 1985).

The REE-bearing breccia pipes were forcefully 

emplaced into the Pea Ridge magnetite deposit. Rock 

fragments rounded by abrasion as well as swirl textures of 

intermixed hematite and rock flour are textural evidence of 

fluidization during pipe emplacement. Emplacement of 

breccia pipes appears to have been contolled by lithologic 

contacts in the footwall along which faults and fractures 

formed.

According to our proposed magmatic-hydrothermal 

breccia model, the REE-bearing breccia pipes of the Pea 

Ridge deposit were emplaced during the waning stages of 

the magnetite ore system. The magnetite orebody was 

emplaced as an iron-rich magmatic-hydrothermal fluid. The 

presence of sanidine phenocrysts (or xenocrysts) confirms a 

magmatic constituent for the origin of the breccia pipes, and 

possibly the entire ore system. Late-stage magmatichydrothermal fluids, which exsolved from the iron ore 

system, were enriched in K, Ba, REE, U, Th, P, SO2, F, Cl, 

and Au. The volatile phase released during second boiling 

provided the mechanical energy for brecciation and fracturing of the wallrocks. The REE-bearing fluids streamed 

upward into the footwall of the magnetite orebody along 

fractures, faults, and zones of weakness at lithologic 

contacts.

The fluids entrained fragments of wallrock, magnetite 

ore, and rocks of the silicified zone and abraded them during 

transport. Extreme abrasion resulted in the milling of 

fragments into rock flour. Some of the pipe-fill minerals 

may have crystallized during second boiling, including 

sanidine, orthoclase, barite, monazite, apatite, quartz, and 

other accessory minerals in the groundmass of the breccia 

pipes. Evidence for boiling includes populations of both 

vapor-rich and liquid-rich fluid inclusions coexisting in 

quartz within the groundmass. Some of the fluids may have 

circulated in the pipes after boiling and replaced microfragments, cemented rock flour and fragments, and formed 

crystal-lined vugs.

During formation of the breccia pipes, quartz veins 

adjacent to the pipes were reopened, and breccia pipe 

minerals of the same suite were deposited in the reopened 

veins. In addition, crackle breccias and vein swarms of

Pea Ridge Iron Ore Mine, Missouri A9
barite and calcite formed adjacent to the pipes. Rebrecciated, recemented fragments record more than one brecciation event during the evolution of the magmatichydrothermal system.

SUMMARY

The Pea Ridge deposit is a tabular body of magnetite 

that sloped upward into the host rhyolitic wallrocks. 

Development of an amphibole-quartz skarn preceded 

magnetite deposition. The deposit is crudely zoned successively outward from a massive magnetite core to 

magnetite-cemented heterolithic breccia, to pseudobreccia, 

and to distal amphibole-quartz skarn. Other rock types 

include a specular hematite zone along the footwall and 

eastern edge of the orebody, massively silicified rock of the 

footwall, banded volcaniclastic rock, aplite dikes, and mafic 

dikes.

The specular hematite is in part an alteration of 

magnetite ore and seems to have developed along fault 

zones. During and after specularite development, the 

massive silicified zone formed by open-space filling and 

wallrock replacement; silicification extends into the hematite zone. Fracture-fill veins of quartz continue from the 

silicified zone into the adjacent altered rhyolite. Potassium 

feldspar flooding and serialization accompanied silicification.

Faults occur throughout the orebody. Some faults 

developed a penetrative fabric that formed in the ductilebrittle transitional regime. A fault zone along the footwall 

contains two, and possibly three, REE-bearing breccia 

pipes; another pipe is along a high-angle reverse fault at the 

eastern edge of the orebody.

Breccia pipes, containing potentially economic concentrations of REE in monazite and xenotime, cut all rock 

types. The pipes include fragments of volcanic wallrock, 

silicified rock, and iron ore. Feldspar, quartz, and barite 

occur as euhedral phenocrysts in chloritic groundmass. 

Barite also occurs as massive replacement cement and 

open-space fill. Monazite and xenotime are present as 

granular crystals in the groundmass, as replacement of 

microfragments, as radial aggregates of acicular crystals in 

the groundmass, and as abraded platy grains that appear to 

have been transported. Total rare-earth oxide content of 

select grab samples of the breccia pipe groundmass 

averages 20 weight percent, whereas bulk ore averages 

about 12 weight percent. Gold is erratically distributed in 

the pipes; concentrations are not commonly greater than 

1 ppm, but assays as high as 371 ppm have been reported.

The REE-bearing breccia pipes formed as magmatichydrothermal breccias, which were localized along fractures, faults, and lithologic contacts. Magmatically derived 

hydrothermal fluids underwent second boiling, during 

which both vapor-rich and liquid-rich fluid inclusions 

were trapped in quartz within the groundmass of the

REE-bearing breccia pipes. Euhedral crystals of barite and 

other accessory minerals may have formed during second 

boiling. The sanidine phenocrysts (or xenocrysts) indicate 

that the breccia pipes had a magmatic component. Release 

of the vapor phase during boiling resulted in fracturing at 

lithologic contacts. Fluidization, coupled with the upward 

streaming of magmatic-hydrothermal fluids, resulted in the 

widening of the fractures and faults and in the brecciation of 

the wallrock. After boiling, some fluids may have circulated 

in the pipes and replaced rock microfragments and rock 

flour, cemented the pipes, and formed crystal-lined vugs.

ACKNOWLEDGMENTS

The study was funded jointly by the U.S. Geological 

Survey Strategic and Critical Minerals Program (contract 

number 14-08-0001-A0486) and the Missouri Department 

of Natural Resources, Division of Geology and Land Survey 

general revenue funds.

The authors are indebted to the personnel of the Pea 

Ridge mine; without their cooperation, this report would not 

be possible. We particularly thank Robert Z. Reed, past 

President of the Pea Ridge Iron Ore Company, and John 

Wright, Chief Executive Officer of Big River Minerals. We 

also thank Gene R. Koebbe, General Manager, and John 

Schoolcraft, Plant Superintendent, for their support. We are 

grateful for the assistance of Don Roberts, Assistant 

Manager, and Larry J. Tucker, Head Mine Engineer. Their 

open-door policy to both the mine and their data files is 

almost unprecedented in the mining industry and reflects 

their philosophy that an understanding of this deposit type 

will ultimately lead to economic benefits for the mining 

industry.

We also wish to thank Marco T. Einaudi and Naomi 

Oreskes for their help during the early stages of our 

mapping program. Mark Marikos, Richard Eisenberg, and 

Jim Husman provided stimulating discussions and crucial 

observations during the course of the study.

REFERENCES CITED

Arundale, J.S., and Martin, J.A., 1970, The mineral industry of 

Missouri, in v. Ill of 1968 Minerals Yearbook: U.S. Bureau 

of Mines, p. 429-443.

Bickford, M.E., 1988, The formation of continental crust; Part 1. 

A review of some principles; Part 2. An application to 

the Proterozoic evolution of southern North America: 

Geological Society of America Bulletin, v. 100, no. 9, 

p. 1375-1391.

Bickford, M.E., and Mose, D.G., 1975, Geochronology of Precambrian rocks in the St. Francois Mountains, southeastern 

Missouri: Geological Society of America Special Paper 165, 

48 p.

A10 Strategic and Critical Minerals, Midcontinent Region, U.S.
Bumham, C.W., 1979, Magmas and hydrothermal fluids, in 

Geochemistry of hydrothermal ore deposits (2nd ed.): New 

York, John Wiley and Sons, p. 71-136.

____ 1985, Energy release in subvolcanic environments 

Implications for breccia formation: Economic Geology, 

v. 80, no. 6, p. 1515-1522.

Day, W.C., Kisvarsanyi, E.B., Nuelle, L.M., Marikos, M.A., and 

Seeger, C.M., 1989, New data on the origin of the Pea Ridge 

iron-apatite deposit, southeast Missouri Implications for 

Olympic Dam-type deposits: Geological Society of 

America Abstracts with Programs, v. 21, no. 6, p. A132.

Emery, J.A., 1968, Geology of the Pea Ridge iron orebody, in Ore 

deposits of the United States, 1933-1967 (Graton-Sales 

volume): New York, American Institute of Mining, 

Metallurgy, and Petroleum Engineers, p. 359-369.

Evensen, N.M., Hamilton, P.J., and O'Nions, R.K., 1978, Rareearth abundances in chondritic meteorites: Geochimica et 

Cosmochimica Acta, v. 42, p. 1637-1665.

Husman, J.R., 1989, Gold, rare earth element, and other potential 

by-products of the Pea Ridge iron ore mine: Missouri 

Department of Natural Resources, Division of Geology and 

Land Survey Contributions to Precambrian Geology, 

No. 21, Open File Report OFR-89-78-MR, 18 p.

Kisvarsanyi, E.B., 1980, Granitic ring complexes and hotspot 

activity in the St. Francois terrane, midcontinent region, 

United States: Geology, v. 8, no. 1, p. 43-47.

____ 1981, Geology of the Precambrian St. Francois terrane, 

southeastern Missouri: Missouri Department of Natural 

Resources, Division of Geology and Land Survey Report of 

Investigations, No. 64, 58 p.

____ 1984, The Precambrian tectonic framework of Missouri as 

interpreted from the magnetic anomaly map: Missouri 

Department of Natural Resources, Division of Geology and 

Land Survey Contributions to Precambrian Geology, 

No. 14, 19 p.

Kisvarsanyi, E.B., and Kisvarsanyi, G., 1989, Alkaline granite ring 

complexes and metallogeny in the Middle Proterozoic 

St. Francois terrane, southeastern Missouri, U.S.A.: 

Geological Association of Canada Special Paper 38, 14 p.

Kisvarsanyi, G., 1975, Genesis of the Precambrian St. Francois 

terrane, midcontinent, U.S.A. A field guide to the Precambrian geology of the St. Francois Mountains, Missouri: 

Cape Girardeau, Mo., Southeast Missouri State University, 

p. 49-54.

Kisvarsanyi, G., and Proctor, P.O., 1967, Trace element content 

of magnetites and hematites, southeast Missouri iron 

metallogenic province, U.S.A.: Economic Geology, v. 62, 

p. 449-471.

Laznicka, P., 1988, Breccias and coarse fragmentites, in 

Developments in economic geology: New York, Elsevier, 

v. 25, 832 p.

Lichte, F.E., Meier, A.L., and Crock, J.G., 1987, Determination of 

the rare earth elements in geological materials by inductive 

coupled plasma mass spectrometry: Analytical Chemistry, 

p. 1150-1157.

Marikos, M.A., Seeger, C.M., and Nuelle, L.M., 1989a, Geology 

of the Pea Ridge mine (field trip stop No. 1), in "Olympic 

Dam-type" deposits and geology of Middle Proterozoic 

rocks in the St. Francois Mountains terrane, Missouri: 

Society of Economic Geologists Guidebook Series, v. 4, 

p. 41-54.

____ 1989b, REE-mineralized breccia pipes in the Pea Ridge 

deposit of southeast Missouri: Geological Society of 

America Abstracts with Programs, v. 21, no. 6, p. A34.

McKown, D.M., and Millard, H.T., Jr., 1987, Determination of 

uranium and thorium by delayed neutron counting: U.S. 

Geological Survey Bulletin 1770, p. 11-112.

Meier, A.L., 1980, Flameless atomic-absorption determination of 

gold in geological materials: Journal of Geochemical 

Exploration, v. 13, no. 1, p. 77-85.

Nelson, B.K., and DePaolo, D.J., 1985, Rapid production of 

continental crust 1.7-1.9 B.Y. ago Nd isotopic evidence 

from the basement of the North American midcontinent: 

Geological Society of America Bulletin, v. 96, no. 6, 

p. 746-754.

Nuelle, L.M., Seeger, C.M., Marikos, M.A., and Day, W.C., 1989, 

Mineral assemblages of the Pea Ridge Fe-REE deposit 

Implications of an Olympic Dam-type variant in southeast 

Missouri: Geological Society of America Abstracts with 

Programs, v. 21, no. 6, p. A34.

Oreskes, N., and Einaudi, M.T., 1990, Origin of rare earth 

element-enriched hematite breccias at the Olympic Dam 

Cu-U-Au-Ag deposit, Roxby Downs, South Australia: 

Economic Geology, v. 85, no. 1, p. 1-28.

Patchett, J.P., and Ruiz, J., 1989, Nd isotopes and the origin of 

Grenville-age rocks in Texas Implications for Proterozoic 

evolution of the United States mid-continent region: Journal 

of Geology, v. 97, p. 685-695.

Rose, A.W., Hawkes, H.E., and Webb, J.S., 1979, Geochemistry in 

mineral exploration (2nd ed.): New York, Academic Press, 

657 p.

Seeger, C.M., Nuelle, L.M., and Marikos, M.A., 1989, Massive 

silicification and late stage quartz veining in the Pea Ridge 

Fe-REE deposit, southeast Missouri: Geological Society of 

America Abstracts with Programs, v. 21, no. 6, p. A34.

Sillitoe, R.H., 1985, Ore-related breccias in volcanoplutonic arcs: 

Economic Geology, v. 80, no. 6, p. 1467-1514.

Snyder, F.G., 1969, Precambrian iron deposits in Missouri, in 

Magmatic ore deposits A symposium: Economic Geology 

Monograph 4, p. 231-238.

Pea Ridge Iron Ore Mine, Missouri A11

Chapter B

Some Mineralogical and Geochemical Aspects of 

Middle and Upper Pennsylvanian Marine Black 

Shales in Part of the Midcontinent Region

By GEORGE A. DESBOROUGH, JOSEPH R. HATCH, and 

JOEL S. LEVENTHAL

U.S. GEOLOGICAL SURVEY BULLETIN 1989

STRATEGIC AND CRITICAL MINERALS IN THE MIDCONTINENT REGION, 

UNITED STATES

WARREN C. DAY and DIANE E. LANE, Editors
CONTENTS

Abstract Bl

Introduction Bl

Deposition and diagenesis B2

Distribution of major and minor minerals in black shales of the Desmoinesian and

Missourian Pennsylvanian strata in part of the midcontinent region B2 

Distribution of selected minor elements and organic carbon in Middle and Upper

Pennsylvanian black shales in the western midcontinent region B5 

Discussion and summary B7 

References cited B8

FIGURES

B1-B4. Maps showing distribution of:

Bl. Average ratios of illite to kaolinite, albite to potassium feldspar, and 

calcite to dolomite, and percentages of samples containing gypsum and 

percentages of samples containing apatite for 85 samples of Middle 

Pennsylvanian marine black shales B3

B2. Thickness and average ratios of illite to kaolinite, albite to potassium 

feldspar, and calcite to dolomite, and percentages of samples 

containing gypsum and percentages of samples containing apatite for 

39 samples of the Upper Pennsylvanian Stark Shale Member of the 

Dennis Limestone B4

B3. Average concentrations of molybdenum, vanadium, chromium, nickel, 

and organic carbon for 83 samples of Middle Pennsylvanian marine 

black shales B5

B4. Thickness and average concentrations of molybdenum, vanadium, 

chromium, nickel, and organic carbon for 39 samples of the Upper 

Pennsylvanian Stark Shale Member of the Dennis Limestone B6

TABLES

Bl. Stratigraphic position and age of units studied in survey of mineralogy and

geochemistry of Middle and Upper Pennsylvanian black shales B7 

B2. X-ray diffraction peaks used for estimation of relative abundances of minerals

other than quartz in Pennsylvanian shales B8 

B3. Organic carbon content and x-ray diffraction intensity data for minerals, except

quartz, in samples of Middle Pennsylvanian black shales B9 

B4. Organic carbon content and x-ray diffraction intensity data for minerals, except

quartz, in samples of Upper Pennsylvanian black shales B12

B5. Selected major and minor elements in Middle Pennsylvanian black shales B14 

B6. Selected minor and trace elements in Middle Pennsylvanian black shales B15 

B7. Selected major and minor elements in Upper Pennsylvanian black shales B18 

B8. Selected minor and trace elements in Upper Pennsylvanian black shales B20

II Contents
STRATEGIC AND CRITICAL MINERALS IN THE MIDCONTINENT REGION, UNITED STATES

Some Mineralogical and Geochemical Aspects of 

Middle and Upper Pennsylvanian Marine Black Shales 

in Part of the Midcontinent Region

By George A. Desborough, Joseph R. Hatch, and Joel S. Leventhal

Abstract

This study assesses the regional variations in mineralogy 

and metal content of thin (<1 m) marine black shales of Middle 

(Desmoinesian) and Upper (Missourian and Virgilian) Pennsylvanian age in the midcontinent region. It can be inferred 

that the ratios of illite to kaolinite, albite to potassium feldspar, 

frequency of occurrence of gypsum, and frequency of occurrence of apatite are probably a function of distance from 

shoreline or are related to proportion of detrital contributions. 

The distribution of kaolinite, potassium feldspar, and gypsum 

seem to reflect a detrital origin, whereas the distribution of 

illite, albite, and iron-rich chlorite indicates an authigenic or 

diagenetic origin.

Although the relative positions with regard to shoreline 

are given, it is very well known that these black shales were 

deposited in deep water during maximum stands of sea level in 

the midcontinent region; thus those referred to as nearer 

shoreline were probably several hundred kilometers from the 

shoreline.

For Middle Pennsylvanian marine black shales the 

samples from Iowa have lower ratios of illite to kaolinite and a 

higher proportion of gypsum than do samples from farther 

south and west, in Missouri, Kansas, and Oklahoma. This is 

apparently due to the detrital origin of kaolinite and gypsum 

from a shoreline or nearshore source to the northeast or north 

of Iowa. The Iowa samples also have a lower ratio of albite to 

potassium feldspar than do samples from farther south, in 

Missouri and Oklahoma, because of the detrital origin of 

potassium feldspar.

The concentrations of both molybdenum and vanadium 

are much greater in the samples from Iowa than in the samples 

from the areas to the south and southwest. This is consistent 

with previous suggestions that these metals tend to be more 

concentrated in areas closer to shoreline. The concentration of

Manuscript approved for publication August 5, 1991.

nickel, in most cases, seems to be related more to the content 

of organic matter than to any other factor.

For the Upper Pennsylvanian (Missourian) Stark Shale 

Member of the Dennis Limestone, the patterns of ratios of illite 

to kaolinite and albite to potassium feldspar and the frequency 

of occurrence of gypsum are similar to the patterns shown by 

the Middle Pennsylvanian black shales. The average 

concentrations of both molybdenum and vanadium in the 

Stark Shale Member are higher in samples from Iowa and 

northeastern Kansas than in those from western Kansas and in 

northern Oklahoma.

INTRODUCTION

This study was conducted as part of the U.S. 

Geological Survey Midcontinent Strategic and Critical 

Minerals Project. This report is an outgrowth of a study of 

Middle and Upper Pennsylvanian black shales of the midcontinent selected for their possible nonfuel mineral 

resource potential. We studied 150 core samples from 12 

black shale members of Middle Pennsylvanian (Desmoinesian) and Upper Pennsylvanian (Missourian and Virgilian) 

age in the midcontinent region to determine their 

mineralogical and geochemical characteristics (table Bl). 

The general characteristics and environment of deposition 

of these thin (<1 m), deep-water (maximum submergence of 

the craton) shales were described by Heckel (1977), who 

concluded that they were deposited during maximum 

marine encroachment.

These marine black shales represent 12 "Kansastype" cyclothems (Weller, 1958) that are present in the 

region studied. Many of the samples investigated during this 

study were described previously and their organic geochemical data were reported (Stanton and others, 1983; 

Hatch and others, 1984).

Middle and Upper Pennsylvanian Marine Black Shales B1
The purpose of the present investigation is to 

determine whether (1) mineralogy of the samples can be 

used to discern subtle differences in depositional environments, (2) what effects diagenesis had on the samples, and 

(3) whether mineralogical and diagenetic differences might 

relate to metal content and amount and type of organic 

matter. Specifically, we wanted to show that such mineralogical and geochemical differences over a large surface 

area were related to facies differences. Due to extremely 

small grain size, x-ray diffraction methods were used to 

quantify the mineralogical contents of the samples. Their 

finely laminated character results in considerable inhomogeneity of both minerals and organic matter on a fine scale.

In a study of the equivalents of the Mecca Quarry 

Shale Member of the Carbondale Formation of Illinois (see 

table Bl), Coveney and others (1987) reported distinctive 

geochemical differences in the nearer shore facies. They 

reported that the nearer shore facies contains more terrestrial organic matter than did more distal age-equivalent 

strata, and that the nearer shore facies has a higher concentration of molybdenum, vanadium, uranium, selenium, 

and antimony. Previous studies of Pennsylvanian black 

shales have not included systematic study of bulk mineralogy to see if, and how, it relates to metals and organic 

matter. Mineralogical x-ray diffraction parameters are given 

in table B2; results are given in tables B3 and B4.

DEPOSITION AND DIAGENESIS

detrital origin, having been transported from humic organic 

sources near the shoreline and deposited as a flocculent 

in a marine environment. Illite is presumed to be chiefly 

diagenetic or an authigenic product developed from alteration of detrital aluminosilicates in a marine environment.

Iron-rich chlorite is not stable under highly oxidizing 

conditions in low-temperature environments. The occurrence of iron-rich chlorite in more than 90 percent of the 

samples indicates an environment of reducing, or nonoxidative, conditions; thus, chlorite is a late diagenetic mineral 

in these strata, taking up the iron that was available after the 

formation of pyrite.

Because gypsum develops only in relatively oxygenated environments, the presence of gypsum in samples is 

inconsistent with development in an anoxic environment 

that contains authigenic and diagenetic pyrite and iron-rich 

chlorite. The gypsum, therefore, was probably deposited 

from terrestrial or nearshore marine environments.

Siderite is found chiefly in those shales that Heckel 

(1977) called "near-shore" shales, although some is found in 

what he called "offshore" shales. Because siderite occurs in 

samples that have an anomalously low hydrogen content in 

the organic matter, it probably developed as a result of 

methanogenesis (bacterial oxidation of organic matter). In 

this process the organic matter is converted to methane and 

carbon dioxide. Whereas siderite is abundant in these strata, 

pyrite is sparse or absent, and total sulfur is very low 

because it was oxidized and removed in solution before 

diagenesis.

Albite in all the studied samples was formed by 

authigenic or diagenetic growth. There is no known detrital 

source (for example, trondhjemite) that could have provided 

a consistent and sufficient source of albite without the 

additional supply of significant amounts of potassium feldspar (for example, granitic sources), which was not detected 

in 55 percent of the samples. The potassium feldspar was 

either derived from igneous or metamorphic cratonic areas 

(Canadian shield) or perhaps from reworking of older 

Paleozoic or Proterozoic clastic rocks to the northeast or 

from the lower or Morrowan and Atokan parts of the 

Fountain Formation in Colorado, which is arkosic (for black 

shales in western Kansas). Thus, the relative proportions of 

albite and potassium feldspar indicate an authigenic source 

for albite and a chiefly detrital origin for potassium feldspar.

Both illite and kaolinite are relatively abundant in all 

samples. Kaolinite in the low-temperature environment is 

normally developed from weathering in acidic (low pH) 

environments, such as peat bogs or swamps containing a 

substantial amount of humic material. In contrast, at low 

temperatures illite tends to be stable or form in nearly 

neutral or slightly alkaline environments. Because marine 

sediments generally undergo diagenesis under nearly neutral or slightly alkaline conditions due to buffering by 

calcite and dolomite, kaolinite in these strata is probably of

DISTRIBUTION OF MAJOR AND MINOR 

MINERALS IN BLACK SHALES OF THE 

DESMOINESIAN AND MISSOURIAN 

PENNSYLVANIAN STRATA IN PART 

OF THE MIDCONTINENT REGION

Figure Bl shows the localities for 85 upper Middle 

Pennsylvanian (Desmoinesian) black shale core samples 

from 10 areas and a summary of some of the mineral ratios 

and percentages of samples in which gypsum and apatite 

occur. Only those black shales considered by Heckel (1977) 

to be "offshore" shales were used for this illustration. Ratios 

of greatest concentrations of illite to kaolinite (ill/kao), 

albite to potassium feldspar (albite/Kf), and calcite to 

dolomite (cal/dol) are given for each of the 10 areas. These 

ratios are based on the means of each sample set. Examination of the illite- to-kaolinite ratios reveals a significant 

increase from Iowa south to Oklahoma and western Kansas. 

In addition, illite-to-kaolinite ratios increase from eastern to 

western Oklahoma. From this increase we infer that the 

kaolinite was derived chiefly from a source area north and 

east of the study area during Desmoinesian time.

Ratios of albite to potassium feldspar are somewhat 

similar; there is a great increase in the ratio from southB2 Stategic and Critical Minerals, Midcontinent Region, U.S.
40°

38°

36°

102°___________100°

I I

EXPLANATION

No. of samples/No, of sites 

ill/kao i % with gypsum

alb/Kf ' % with apatite 

~j cal/dol

98° 96° 

~7 T

V

94° 92°

100 MILES 

I

26/5 

1.1 58%

100 KILOMETERS

IOWA

KANSAS

3'

8

f - - _ _ ___ _ NEBRASKA^ ___

2/1 

1.9 | 0*3

1.7MC100% 

1.5

3/1 

2.4 i 0%

4/2 

1.3 | 50%

7.0"75%

6.9

100%

1.5

TEXAS

2/1 OKLAHOMA

2.9 10%

_ _100750%

0.7

7/2

1.5 | 0%

16 I 100% 

1.2

13/3 

1.5 | 0%

26"85% 

1.9

6/6 

I 2.0 | 50%

3.6~l"83% 

2.5

u

12/7 

1.5 | 8%

27^83%

I _MISSOUM_____. *~ ~ " ~ "ARKANSAS

I

\

1.3

Figure B1 . Average ratios of illite to kaolinite (ill/kao), albite to potassium feldspar (alb/Kf), and calcite to dolomite (cal/dol), and 

percentages of samples containing gypsum and percentages of samples containing apatite for 85 samples of Middle 

Pennsylvanian (Desmoinesian) marine black shales from 10 areas in southern Iowa, Missouri, northern Oklahoma, and western 

Kansas.

central Iowa to northern Oklahoma, and in many samples 

from northern Oklahoma potassium feldspar is not 

detectable (for these a value of alb/Kf of 100 was arbitrarily 

assigned). These relations are taken to indicate that the 

chiefly detrital potassium feldspar was derived from areas 

north and east of the western interior basin during the 

Desmoinesian. The intermediate ratios of albite to potassium feldspar in western Kansas may reflect in part 

contributions of potassium feldspar from the ancestral 

Rocky Mountain uplift 350 km to the west in Colorado, 

which shed large quantities of arkosic material (lower part 

of Fountain Formation) to the east.

The distribution of the percent of samples containing 

detectable gypsum decreases significantly from Iowa and 

Missouri to northern Oklahoma and western Kansas; this is 

consistent with the interpretation that gypsum was detrital 

and was derived like kaolinite and potassium feldspar from 

a source to the northeast of the study area.

The percentage of samples containing detectable 

apatite increases from Iowa and Missouri to western

Kansas, but the differences in the percentages for samples 

from Iowa and Missouri are not significantly different from 

some areas of northern Oklahoma. The greater percentages 

of samples containing apatite in western Kansas and 

Oklahoma are consistent with deposition in deeper water 

more remote from shoreline .

Ratios of calcite to dolomite are highest in central 

Missouri and decrease significantly westward and southward into western Kansas and northern Oklahoma, respectively. This is consistent with an authigenic or diagenetic 

origin for dolomite in the southwestern midcontinent and a 

largely detrital origin for calcite in the northeastern midcontinent. The greater ratio of magnesium to calcium at places 

more distal from shoreline is also consistent with a marine 

(algal) origin for the magnesium in the dolomite.

These relations are consistent with a northeasterly 

source of very fine grained detrital material that contributed 

sediments to the marine environment of the western interior 

basin during late Middle Pennsylvanian (Desmoinesian) 

time.

Middle and Upper Pennsylvanian Marine Black Shales B3
40°

38°

36°

102° 100° 98° 96°

I i i /i

V

EXPLANATION \

No. of samples/thickn

ill/kao i % with gyp

94° 92°

I I '

^^

4/18 { "

ass, cm 0 100 MILES , 1.4jJOO% V 

I ' 90 I 9R% J

sum | N n ? /

lu/wTT^ *, + * ° 100 KILOMETERS [ "'" J alb/Kf ' % with apatite ^ IOWA __ _ ___ \ f

~j cal/dol -. ~~

1 i 

f -- __ ___ . NEBRASKA \

1

1

of

1

1

1

1

' 5/73

[ 2.4 | 20%

1 1.9l~60%

I 1 '7

"TEXAS" "" ]

-

i i

i .

KANSAS s^

4/61 (

1.8i25% \ 

1.9l75% 20/53

1.5 1.9 | 10% 

13150%

3.6

1

(

\A

\

\_" ?

t

^

OKLAHOMA

Missoum_ __ _ _ _ .

1.3^12% p ^KANSAS

4.2

I i

\

\

\

l i

Figure B2. Thickness and average ratios of illite to kaolinite (illAao), albite to potassium feldspar (alb/Kf), and calcite to 

dolomite (cal/dol), and percentages of samples containing gypsum and percentages of samples containing apatite for 39 samples 

of the Upper Pennsylvanian (Missourian) Stark Shale Member of the Dennis Limestone from six areas in southern Iowa, Kansas, 

and Oklahoma.

Only 57 samples from the Upper Pennsylvanian 

Missourian black shales were available for study; 39 of 

these are from the Stark Shale Member in Iowa, Kansas, and 

Oklahoma. Figure B2 shows the mean values for mineral 

ratios, the percentages of samples containing gypsum and 

apatite, and the thickness of the Stark Shale Member for six 

drill holes in southwestern Iowa and in Kansas and 

Oklahoma. The thickness of the Stark Shale Member is 

about three-fold greater in Kansas than it is in Iowa. The 

ratio of illite to kaolinite increases substantially from Iowa 

to southwestern Kansas, but this ratio is lowest in northern 

Oklahoma. The ratio of albite to potassium feldspar is 

greatest in eastern Kansas and northern Oklahoma, but it is 

the same in Iowa and western and northern Kansas. The 

ratio of calcite to dolomite increases significantly from Iowa 

to Kansas, and this ratio is greatest in eastern Kansas and 

northern Oklahoma; these relations are different from those 

observed for the Middle Pennsylvanian (Desmoinesian)

strata (fig. Bl). Gypsum is present in all samples from 

southwestern Iowa, but it is least abundant in eastern Kansas 

and northern Oklahoma. The percentage of samples containing apatite increases significantly from Iowa to Kansas; 

however, the percentage of samples containing gypsum in 

northern Oklahoma is similar to the Iowa samples.

Only seven samples of the Upper Pennsylvanian 

Virgilian black shales from three localities in southwestern 

Iowa were available for study; these included the Larsh 

Shale Member of the Deer Creek Limestone, Queen Hill 

Shale Member of the Lecompton Limestone, and the 

Heebner Shale Member of the Oread Limestone. The 

maximum thickness of these black shales is less than 15 cm 

for cores from southeastern Iowa (P.H. Heckel, written 

commun., 1982). Six of these (86 percent) contained gypsum, five of seven (71 percent) contained siderite, and only 

one contained apatite, suggesting a nearshore environment.

B4 Stategic and Critical Minerals, Midcontinent Region, U.S.
40°

38°

36°

102° -~T- 100° 98° 94° 92°

EXPLANATION

No. of samples/No, of sites

Mo, ppm | V, ppm 

Cr, ppm ' INi, ppm

j

( 

im i V, p

im ' Ni, 

C, organic 

weight %

100 MILES

\ '

I 

100 KILOMETERS

25/5 

170 u- i12R1 \i

I 729T243

\___ _ IOWA _ _ ___ _15.1__. - -

- - _ _ ___ _ NEBRASKA^

KANSAS

~\

2/1 

40465

5.1

30|_l63

385M80

6- 9

^

4/2 

4lL?61 38 ~95

5/5 

30 j 716

684"218 

10.0

,0.0

2/1 OKLAHOMA"

12/7 

16 i 210 -4-

300 < 190 

6.9

7/2 13/3

10/2

27

M.SSOUR.

Figure B3. Average concentrations of molybdenum, vanadium, chromium, nickel, and organic carbon for 83 samples of 

Middle Pennsylvanian (Desmoinesian) marine black shales from 10 areas in southern Iowa, Missouri, northern Oklahoma, and 

western Kansas. Samples are from same set plotted on figure B1; ppm, parts per million.

DISTRIBUTION OF SELECTED MINOR 

ELEMENTS AND ORGANIC CARBON IN 

MIDDLE AND UPPER PENNSYLVANIAN 

BLACK SHALES IN THE WESTERN 

MIDCONTINENT REGION

Concentrations of major, minor, and trace elements in 

about 160 samples of Middle and Upper Pennsylvanian 

black shales are given in tables B5-B8. Figure B3 shows the 

average concentrations of molybdenum, vanadium, chromium, nickel, and organic carbon for 83 samples of Middle 

Pennsylvanian (Desmoinesian) "offshore" shales (Heckel, 

1977) for 29 localities in 10 areas of Iowa, Missouri, 

Kansas, and Oklahoma. These are the same areas for which 

mineral proportions of these samples are given on figure Bl.

Figure B3 shows that the average value for molybdenum in samples from Iowa (170 ppm, or parts per million) 

is four to eight times greater than in samples from areas in 

Missouri, Kansas, and Oklahoma. The high concentrations 

of molybdenum in samples of the Middle Pennsylvanian

Mecca Quarry Shale Member in Indiana and Illinois were 

attributed by Coveney and others (1987) to near-shore 

proximity of the depositional setting. Our interpretation of 

the relative depositional settings, based on mineral ratios 

and relative abundances of gypsum and apatite in our suite 

of samples, is in agreement with Coveney and others 

(1987).

The average vanadium value for Middle Pennsylvanian black shales is significantly higher (1,251 ppm) 

in southern Iowa than in Missouri (588 ppm), Kansas 

(314 ppm), and Oklahoma (336 ppm). Average vanadium 

values for samples from the Oklahoma panhandle (640 

ppm) are two to three times higher than for samples from 

other areas (210-307 ppm) in Oklahoma. The lower values 

of vanadium are generally, but not in all cases, associated 

with samples that have a low content of organic matter.

The average value of chromium is highest (715 ppm) 

in samples from the Oklahoma panhandle and lowest 

(148 ppm) in samples from an area of Osage County in 

northeastern Oklahoma. The average concentrations of 

chromium (fig. B3) do not appear to follow any systematic

Middle and Upper Pennsylvanian Marine Black Shales B5
102° 100° 98° 96° 94° 92°

40°

38°

36°

1

EXPLANATIO

No. of samples/thickn 

Mo, ppm i V, pp 

__ Cr, ppm 1 Ni, pp

1 C, organic 

i weight %

1 -- __ 

1

1 

1

5/73 

42 | 346

768"294 

12.1

TEXAS" ~ 

i i /i i i »

N \ 4/18 f 

ess, cm 0 100 MILES ' 490M550 V 

I I i 345 1 380 I

m l ' / is i ' 0 100 KILOMETERS ( ) 

>m y IOWA _ __ __- v f

\ Y 

. ___ _ NEBRASKA V, \ -

KANSAS ^^. \<£

4/61 < N ^ 

94 | 527 \ \

555T272 20/53 | ^~^ 

13.3 539M831 I /

448"290 '; 

12.7 /

I

OKLAHOMA

2/7 MISSOURI _ ___

i 5 i 186 (__ ___ _- -- ~"

4/7 195M30 \ 

21 i 338 3.0 *

287l80 \ 

,0

I I I I

Figure B4. Thickness and average concentrations of molybdenum, vanadium, chromium, nickel, and organic carbon for 39 

samples of the Upper Pennsylvanian Stark Shale Member of the Dennis Limestone (Missourian) from six areas in southern Iowa, 

Kansas, and Oklahoma. Samples are from same set plotted on figure B2; ppm, parts per million.

pattern on either a local or regional basis in these Middle 

Pennsylvanian black shales. The range in six of the average 

chromium values is comparable to those reported by Coveney and others (1987) for the Mecca Quarry Shale Member 

in Indiana and Illinois, but the values of organic carbon are 

much lower for samples from our study area.

The average values for nickel (fig. B3) have an 

approximately twofold variation that does not appear to be 

related to average values of organic carbon content. The 

values are highest for samples from northwestern and northcentral Oklahoma, but these values are not significantly 

higher than for samples from southern Iowa. The lowest 

average values are for samples from strata having an 

average organic carbon content of less than 10 weight 

percent.

The average values of organic carbon are highest for 

samples from southern Iowa and north-central Missouri 

(fig. B3). The highest values for samples from elsewhere are 

for north-central Oklahoma; the lowest values are for 

northwestern Kansas.

Tables B7 and B8 give the concentrations of selected 

major, minor, and trace elements in Middle and Upper 

Pennsylvanian black shales from southern Iowa, Kansas, 

and northern Oklahoma, including samples of eight black 

shales of Missourian and Virgilian ages (table Bl). Data for 

thickness and average values of molybdenum, vanadium, 

chromium, nickel, and organic carbon for the Stark Shale 

Member of the Dennis Limestone at one locality in southwestern Iowa, three localities in Kansas, and two localities 

in northern Oklahoma are summarized on figure B4.

The average concentration of molybdenum decreases 

tenfold from Iowa to southwestern Kansas (fig. B4); this 

relationship is consistent with much lower concentrations of 

molybdenum in areas more distal from shoreline for Middle 

Pennsylvanian strata studied here and those studied by 

Coveney and others (1987).

Average concentrations of vanadium are highest in 

eastern Kansas and southern Iowa, but the total amount 

(concentration x thickness) of vanadium at the eastern 

Kansas locality is two to three times more than that at the 

other localities (fig. B3).

B6 Stategic and Critical Minerals, Midcontinent Region, U.S.
Average chromium concentrations increase twofold 

from southern Iowa to southwestern Kansas in the Stark 

Shale Member, whereas the total amount (concentration x 

thickness) in the interval is almost ten times higher in 

southwestern Kansas than it is at the Iowa locality. While 

the average value for chromium does not correlate with total 

organic carbon, it probably correlates with the amount of 

marine (as opposed to terrestrial) organic matter. It is 

noteworthy that the most chromium in the Stark Shale 

Member occurs in the area considered most distal from 

shoreline, a conclusion based on mineral ratios and apatite 

and gypsum occurrences (fig. B3).

The average nickel concentrations in the Stark Shale 

Member are greatest in Iowa, but the total amount (concentration x thickness) of nickel is three times more in 

southwestern Kansas due to the greater thickness of the 

interval. The average values for nickel correlate with the 

amount of organic carbon (fig. B4).

The average concentration of organic carbon is highest in Iowa, but the total amount in southwestern Kansas is 

three times greater than the Iowa locality due to greater 

thickness of the Stark Shale Member in southwestern 

Kansas (fig. B4).

Average values for 16 black shale samples from the 

seven other black shale members of the Upper Pennsylvanian (table B8) in southern Iowa are molybdenum, 

463 ppm; vanadium, 1,445 ppm; chromium, 330 ppm; 

nickel, 418 ppm; and organic carbon, 13.7 percent. These 

values are very close to the average values for the Stark 

Shale Member in Iowa (fig. B4).

DISCUSSION AND SUMMARY

Mineral assemblages in samples of these marine 

strata cannot be considered in terms of conventional 

equilibrium relations because some minerals are detrital (for 

example, gypsum, potassium feldspar, kaolinite, calcite, and 

quartz) and others are authigenic (illite, albite, apatite, 

pyrite, iron-rich chlorite, and siderite). Because of the 

intimate mixtures of the very fine grained minerals with 

organic matter (kerogen), mineral-water equilibrium reactions are substantially retarded or impeded. In addition, 

lamination of minerals and organic matter inhibits vertical 

water-mineral interactions. These circumstances lead to

micro-environments having different "equilibrium" conditions on a millimeter scale that generally are not indicated 

by a sample a few centimeters thick.

It is not clear whether the type of organic matter 

(humic or algal) has any influence on the metals that 

become concentrated in these black shales. We believe the 

concentrations of metals such as vanadium, chromium, 

nickel, molybdenum, selenium, and uranium may depend 

chiefly on highly reducing conditions that may be influenced by influx of fresh water from land.

The mineralogical data presented herein are taken to 

indicate that detrital material originated from a northerly 

source during deposition of the Middle and Upper Pennsylvanian black shales. However, a significant amount of 

the minerals present in the black shales is of authigenic or 

diagenetic origin.

Table B1 . Stratigraphic position and age of units studied 

in survey of mineralogy and geochemistry of Middle and 

Upper Pennsylvanian black shales in the midcontinent 

region

[Modified from Heckel, 1977]

UPPER PENNSYLVANIAN 

______________Virgilian Series______________

Larsh Shale Member of the Deer Creek Limestone

Queen Hill Shale Member of the Lecompton Limestone

Heebner Shale Member of the Oread Limestone 

_____________Missourian Series______________ 

Eudora Shale Member of the Stanton Limestone

Quindaro Shale Member of the Wyandotte Limestone 

Muncie Creek Shale Member of the lola Limestone 

Stark Shale Member of the Dennis Limestone

Hushpuckney Shale Member of the Swope Limestone __

MIDDLE PENNSYLVANIAN

_____________Desmoinesian Series_____________ 

Anna Shale Member of the Pawnee Limestone

Little Osage Shale Member of the Fort Scott Limestone 

Excello Shale Member of the Fort Scott Limestone

Mecca Quarry Shale Member equivalents in Missouri, 

Kansas, and Oklahoma

Middle and Upper Pennsylvanian Marine Black Shales B7
Table B2. X-ray diffraction peaks used for estimation of relative abundances of minerals other than quartz in 

Pennsylvanian shales

Mineral

Iron-rich chlorite . . 

Illite ...........

Gypsum ........

Kaolinite .......

Albite .........

Potassium .......

feldspar 

Calcite .........

Dolomite .......

Apatite .........

Siderite1 ........

2Pyrite-pyl ......

3Pyrite-py2 ......

hkl

001 

001

020

001

002

040,

002 

104

104

112

104

002

021

d-value used 

(A)

14.1-14.2

7.56

715

3.186-3.198

3 220-3 250

3.03

2.88

279

2.79

2.71

242

Approximate 

29° (CuKa)

6.2 

8.7

11.7

12.4

27.90-28.00

27.45-27.70

29.5

30.%

32.05

32.05

33.16

3715

Lowest percentage 

identifiable 

(Carrol), 1970, 

table 12)

10 

5

Not reported

5

5

5

5

1

Not reported

Not reported

Not reported

Not reported

1Siderite cannot be detected in minor amounts due to interference of apatite.

^This line of pyrite is coincident with the second strongest line (202) of apatite. This line is not reported for samples containing 

detectable apatite.

^is line was measured for all samples because there are no interferences with other minerals.

REFERENCES CITED

Carroll, Dorothy, 1970, Clay minerals A guide to their identification: Geological Society of America Special Paper 126, 

80 p.

Coveney, R.M., and Glascock, M.D., 1989, A review of the origins 

of metal-rich Pennsylvanian black shales, central U.S.A., 

with an inferred role for basinal brines: Applied Geochemistry, v. 4, p. 347-367.

Coveney, R.M., Leventhal, J.S., Glascock, M.D., and Hatch, J.R., 

1987, Origins of metals and organic matter in the Mecca 

Quarry Shale Member and stratigraphically equivalent beds 

across the Midwest: Economic Geology, v. 82, p. 915-933.

Hatch, J.R., Daws, T.A., Lubeck, C.M., Pawlewics, M.J., 

Threlkeld, C.N., and Vuletich, A.K., 1984, Organic geochemical analysis of 247 organic-rich-rock and 11 oil

samples from the Middle Pennsylvanian Cherokee and 

Marmaton Groups, southeastern Iowa, Missouri, southeastern Kansas, and northeastern Oklahoma: U.S. 

Geological Survey Open-File Report 84-160, 39 p.

Heckel, P.H., 1977, Origin of phosphatic black shale facies in 

Pennsylvanian cyclothems of mid-continent North America: 

American Association of Petroleum Geologists Bulletin, 

v. 61, p. 1045-1068.

Stanton, M.R., Leventhal, J.S., and Hatch, J.R., 1983, Short-range 

vertical variation in organic carbon, carbonate carbon, total 

sulfur contents and Munsell color values in a core from the 

Upper Pennsylvanian Stark Shale Member of the Dennis 

Limestone, Wabaunsee County, Kansas: U.S. Geological 

Survey Open-File Report 83-315, 8 p.

Weller, J.M., 1958, Cyclothems and larger sedimentary cycles of 

the Pennsylvanian: Journal of Geology, v. 66, p. 195-207.

B8 Stategic and Critical Minerals, Midcontinent Region, U.S.
Table B3. Organic carbon content and x-ray diffraction intensity data for minerals, except quartz, in samples of Middle 

Pennsylvanian (Desmoinesian) black shales from the midcontinent

[C%, weight percent organic C; ill, illite; kao, kaolinite; a, albite; k, potassium feldspar; cal, calcite; dol, dolomite; ap, apatite; py2, line of pyrite 

measured for all samples because there are no interferences with other minerals; gy, gypsum; sid, siderite; chl, chlorite; pyl, line of pyrite that 

is coincident with second strongest line (202) of apatite (line not reported for samples containing detectable apatite); M, major mineral having 

peak intensity greater than 100; , not detected or not measured due to interference; n.d., not determined; data are reported relative to 100 

percent peak intensity for quartz]

Sample No. C% ill kao a k cal dol ap py2 9V sid chl py1

MIDDLE PENNSYLVANIAN SHALES FROM SOUTH-CENTRAL IOWA

SE1/4SW1/4 sec. 36, T. 75 N., R. 20 W., Marion County

41-1 

41-13f 

41-17 

41-31 

41-37a 

41-37b

4.0 

7.9 

24.8 

5.8 

1.7 

3.8

21 

33 

22 

29 

34 

17

9 11-30 12 15 0 

34 24 - 0 0 0 7 

33 11 27 11 26 7 

51 11 8 0 0 14 6 

74 11 - 0 8 0 5 

52 7 - 10 0 0 10

3 

0 

8 

3 

0 

0

11

10 

15

6 

7 

5 

0 

6 

0

0

12

7 

16

SW1/4SE1/4 sec. 36, T. 70 N., R. 19 W., Appanoose County

22-6d 

22-11 

22-14 

22-22c 

22-22e 

22-32a 

22-32b

16.4 

18.7 

43 

4.8 

25.1 

1.1 

10.6

25 

19 

20 

37 

31 

46 

30

20 11 60 22 12 9 

14 12 7 16 14 24 4 

10 9 6 6 5 34 2 

30 23 10 0 0 06 

36 9 10 20 15 10 8 

56 13 9 10 6 0 4 

38 11 8 16 16 11 7

7 

3 

0 

0 

0 

4 

5

10

6

4 

6 

7 

6 

1 

4

9 

6

Core CP78-1; NE1/4 sec. 12, T. 70 N^ R. 22 W., Wayne County

CP784A 

CP784B 

CP7813B 

CP7813D 

CP7826 

CP7828A 

CP7828B 

CP7828C 

CP7828D

18.7 

27.6 

6.5 

23.7 

7.5 

16.4 

21.5 

29.1 

193

18 

21 

28 

14 

27 

14 

21 

12 

23

21 13 7 21 20 70 

14 10 5 21 24 43 3 

21 16 11 0 0 18 0 

15 7 9 8 24 3 0 

36 18 10 0 18 8 10 

22 9 0 25 7 58 4 

23 13 6 0 0 10 8 

7 8 6 41 6 53 5 

17 8 4 32 14 19 6

5 

4 

0 

0 

0 

3 

7 

0 

6

0 

0 

0 

0

0

5 

6 

4 

5 

9 

3 

6 

3 

6

-

Core CP 53; NE1/4SE1/4NE1/4 sec. 1, T. 71 N., R. 18 W., Monroe County

Excello Shale Member

CP534A 

CP534B

1.4 

3.8

24 

18

23 9 7 8 41 28 0 

8 7 5 0 0 35 0

0 

0 __

17 

5 __

Mecca Quarry Shale Member equivalent

CP5312A 

CP5312B 

CP5312C 

CP5312D 

CP5312E 

CP5312F

7.1 

6.7 

3.6 

17.2 

26.0 

27.0

27 

21 

12 

19 

19 

19

24 27 5 29 5 8 11 

19 12 4 13 0 0 3 

14 6 - 47 0 0 45 

21 9 6 15 0 17 7 

15 5 6 15 22 6 5 

10 7 4 50 7 52 0

4 

0 

6 

5 

0 

3

0 

0 

0 

0 

0

8 

7 

12 

7 

6 

6

13 

M

34

Whitebreast coal

CP5313Z 

CP5313Y 

CP5313A

56.1 

48.5 

50.1

0 

7 

0

9 0 - M 0 0 7 

10 0 - M 0 0 11 

21 7 55 0 0 11

0 

5 

0

0 

0 

6

8 

0 

0

13 

27 

16

MIDDLE PENNSYLVANIAN SHALES FROM MISSOURI

SW1/4SW1/4 sec. 23, T. 65 N., R. 18 W., Putnam County

Anna n.d. 21 14 8 - 20 27 48 4 3 - 4 -

NW1/4NE1/4 sec. 19, T. 56 N., R. 16 W., Chariton County

BM14-2 

BM14-3

23.1 

15.0

21 

16

13 9-73 14 49 6 

15 13 - M 12 0 12

0

5 6

5 

4 19

Middle and Upper Pennsylvanian Marine Black Shales B9
Table B3. Organic carbon content and x-ray diffraction intensity data for minerals, except quartz, in samples of Middle 

Pennsylvanian (Desmoinesian) black shales from the midcontinent-Continued

Sample No. C% kao cal dol ap py2 gy sid chl py1

NW1/4NW1/4 sec. 4, T. 54 N., R. 14 W., Randolph County

BM2-3 

BM2-5

5.2 

21.2

48

19

36

14

23

6

23

24

14

21

11

4

NW1/4NW1/4 sec. 25, T. 46 N., R. 27 W., Johnson County

MC105-2 

MC105-6

9.6

3.8

22

45

24

13

13

14 10

13

0

19

0

36

18

SW1/4SW1/4 sec. 9, T. 44 N., R. 26 W., Johnson County

MC86-2 

MC86-5

9.2 

2.9

29 

50

10

45

11 

17

10 

9

13 

6

12 

0

30 

0

6 

9

3 

10 15

7 

12 12

SW1/4SE1/4 sec. 7, T. 45 N, R. 25 W., Johnson County

MC204-5A 2.6 M 13 0

SW1/4 sec. 1, T. 40 N., R. 32 W., Bates County

MC121-2 

MC121-5

19.7 

1.7

34 

19

16 

10

15 

12

30 

M

14 

16

35 

0

6

4

4 

0

6 

6

SW1/4 sec. 29, T. 39 N., R. 30 W, Bates County

MC142-3 6.0 30 38 8 0 0 0 10 17

NE1/4SE1/4 sec. 35, T. 37 N., R. 30 W, Vernon County

MC168-4 

MC168-5 

MC168-7

2.4

18.0

1.7

55

33

34

59

20

32

15

17

10 14

0

14

0

0

10

0

0

23

0

0

10

0

26

30

12

6

7

MIDDLE PENNSYLVANIAN SHALES FROM SOUTHEASTERN KANSAS

SW1/4SE1/4 sec. 8, T. 32 &, R. 22 E^ Cherokee County

6-1

6-12

6-27

9.4

8.5

3.0

27

29

40

17

37

64

14

15

12

75

38

0

19

14

0

11

15

0

9

10

5

0

0

0

~

23

7

9

9

_

~

-

MIDDLE PENNSYLVANIAN SHALES FROM WESTERN KANSAS

Crist B-l; sec. 32, T. 20 S., R. 34 W., Scott County, southwestern Kansas

CR4613.5

CR5614.5

CR4620.5

11.2

8.7

0.8

18

20

12

9

6

6

9

7

13

9

11

7

17

32

M

40

45

16

24

12

4

11

6

10

0

0

0

0

0

0

5

7 

12

Knudson A core; sec. 16, T. 7 S., R. 32 W., Thomas County, northwestern Kansas

KNUD4477 

KNUD4480

2.6

7.6

13 

17

7 

9

5 

5

4 

7

M 

70

60 

50

3 

10

7 

9

0 

0

0 

0

6 

9 _

MIDDLE PENNSYLVANIAN SHALES FROM NORTHEASTERN OKLAHOMA

NE1/4SE1/4 sec. 30, T. 29 N., R. 18 E., Craig County

1535u-5

1535u-23a

1535u-25

1535-7

1535-12

1535-23

1535-25

1535-66

1535-78

1535-144

1535-159

9.5

7.6

11.0

14.8

4.7

7.2

14.6

7.9

10.3

1.7

2.7

27

11

30

15

44

32

35

25

25

38

69

18

6

12

8

33

31

24

31

29

56

98

18

7

20

12

15

14

13

12

9

11

21

26

M

15

0

68

36

18

0

0

12 0

0

14

M

12

10

14

27

14

0

0

0

0

16

0

9

16

8

9

27

77

0

0

0

9

6

9

12

12

7

16

6

33

6

0

0

0

0

0

0

0

0

0

0

0

0

~

~

~

~

8

39

22

6

3

5

0

10

5

7

6

6

7

14

~

10

~

~

58

8

6

NE1/4NW1/4 sec. 4, T. 23 N, R. 10 E^ Osage County

1051-49 

1051-50

3.0 

11.9

21

25

12

15

13

15

M 

0

29

23

6

11

9

20

B10 Stategic and Critical Minerals, Midcontinent Region, U.S.
Table B3. Organic carbon content and x-ray diffraction intensity data for minerals, except quartz, in samples of Middle 

Pennsylvanian (Desmoinesian) black shales from the midcontinent-Continued

Sample No. C% ill kao a k cal dol ap py2 gy sid chl py1

NW1/4NW1/4 sec. 12, T. 27 N, R. 6 E^ Osage County

1044-19 

1044-32 

1044-38 

1044-46 

1044-47 

1044-97 

1044-111

3.5 

9.9 

4.1 

5.5 

15.2 

4.7 

2.0

33 

16 

29 

19 

26 

27 

27

19 29 - 64 27 6 8 

9 17 11 25 17 13 

20 13 M 15 0 12 

19 13 - M 23 5 12 

22 13 23 23 35 12 

51 11 - 0 0 0 11 

48 12 - 0 0 0 5

0 

0 

0 

0 

0 

0 

0

17 

17

7 

5 

6 

7 

6 

3 

4

18

7

MIDDLE PENNSYLVANIAN SHALES FROM NORTHEASTERN OKLAHOMA

NW1/4NW1/4 sec. 34, T. 25 N, R. 3 E^ Osage County

1065-2a 

1065-2b 

1065-6a 

1065-6b 

1065-15 

1065-20 

1065-22 

1065-23 

1065-39 

1065-48

2.4 

73 

8.1 

11.6 

10.0 

13 

1.5 

3.5 

1.1 

1.2

30

32 

26 

17 

28 

43 

42 

27 

47 

31

11 32 - 57 29 0 8 

15 25 - 40 25 7 7 

14 20 - 0 17 9 6 

9 12 - 2 22 23 11 

22 22 31 19 12 10 

32 26 10 47 13 0 7 

48 25 - 0 0 0 3 

35 12 55 14 0 12 

49 13 9 13 12 13 0 

64 21 - 0 0 0 0

0 

0 

0 

0 

0 

0 

0 

0 

0 

0

7

19

13 

5

9

5 

6 

6 

4 

5 

6 

8 

7 

7 

10

13

13 

6

14

MIDDLE PENNSYLVANIAN SHALE SAMPLES FROM WESTERN OKLAHOMA

Core 1580; sec. 2, T. 23 N, R. 12 W., Alfalfa County

5991 

6039.5 

60403 

6041.2

16.8 

3.4 

8.1 

15.2

17 

19 

35 

23

9 21 5 0 14 4 10 

14 15 - M 18 4 0 

26 23 7 0 18 86 

15 18-20 41 18 5

0 

0 

0 

0

0 

0 

0

0

5 

8 

10 

6

-

Core 1683; sec. 4, T. 25 N., R. 8 W., Grant County

5166.7 

5206.8 

5222.7

7.4 

12.5 

17.9

20

25 

34

17 15 7 40 22 12 7 

14 15 6 48 34 19 8 

20 18 - 0 27 6 7

0 

0 

0

0 

0 

0

4 

7 

8

-

Core 600; sec. 31, T. 17 N., R. 5 W., Kingfisher County

6471 

6487.5

11.5 

1.6

52 

43

24 21 10 0 0 90 

43 54 7 0 0 13 0

5 

0

0 

0

9 

9

Core 330; sec. 28, T. 13 N, R. 23 W, Roger Mills County

12,165 

12,174

1.9

3.7

25 

23

16 25 6 34 35 5 8 

14 27 8 44 26 5 4

0 

0

0 

0

6

5 __

Core 698; sec. 11, T. 17 N., R. 20 W., Dewey County

9503 

9504

5.8 

10.7

19 

16

11 31 - 6 16 72 

12 40 ~ 0 6 0 17

0 

0

0

0

3 

5 28

Core 707; sec. 18, T. 17 N, R. 20 W, Dewey County

9807 

9813

2.3 

3.4

18 

21

14 15 7 M 22 3 5 

17 24 8 36 35 7 8

0 

0

0 

0

5 

6 _

Core 1609; sec. 13, T. 13 N., R. 6 W., Canadian County

7331 12.3 9 68 33 13 68 20 0 0 4 -

Core 1567; sec. 11, T. 13 N., R. 6 W., Canadian County

7402.2 

7402.4

8.4 

14.9

13

22

7 8 4 47 27 67 14 

12 28 5 0 17 0 14

0 

0

0 

0

4 

4 20

Core 497; sec. 18, T. 14 N, R. 12 W., Blaine County

9704 5.7 13 5 15 3 0 26 57 10 0 0 4 -

Core 333A; sec. 25, T. 2 N, R. 27 E, EMC, Beaver County

6893 

6894

10.7 

9.4

18 

26

6 14 - 8 20 60 11 

9 24 7 22 24 0 18

0 

0

0 

0

4 

7 31

Middle and Upper Pennsylvanian Marine Black Shales B11
Table B4. Organic carbon content and x-ray diffraction intensity data for minerals, except quartz, in samples of Upper 

Pennsylvanian black shales from the midcontinent

[C%, weight percent organic C; ill, illite; kao, kaolinite; a, albite; k, potassium feldspar; cat, calcite; dol, dolomite; ap, apatite; py2, line of pyrite 

measured for all samples because there are no interferences with other minerals; gy, gypsum; sid, siderite; chl, chlorite; pyl, line of pyrite that 

is coincident with second strongest line (202) of apatite (line not reported for samples containing detectable apatite); M, major mineral having 

peak intensity greater than 100; -, not detected or not measured due to interference; data are reported relative to 100 percent peak intensity 

for quartz]

Sample No. C% ill kao a cal dol ap py2 sid chl py1

UPPER PENNSYLVANIAN BLACK SHALES FROM IOWA

Core IBCD (Bedford core); sec. 4., T. 67 N^ R. 34 W., Taylor County

Larsh Shale Member of the Deer Creek Limestone (4.5-4.9 ft)

A 

B 

C

19.5

9.8

20.7

29

24

21

15

23

12

15

24

18

20

21

9

13

17

10

0

0

17

10

11

6

14

18

Queen Hill Shale Member of the Lecompton Limestone (102.1-102.5 ft)

A 

B 

C

10.1

21.0

5.2

37

32

34

21

17

24

23

18

26

35

27

26

10

17

7

11

8

8

18

13

14

Core IHC (Hillsdale/Buffington); sec. 22, T. 72 N, R. 42 W., Mills County

Heebner Shale Member of the Oread Limestone (6.2-6.6 ft)

D249924 16.9 20 13 16 8 60 38 0 12 15

Eudora Shale Member of the Stanton Limestone (100.2-1003 ft)

D249925 15.2 23 14 13 10 0 24 48

Quindaro Shale Member of the Wyandotte Limestone (166.1-166.4 ft)

Al

Bl

Cl

5.7

16.8

7.5

36

31

33

23

12

19

31

14

28

13

11

12

5

8

8

14

10

12

0

0

0

10

6

10

7

7

4

7

8

7

7

6

6

15

12

15

Stark Shale Member of the Dennis Limestone (218.2-218.5 ft)

4.4 35 17 20 13 50 25 0 0

Core ISC (Stanzel Qy); sec. 5, T. 75 N., R. 29 W., Madison County

Quindaro Shale Member of the Wyandotte Limestone (36.9-37.3 ft)

A2 

B2

5.2 

16.4

28 

25

20 

9

30

18

36 

11

8 

10

0

0

9 

0

0

12

7 

6

9 

9

19

7

Muncie Creek Shale Member of the lola Limestone (56.9-57.3 ft)

D249928 1.2 14 22 33 10 0 0 15 0 11

Core UCL (Jefferson Qy, lower); sec. 17, T. 77 N., R. 31 W., Adair County

Stark Shale Member of the Dennis Limestone (51.6-52.2 ft)

2A

2B

2C

2D

18.4

11.8

233

11.0

22

22

22

24

18

15

16

18

13

15

15

23

8

8

9

7

17

20

12

14

52

80

64

44

0

8

0

0

11

9

11

8

8

7

6

6

0

0

6

6

8

4

7

17

17

13

Hushpuckney Shale Member of the Swope Limestone (85.3-853 ft)

A 

B

27.3 

21.4

24 

28

16 

20

14 

17

7 31 

33

27 

26

0 

0

14 

12

11 

10

7 

5

8 

6 _

UPPER PENNSYLVANIAN BLACK SHALES FROM KANSAS

SE1/4SE1/4SW1/4 sec. 2, T. 6 N, R. 27 W, Sheridan County

Muncie Creek Shale Member of the lola Limestone (3,708-3,7083 ft)

406A 3.0 31 22 30 12 42 30 0 0

SW1/4SE1/4SW1/4 sec. 16, T. 9 S^ R. 16 W, Rooks County

Muncie Creek Shale Member of the lola Limestone (3,293.7-3,294.1 ft)

506MC 10.6 29 22 23 30 15 0 11 0 13

B12 Stategic and Critical Minerals, Midcontinent Region, U.S.
Table B4. Organic carbon content and x-ray diffraction intensity data for minerals, except quartz,in samples of Upper 

Pennsylvanian black shales from the midcontinent-Continued

Sample No. C% ill kao a k cal dol ap py2 gy sid chl py1

Stark Shale Member of the Dennis Limestone (3,362-3,364 ft)

506SA 

506SD 

506SF 

506SG

16.0 

16.4 

4.0 

16.7

29 

21 

17 

25

15 24 10 19 28 20 3 0 

13 11 8 26 17 10 11 0 

8 86M43085 

14 19 9 34 31 12 7 0

5

7 

4 

6 

7

-

Hushpuckney Shale Member of the Swope Limestone (3,3893-3,392 ft)

506HA 

506HB 

506HC

1.1 

2.5 

2.5

33 

32 

15

16 16 11 80 43 11 6 0 

15 20 15 19 43 24 5 3 

7 11 25 25 11 3 0

-

8 

8

5

~

Ceik, NW1/4NW1/4 sec. 30, T. 30 &, R. 33 W, Haskell County

Stark Shale Member of the Dennis Limestone (4,533-4,535.4 ft)

2A,l-5 

8-9 

10-12 

13-15 

16-19

9.6 

10.2 

12.8 

13.6 

14.4

24 

19 

23 

23 

29

9 22 11 14 12 0 10 5 

10 16 9 27 16 19 9 0 

9 18 10 23 16 9 9 0 

11 18 8 28 18 12 9 0 

11 17 10 33 13 0 11 0

7 

8

6

5 

5 

7 

5

18 

14

A-l Holmdan 1, Rawlins County

Stark Shale Member of the Dennis Limestone (interval unknown)

D249932 0.2 26 14 22 9 72 33 10 0 0 - 8 -

UPPER PENNSYLVANIAN BLACK SHALES FROM OKLAHOMA

Core 1389; sec. 5, T. 28 N., R. 1 W., Kay County (interval unknown)

1389C 

1389E

4.2 

1.8

22 

34

19 16 5 15 0 0 14 0 

29 13 6 4 6 0 6 8

0 

0

6 

10

22 

8

Core 508; sec. 1, T. 17 N., R. 51 W., Dewey County (interval unknown)

508B 

508C 

508D 

508E

1.4 

2.9 

2.9 

12.9

17 

17 

13 

17

13 17 - 51 11 4 5 0 

12 18 - 36 15 0 4 0 

8 12-M8 040 

12 14 38 18 5 14 0

0 

0 

0 

0

4 

3 

9

7

6 

6

Middle and Upper Pennsylvanian Marine Black Shales B13
Table B5. Selected major and minor elements in Middle Pennsylvanian (Desmoinesian) black shales from the 

midcontinent

[Organic carbon and sulfur analyzed with Leco WR-12 and Leco IR-32 determinators, respectively; other elements determined by inductively 

coupled plasma method; all in weight percent]

Sample No. Org. C AJ Fe Mg Ca Na K Tl

MIDDLE PENNSYLVANIAN BLACK SHALES FROM SOUTH-CENTRAL IOWA

Core CP78-1; NE1/4 sec. 12, T. 70 N, R. 22 W, Wayne County

CP784A

CP7813B

CP7813D

CP7826

CP7828A

CP7828C

18.7

6.5

23.7

7.5

16.4

29.1

6.4

7.9

5.5

7.7

5.7

2.8

3.2

3.1

4.9

5.3

2.6

2.5

1.4

13

1.4

1.5

1.1

0.6

2.2

2.0

1.5

1.8

9.7

8.7

030

.48

.25

.68

.48

.26

2.2

3.0

2.0

2.7

1.9

1.0

031

32

.27

37

.21

.11

0.18

.83

.02

.21

3.60

3.10

1.4

0.5

3.3

1.6

1.0

2.0

MIDDLE PENNSYLVANIAN BLACK SHALES FROM WESTERN KANSAS

Crist B-l; sec. 32, T. 20 S, R. 34 W, Scott County

CR4613

CR4614

CR4620

11.2

8.7

.8

4.9

5.2

5.9

3.2

2.4

33

2.7

2.6

4.3

6.9

4.7

6.6

.61

.59

1.0

2.5

2.6

2.2

.21

.21

.30

2.20

.70

.12

3.2

1.4

1.5

Knudson A core; sec. 16, T. 7 SL, R. 32 W, Thomas County

KNUD4477 

KNUD4480

2.6

7.6

4.9 

5.1

2.6 

3.0

3.5 

3.3

93

73

.49 

.46

2.1

2.4

.21 

.22

.16

.71

1.1 

1.6

MIDDLE PENNSYLVANIAN BLACK SHALES FROM WESTERN OKLAHOMA

Core 1580; sec. 2, T. 23 N., R. 12 W., Alfalfa County

5991

6039

6040

6041

16.8

3.4

8.1

15.2

6.8

6.5

7.5

5.2

3.6

2.8

3.6

3.4

1.8

2.3

2.3

2.3

.8

93

1.5

6.9

.89

.85

.91

.58

2.0

2.0

23

1.6

30

.25

31

.21

.13

.07

32

2.00

1.4

1.0

1.0

13

Core 1683; sec. 4, T. 25 N., R. 8 W, Grant County

5166.7

5206.8

5222.7

7.4

12.5

17.9

6.9

5.7

6.2

4.0

3.5

3.6

2.3

23

2.0

5.6

8.0

1.0

.87

.63

.70

1.8

1.9

2.1

.25

.19

.28

.99

1.90

.10

1.6

1.2

1.5

Core 600; sec. 31, T. 17 N., R. 5 W., Kingfisher County

6471 

6487.5

11.5 

1.6

9.6

7.6

3.1 

43

1.1 

1.0

.1 

.3

.66 

.95

3.0 

1.9

.40 

39

.02 

.07

1.0

.4

Core 330; sec. 28, T. 13 N, R. 23 W., Roger Mills County

12,165 

12,174

1.9

3.7

8.0 

8.0

4.5 

3.7

1.7 

1.7

4.7 

4.0

.80 

.83

2.9 

2.9

38 

37

.07 

.07

1.5 

1.1

Core 698; sec. 11, T. 17 N., R. 20 W, Dewey County

9503 

9504

5.8 

10.7

8.9 

7.9

3.9 

5.1

1.7 

1.4

1.7 

.6

1.10 

1.10

2.7 

2.2

39 

39

.23 

.12

1.4 

3.0

Core 707; sec. 18, T. 17 N, R. 20 W, Dewey County

9807

9813

2.3 

3.4

7.7 

7.9

3.5 

3.9

1.8

1.9

7.9

4.2

.83 

.95

2.4 

2.6

34

34

.06

.25

1.0 

1.4

Core 1609; sec. 13, T. 13 N., R. 6 W., Canadian County

7331 12.3 4.5 4.7 1.4 13 .63 1.4 .14 4.70 4.0

Core 1567; sec. 11, T. 13 N, R. 6 W, Canadian County

7402.2

7402.7

8.4 

14.9

4.4 

7.5

3.5 

4.0

1.4 

1.6

13

1.0

.56 

.95

1.4 

2.4

.15 

.35

4.5 

.09

2.6 

2.3

Core 497; sec. 18, T. 14 N, R. 12 W., Blaine County

9704 5.7 6.4 3.3 1.3 9.9 .75 2.1 .18 4.40 23

Core 333A; sec. 25, T. 2 N., R. 27 E., EMC, Beaver County

6893

6894

10.7 

9.4

5.8

7.3

2.9 

4.6

1.7 

2.2

11

3.2

.82 

.95

2.2 

2.9

.24

35

4.70 

.31

2.2 

3.6

B14 Stategic and Critical Minerals, Midcontinent Region, U.S.
Table B6. Selected minor and trace elements in Middle Pennsylvanian (Desmoinesian) black shales from the midcontinent

[Selenium was determined by energy dispersive analysis; other elements were determined by optical-emission spectroscopy. N, "nearshore" 

fades of Heckel (1977); others are "offshore" of Heckel (1977). Ag, As, Ba, Cd, and Sr were not determined for some samples; -, not 

determined. All in parts per million except P, which is in weight percent; <, less than]

Sample No. Ag As Ba Cd Cr Mo Ni Se Sr V Zn P

MIDDLE PENNSYLVANIAN BLACK SHALES FROM SOUTH-CENTRAL IOWA

SE1/4SW1/4 sec. 36, T. 75 N, R. 20 W, Marion County

41-1 

41-13f 

41-17 

41-31 

41-37a 

41-37b

-

541 70 180 25 

185 <10 130 10 

570 420 100 170 

241 50 110 10 

136 <10 70 <10 

143 10 90 10

1,690 

439 

1,790 

231 

147 

145

1,140 

320 

4,510 

130 

60 

50

0.86 

.24 

1.33 

1.10 

.13 

.13

SW1/4SE1/4 sec. 36, T. 70 N, R. 19 W., Appanoose County

22-6d 

22-11 

22-14 

22-22c 

22-22e 

22-32a 

22-32b

-

-

590 80 60 70 

- 486 170 80 70 

914 60 170 30 

- - 206 <10 130 <10 

637 450 120 190 

143 <10 80 <10 

480 20 250 50

465 

1,180 

1,390 

458 

2,330 

188 

304

50 

1,770 

410 

330 

15,400 

140 

250

.94 

1.75 

2.58 

.13 

.44 

.10 

.60

Core CP78-1; NE1/4 sec. 12, T. 70 N, R. 22 W, Wayne County

CP784A 

CP784B , 

CP7813B" 

CP7813D 

CP7826 

CP7828A 

CP7828B 

CP7828C 

CP7828D

2 

4 

14 

4 

3 

2 

4 

8 

5

30 

20 

30 

90 

20 

10 

20 

20 

30

220 26 500 260 400 135 120 

150 235 1160 105 390 145 180 

260 < 2 960 800 280 80 150 

160 <2 360 170 150 120 110 

300 2 140 9 190 15 140 

160 6 460 5 210 25 320 

205 20 780 120 375 105 120 

95 240 860 310 420 215 300 

185 95 640 225 320 170 205

670 

1,020 

620 

1,600 

400 

160 

1,170 

3,200 

2,040

510 

7,120 

430 

110 

410 

690 

1,150 

10,000 

2,400

-

Core CP 53; NE1/4SE1/4NE1/4 sec. 1, T. 71 N, R. 18 W, Monroe County

Excello Shale Member

CP534A 

CP534B

<2 

<2 <lo

260 <2 760 4 170 <10 145 

255 <2 1,240 10 205 <10 150

220 

2,230

280 

695

Mecca Quarry Shale Member equivalent

CP5312A 

CP5312B 

CP5312C 

CP5312D 

CP5312E 

CP5312F

<2 

<2 

3 

3 

7 

8

20 

20 

120 

30 

30 

30

290 4 230 5 160 <10 180 

305 4 230 4 145 <10 175 

295 2 105 20 290 <10 150 

210 25 665 80 290 105 175 

175 145 885 485 465 240 115 

110 85 1,000 325 415 205 285

455 

460 

155 

795 

2,800 

3,450

485 

575 

120 

1,420 

5,530 

3,940

_

Whitebreast coal

CP5313Z 

CP5313Y 

CP5313A

<2 

<2 

<2

10 

20

20 4 80 55 55 140 65 

15 9 10 30 30 60 35 

5 <2 8 20 30 210 20

445 

10 

15

220 

885 

40

-

MIDDLE PENNSYLVANIAN BLACK SHALES FROM MISSOURI

NW1/4NE1/4 sec. 19, T. 56 N, R. 16 W, Chariton County

BM14-2 

BM14-3 _

638 50 70 80 

- 158 20 80 <10

805 

142

2,280 

190

3.26

.23

NW1/4NW1/4 sec. 4, T. 54 N, R. 14 W, Randolph County

BM2-3 

BM2-5 :

187 <10 90 <10 

- 542 90 140 80

205 

694

670 

1,460

.35 

1.60

Middle and Upper Pennsylvanian Marine Black Shales B15
Table B6. Selected minor and trace elements in Middle Pennsylvanian (Desmoinesian) black shales from the 

midcontinent-Continued

Sample No. As Ba Cd Cr Mo Ni Se Sr 

NW1/4NW1/4 sec. 25, T. 46 N, R. 27 W., Johnson County

Zn

MC105-2 

MC105-6

894

695

10

20

270

210

75

25

1,710

503

200

350

2.83

1.17

SW1/4SW1/4 sec. 9, T. 44 N, R. 26 W, Johnson County

MC86-2 

MC86-5

622

123

50 300

70

140 642

226

1,960

80

1.68 

.12

SW1/4SE1/4 sec. 7, T. 45 N., R. 25 W., Johnson County

MC204-5A 60 110 69 1,010 .13

SW1/4 sec. 1, T. 40 N, R. 32 W., Bates County

MC121-2 

MC121-5

784 

65

40 110 

40

140 522 

63

1,190 

30

1.92 

.07

SW1/4 sec. 29, T. 39 N., R. 30 W., Bates County

MC142-3 132 150 127 40 .11

NE1/4SE1/4 sec. 35, T. 37 N, R. 30 W, Vernon County

MC168-4 

MC168-5 

MC168-7

119

427

127

30

50

200

80

60

184

205

143

120

160

60

.11

1.10

.13

MIDDLE PENNSYLVANIAN BLACK SHALES FROM SOUTHEASTERN KANSAS

SW1/4SE1/4 sec. 8, T. 32 S^ R. 22 E, Cherokee County

6-1

6-12

6-27

323

245

- 156

20

30

<10

170

140

110

55

10

<10

255

200

165

1,030

120

140

.84

.99

.13

MIDDLE PENNSYLVANIAN BLACK SHALES FROM WESTERN KANSAS

Crist B-l; sec. 32, T. 20 S^ R. 34 W., Scott County, southwestern Kansas

CR4613.5

CR4614.5

CR4620.5

4

3

<2

20

20

<10

180

180

220

20

<2

<2

670

410

76

39

20

<2

260

220

57

70

70

10

250

160

290

260

140

90

1,500

29

45 -

Knudson A core; sec. 16, T. 7 JL, R. 32 W., Thomas County, northwestern Kansas

KNUD4477 

KNUD4480

<2 

3

20

10

170

180

220

390

22

58

82

180

15

45

250

190

210

720

350

170

MIDDLE PENNSYLVANIAN BLACK SHALES FROM NORTHEASTERN OKLAHOMA

NE1/4SE1/4 sec. 30, T. 29 N, R. 18 E, Craig County

1535u-5

1535u-23a

1535u-25

1535-7

1535-12

1535-23

1535-25

1535-66

1535-78

1535-144

1535-159

_____ 421

----- 170

- - - - 370

__ c-»7 jj i

 J..5.5

241

_____ 582

- - - - 223

109

144

146

20

<10

40

110

<10

20

30

20

<10

<10

<10

140

80

160

200

120

160

240

230

110

80

80

45

<10

50

90

<10

10

70

<10

<10

<10

<10

266

67

508

865

167

202

 344

200

157

172

181

430

40

600

1,280

80

410

910

680

50

60

160

.83

.09

.48

.30

.26

.48

1.65

4.76

.08

.15

.14

NE1/4NW1/4 sec. 4, T. 23 N., R. 10 E, Osage County

1051-49 

1051-50

139

576

10

30

100

270 60

95

382

40

750

.48 

.76

B16 Stategic and Critical Minerals, Midcontinent Region, U.S.
Table B6. Selected minor and trace elements in Middle Pennsylvanian (Desmoinesian) black shales from the 

midcontinent-Continued

Sample No. Ag As Ba Cd Cr Mo Ni Se Sr V Zn P

NW1/4NW1/4 sec. 12, T. 27 N, R. 6 E^ Osage County

1044-19 

1044-32 

1044-38 

1044-46 

1044-47 

1044-97 

1044-111

-

-

131 <10 150 <10 

472 40 210 80 

116 <10 80 <10 

198 10 140 <10 

492 40 230 45 

104 <10 70 <10 

128 <10 70 <10

-

132 

449 

123 

147 

333 

126 

159

340 

1,090 

60 

420 

810 

50 

130

.21 

.96 

.15 

35 

2.72 

.20 

.13

NW1/4NW1/4 sec. 34, T. 25 N, R. 3 E^ Osage County

1065-2a 

1065-2b 

1065-6a 

1065-6b 

1065-15 

1065-20 

1065-22 

1065-23 

1065-39 

1065-48

-

-

133 <10 130 <10 

- 346 30 150 40 

- 255 10 190 50 

623 50 210 105 

445 40 220 65 

91 <10 60 <10 

115 <10 60 <10 

165 <10 110 <10 

261 <10 170 <10 

105 <10 60 <10

133 

344 

189 

562 

324 

117 

169 

148 

237 

139

300 

590 

770 

930 

740 

350 

160 

150 

160 

90

.20 

.43 

.43 

1.73 

.64 

.08 

.10 

.19 

.52 

.12

MIDDLE PENNSYLVANIAN BLACK SHALES FROM WESTERN OKLAHOMA

Core 1580; sec. 2, T. 23 N, R. 12 W., Alfalfa County

5991 

6039.5 

60403 

6041.2

4 

<2 

<2 

4

20

10 

20

160 3 550 15 380 110 

180 <2 170 5 160 10 

250 3 290 11 210 35 

150 11 800 30 260 105

250 

760 

250 

570

230 

110 

200 

490

1,000 

290 

540 

840

-

Core 1683; sec. 4, T. 25 N., R. 8 W., Grant County

5166.7 

5206.8 

5222.7

<2 

3 

4

10 

20 

20

130 <2 410 5 230 35 

180 8 630 22 220 50 

180 4 420 21 440 80

400 

530 

160

130 

440 

230

360 

850 

950

-

Core 600; sec. 31, T. 17 N., R. 5 W., Kingfisher County

6471 

6487.5

<2 

<2

10 

10

400 <2 81 12 54 10 

340 <2 83 <2 44 <10

220 

200

140 

92

120 

100 _

Core 330; sec. 28, T. 13 N, R. 23 W., Roger Mills County

12,165 

12,174

<2 

<2

10 

10

390 <2 72 4 130 <10 

500 <2 180 9 170 10

360 

310

130 

280

270 

470 __

Core 698; sec. 11, T. 17 N, R. 20 W, Dewey County

9503 

9504

<2 

4

10 

30

290 <2 240 16 220 <10 

200 2 430 18 320 75

540 

430

230 

400

670 

840 _

Core 707; sec. 18, T. 17 N., R. 20 W., Dewey County

9807 

9813

<2 

<2 <M

280 <2 140 <2 150 <10 

310 <2 180 3 200 <10

930 

640

110 

150

230 

450 _

Core 1609; sec. 13, T. 13 N., R. 6 W., Canadian County

7331 3 60 100 3 550 54 250 20 1,200 150 610 -

Core 1567; sec. 11, T. 13 N., R. 6 W., Canadian County

7402.2 

7402.7

2 

8

30 

30

110 <2 590 25 200 15 

200 11 800 41 320 125

1,000 

190

140 

560

480 

840

Core 497; sec. 18, T. 14 N., R. 12 W., Blaine County

9704 <2 30 180 <2 270 14 230 <10 1,500 150 670 -

Core 333A; sec. 25, T. 2 N., R. 27 K, EMC, Beaver County

6893 

6894

5 

5

20 

30

150 13 840 27 200 15 

180 9 590 41 250 65

660 

200

540 

740

680 

320 _

Middle and Upper Pennsylvanian Marine Black Shales B17
Table B7. Selected major and minor elements in Upper Pennsylvanian black shales from the midcontinent

[Organic carbon was measured with a Leco WR-12 carbon determinator, other elements were determined by inductively coupled plasma 

method; all in weight percent; -, not determined]

Sample No. Org. C Al Fe Mg Ca Na K Ti

UPPER PENNSYLVANIAN BLACK SHALES FROM SOUTH-CENTRAL IOWA

Core IBCD (Bedford core); sec. 4., T. 67 N^ R. 34 W., Taylor County

Larsh Shale Member of the Deer Creek Limestone (4.5-4.9 ft)

A

B

C

19.5

9.8

20.7

5.9

6.6

6.1

3.8

3.8

3.4

1.5

1.4

1.4

1.9

23

3.0

0.35

.55

.45

2.0

2.0

2.1

0.23

.27

.23

0.03

.03

.93

Queen Hill Shale Member of the Lecompton Limestone (102.1-1023 ft)

A 

B 

C

10.1

21.0

5.2

6.2 

4.9 

6.3

3.6 

3.2 

3.6

1.3 

1.2 

1.2

2.7 

2.4 

2.3

.64 

.44 

.74

2.0 

1.6 

1.9

.26 

.20 

.26

.02 

.02 

.02

Core IHC (Hillsdale/Buffington); sec. 22, T. 72 N, R. 42 W., Mills County

Heebner Shale Member of the Oread Limestone (6.2-6.6 ft)

D249924 16.9 4.8 3.6 1.9 4.8 .44 2.0 .20 .02

Eudora Shale Member of the Stanton Limestone (100.2-1003 ft)

D249925 15.2 4.8 2.8 1.4 6.4 .42 2.1 .10 2.6

Quindaro Shale Member of the Wyandotte Limestone (166.1-166.4 ft)

Al

Bl

Cl

5.7

16.8

7.5

7.1

5.0

6.7

3.7

3.3

3.6

1.6

1.3

1.7

1.2

1.0

1.2

.81

.45

.60

2.7

2.2

2.7

31

.22

.28

.16

.05

.03

Stark Shale Member of the Dennis Limestone (218.2-218.5 ft)

4.4 6.9 2.9 1.9 3.6 .68 2.9 .28 .03

Core ISC (Stanzl Qy); sec. 5, T. 75 N., R. 29 W., Madison County

Quindaro Shale Member of the Wyandotte Limestone (36.9-37.3 ft)

A2 

B2

5.2 

16.4

6.4 

5.8

4.1 

3.8

1.5 

13

3.0 

1.2

.73 

.48

2.1 

2.0

.26

.23

.02 

.02

Muncie Creek Shale Member of the lola Limestone (56.9-57.3 ft)

D249928 1.2 7.5 2.9 1.5 1.9 .74 2.6 .27 .75

Core IJCL (Jefferson Qy, lower); sec. 17, T. 77 N, R. 31 W, Adair County

Stark Shale Member of the Dennis Limestone (51.6-52.2 ft)

2A

2B

2C

2D

18.4

11.8

233

11.0

4.9

4.8

4.4

6.3

3.7

3.7

3.5

3.9

2.1

2.5

2.1

2.1

3.3

4.9

3.1

3.1

.34

.34

30

.57

1.7

1.7

1.6

2.1

.21

.20

.20

.26

.02

.18

.03

.03

~

-

Hushpuckney Shale Member of the Swope Limestone (85.3-853 ft)

A 

B

27.3 

21.4

4.0 

4.8

3.9

3.8

1.4 

1.5

3.0 

2.8

.28 

36

1.4 

1.7

.17 

.20

.03 

.03 _

UPPER PENNSYLVANIAN BLACK SHALES FROM KANSAS

SE1/4SE1/4SW1/4 sec. 2, T. 6 N, R. 27 W., Sheridan County

Muncie Creek Shale Member of the lola Limestone (3,708-3,7083 ft)

406A 3.0 7.0 2.6 2.5 4.5 .97 2.5 .29 .09

SW1/4SE1/4SW1/4 sec. 16, T. 9 S, R. 16 W, Rooks County

Muncie Creek Shale Member of the lola Limestone (3,293.7-3,294.1 ft)

506MC 10.6 5.7 3.6 1.9 3.2 .75 2.1 .24 .03

Stark Shale Member of the Dennis Limestone (3,362-3,364 ft)

506SA

506SD

506SF

506SG

16.0

16.4

4.0

16.7

5.6

5.2

4.7

5.1

2.3

3.6

2.9

2.7

1.9

1.8

2.2

1.9

4.5

4.4

13

5.2

.69

.61

.61

.56

2.2

2.0

1.9

2.1

.22

.21

.17

.19

1.1

.61

.11

.81

--

B18 Stategic and Critical Minerals, Midcontinent Region, U.S.
Table B7. Selected major and minor elements in Upper Pennsylvanian black shales from the midcontinent-Continued

Sample No. Org. C Al Fe Mg Ca Na K Ti P S

Hushpuckney Shale Member of the Swope Limestone (3,389 .5-3,392 ft)

506HA 

506HB 

506HC

1.1 

2.5 

2.5

6.3 2.7 2.4 6.8 .71 2.6 

6.5 2.6 2.4 4.9 .71 2.7 

6.0 2.5 2.2 7.2 .73 2.5

.24 

.23 

.10

.42 

.61 

2.4

-

Cen. NW1/4NW1/4 sec. 30, T. 30 &, R. 33 W, Haskell County

Stark Shale Member of the Dennis Limestone (4,533-4,535.4 ft)

2A.1-5 

8-9 

10-12 

13-15 

16-19

9.6

10.2 

12.8 

13.6 

14.4

6.1 3.8 1.7 1.9 .79 2.4 

5.0 2.7 1.7 6.2 .63 2.0 

5.4 3.1 1.7 4.0 .67 2.2 

5.3 2.8 1.6 4.1 .67 2.0 

5.9 2.7 1.7 3.3 .68 2.3

.25 

.14 

.21 

.22 

.23

.17 

1.5 

.80 

.80 

.23

-

A-l Holmdan 1, Rawlins County

Stark Shale Member of the Dennis Limestone (interval unknown)

D249932 0.2 6.7 2.4 2.5 6.6 .85 2.6 .29 .39 -

UPPER PENNSYLVANIAN BLACK SHALES FROM OKLAHOMA

Core 1389; sec. 5, T. 28 N., R. 1 W., Kay County (interval unknown)

1389C 

1389E

4.2 

1.8

7.9 7.6 1.3 1.6 .73 2.7 

9.6 4.7 1.4 1.1 .77 3.1

.26 

.29

.05 

.06

5.5 

1.2

Core 508; sec. 1, T. 17 N., R. 51 W., Dewey County (interval unknown)

508B 

508C 

508D 

508E

1.4 

2.9 

2.9 

12.9

7.2 3.7 1.4 6.2 .86 23 

7.7 4.0 1.6 3.6 .83 2.6 

5.9 3.0 1.2 9.9 .61 2.0 

6.1 4.9 1.5 4.2 .58 2.0

.25 

.29 

.21 

.20

.07 

.05 

.22 

.24

1.0 

1.1 

1.0 

3.0

Middle and Upper Pennsylvanian Marine Black Shales B19
Table B8. Selected minor and trace elements in Upper Pennsylvanian black shales from the midcontinent

[Selenium was determined by energy dispersive analysis. Other elements were determined by inductively coupled plasma method. -, not 

determined; <, less than; all in parts per million]

Sample No. As Ba Cd Cr Mo Ni Se Sr U Zn

UPPER PENNSYLVANIAN BLACK SHALES FROM IOWA

Core IBCD (Bedford core); sec. 4, T. 67 N^ R. 34 W., Taylor County

Larsh Shale Member of the Deer Creek Limestone (43-4.9 ft)

A

B

C

<4

<4

<4

20

30

20

140

220

150

11

20

19

310

220

470

520

460

120

420

330

440

85

60

80

72

110

140

74

55

-

1,900

1,100

990

340

720

480

Queen Hill Shale Member of the Lecompton Limestone (102.1-1023 ft)

A 

B 

C

<4 

<4 

<4

<20 

<20 

<20

190

140

270

32

180

92

180

280

180

610

1,000

280

260

400

210

45

55

20

120

110

120

58

60

930

1,800

1,000

1,100

9,700

5,000

Core IHC (Hillsdale/Buffington); sec. 22, T. 72 N., R. 42 W., Mills County

Heebner Shale Member of the Oread Limestone (6.2-6.6 ft)

D249924 <4 50 160 85 320 430 330 85 140 48 1,800 2,400

Eudora Shale Member of the Stanton Limestone (100.2-1003 ft)

D249925 <4 20 150 <4 570 130 680 90 150 81 1,100 40

Quindaro Shale Member of the Wyandotte Limestone (166.1-166.4 ft)

Al

Bl

Cl

<4

<4

<4

30

30

30

310

150

290

<4

<4

<4

190

480

310

840

630

140

340

890

430

110

175

100

110

61

67

1,300

2,300

690

50

50

1,600

Stark Shale Member of the Dennis Limestone (218.2-2183 ft)

<4 <20 300 <4 370 51 140 95 130 64 1,600 40

Core ISC (Stanzel Qy); sec. 5, T. 75 N, R. 29 W., Madison County

Quindaro Shale Member of the Wyandotte Limestone (36.9-37.3 ft)

A2 

B2

<4 

<4

30 

30

270 

160

31 

130

160 

270

270 

750

250 

410

75 

140

130 

110

36 

49

810 

1,500

480 

2,100

Muncie Creek Shale Member of the lola Limestone (56.9-57.3 ft)

D249928 <4 <20 290 <4 400 <4 240 120 1,100 770

Core UCL (Jefferson Qy, lower); sec. 17, T. 77 N., R. 31 W., Adair County

Stark Shale Member of the Dennis Limestone (51.6-52.2 ft)

2A

2B

2C

2D

<4

<4

<4

<4

50

60

40

50

170

160

150

280

130

54

82

35

460

290

390

240

330

170

870

590

410

300

510

300

100

80

115

75

60

70

50

66

1,700

1,300

1,900

1,300

3,700

1,600

2,300

950

Hushpuckney Shale Member of the Swope Limestone (85.3-853 ft)

A 

B

<4 

<4

70 

90

140 

150

170 

140

490 

430

2,000 

640

570 

480

175 

130

80 

100

153 

202

2,500 

2^00

6,200 

4,900

UPPER PENNSYLVANIAN BLACK SHALES FROM KANSAS

SE1/4SE1/4SW1/4 sec. 2, T. 6 N., R. 27 W., Sheridan County

Muncie Creek Shale Member of the lola Limestone (3,708-3,7083 ft)

406A <4 30 260 370 130 150 45 130 48 330 340

SW1/4SE1/4SW1/4 sec. 16, T. 9 S, R. 16 W., Rooks County

Muncie Creek Shale Member of the lola Limestone (3,293.7-3,294.1 ft)

506MC <4 30 180 23 380 130 320 80 130 34 910 490

Stark Shale Member of the Dennis Limestone (3,362-3,364 ft)

506SA

506SD

506SF

506SG

<4

5

<4

5

20

50

70

30

160

150

130

150

32

63

210

88

770

830

150

470

76

150

30

120

310

300

160

320

55

100

45

90

140

150

420

170

54

62

53

300

620

88

1,100

1,200

1,100

8,500

1,900

B20 Stategic and Critical Minerals, Midcontinent Region, U.S.
Table B8. Selected minor and trace elements in Upper Pennsylvanian black shales from the midcontinent-Continued

Sample No. Ag As Ba Cd Cr Mo Ni Se Sr U V Zn

Hushpuckney Shale Member of the Swope Limestone (3,389.5-3,392 ft)

506HA 

506HB 

506HC

<4 

<4 

<4

<20 

<20 

<20

230 <4 480 5 140 <10 200 

170 <4 870 14 180 35 140 

160 <4 990 19 160 20 200

31 

47 

74

160 

190 

310

180 

270 

250

Cen. NW1/4NW1/4 sec. 30. T. 30 S., R. 33 W., Haskell County

Stark Shale Member of the Dennis Limestone (4,533-4,535.4 ft)

2A,l-5 

8-9 

10-12 

13-15 

16-19

<4 

<4 

<4 

6 

5

<20 

<20 

<20 

<20 

<20

150 <4 540 13 290 45 130 

140 6 820 36 270 55 260 

130 7 910 28 310 80 200 

150 35 870 79 280 85 160 

150 17 700 53 320 95 150

22 

31 

30 

54 

41

150 

200 

230 

580 

570

760 

1,300 

960 

970 

590

A-l Holmdan 1, Rawlins County

Stark Shale Member of the Dennis Limestone (interval unknown)

D249932 <4 <20 170 <4 380 <4 110 <10 200 15 88 140

UPPER PENNSYLVANIAN BLACK SHALES FROM OKLAHOMA

Core 1389; sec. 5, T. 28 N., R. 1 W., Kay County (interval unknown)

1389C 

1389E __

3 

5

130 275 <2 240 10 145 45 

20 150 <2 150 <2 115 <10

155 

165

215 

155

290 

240

Core 508; sec. 1, T. 17 N., R. 51 W., Dewey County (interval unknown)

508B 

508C 

508D 

508E

-

<2 

<2 

<2 

9

<10 325 <2 115 <2 85 <10 

10 375 <2 245 2 130 15 

10 215 <2 135 <2 100 <10 

70 210 60 655 80 310 130

455 

255 

590 

230

105 

145 

95 

1,010

245 

300 

260 

1,180

Middle and Upper Pennsylvanian Marine Black Shales B21

Chapter C

Mineralogical and Geochemical Analysis of the 

Metal- and Organic-Rich Grassy Creek 

Shale of the New Albany Group 

(Upper Devonian and Lower Mississippian) in 

Hardin County, Southern Illinois

By GEORGE A. DESBOROUGH

U.S. GEOLOGICAL SURVEY BULLETIN 1989

STRATEGIC AND CRITICAL MINERALS IN THE MIDCONTINENT REGION, 

UNITED STATES

WARREN C. DAY and DIANE E. LANE, Editors
CONTENTS

Abstract Cl 

Introduction Cl 

Methods of study C2 

Mineralogy C2 

Geochemistry C3 

Economic aspects C4 

References cited C4

FIGURES

Cl. Map showing approximate locality for Rose core near Hicks dome C2 

C2-C6. Graphs showing:

C2. Relation of sodium concentration to abundance of albite in Grassy 

Creek Shale C3

C3. Relation of potassium concentration to abundance of potassium feldspar in Grassy Creek Shale C3

C4. Relation of arsenic concentration to abundance of pyrite in Grassy 

Creek Shale C4

C5. Variation in vanadium concentration in Grassy Creek Shale C4

C6. Variations in concentrations of chromium, copper, and nickel in Grassy 

Creek Shale C4

TABLES

Cl. X-ray diffraction intensity data for minerals in drill-core samples from the upper

61 ft of the Upper Devonian and Lower Mississippian New Albany Group C5 

C2. X-ray diffraction peaks used for estimation of relative abundances of minerals in

the New Albany Group C6 

C3. Selected major and minor elements in the uppermost interval of the New Albany

Group east of Hicks dome C7 

C4. Selected minor and trace elements in the uppermost interval of the New Albany

Group east of Hicks dome C9 

C5. Statistical data for selected major, minor, and trace elements in 54 samples from

the upper part of the Grassy Creek Shale of the New Albany Group Cll

II Contents
STRATEGIC AND CRITICAL MINERALS IN THE MIDCONTINENT REGION, UNITED STATES

Mineralogical and Geochemical Analysis of the 

Metal- and Organic-rich Grassy Creek Shale of the 

New Albany Group (Upper Devonian and 

Lower Mississippian) in Hardin County, 

Southern Illinois

By George A. Desborough

Abstract

The mineralogy and geochemistry of continuous core 

samples of the uppermost part of the Upper Devonian and 

Lower Mississippian New Albany Group on the east flank of 

Hicks dome in southeastern Illinois were studied in order to 

place constraints on its mineral content. Fifty-four samples 

from 61 ft of a single core were studied, including the 

Henryville Bed, the Falling Run Bed, and the underlying 

additional parts of the Grassy Creek Shale. Shales in the study 

area have high metal and organic contents because they occur 

in the depocenter of the basin and are thus least diluted by 

detrital material. Thermal alteration of the shale has been high, 

and, therefore, it is past the oil-generation window. Therefore, 

the shale would not yield significant oil by retorting (pyrolysis).

Geochemical data for bulk samples indicate that the 

metal content is low. Therefore, these shales will be of minimal 

economic interest during the next several decades in the 

absence of technological advances in metal recovery from 

metalliferous black shales.

Mineralogical studies show that the shale consists predominantly of illite, quartz, feldspar, and minor pyrite. Dolomite is abundant in the lower part, whereas the upper part is 

essentially free of carbonates.

The observed sodium content in the shales correlates 

strongly (r=0.90, where r is correlation coefficient) with the 

albite peak as measured by x-ray powder diffraction (XRD). 

The potassium content also correlates well with the intensity of 

the potassium feldspar peak (r=0.76). For pyrite, the intensity 

of the py2 (XRD) peak correlates well with both the sulfur 

content (r=0.93) and the iron content (r=0.82). In addition,

Manuscript approved for publication August 5, 1991.

arsenic content correlates with the pyrite (XRD) peak intensity 

(r=0.71).

Cobalt, copper, chromium, nickel, vanadium, strontium, 

zinc, thorium, and lead are highest in concentration in the 

upper 10 ft of the interval studied, whereas arsenic and pyrite 

are highest in the lowest 10 ft of the interval studied. The 

Henryville Bed has the highest concentrations of copper, 

molybdenum, and nickel.

INTRODUCTION

This study was conducted as part of the U.S. Geological Survey Midcontinent Strategic and Critical Minerals 

Project. This report presents the results of mineralogical and 

chemical investigations of the Rose core from the upper 

66 ft of the Grassy Creek Shale of the New Albany Shale 

Group (Upper Devonian and Lower Mississippian) on the 

east side of Hicks dome, in Hardin County, 111. (fig. Cl). 

Stratigraphic nomenclature is that of Cluff and others 

(1981), with the exception that their term "New Albany 

Shale Group" is here changed to "New Albany Group." 

These strata consist of laminated to massive Grassy Creek 

Shale (table Cl) that includes the Henryville Bed at the top 

(1.9 ft thick), the Falling Run Bed (1.7 ft thick), and 

undivided Grassy Creek Shale at the bottom of the core. The 

Henryville Bed is very dark brown to black and massive to 

only weakly laminated. The Falling Run Bed is massive, 

dark-gray-green to green shale that contains carbonate 

fluorapatite. The rest of the Grassy Creek Shale is massive 

to strongly laminated, containing thin (< 2 mm) gray layers

Grassy Creek Shale, Illinois C1
of detrital quartz. Pyrite nodules as much as 3 cm in 

diameter are present at 93 ft.

The purpose of this study was to determine the 

mineralogy and metal content in the most organic-rich part 

of the New Albany Group in an area considered to be near 

the basin depocenter of the Grassy Creek Shale (Cluff and 

others, 1981). Frost and others (1985) reported that, 

compared to other stratigraphic units in the New Albany 

Group, the Grassy Creek Shale has the greatest enrichment 

in organic material and pyrite, and higher than usual 

enrichment in selenium, antimony, vanadium, zinc, and 

silver. Beier and Hayes (1989) studied core from the upper 

part of age-equivalent strata (New Albany Shale) in 

southern Indiana and found that the most metal-rich and 

organic-rich parts were near the top of the black shale

HARDIN COUNTY 

Hicks dome

10 MILES

10 KILOMETERS

Figure Cl . Approximate locality for Rose core near Hicks 

dome, Hardin County, III. Hicks dome outline is outcrop of 

New Albany Group.

interval. For these reasons it was thought that the Devonian 

black shale that would have the greatest potential for metals 

would be the uppermost part of the New Albany Group in 

southern Illinois, where it is thickest and richest in organic 

material. However, the core was drilled for exploration 

purposes to study mineral occurrences unrelated to black 

shales.

Organic petrographic studies show that the New 

Albany Group in the study area has a mean random vitrinite 

reflectance of R = 1.2 (Barrows and others, 1980, p. 68) and, 

thus, indicates organic maturation at the upper limit of oil 

generation due to heating on a regional scale that was 

probably related to the emplacement of the Hicks dome 

intrusive body.

METHODS OF STUDY

The core studied extends from a depth of 88.9 to 

150.2 ft; a carbonatite dike (or sill) of the Hicks dome 

breccia complex occurs at the base of the black shale 

interval that was sampled. Segments of core (broken for 

boxing) were sawed into quarters, and one quarter was 

crushed and pulverized for geochemical and mineralogical 

studies.

The mineralogy of the samples (table Cl) was determined by means of nickel-filtered Cu-I^ radiation at a 

diffractometer scan rate of 2°/min. The same operating 

conditions and x-ray tube were used for all analyses. 

Powdered samples were packed into 2-mm-thick mounts. 

X-ray peak intensities reported were corrected for background. For each mineral, except quartz, the x-ray diffraction maximum was used (table Cl).

Selenium was determined by x-ray fluorescence using 

a cadmium radio-isotope source and an energy-dispersive 

analyzer. The geochemical abundances, except for selenium, were determined by the inductively coupled plasma 

atomic-emission spectroscopy method as described by 

Lichte and others (1987), for which the precision is 1-2 

percent of the relative standard deviation.

MINERALOGY

The very fine grained nature of the Grassy Creek 

Shale (Cluff and others, 1981), in which individual mineral 

grains are mostly less than 10 pin, and laminae of mineral 

grains are commonly only 20 [im to 1 cm thick, precludes 

using polished thin sections for accurate mineral identification. Near the contact with the carbonatite dike there is 

no obvious recrystallization of the black shale, nor is there 

any introduction or mobilization of elements in the black 

shale.

Illite is present in all samples, and it has been shown 

by Cluff and others (1981) to be the most abundant clay 

mineral in the Grassy Creek Shale (table Cl). Kaolinite is a

C2 Strategic and Critical Minerals, Midcontinent Region, U.S.
minor or trace mineral that was detectable in 63 percent of 

the samples. Only 30 percent of the samples have detectable 

chlorite. Albite is present in 89 percent of the samples, but 

is apparently absent in the Henryville Bed (table Cl, 

fig. C2). Potassium feldspar is relatively abundant in all 

samples (table Cl, fig. C3). Calcite was detected in only 

four samples. Dolomite is present in 44 percent of the 

samples and is most abundant in the lower part of the 

interval studied (table Cl). Dolomite is absent in both the 

Henryville Bed and the Falling Run Bed. Apatite was 

detected only in the Falling Run Bed, which is defined as a 

bed containing phosphatic nodules (Cluff and others, 1981); 

the apatite occurs as nodules as much as 3 cm in diameter in 

the core studied. Pyrite is present in all samples, occurring 

as framboids, subhedral to euhedral grains, and nodules 

several centimeters in diameter.

GEOCHEMISTRY

Geochemical data for certain major, minor, and trace 

elements are given in tables C2 and C3. Correlations of 

these data with mineral abundances determined by x-ray 

diffraction techniques were used to determine the most 

likely mineralogical residence of various elements whether 

or not metals occur in concentrations sufficient to be of 

economic interest.

Correlations between element concentrations and 

mineral abundances determined by x-ray diffraction (table 

Cl, figs. C2 and C3) help constrain the occurrence of 

elements of interest. For instance, the absence of correlation 

between vanadium concentrations and illite abundance in 

midcontinent Pennsylvanian black shales demonstrates that 

the vanadium residence is not in illite (Desborough and 

others, this volume). The sodium concentration correlates 

well with the intensity of the albite peak (r=0.90, see

100

90

80

I 70

!< 60

cc

tj 50 

LU 

O 40

830

20

10

EXPLANATION

 Albite

 - - - Sodium

80 90 100 110 120 130 

DEPTH, IN FEET

140 150

Figure C2. Relation of sodium concentration (weight 

percent x100) to abundance of albite (x-ray diffraction peak) 

in Grassy Creek Shale, Hardin County, III.

100

90

80

70

!< 60

g 50

111 

O 40

830

20

10

EXPLANATION

 Potassium 

feldspar

- - - - Potassium

 <? v

I_______I_______I

80 90 100 110 120 130 

DEPTH, IN FEET

140 150

Figure C3. Relation of potassium concentration (weight 

percent x10) to abundance of potassium feldspar (x-ray 

diffraction peak) in Grassy Creek Shale, Hardin County, HI.

fig. C2), and the potassium content correlates fairly well 

with the intensity of the potassium feldspar peak (r=0.76, 

fig. C3). This suggests that most of the sodium is in albite 

and that most of the potassium is in potassium feldspar. For 

pyrite, correlation of the py2 peak intensity (table Cl) with 

sulfur is very good (r=0.93). Correlation of iron content 

with the py2 peak intensity is good (r=0.82). The data 

suggest that some of the arsenic (table C3) is in pyrite: there 

is a positive correlation (r=0.71) between the intensity of the 

pyrite peak (py2) and the arsenic concentration (fig. C4). 

Frost and others (1985) found that arsenic concentrations 

correlated with both pyritic sulfur content (r=0.84) and 

organic content (r=0.73). They also found that uranium, 

nickel, copper, molybdenum, lead, and pyritic sulfur 

correlated with organic carbon. I observe no correlation of 

these elements with any mineral.

The vanadium concentrations are higher in the upper 

part of the core studied than in the lower (fig. C5). Also, the 

highest chromium, copper, and nickel concentrations are 

near the top of the interval studied (fig. C6)

Statistical data for selected major, minor, and trace 

elements are given in table C4 for the purpose of comparison with the summary statistics of Frost and others 

(1985, table 9) for the Grassy Creek Shale and undivided 

Grassy Creek and Sweetland Creek Shales in Illinois. The 

average values for cobalt, chromium, copper, and molybdenum in the present study are essentially the same (within 

15 percent) as those of Frost and others (1985, table 9). The 

average value for lead obtained in the present study is about 

one-half as much as the average found by Frost and others 

(1985). Average values for nickel, selenium, thorium, 

vanadium, and zinc are about two times those of Frost and 

others (1985). This is explained by the fact that the samples 

of the present study were taken from the deepest part of the 

basin, whereas those of Frost and others (1985) were taken 

from many localities basinwide.

Grassy Creek Shale, Illinois C3
25

20

5 15

cc

LU 

O 10

o

O

EXPLANATION

 Pyrite (py2)

- - - - Arsenic

80 90 100 110 120 130 

DEPTH, IN FEET

140 150

Figure C4. Relation of arsenic concentration (parts per 

million xlO) to abundance of pyrite (py2 x-ray diffraction 

peak) in Grassy Creek Shale, Hardin County, III.

500

450

z 400

Z"§ 350

Ei soo 

cccc 

zo. 2 °

zlr

O^ O 150 0-

2 100

50

EXPLANATION

 ---- Chromium

 Copper

 Nickel

80 90 100 110 120 130 

DEPTH, IN FEET

140 150

Figure C6. Variations in concentrations (parts per million) 

of chromium, copper, and nickel in Grassy Creek Shale, 

Hardin County, III.

Frost and others (1985, p. 77) noted that the Grassy 

Creek Shale was the unit of the New Albany Group that had 

the "... greatest enrichment of trace metals and black shale 

indicators: pyritic S, Co, Zn, As, Se, Mo, Sb, Pb, and 

U ..." and "... samples with an unusually high enrichment 

of Se, V, and Zn were from the top 30 feet of the Grassy 

Creek Shale." The present study shows general agreement 

with Frost and others (1985).

Grassy Creek Shale in the study area are too low to be 

considered of economic interest at the present. The most 

metal-rich zones are too thin (<3 ft), and, furthermore, there 

is no known extraction technology for metals such as 

chromium, molybdenum, nickel, selenium, vanadium, and 

zinc in black shales that are thermally altered beyond the oil 

generation window.

ECONOMIC ASPECTS

The average amounts of metals such as Cr (94 ppm, 

or parts per million), Mo (67 ppm), Ni (160 ppm), Se (19 

ppm), V (533), and Zn (392 ppm) in the upper part of the

1,400

1,200

Z

R 1,000 

^ ?s

o- 800

-£ 

Q600

400

200

80

EXPLANATION

 Vanadium

90 100 110 120 130 140 150 

DEPTH, IN FEET

Figure C5. Variation in vanadium concentration (parts per 

million) in Grassy Creek Shale, Hardin County, III.

REFERENCES CITED

Barrows, M.H., Cluff, R.M., and Harvey, R.D., 1980, Organic 

petrography, in Geologic and geochemical studies of the 

New Albany Shale Group (Devonian-Mississippian) in 

Illinois: Illinois State Geological Survey (Final report, U.S. 

Department of Energy Contract DE-AC21-76ET12142), 

183 p.

Beier, J.A., and Hayes, J.M., 1989, Geochemical and isotopic 

evidence for paleoredox conditions during deposition of the 

Devonian-Mississippian New Albany Shale: Geological 

Society of America Bulletin, v. 101, p. 774-782.

Carroll, Dorothy, 1970, Clay minerals A guide to their identification: Geological Society of America Special Paper 126, 

 80 p.

Cluff, R.M., Reinbold, M.L., and Lineback, J.A., 1981, The New 

Albany Shale Group in Illinois: Illinois State Geological 

Survey Circular 518, 83 p.

Frost, J.K., Zierath, D.L., and Shimp, N.F., 1985, Chemical 

composition and geochemistry of the New Albany Shale 

Group (Devonian-Mississippian) in Illinois: Illinois State 

Geological Survey (Supplement to the Final Report, U.S. 

Department of Energy Contract DE-AC21-76ET12142), 

134 p.

Lichte, F.E., Golightly, D.W., and Lamothe, P.J., 1987, 

Inductively coupled plasma-atomic emission spectrometry, 

in Baedecker, P.A., Methods for geochemical analysis: U.S. 

Geological Survey Bulletin 1770, p. B1-B10.

C4 Strategic and Critical Minerals, Midcontinent Region, U.S.
Table C1 . X-ray diffraction intensity data for minerals in drill-core samples from the upper 61 ft of the Upper Devonian and 

Lower Mississippian New Albany Group in Hardin County, III.

[ill, illite; kao, kaolinite; a, albite; k, potassium feldspar; cal, calcite; dol, dolomite; ap, apatite; py2, line of pyrite measured for all samples 

because there are no interferences with other minerals; f, fluorite; gy, gypsum; q2, quartz; chl, chlorite; pyl, line of pyrite that is coincident with 

second strongest line (202) of apatite (line not reported for samples containing detectable apatite); M, major mineral having peak intensity 

greater than 100; , interference with apatite. USGS black shale standard SDO-1 is given for comparison. Query (?) indicates detection is 

questionable; data are reported relative to 100 percent peak intensity for quartz]

Sample interval,

in feet

ill kao a k cal dol ap py2 f gy q2 chl pyl

USGS STANDARD SDO-1

30 20 12 7 0 11 0 15 0 4? M 5 32

GRASSY CREEK SHALE

Henryville Bed

88.9-89.4

89.4-89.9

89.9-90.8

33

35

29

7

5

5

0

0

0

17

22

22

000

000

000

5

11

9

0

0

0

2?

0

3

M

81

M

0

0

3

9

16

16

Falling Run Bed

90.8-91.1

91.1-91.7

27

31

3

3

6

15

20

18

0 0 36

0 0 15

5

3

0

0

0

5

M

78

3

4 -

Grassy Creek Shale, undivided

91.7-91.8

91.8-92.4

92.4-93.5

93.5-93.9

93.9-95.0

95.0-95.2

95.2-96.1

96.1-97.0

97.5-98.2

98.2-99.2

99.2-99.8

99.8-100.1

100.1-101.1

101.1-101.7

101.7-102.2

102.2-102.9

102.9-103.6

104.0-105.2

107.2-108.0

108.0-108.8

108.8-109.2

109.5-110.5

110.5-111.7

111.7-113.0

113.0-113.5

114.0-115.0

115.0-116.0

116.0-117.4

117.5-118.7

118.7-120.1

39

35

33

38

32

25

25

22

28

26

20

18

19

28

42

24

19

23

29

25

35

21

31

26

25

22

31

23

25

31

3

4

4

0

2

0

3

3

5

0

2

3

0

6

5

3

4

2

2

0

0

0

0

0

0

5

4

0

2

0

9

11

13

15

23

13

15

14

13

0

9

0

0

8

10

8

8

9

12

16

16

6

18

14

17

16

19

16

17

18

15

21

33

30

30

25

23

26

29

22

30

44

21

33

30

28

30

22

23

17

20

13

18

16

32

24

22

21

22

21

000

0 32 0

0 46 0

000

000

000

000

000

000

000

000

000

000

000

000

000

000

000

060

000

0 10 0

080

0 18 0

090

000

000

000

000

0 15 0

000

2

5

6

12

13

7

11

8

10

4

12

6

3

8

8

10

7

6

9

6

8

8

9

7

5

5

7

7

5

12

7

4

10

7

0

0

0

0

0

0

6

5

0

0

0

5

10

11

0

0

0

0

0

0

0

0

0

0

0

0

3

0

0

0

0

0

0

0

0

0

0

0

0

0

4

3

0

0

0

0

0

0

0

0

0

0

0

0

0

0

78

87

88

M

M

M

M

M

M

67

84

M

65

M

M

M

M

M

M

M

M

81

M

M

M

M

M

M

M

M

0

0

3

0

0

3

3

0

0

5

0

0

4

2

3

0

0

0

0

0

0

3

0

3

0

3

3

3

0

0

9

7

13

20

18

12

15

14

20

9

26

14

8

20

16

26

14

15

16

11

13

12

13

9

9

10

13

12

11

13

Grassy Creek Shale, Illinois C5
Table C1 . X-ray diffraction intensity data for minerals in drill-core samples from the upper 61 ft of the Upper Devonian and 

Lower Mississippian New Albany Group in Hardin County, Ill.-Continued

Sample interval,

in feet

120.1-121.4

121.4-122.9

122.9-123.8

124.0-125.2

125.2-126.6

126.6-127.8

127.8-129.2

129.2-130.5

130.5-132.1

132.9-133.0

133.0-134.0

134.0-134.9

134.9-135.8

136.0-138.7

138.7-141.2

141.2-143.5

143.5-144.8

1453-147.2

147.2-150.2

Table C2. X-ray

County, III.

Mineral

Iron-rich chlorite

Iffite .........

Gypsum ......

Kaolinite .....

Albite .......

Potassium .....

feldspar

Calcite .......

Dolomite .....

Apatite .......

1Pyrite-pyl ....

2Pyrite-py2 ....

Quartz3 .........

Fluorite ..... .

ill

28

34

30

33

26

19

23

26

17

7

13

15

21

37

33

26

23

26

17

diffraction

kao

5

4

0

0

0

0

0

3

0

3

0

3

0

5

0

4

3

3

3

peaks

hkl

001

001

020

001 WJ.

002

040,

002

104 -l.\/"T

104 XV T

112

002

021 \J**±.

100 AW

220

a

25

20

16

20

19

22

20

15

19

28

15

25

13

21

20

18

25

37

48

used

k cal

24 0

23 0

20 8

20 7

19 0

38 0

33 0

15 0

14 37

10 19

41 0

30 0

16 0

25 0

21 0

15 0

15 0

19 0

16 0

dol

28

25

0

9

19

8

7

5

M

M

51

34

10

26

40

34

29

42

60

for estimation of relative

d-value used

(A)

14.1-14.2

10.2

7.56

7.15

3.186-3.198

3.220-3.250

3.03

2.88

2.79

2.71

242 Ar.f At

4.26

1.93

ap

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

py2

6

7

13

7

5

16

9

12

11

10

17

25

16

17

18

16

12

12

9

f

0

0

0

0

0

5

0

3

0

0

6

5

0

0

0

0

0

0

5

abundances of minerals

gy

0

0

0

0

0

0

0

3

0

0

0

0

0

0

0

0

0

0

0

q2 chl

M 0

M 3

M 0

M 0

61 0

73 0

82 0

73 0

34 0

20 0

58 0

53 0

77 0

83 0

87 0

M 0

M 0

80 0

87 0

in the New Albany Group,

Approximate

29' (CuKa)

6.2

8.7

11.7

12.4

27.90-28.00

27.45-27.70

295 4*J*+J

30.%

3205 +ji**\j-*j

33.16

37.15

20.85

47.06

Lowest percentage

identifiable

(Carroll, 1970,

table 12)

10

5

Not reported

5

5

5

5

1

Not reported

Not reported

Not reported

Not reported

Not reported

pyi

12

14

20

18

15

20

17

19

17

13

28

42

27

31

37

27

29

26

21

Hardin

'This line of pyrite is coincident with the second strongest line (202) of apatite. This line is not reported for samples containing 

detectable apatite.

*This line was measured for all samples because there are no interferences with other minerals. 

3Second strongest peak of quartz.

C6 Strategic and Critical Minerals, Midcontinent Region, U.S.
Table C3. Selected major and minor elements in the uppermost interval of the New Albany Group east 

of Hicks dome, Hardin County, III.

[Sulfur was analyzed with a Leco IR-32 determinator; other elements determined by the inductively coupled plasma 

method; N/A, not analyzed; all values in weight percent]

Sample

No.

Al Ca Fe K Mg Na P Ti S F

USGS STANDARD SDO-1

6.49 1.1 6.53 2.78 0.93 0.28 0.05 0.02 5.35 N/A

GRASSY CREEK SHALE

Henryville Bed

R89.0

R89.4

R89.9

63

6.24

6.07

036

.13

33

3.76

.41

2.99

339 .48 .09

3.64 .47 .10

3.71 .42 .15

.06

.06

.17

.31

.28

.29

N/A

N/A

N/A

N/A

N/A

N/A

Falling Run Bed

R90.8

R91.1

533

7.21

6.83

2.41

1.58

2.07

3.51 30 .23

4.00 .53 .20

3.46

1.12

.21

.25

N/A

N/A

N/A

N/A

Grassy Creek Shale, undivided

R91.7

R91.8

R92.4

R93.5

R93.9

R95.0

R95.2

R96.1

R97.5

R98.2

R99.2

R99.8

R100.1

R101.1

R101.7

R102.2

R102.9

R104.0

R107.5

R108.0

R108.8

R109.5

R110.5

R111.7

R113.0

R114.0

R115.0

R116.0

R117.5

R118.7

7.70

7.40

7.02

6.74

6.05

5.90

5.46

5.62

539

5.88

5.46

5.51

5.98

5.91

6.44

5.19

4.93

4.73

5.14

4.94

5.03

4.63

5.24

5.30

5.25

5.42

5.05

5.40

5.60

6.09

.84

1.50

2.08

.45

.73

31

39

.19

.25

33

.36

.14

.12

.13

.10

.21

.46

36

.41

33

.68

.67

.64

.46

.19

.21

.32

.52

.41

.28

1.60

2.86

2.83

3.09

2.44

2.07

2.64

1.95

3.01

1.97

4.26

1.89

2.12

2.67

2.42

2.92

2.03

2.80

2.63

2.12

2.16

3.60

232

1.98

1.94

1.78

2.20

2.03

2.14

236

4.46 .54 .25

4.41 .88 33

5.06 .81 34

4.69 .47 37

4.07 .40 .40

3.% 39 .42

3.41 .48 33

3.76 37 .27

3.82 38 .24

4.14 38 .27

4.48 .22 .18

4.83 .21 .13

4.21 34 .12

4.29 31 .12

435 38 .11

3.73 .24 .15

3.69 .20 .19

3.02 33 .22

3.27 .47 30

3.02 .44 .29

2.97 .57 .29

2.74 .54 .26

3.13 .52 33

3.24 .49 .34

3.64 31 34

3.60 33 32

3.03 .45 32

334 .52 38

3.45 .49 .40

3.79 .45 .46

.27

.11

.10

.08

.31

.11

.09

.08

.04

.09

.07

.06

.05

.06

.05

.05

.04

.03

.03

.03

.04

.03

.03

.03

.04

.03

.03

.03

.03

.03

37

32

.31

31

.27

.27

.23

.25

.24

.26

.23

.24

.28

.27

.30

.23

.22

.22

.23

.22

.22

.21

.24

.24

.27

.27

.21

.22

.22

.22

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

Grassy Creek Shale, Illinois C7
Table C3. Selected major and minor elements in the uppermost interval of the New Albany Group east 

of Hicks dome, Hardin County, Ill.-Continued

Sample 

No.

R120.1

R121.4

R122.9

R124.0

R125.2

R126.6

R127.8

R129.2

R130.5

R132.1

R133.0

R134.0

R134.9

R136.0

R138.7

R141.2

R143.5

R1453

R147.2

Al

6.46

5.70

6.16

6.26

5.79

6.06

6.25

6.65

4.85

2.5

6.20

6.50

5.07

6.02

5.53

5.03

5.61

5.49

5.01

Ca

1.28

1.10

.47

.83

.89

.40

.74

.42

834

14.7

2.16

1.47

.75

1.30

1.52

1.67

1.28

2.00

2.24

Fe

2.77

2.67

4.22

2.85

3.45

4.67

3.67

4.29

436

334

4.74

6.37

4.51

439

4.51

4.92

3.42

3.99

3.83

K

4.04

3.44

3.61

3.71

3.49

4.93

4.51

4.11

2.77

1.43

5.53

4.67

2.99

3.62

3.27

2.82

3.15

2.78

2.12

Mg

.88

.79

.53

.62

.69

33

.75

.71

4.45

7.84

1.11

.84

.58

.87

.97

.91

.81

1.10

1.09

Na

.57

.44

.44

.52

.55

.63

.68

.61

.65

.83

.58

.74

.41

.53

.50

.54

.70

1.18

1.61

P

.03

.03

.06

.08

.05

.04

.03

.04

.07

.04

.04

.04

.03

.04

.03

.03

.03

.03

.05

Ti

.22

.20

.23

.27

32

.28

.28

30

.20

.10

.26

.26

.20

.23

.22

.20

.22

.21

.20

S

N/A

N/A

N/A

N/A

N/A

4.5

2.7

3.5

33

2.2

4.4

6.5

4.5

4.2

4.1

4.9

3.1

3.5

33

F

N/A

N/A

N/A

N/A

N/A

.03

.05

.08

.08

.03

.05

.11

.06

.07

.05

.12

.06

.05

.04

C8 Strategic and Critical Minerals, Midcontinent Region, U.S.
Table C4. Selected minor and trace elements in the uppermost interval of the New Albany Group east of Hicks 

dome, Hardin County, III.

[Selenium was determined with an energy-dispersive analyzer; other elements were determined by the inductively coupled plasma 

method; <, less than; all data are in parts per million]

Sample

No.

As Ba Cd Co Cr Cu Mo Ni Pb Se Sr Th V Zn

USGS STANDARD SDO-1

69 397 79 47 66 60 134 100 28 3-7 75 10 160 64

GRASSY CREEK SHALE

Henryville Bed

R89.0

R89.4

R89.9

80

80

70

447

518

558

51

25

9

13

20

15

114

116

134

228 184 304

115 242 458

109 110 279

31

35

30

10

<10

<10

97

137

176

14

10

14

959

1,220

1,170

744

1,570

642

Falling Run Bed

R90.8

R91.1

30

50

3%

413

3

<2

14

21

118

92

78 31 169

45 13 97

19

24

<10

<10

715

275

59

36

404

306

261

306

Grassy Creek Shale, undivided

R91.7

R91.8

R92.4

R93.5

R93.9

R95.0

R95>2

R96.1

R97.5

R98.2

R99.2

R99.8

R100.1

R101.1

R101.7

R102.2

R102.9

R104.0

R107.5

R108.0

R108.8

R109.5

R110.5

R111.7

R113.0

R114.0

R115.0

R116.0

R117.5

R118.7

50

60

60

90

60

50

50

40

60

40

80

50

60

60

60

60

50

70

80

60

70

70

60

50

50

50

60

50

40

40

409

635

420

371

424

372

429

324

311

329

317

310

328

315

339

295

278

296

321

350

308

269

311

314

293

311

309

322

343

333

<2

<2

<2

17

13

8

14

7

9

11

14

38

11

6

2

3

3

12

4

8

6

9

<2

3

<2

11

5

3

<2

<2

30

67

48

20

13

12

11

11

10

10

10

11

12

11

12

11

12

13

15

12

13

13

12

12

14

14

14

12

13

12

78

%

110

151

144

139

129

130

132

141

112

120

149

122

129

88

83

76

82

83

85

74

82

84

82

81

77

81

82

91

45 8 95

51 2 127

65 9 117

144 73 267

132 52 205

128 46 189

123 55 188

113 28 166

115 38 184

115 25 168

113 32 163

126 51 198

118 36 178

110 34 151

105 32 146

88 42 133

85 54 145

91 88 175

% 102 1%

89 83 156

92 92 177

88 98 172

81 59 146

83 64 147

88 95 177

95 94 163

81 83 152

72 59 132

71 51 122

76 32 115

21

21

22

36

26

22

25

22

36

24

40

29

24

28

27

34

30

31

29

19

25

32

26

24

22

16

18

17

14

13

<10

<10

<10

20

30

35

40

35

45

35

<10

70

55

40

25

10

35

35

25

30

75

25

30

50

55

50

50

35

20

15

158

126

202

123

159

105

%

78

80

119

244

147

118

103

97

121

169

210

164

125

95

82

90

81

78

181

116

137

151

137

40

22

41

25

21

18

12

16

27

23

42

58

22

22

20

23

38

15

19

12

7

9

9

13

37

17

9

10

11

11

330

275

465

1,310

1,010

873

1,070

681

897

705

605

665

852

584

583

438

478

743

866

881

890

802

642

657

570

664

586

441

335

291

269

106

182

894

723

481

663

445

438

743

901

2,320

614

448

236

250

27

823

234

420

410

702

92

233

170

1,100

449

287

138

262

Grassy Creek Shale, Illinois C9
Table C4. Selected minor and trace elements in the uppermost interval of the New Albany Group east of Hicks 

dome, Hardin County, Ill-Continued

Sample

No.

R120.1

R121.4

R122.9

R124.0

R125.2

R126.6

R127.8

R129.2

R130.5

R132.1

R133.0

R134.0

R134.9

R136.0

R138.7

R141.2

R143.5

R1453

R147.2

Table C5.

As

40

40

70

60

80

100

70

80

70

50

90

110

100

80

80

100

70

80

70

Ba Cd

335 <2

319 2

352 <2

349 <2

335 <2

291 3

309 3

366 3

265 <2

115 <2

249 <2

303 2

280 <2

376 <2

353 <2

376 <2

479 3

299 <2

189 <2

Co Cr

14 88

15 78

16 91

19 92

31 82

37 86

31 86

37 91

37 62

23 33

42 75

55 86

31 65

31 73

29 66

29 61

31 67

30 65

30 65

Statistical data for selected major, minor,

trace elements in 54

Grassy Creek Shale

County, III.

Cu

79

77

85

84

80

79

71

79

69

36

70

82

65

61

58

56

59

56

58

and

Mo

28

54

55

61

80

80

75

83

74

39

71

98

78

93

94

98

84

86

79

samples from the upper part of the

Ni

93

120

152

167

197

222

193

217

121

67

141

169

89

97

88

82

90

83

98

Element

of the New Albany Group in Hardin

Pb

15

16

23

18

20

24

18

17

14

10

23

17

29

15

22

32

24

31

47

uses

standard

SDO-1

Se Sr

<10 151

<10 128

<10 139

<10 165

10 164

<10 266

10 218

<10 151

<10 440

<10 580

<10 299

<10 193

<10 172

<10 114

<10 179

<10 114

<10 121

<10 117

15 159

Average

Th

10

9

7

10

9

18

14

9

10

11

18

19

10

12

12

12

18

15

26

Sample

standard

deviation

V

202

271

632

582

382

259

284

319

172

86

158

195

139

163

154

138

146

136

138

Min.

Zn

120

307

115

198

204

298

172

254

49

10

82

95

42

64

39

48

169

49

23

Max.

Weight percent

[Selenium was determined with an energy-dispersive analyzer; other 

elements were determined by the inductively coupled plasma 

method; min., lowest value or lowest limit of detectability; max.,

highest value reported;

million]

<, less than; all data are in parts per

Al 

Ca 

Fe

K

Mg

Na

P

Ti

6.49 

1.1 

6.53

339

0.93

.28

.05

31

5.7 

1.25 

3.0

3.7

0.76

.41

.14

.25

0.8 

2.4 

1.0

0.7

1.1

.27

.48

.04

2.6 

0.1 

1.6

1.4

0.2

.09

.03

.10

7.7 

14.7 

6.4

5.5

7.8

1.61

3.46

37

Parts per million

As

Ba

Cd

Co

Cr

Cu

Mo

Ni

Pb

Se

Sr

Th

V

Zn

69

397

79

47

66

60

134

100

28

3-7

75

10

160

64

64

344

6

21

94

88

67

160

24

19

170

19

533

392

18

82

9

13

26

31

40

65

7

21

115

12

321

412

30

115

<2

10

33

36

2

67

10

<10

78

7

86

10

110

635

51

67

151

228

242

458

47

75

715

59

1310

2,320

C10 Strategic and Critical Minerals, Midcontinent Region, U.S.

. GOVERNMENT PRINTING OFFICE: 1992-673-049/46022