GEOLOGICAL SURVEY CIRCULAR 869 

Mineral-Resource Appraisal of the 

Rolla 1° X 2° Quadrangle, Missouri, 

As of September 1980-

A Nontechnical Summary 

Mineral-Resource Appraisal of the 

Rolla 1 ° X 2° Quadrangle, Missouri, 

As of September 1980-

A Nontechnical Summary 

By Walden P. Pratt 

GEOLOGICAL SURVEY CIRCULAR 869 

Prepared in cooperation with the 

Missouri Department of Natural Resources, 

Division of Geology and Land Survey 

1983 
United States Department of the Interior 

JAMES G. WATT, Secretary 

Geological Survey 

Dallas L. Peck, Director 

Free on application to Branch of Distribution, U.S. Geological Survey, 604 South Pickett Street, Alexandria, VA 22304 
CONTENTS 

Page 

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 

Methodology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 

Resource potential of the Rolla quadrangle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 

Reference cited . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 

ILLUSTRATIONS 

• ·=uRES 1-3. Maps of: 

Page 

1. Rolla 1°X2° quadrangle, Missouri, showing principal towns, highways, and base-metal mining districts . 2 

2. Areas of very high potential for base-metal deposits and high-grade iron ores in the Rolla quadrangle . . 3 

3. Areas of high potential for small barite deposits, tin-tungsten veins, and veins of rare-earth minerals and thorium 

in the Rolla quadrangle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 

III 

Minerai-Resource Appraisal of the Rolla l 0 X2° Quadrangle, 

Missouri, as of September 1980-

A Nontechnical Summary 

By Walden P. Pratt 

INTRODUCTION 

For several years the U.S. Geological Survey 

has been conducting research on methods of mineral-resource appraisal for large rectangular map 

areas or quadrangles measuring 1 degree (69 

miles) north-south and 2 degrees east-west (90-120 

miles, depending on the latitude). One such area 

that has been under study is the Rolla 1 ox 2° quadrangle, southeast Missouri (fig. 1). The Rolla quadrangle was selected for this purpose because it includes most of the Southeast Missouri lead mining 

district and parts of the barite and iron-ore mining 

areas. In recent years Missouri has ranked first 

among the 50 States in mine production of lead 

(used principally in automobile batteries and 

gasoline additives), second in zinc (used to galvanize iron and in several alloys), second in barite 

(used in drilling muds for oil and gas wells), and 

sixth in silver (used in the photographic and electronic industries as well as for sterling and plateware). Nearly all this mineral production came 

from the Rolla quadrangle, which still contains the 

largest known lead reserves in the world plus important resources of zinc, barite, silver, copper, 

iron, and the strategic ferrous metals nickel and 

cobalt. 

The important base-metal ores of the Southeast 

Missouri district occur in geologic formations that 

extend in the subsurface for hundreds of miles 

north, west, and northeast through the midcontinental United States; hence it was reasoned that 

the Rolla quadrangle should serve as a testing 

ground for appraisal methods that might later be 

used throughout the midcontinent region, and in 

other regions where similar geologic environments 

1 

suggest a potential for similar kinds of mineral deposits. 

The mineral-resource study of the Rolla quadrangle was a cooperative project of the U.S. 

Geological Survey and the Missouri Division of 

Geology and Land Survey. The project involved 

about 19 professional man-years of effort, contributed by 24 geologists and other scientists of both 

organizations during the period 1975-1980. The 

full mineral-resource appraisal of the Rolla quadrangle, including all the technical data and interpretations, has been released as U.S. Geological 

Survey Open-File Report 81-518 (see reference at 

end of paper). This Circular is a nontechnical summary of the methodology and results of the appraisal, written mainly for non-geologists. 

The date of September 1980 is an essential part 

of the title of the Rolla mineral-resource appraisal. 

A mineral resource is defined as a natural concentration of elements in such form that a usable commodity can be extracted from it. Critical factors 

in the appraisal of a potential resource are its 

economic viability-whether or not it can be extracted at a profit- and the certainty of its existence. With changes in economic and legal conditions, development of new technologies of mining 

and mineral processing, improved understanding 

and theories of ore genesis, more detailed knowledge of the geology of the area, and development 

of new prospecting methods, an undeveloped or 

undiscovered mineral deposit may become a resource almost overnight. Thus any appraisal of resource potential is time-dependent, being based on 

economic and legal conditions, scientific and technologic knowledge, and data available, at a given 
QUADRANGLE LOCATION 

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FIGURE 1. Rolla 1 ox 2° quadrangle, Missouri, showing principal towns, highways, and base-metal mining districts. 

time. There is no such thing as a "final" appraisal 

of the resource potential of any area. Therefore 

it is emphasized that this report summarizes the 

resource potential of the Rolla quadrangle as appraised in September 1980. 

METHODOLOGY 

Prospectors have roamed the lower 48 States 

for generations, and most important mineral deposits that occur at the surface have long since 

been found. Therefore the task in appraising the 

resource potential of an area such as the Rolla 

1 ox 2° quadrangle is to evaluate the likelihood that 

undiscovered mineral deposits of economic value 

may lie at depths of tens to thousands of feet beneath the surface. Many such deposits have already been found, through many years of 

painstaking and costly exploration programs conducted by the mining industry. The following 

questions are addressed by the resource appraisal 

of the Rolla quadrangle: is there a reasonable 

likelihood that other such deposits exist, and if 

2 

so, how great is the probability, where are they, 

and what kinds of minerals do they contain? 

Although no two mineral deposits are exactly 

alike, all deposits can be grouped according to the 

kinds of minerals they contain, the form in which 

they occur, and especially, the particular kinds of 

rocks and geologic structures they are associated 

with. Diamonds, for example, invariably are 

formed in a distinctive rock called kimberlite, and 

the informed prospector doesn't bother to look for 

diamonds unless he has good reason to think there 

is some kimberlite in the vicinity. Most other minerals are not so exclusive in their associations, but 

the fact remains that the world over, certain kinds 

of mineral deposits are associated with certain 

geologic environments, or critical combinations of 

rock type, age, and structure. This relationship 

is the principal basis for our resource appraisal 

of the Rolla quadrangle, and our method consists 

of six steps. 

First, we compiled surface and subsurface 

maps, using surface observations, analyses of the 

mineral and chemical composition of outcrop and 
drill-hole samples, and geophysical maps showing 

the magnetic intensity and specific gravity of 

deeply buried "basement" rocks, to show the various geologic environments known or inferred to 

exist in the quadrangle. (In addition to compilation 

of existing data, this step required new reconnaissance geologic mapping of approximately 65 percent of the quadrangle, aeromagnetic surveying of 

the west half of the quadrangle, integration of 

data on rock composition from logs of some 1,000 

drill holes, and spectrographic and chemical 

analyses of about 11,000 individual samples from 

62 drill holes.) 

Second, we determined all the types of mineral 

deposits that could reasonably be expected to 

occur in these geologic environments, on the basis 

of worldwide associations as well as known mineral occurrences in the Rolla quadrangle. 

Third, we developed descriptive "models" of 

each deposit type-summary descriptions of the 

size, shape, tonnage, and mineral composition of 

a typical deposit, as well as the form, composition, 

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structure, and any peculiar geological characteristics of the rocks the deposit is associated with. 

The models also include geochemical or geophysical "signatures" of the deposits that may be detected by chemical analysis of overlying or nearby 

rocks, or by surface or airborne measurements of 

the Earth's magnetic and gravity fields. 

Fourth,- from each model we derived sets of 

"recognition criteria"-distinctive geological, 

geochemical, or geophysical features that are so 

commonly associated with the deposits that they 

may be considered either essential or favorable for 

the occurrence of such deposits. (In the example 

given above, kimberlite is the principal essential 

recognition criterion for the occurrence of diamonds. There is no guarantee that every kimberlite body will contain diamonds, but we can safely 

assume that any diamonds to be found will be 

found in or close to kimberlites-or in gravels that 

have been eroded from kimberlites.) 

Fifth, for each model, we systematically 

examined all the available data on the Rolla quadFIGURE 2. Areas of very high potential for base-metal deposits (A, B, and C) and for high-grade iron ores (D, E, and F) 

in the Rolla quadrangle. 

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FIGURE 3. Areas of high potential for small barite deposits (A) and tin-tungsten veins (B), and areas that may have a potential 

for veins of rare-earth minerals and thorium (C, D, and E) in the Rolla quadrangle. 

rangle, including much new data collected for this 

study, for the presence or absence of each of the 

recognition criteria. 

Sixth, for each model, by plotting the areal distribution of the recognition criteria on a map of 

the quadrangle and evaluating their relative importance, we divided the quadrangle into areas in 

which various combinations of criteria indicate a 

high or low favorability for the occurrence of that 

type of deposit. In a few cases, our subjective 

evaluation has permitted us to rank favorable 

areas relative to each other. 

RESOURCE POTENTIAL OF THE 

ROLLA QUADRANGLE 

Applying the method just described, we considered the recognition criteria for 17 different 

types of mineral deposits that might reasonably 

be expected to occur in the Rolla quadrangle. Our 

principal conclusions were as follows: 

4 

A very high potential exists for two distinct 

types of deposits. The first of these is "basemetal" deposits--containing lead, zinc, and copper, as well as silver and the ferrous metals nickel 

and cobalt-like the deposits that were mined in 

the past in the Old Lead Belt and FredericktownMine La Motte area and are currently being mined 

in the Viburnum Trend (see fig. 1). Three specific 

areas in the quadrangle contain such favorable 

combinations of the recognition criteria for this 

type of deposit that we believe there is a very 

high probability that each area contains at least 

one major deposit, at unknown depths ranging 

from 600 to 2, 000 feet; these areas are in 

Washington County north of county highway C 

(fig. 2, area A), southeast from about 8 miles west 

of Ellington to the southern boundary of the quadrangle (area B), and southwest from Marquand to 

beyond Greenville (area C). Moreover, we estimate that if each of these postulated deposits is 

similar to the nearby deposits of the same type, 

then the metals in the ground in these deposits 
would have a combined total value on the order 

of 3 billion dollars, using metal prices of September 30, 1980. The cobalt that may be present 

in these deposits would be of special importance 

to the United States, because nearly all of this 

critically important metal is currently imported 

from politically unstable regions; the resource here 

could amount to as much as 30-55 million pounds, 

on the order of 2-3 years' consumption. (Even 

now, the Madison mine near Fredericktown is 

being reopened to recover its cobalt and nickel resources.) 

The other type of deposit for which a very high 

potential exists is large to moderate-sized underground deposits of high-grade iron ores of the type 

that have been mined at Pilot Knob and are known 

to exist at Boss and Camels Hump (see fig. 1). 

Three areas in the quadrangle have a very high 

potential for deposits of this type: these areas are 

northeast of Lake Spring (fig. 2, area D), between 

Potosi and Belgrade (area E), and northeast of 

Bonne Terre (area F). 

In addition, a large area in the north-central 

part of the quadrangle has a high potential for 

small barite deposits in the clayey subsoil near the 

surface, which though individually small could be 

cumulatively large (fig. 3, area A); an irregular 

area- extending north and west from Fredericktown has a high potential for small vein deposits of tin and tungsten near the surface (area 

B); and much of the quadrangle may have a high 

potential for uranium deposits in granitic rocks at 

depths of 1,000 feet or more beneath the surface. 

Three areas contain occurrences of kimberlitic 

rocks (fig. 3, areas C, D, and E), and may have 

a potential for deeply buried veins of rare-earth 

minerals and thorium, as well as diamonds, but 

the information on these areas is too scanty for 

us to say how great this potential is. Likewise, 

an apparent but unappraisable potential exists in 

several areas for uranium deposits in sandstones, 

and for deeply buried copper-nickel-cobalt-chromium-platinum deposits. Small deposits of manganese, iron, and copper minerals may exist in several areas of the quadrangle but would not be of 

commercial interest in the near future, either because they would be too small or because their 

physical properties would not be suited to presentday ore-processing requirements. 

Important resources of industrial, nonmetallic 

minerals, notably cement-grade limestone, agricultural limestone, construction stone, and industrial 

sand, probably occur in the quadrangle but are 

only now being evaluated as a part of the Rolla 

,1°X2° study. 

REFERENCE CITED 

5 

Pratt, W. P., editor, 1981, Metallic mineral-resource potential 

of the Rolla 1°X2° quadrangle, Missouri, as appraised in 

September 1980: U.S. Geological Survey Open-File Report 

81-518, 82 p. 

U.S. GOVERNMENT PRINTING OFFICE: 676-041-1983