i. 887

GEOLOGICAL SURVEY CIRCULAR 887

Mineral Resource Assessment of the 

Iron River 1 ° X 2° Quadrangle, 

Michigan and Wisconsin

Prepared in cooperation with Geological Survey Division, Michigan 

Department of Natural Resources, and Wisconsin Geological and 

Natural History Survey
Mineral Resource Assessment of the 

Iron River 1 ° X 2° Quadrangle, 

Michigan and Wisconsin

By W. F. Cannon

GEOLOGICAL SURVEY CIRCULAR 887

Prepared in cooperation with Geological Survey Division, Michigan 

Department of Natural Resources, and Wisconsin Geological and 

Natural History Survey

An assessment of the mineral resources and of areas judged

to have varying degrees of favorability for undiscovered mineral

deposits in the Iron River 1° X 2° quadrangle

1983
United States Department of the Interior

JAMES G. WATT, Secretary

Geological Survey

Dallas L. Peck, Director

Library off Congress Cataloging in Publication Data

Cannon, William F.

Mineral resource assessment of the Iron River 1° X 2° quadrangle, Michigan and Wisconsin.

(Geological Survey circular ; 887)

Bibliography: p.

Supt. of Docs, no.: I 19.4/2:887

1. Mines and mineral resources Michigan. 2. Mines and mineral resources Wisconsin. I. Michigan.

Geological Survey Division. II. Wisconsin Geological and Natural History Survey. III. Title. IV. Series.

QE75.C5 no. 887 557.3s [553'.09774'975] 83-600055

[TN24.M5]

 _____________________________________________________________________

Free on application to Distribution Branch, Text Products Section, 

U. S. Geological Survey, 604 South Pickett Street, Alexandria, MA 22304
CONTENTS

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The Iron River CUSMAP Project 

Surficial geologic map 

Structural and tectonic map 

RrtiicnifM" ffrsivitv m$m _____ -_,..___, _. .-

Aeromagnetic map 

Metamorphic map 

Identified resources 

Reserves 

Hypothetical resources 

Speculative resources 

Assessment of identified resources 

Assessment of undiscovered resources 

Classification of resources in the Iron River quadrangle - 

Identified resources 

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Classification of resources in the Iron River quadrangle 

 Continued 

Undiscovered resources 

Unfavorable areas 

Mineral resources of the Iron River quadrangle 

Identified resources 

Copper 

Iron 

Hypothetical resources 

Copper 

Iron 

Volcanogenic massive sulfide deposits 

Shale and iron-formation hosted deposits 

Deposits associated with mafic intrusive rocks 

Silver-bearing shale 

Diamond 

Conclusions 

Bibliography 

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ILLUSTRATIONS

FIGURE 1. Classification of resource categories 

2. Generalized mineral resource map of the Iron River 1° x 2° quadrangle

Page 

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TABLES

TABLE 1. Mineral resources of the Iron River 1 ° x 2° quadrangle 10

HI
Mineral Resource Assessment of the Iron River 

1° X 2° Quadrangle, Michigan and Wisconsin

By W. F. Cannon

ABSTRACT

The Iron River 1° x 2° quadrangle contains identified resources 

of copper and iron. Copper-rich shale beds in the north part of the 

quadrangle contain 12.2 billion pounds (5.5 billion kilograms) of 

copper in well-studied deposits including 9.2 billion pounds (4.2 billion kilograms) that are economically minable by 1980 standards. At 

least several billion pounds of copper probably exist in other parts of 

the same shale beds, but not enough data are available to measure 

the amount.

A small amount, about 250 million pounds (113 million kilograms), of native copper is known to remain in one abandoned 

mine, and additional but unknown amounts remain in other abandoned mines.

About 13.25 billion tons (12.02 billion metric tons) of banded 

iron-formation averaging roughly 30 percent iron are known within 

500 feet (152.4 meters) of the surface in the Gogebic, Marquette, and 

Iron River-Crystal Falls districts. A small percentage of that might 

someday be minable as taconite, but none is now believed to be 

economic. Some higher grade iron concentrations exist in the same 

iron-formations. Such material was the basis of former mining of 

iron in the region, but a poor market for such ore and depletion of 

many deposits have led to the decline of iron mining in the 

quadrangle. Iron mines of the quadrangle were not being worked in 

1980.

Many parts of the quadrangle contain belts of favorable host 

rocks for mineral deposits. Although deposits are not known in 

these belts, undiscovered deposits of copper, zinc, lead, silver, 

uranium, phosphate, nickel, chromium, platinum, gold, and 

diamonds could exist.

INTRODUCTION

The Iron River 1° x 2° quadrangle is bounded by 

lats 46° and 47° N. and longs 88° and 90° W. and includes several major mining districts that have produced large amounts of copper and iron. At present, 

only the White Pine mine, where copper is recovered 

from an extensive unit of copper-rich shale, remains 

active. In the past, a large number of mines, which are

now abandoned, produced native copper. Parts of 

three major iron-mining districts the Marquette 

Range, the Gogebic Range, and the Iron RiverCrystal Falls district are in the quadrangle. All have 

produced large amounts of iron ore but are now inactive. (Mining is still being done in the Marquette 

Range east of the Iron River quadrangle.) Large quantities of mineralized rock remain in the ground, mostly 

in subeconomic form, but changes in price, mining 

and processing technology, or demand could revitalize 

mining.

In addition, many parts of the quadrangle are 

judged to be favorable ground for undiscovered mineral deposits. Much exploration by the mining industry was carried out during the 1970's, and a high 

level of exploration activity is likely to continue into 

the 1980's. Such exploration could expectably lead to 

the discovery of additional deposits or districts.

Although present mineral production is relatively 

small, about 150 million pounds (68 million kilograms) or less of copper per year, the potential for 

future mineral production is great. The mineral potential of the quadrangle should enter into economic and 

land-use planning for the region and into considerations of future mineral supplies for the United States.

This report summarizes a mineral resource appraisal 

of the quadrangle carried out between 1977 and 1980 

by a team of geoscientists from the U.S. Geological 

Survey (USGS) as part of the Conterminous United 

States Mineral Assessment Program (CUSMAP). 

During that period, much new information was gathered, and older data were compiled and evaluated. All 

data were then considered to estimate the known 

mineral resources of the quadrangle and the potential 

for the existence of undiscovered resources.
The report summarizes the subactivities within the 

project, discusses the philosophy and techniques of 

resource assessment, and summarizes findings and 

conclusions about the mineral resources of the quadrangle. More detailed technical information is presented in the Iron River CUSMAP folio (USGS Maps 

I-1360-A to N).

ACKNOWLEDGMENTS

This resource assessment was made possible by the 

acquisition of a wealth of data and by the contributions from the Iron River project participants. These 

contributors are Henry Alminas, Maurice Brock, 

David Frishman, J. A. Kalliokoski, Elizabeth King, 

John Klasner, Richard Ojakangas, Warren Peterson, 

Bruce Smith, and Karen Wier. Anita Fenichel assisted 

in compiling much of the data and in drafting maps. 

Most of the annotated bibliographic entries were compiled by Alice Weis and Martina Johnson.

THE IRON RIVER CUSMAP PROJECT

Between 1977 and 1980, a team of geoscientists 

from the USGS constructed the detailed data base 

from which the mineral resource assessment of the 

Iron River quadrangle has been made. This team of 

experts in a number of scientific fields has made possible the acquisition and evaluation of a wide variety 

of data. A folio of maps presents this information in 

technical detail. Each component of the project is described briefly below.

MINERAL RESOURCE MAP

Map I-1360-A (Cannon, 1983a) shows the distribution of identified resources and areas of potential for 

undiscovered resources, The resource map was constructed by compiling information on known mineral 

deposits and by interpreting geologic, geochemical, 

and geophysical data to predict areas where resources 

are likely to occur.

BEDROCK GEOLOGIC MAP

The bedrock geology of the quadrangle is presented 

in map I-1360-B (Cannon, 1983b). The map was 

made largely from data gathered during detailed mapping by many geologists during the past 40 years. Two 

years were devoted to mapping areas that had not been 

mapped previously and to resolving the structure and 

correlation of some rock units. Interpretation of geophysical data also played a major role in understanding the bedrock geology in many parts of the quadrangle that are covered by sand, gravel, and other 

surficial deposits.

SURFICIAL GEOLOGIC MAP

The distribution of various types of unconsolidated 

deposits, mostly glacial deposits, is presented in 

map I-1360-C (Peterson, 1983). At the start of the 

project, little information was available on a regional 

scale, therefore, 3 years of field studies combined with 

an analysis of landforms as revealed by aerial photographs and topographic maps were needed to produce 

an adequately detailed map. The surficial geologic 

map is of great use in determining whether geochemical data and some types of geophysical data are related to surficial deposits only or possibly are caused 

by mineralization in underlying bedrock.

STRUCTURAL AND TECTONIC MAP

Additional information on the bedrock of the quadrangle is given in map I-1360-D (Cannon, 1983c). The 

structural and tectonic map provides information on 

the age, mode of origin, and subsequent history of 

rock units. Such information is useful in predicting 

rock units in which mineral deposits might have 

formed. As with the bedrock geologic map, much information was compiled from previous studies, but 

some new information was gathered during the 

CUSMAP study.

BOUGUER GRAVITY MAP

Map I-1360-E (Klasner and Jones, 1983) shows 

variations in Bouguer gravity values, identifies gravity 

anomalies, and includes interpretations of many of 

them. The CUSMAP project involved compiling data 

from previous surveys and performing additional 

surveys to provide a uniform coverage of the quadrangle and to adjust various older surveys to ,a common base value. The gravity map is useful in recognizing and tracing some broad tectonic features, in 

providing information on the density of rocks in the
subsurface, and in placing constraints on estimates of 

the depth of geologic features.

AEROMAGNETIC MAP

A map showing variations in magnetic attraction in 

the quadrangle (map I-1360-F) was compiled by King 

(1983). Data were from previous airborne surveys by 

the USGS in Michigan (Zietz and Kirby, 1971) and 

from John Karl of the University of Wisconsin at 

Oshkosh for Wisconsin. The Wisconsin data were 

compiled and published by Zietz and others (1977). 

For the current map, the Wisconsin data were recontoured by computer to add detail not shown in 

previous maps and were adjusted to match the 

Michigan data. Aeromagnetic data are invaluable in 

the Iron River quadrangle because they enable the 

tracing of numerous iron-rich magnetic units through 

areas where bedrock is not exposed and are an important source of information in making geologic maps. 

In addition, magnetic data can directly indicate some 

resources, such as iron-formations of possible economic value.

METAMORPHIC MAP

A map showing zones of metarnorphic intensity of 

various ages was published as map I-1360-G (Wier, 

1983). Information was obtained by previous studies 

and by the microscopic examination of many new rock 

samples to determine their mineralogic makeup. The 

metarnorphic pattern is believed to control the 

distribution of some types of ore deposits, and the 

refinements and detail added by this study to the 

understanding of the metarnorphic pattern of the 

quadrangle have resulted in the definition of some 

belts of resource potential.

GEOCHEMICAL MAPS

Maps I-1360-H to N (Alminas and others, 1983a, 

b, c; Hoffman and others, 1983a, b; Hopkins and 

others, 1983a, b) present the results of an extensive 

survey of the trace-element content of soils. A total of 

3,156 B-horizon soil samples (about 1 sample per 

2 mi2) were collected and analyzed spectrographicaUy. 

The distribution and amounts of several important 

metals are shown on the maps along with interpretations of the distribution patterns of these elements.

The variations of metal content in the soils reflect both 

regional trends in bedrock composition and more local 

variations, possibly related to mineralized areas in the 

underlying bedrock. An interpretation of the geochemical data has led to the identification of several 

areas where undiscovered mineral deposits might exist.

ELECTROMAGNETIC STUDIES

Airborne electromagnetic surveys were performed 

in parts of the quadrangle where such data are essential to a mineral resource appraisal. Results have been 

published in USGS Open-File Report 80-297 (Heran 

and Smith, 1980). Electromagnetic surveys identify 

units of rock that are electrically conductive. Information from the surveys is useful for mapping such 

conductive units in areas where bedrock is not exposed 

and also for more directly indicating the presence of 

some types of mineral deposits that are electrically 

conductive.

URANIUM RESOURCE STUDIES

Uranium resources were not a direct concern of the 

CUSMAP program. Concurrent studies were carried 

out, however, by Maurice Brock, J. A. Kalliokoski, 

Richard Ojakangas, and David Frishman of the 

USGS, funded in part by the National Uranium Resource Evaluation program of the Department of 

Energy. Information and advice provided by these 

geologists have been incorporated into the overall 

resource evaluation of the Iron River quadrangle.

MINERAL RESOURCE TERMINOLOGY

Mineral resources are naturally occurring concentrations of materials that are useful to man and that 

can be economically extracted now or potentially in 

the future. Resources, in their broadest sense, include 

all such existing concentrations, whether or not they 

have yet been discovered. Mineral resources can be 

broadly classified, therefore, into identified resources 

(those that have been discovered) and undiscovered 

resources (those that reasonably may exist but that 

have not yet been found). Identified resources are further subdivided into reserves (material that is presently 

profitable to mine) and subeconomic resources 

(material that requires either some increase in price or
improved mining or processing technology to become 

economically minable).

Undiscovered resources are subdivided into hypothetical resources (material yet to be found in known 

mining or mineralized districts) and speculative 

resources (deposits in yet unrecognized districts or yet 

unrecognized types of deposits). The classification of 

mineral resources is discussed in detail in USGS Circular 831 (U.S. Bureau of Mines and U.S. Geological 

Survey, 1980). A simplified version of that classification system is used here (fig. 1), and the definition of 

categories as they apply to the Iron River quadrangle 

is given below.

IDENTIFIED RESOURCES

Identified resources are concentrations of elements 

known to exist in specific locations. Information on 

their existence and nature is derived from direct 

observations of mineralized rock at the Earth's surface, in drill holes, or in mine workings. In general, 

enough information exists to make at least semiquantitative estimates of the tonnage and grade of mineralized rock.

RESERVES

A reserve is an identified resource that has been 

thoroughly measured and tested and that is known 

with reasonable certainty to be economically exploitable by current technology and under current 

economic conditions. The copper-rich shale at the 

White Pine orebody is the only material in the Iron 

River quadrangle classed as a reserve in this report.

SUBECONOMIC RESOURCES

A subeconomic resource is that portion of identified 

resources that is not economically exploitable at present. Future increases in price or cost savings from improved mining or processing technology may convert 

subeconomic material to the reserve category.

HYPOTHETICAL RESOURCES

Hypothetical resources are concentrations of 

elements that can reasonably be inferred to exist in 

known mining or mineralized districts or extensions of

those districts but that have not yet been found. In the 

Iron River quadrangle, for instance, hypothetical 

resources include deposits of native copper that might 

exist but have not yet been discovered in or near the 

abandoned mining district near Greenland and 

Winona. Future exploration may find some of these 

deposits and convert them to the identified-resource 

category.

SPECULATIVE RESOURCES

Speculative resources are undiscovered concentrations of elements whose existence is believed possible on the basis of broad geologic reasoning but for 

which there is no direct indication of their existence. 

No deposits of the elements are known in the immediate vicinity. Exploration of belts deemed likely to 

contain speculative resources may discover deposits of 

such materials and thereby convert them to identified 

or hypothetical resources. In the Iron River quadrangle, speculative resources include massive sulfide 

deposits of copper, zinc, and lead that are not yet 

known to exist but that are considered possible 

because the geology of parts of the quadrangle is very 

similar to the geology of other areas that contain 

massive sulfide deposits.

MINERAL RESOURCE ASSESSMENT TECHNIQUES

Mineral resource assessment is the quantification 

and estimation of the amount and nature of potentially useful minerals and the identificaton of areas where 

resources exist or may exist. Assessment is based on 

data from many sources, including geologic mapping, 

geochemical and geophysical surveys, studies of oreforming processes, and the distribution patterns of ore 

deposits and their size and grade in well-explored mining districts.

The objective of the Iron River CUSMAP project 

has been to assemble the best possible and the most 

up-to-date data base on which to make a resource 

assessment. Such data, however, are never complete 

and commonly are not totally diagnostic of the presence or lack of mineralization. Any resource appraisal 

is a state-of-the-art estimate and is subject to revision 

and revaluation as more data are obtained and as a 

better understanding of ore-forming geologic processes is achieved. The assessment presented here is 

based on our knowledge in 1980.
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IDENTIFIED RESOURCES

Reserves

Subeconomic 

resources

UNDISCOVERED RESOURCES

 .

Hypothetical 

resources

Speculative 

resources

Increasing degree of geologic assurance

 < 

FIGURE 1. Classification of resource categories as used in this report. Modified from U.S. Bureau of Mines and U.S.

Geological Survey (1980).

Judgment is an important factor, especially in estimating undiscovered resources, and somewhat different assessments probably would be made by different 

individuals using the same data.

In short, a mineral resource assessment must be 

viewed as an estimate. The accuracy of the estimate 

reflects the quality and amount of data available and 

the degree of understanding of the geologic occurrence 

of ore deposits and the processes that formed them. 

Future exploration and research probably will provide 

new data and insights that will allow improved estimates to be made.

In the Iron River quadrangle, identified resources 

include the copper-bearing shale in and around the 

White Pine orebody, native copper in and near the 

Greenland and Winona mining districts, and iron in 

banded iron-formation in the Gogebic, Marquette, 

and Iron River-Crystal Falls districts. All areas of 

identified resources either have had past mining or 

have been thoroughly tested by mining company drilling programs. Those companies generally have made 

much information available for use in evaluation of 

the resources.

ASSESSMENT OF IDENTIFIED RESOURCES

The assessment of identified resources is relatively 

straightforward. It is based on data directly indicating 

the tonnage, grade, and location of mineralized rock. 

Calculations and estimates of tonnage and grade can 

be made from available data, and the degree of certainty of the assessment commonly can be expressed in 

quantitative or qualitative terms.

ASSESSMENT OF UNDISCOVERED RESOURCES

The assessment of undiscovered resources is an 

estimation generally based on an analogy between the 

geologic setting of well-known deposits or districts 

throughout the world and the geologic setting of the 

area being assessed. As suggested and portrayed on 

the resource map that accompanies this report, undiscovered resources are probably restricted to certain 

belts or zones. Furthermore, only those zones at or
near enough to the Earth's surface in areas that contain deposits that are likely to be discovered are 

shown. Hence, zones having a potential for undiscovered resources might be viewed as areas where mineral 

exploration is most likely to occur and where discoveries might be made. As such, the assessment is a 

prediction of future events mineral exploration and 

possible discovery of deposits that might occur. As a 

prediction, it is subject to uncertainty and error but 

should be considered in planning.

Mineral deposits can be grouped into genetic types 

by placing together all deposits that have formed as a 

result of similar processes, regardless of their location. 

For each type of deposit, a genetic model can be 

developed to describe the process or set of processes 

that operated in the geologic past to form the deposit. 

A set of features recognizable in rocks and deposits 

caused by those processes can be defined. Such processes commonly operated over an area larger than that 

within the ore deposit and therefore have recognizable 

features that provide a larger target for mineral exploration than the deposit itself. Recognition of the 

features indicative of ore-forming processes may lead 

to the supposition that an orebody could exist nearby, 

even though it may not be observable at the surface.

Furthermore, ore-forming processes commonly 

take place in a broader geologic framework. For instance, processes that may form one genetic type of 

ore deposit may occur only in volcanic regions, 

whereas processes that form a second type may occur 

only along marine shorelines. The presence and recognition of rocks formed in such widespread environments provide a regional framework for resource 

assessment.

As an example of how such reasoning leads to a 

resource assessment, let us examine a specific case. 

Massive sulfide deposits are ores of copper, zinc, lead, 

and various byproducts. Such ores are common in 

many parts of the world; thorough study of them on a 

worldwide basis reveals striking similarities in the way 

that they formed and in the types of rocks that commonly surround them.

It is generally agreed that many massive sulfide 

deposits form on the sea floor when material crystallizes from fluids emitted by submarine hot springs in 

areas of volcanic activity. Such deposits commonly are 

interlayered with submarine volcanic and sedimentary 

rocks near ancient volcanic vents. The vent areas are 

recognized by characteristic textures preserved in the 

rocks.

No massive sulfide deposits are known in the Iron 

River quadrangle, but some have recently been discovered as little as 20 miles (32 kilometers) south of the

quadrangle. To determine if undiscovered massive 

sulfide deposits might exist in the Iron River quadrangle, one first looks for areas that contain submarine volcanic rocks because massive sulfides might 

have formed in the general environment where such 

rocks formed. Submarine volcanic rocks are found in 

several belts in the south half of the quadrangle, and 

these belts are judged to have at least broad favorability for the occurrence of massive sulfides.

Each volcanic belt is then examined in more detail 

to determine if areas within it can be identified as having been near volcanic vents. If such vent areas can be 

identified, their potential is considered to be even 

higher than that of the volcanic belts in general, 

because rocks within these areas have formed not only 

in a generally favorable setting but also in the specific 

part of that setting where massive sulfides typically 

have formed elsewhere in the world. Within identified 

vent areas, further examination might reveal features 

directly indicative of ore-forming processes, or 

geochemical or geophysical measurements may suggest that ore is buried beneath the surface. In some 

cases, mineralized rock might be directly observed, but 

such is not likely to be the case in the Iron River quadrangle because most bedrock is covered by a veneer of 

glacially transported sand and gravel.

By using such evidence and reasoning, various parts 

of the quadrangle can be classified as being broadly 

favorable for mineral occurrence (class C areas of this 

report). Parts of some class C areas are given additional importance because rocks within them are 

known to have formed in specific environments where 

ore might have formed (class B areas). Parts of some 

class B areas are further identified as having experienced potentially ore-forming processes (class A 

areas). (See section on "Undiscovered Resources.")

The ability to classify areas in this manner is limited 

by the amount of geologic information on the area 

and by the detail known and the assurance about the 

mode of origin of a genetic type of deposit.

In many parts of the Iron River quadrangle, knowledge of the bedrock is not detailed because of the 

cover of sand and gravel. Hence, the information required to define class A and class B areas commonly is 

lacking, and most areas of undiscovered resources can 

be identified only as class C. Likewise, incomplete 

understanding of the mode of origin of some genetic 

types of deposits does not allow a definition of criteria 

specific enough to differentiate class A or class B areas 

from the general belts of class C favorability. As a 

result, many favorable belts in the Iron River quadrangle are classified only as class C. Within these belts, 

the lack of class A or class B zones in the present
assessment may reflect the lack of information more 

than the absence of mineralization.

CLASSIFICATION OF RESOURCES IN THE 

IRON RIVER QUADRANGLE

The Iron River quadrangle has been zoned into 

seven categories of resource potential, as shown in 

figure 2.

UNFAVORABLE AREAS

Unfavorable areas are those for which no strong indications of economic minerals occur either directly or 

by an analogy with known deposits elsewhere. Unfavorable areas contain types of rocks in which few, if 

any, important ore deposits occur anywhere in the 

world. No area, however, can be considered totally 

unfavorable. Additional knowledge, discovery of new 

classes of deposits, or future needs for minerals not 

currently in demand could cause areas now considered 

unfavorable to be reclassified eventually as favorable.

IDENTIFIED RESOURCES

Identified resources are known deposits whose location can be shown on a map and for which some information on size and grade exists. Three categories of 

identified resources are used in this report:

1. Reserves. Known concentrations of materials 

economically exploitable in 1980.

2. Outcrop belts of mineralized strata. Areas in 

which continuously or discontinuously mineralized rock is exposed or. exists in the shallow 

subsurface.

3. Subsurface mineralized rock. Areas in which 

mineralized rock is known to exist underground 

but is overlain by unmineralized rock. These 

areas are, in general, the subsurface extensions of 

outcrop belts of mineralized rocks.

FAVORABLE AREAS

Favorable areas are those where some indication, 

either direct or indirect, of undiscovered mineral 

deposits is known. Favorable areas are here subdivided into three categories.

Class C areas are those areas for which geologic 

evidence indicates a general environmental setting 

where mineral deposits could occur, but no direct 

evidence of mineralization is known.

Class B areas are those areas where the contained 

rocks represent the specific parts of the generally 

favorable environment where mineral deposits could 

have formed and, hence, have a higher favorability 

than class C areas.

Class A areas, the most favorable areas, are areas 

where actual mineralizing processes are known to have 

occurred. Whether those processes formed ore anywhere is not necessarily known.

UNDISCOVERED RESOURCES

Undiscovered resources are deposits likely to exist 

but not yet discovered. They, of course, cannot be 

shown on a map. Rather, areas can be shown for 

which varying degrees of favorability for the discovery 

of such deposits can be inferred. The zones shown in 

figure 2 are belts in which potentially mineralized rock 

is at or very near the surface and in which contained 

deposits could be found by standard exploration techniques. Such potentially mineralized rocks generally 

extend into the subsurface away from their outcrop 

belts, but these subsurface extensions are not shown in 

figure 2. Although the rocks in the subsurface may be 

as likely to be mineralized as those at the surface, 

deposits that might exist at deep levels are not likely to 

be discovered in the near future. Areas are broadly 

classified as favorable and unfavorable.

MINERAL RESOURCES OF THE 

IRON RIVER QUADRANGLE

Figure 2 shows areas of the Iron River quadrangle 

where resources are known to exist or thought likely to 

exist, and table 1 summarizes the resources of the 

quadrangle. The resources are discussed separately in 

identified, hypothetical, and speculative categories.

IDENTIFIED RESOURCES

COPPER

Zones Cui through Cus contain identified copper 

resources. Zone Cui is the area underlain by the 

reserves of the White Pine mine. The reserves, for the 

most part, are in the deep subsurface. The material
TABLE 1. Mineral resources of the Iron River I°x2° quadrangle

Reserves

Copper: 

White Pine orebody 9.2 billion pounds (4.2 billion kilograms) sulfide and native

copper.

Snbeconomic identified resources 

Copper: 

Presque Isle deposit 2.7 billion pounds (1.2 billion kilograms) native and sulfide

copper.

Caledonia mine 250 million pounds (113 million kilograms) native copper. 

Extensions of mineralized bed at White Pine Probably at least several billion

pounds sulfide and native copper. 

Iron: 

Banded iron-formation within 500 feet (152.4 meters) of the surface containing an

unknown percentage of potential taconite bodies. 

Marquette range 1.5 billion tons (1.4 billion tonnes) iron-formation. 

Gogebic range 10 billion tons (9 billion tonnes) iron-formation. 

Iron River-Crystal Falls 1.75 billion tons (1.59 billion tonnes) iron-formation. 

Hypothetical resources (not quantified)

Copper: Native copper in extensions of Greenland and Winona districts. 

Iron: High-grade iron ore in Marquette, Gogebic, and Iron River-Crystal Falls

districts.

Speculative resources

Copper, zinc, lead, silver, gold, platinum, chromium, nickel, cobalt, uranium, 

phosphate, and diamonds could possibly exist in many belts of favorable host rocks 

in the quadrangle.

classified as reserves has an average grade of 1.2 percent copper, a cutoff grade of 1.0 percent copper, and 

a minimum mining height of the mineralized layer of 

7.5 feet (2.3 meters). The deposit is a gently dipping 

layer of copper-rich shale extending from the surface 

to considerable depth, the deepest parts are toward the 

east. The deposit contains 360 million tons (327 million tonnes) of ore and about 9.2 billion pounds (4.2 

billion kilograms) of copper. Copper is contained in 

both sulfide minerals and native copper. Small quantities of silver are also in the ore. Part of the silver is 

recovered as a separate product during refining.

Zone Cu2 is the belt along which the copper-bearing 

shale is at or near the surface. Although it is generally 

mineralized, it is not economic because it has lower 

grade, is in thinner beds, or is more difficult to mine 

than the material that constitutes the White Pine 

reserve.

Zone Cu3 consists of areas where the copper-rich 

shale is known from drilling to exist in the subsurface. 

None is now economic because of low grade, thin 

beds, or mining problems including great depth. An 

area peripheral to the White Pine reserve is probably 

close to being economic. The material in the Presque 

Isle deposit, including belts Cu2 and Cu3 , is also close 

to being economic. The Presque Isle deposit is estimated to contain 95 million tons (86 million tonnes) of 

ore at an average grade of 1.27 percent copper, for a 

total of about 2.7 billion pounds (1.2 billion kilograms) of copper (Wilband, 1978). The remaining areas 

of Cu3 are conservatively estimated to contain at least 

several billion pounds of copper.

Zone Cu4 contains volcanic rocks (basalt) that are 

mineralized with native copper. Many inactive mines 

are in the area. An unknown amount of mineralized 

rock of subeconomic grades is still in the ground at 

some mines, and additional mineralized rock may yet 

be found in the belt. At the Caledonia mine, about 

11.5 million tons (10.4 million tonnes) of rock having 

an average grade of 1.1 percent copper is known to remain in the ground (Wilband, 1978). The discontinuously mineralized rock of Cu4 forms a thick slab inclined northward so that it continues in the subsurface 

north of the outcrop belt.

Zone Cu5 is the extension of known mineralized 

rock at depth from Cu4 . Its northern limit is defined 

approximately by the limit of data from mine workings and drilling, but mineralization may extend 

downward and northward beyond the deepest data 

points.

IRON

Very large quantities of iron-rich rocks exist in the 

quadrangle. All those of potential resource importance are banded iron-formations. Production of ore 

between 1872 and 1978 totaled about 210 million tons 

(191 million tonnes), mostly from the Iron RiverCrystal Falls district. All of that production was of 

relatively high grade ore (generally 50-60 percent 

iron), which occurred as irregular bodies within lower 

grade iron-formation having about 30 percent iron. 

Since the 1950's, the production of iron in the United 

States has shifted away from the use of natural highgrade ores to pelletized iron concentrates produced 

from iron-formations containing about 30 percent 

iron, commonly called taconite. As a consequence, the 

market for high-grade ores has greatly diminished, 

and exploration for new deposits has virtually ceased 

in the area.

Although most of the iron-formation in the Iron 

River quadrangle does contain 30 percent iron or 

more, none now is commercially workable as taconite. 

Various problems, including thinness of ironformation layers, steep dips, and large amounts of 

waste rock above and interlayered with the taconite, 

make it difficult to mine profitably large tonnages of 

ore from open pits, as taconite must now be mined. In 

addition, the mineralogic complexity of much of the 

iron-formation makes most of it untreatable by current metallurgical concentrating processes.

Zones Fd through Fe7 contain identified resources 

of iron. The iron-resource potential of these zones is 

shown in figure 2 and described briefly below.

8
Areas in which iron-formation exists in the subsurface are of little short-term resource importance. 

Although they could contain undiscovered deposits of 

high-grade ore, the present poor market for such ores 

make it unlikely that subsurface iron deposits will be 

explored for and found in the foreseeable future. 

Some of the material could be used as taconite but 

would not be commercially minable unless mining 

technology were improved so that underground mining became economically competitive with open-pit 

mining.

Such areas could have some resource importance 

sometime in the 21st century if near-surface iron 

deposits now being exploited elsewhere become 

depleted and if improved mining and metallurgical 

technology permit their mining and processing.

The two areas having the best potential for taconite 

are probably zones Fd and Fe2 in the western part of 

the Marquette Range. Both areas contain substantial 

amounts of iron-formation very similar to that now 

being mined at the Republic mine, which is only about 

1 mile (1.6 kilometers) east of the quadrangle.

Zone Fd is the outcrop belt of iron-formation in the 

western Marquette Range. Some high-grade ore has 

been produced in the past. Parts of the formation may 

be amenable to treatment as taconite. About 0.75 billion tons (0.68 billion tonnes) of iron-formation are 

within 500 feet (152.4 meters) of the surface. About 

250,000 tons (227,000 tonnes) of that contain a mineralogic makeup that may be treatable by existing 

concentration processes. The deposits of the western 

Marquette Range are probably not economic now 

because of the thinness of iron-formation layers and 

the relatively large amounts of waste rock that would 

have to be moved to recover the iron-formation.

Zone Fe2 is a second outcrop belt of iron-formation 

having some taconite potential in the western Marquette Range. The tonnages of available rocks are 

about the same as those for zone Fd, and development of the area faces the same problems.

Zone Fe3 is the outcrop belt of iron-formation in the 

Gogebic Range. The area has had some past production of high-grade ore. Some high-grade ore may remain to be found. The area contains about 10 billion 

tons (9 billion tonnes) of iron-formation within 500 

feet (152.4 meters) of the surface. Some of that 

material might be useful as taconite in the future if 

metallurgical improvements allow treatment of the 

mineralogically complex iron-formation.

Zone Fe4 is the outcrop belt of iron-formation in the 

Iron River-Crystal Falls district. The area has had a 

large production, about 210 million tons (191 million 

tonnes), of high-grade ore. James and others (1968)

estimated that about 50 million tons (45 million 

tonnes) of identified ore remain in the ground and 

that about 90 million tons (82 million tonnes) of 

undiscovered ore exist. About 1.75 billion tons (1.59 

billion tonnes) of iron-formation are within 500 feet 

(152.4 meters) of the surface (James and others, 1968), 

but this material has very little taconite potential 

because of mining problems and unsuitable 

mineralogy.

Zone Fes is the subsurface extension of the ironformation of the Gogebic Range projected to about a 

1-mile (1.6-kilometer) depth. The iron-formation has 

some potential for high-grade ores and very limited 

short-term potential as taconite.

Zone Fe6 is the subsurface extension of the ironformation of the Marquette Range to a depth of about 

1 mile (1.6 kilometers). The iron-formation contains 

some potential resources of high-grade ore and, largely because of depth, has very small potential as a 

resource of taconite.

Zone Fe7 is the subsurface extension of the ironformation of the Iron River-Crystal Falls district to a 

depth of about 1 mile (1.6 kilometers). The material 

probably contains undiscovered deposits of high-grade 

ore but has very limited taconite potential because of 

depth and unsuitable mineralogic form.

HYPOTHETICAL RESOURCES

Hypothetical resources are undiscovered deposits in 

known mineral districts, as shown in figure 2, that are 

restricted to parts of the native copper district and the 

iron-mining districts.

COPPER

Zone Cu6 in figure 2 is the extension along the 

geologic trend of the same rocks that are mineralized 

in belts Cu4 and Cu5 , but only minor (subeconomic) 

mineralization is known. A high potential for undiscovered native copper and perhaps sulfide copper is 

indicated by strong similarities in nearly all details between these rocks and the mineralized rocks in zones 

Cu4 and Cus. Areas of subeconomic mineralization 

are widespread. A high copper content of soils overlying these rocks, especially in the western part of the 

quadrangle, is another favorable sign.

Zone Cu7 contains volcanic rocks that are in many 

ways similar to those in zones Cu4 and Cus but that 

differ in some important details relating principally to
90° 00'

46°00'

0 10 15 20 25 MILES

0 5 10 15 20 25 30 35 KILOMETERS 

FIGURE 2. Generalized mineral-resource map of the Iron River I°x2° quadrangle, Michigan ar

10
88°00'

EXPLANATION

IDENTIFIED RESOURCES 

Areas underlain by reserves

Areas where iron-formations are at or near the surface

Areas where copper-mineralized rocks are at or near the surface

Subsurface extensions of mineralized rocks. For iron-formations a 1-mile 

(2.6-km) depth cutoff was chosen although units can be inferred 

confidently to continue to greater depth

UNDISCOVERED RESOURCES 

Areas with class A favorability

Areas with class 6 favorability

Areas with class C favorability

Unconformity near which unconformity-type uranium deposits might 

occur. Tick-marks are on side of unconformity where older rocks are 

found

Unconformity near which uraniferous phosphate deposits might be found. 

Tick-marks are on side of unconformity where deposits are probable

Ss-i, Fe3, Identifying symbols for specific resource-potential areas. See text for 

and so on details

Wisconsin. Modified from Cannon (1983a). Base from U.S. Geological Survey, 1958 (1:250,000).

11
composition of the rocks. No substantial copper mineralization is known. The existence of undiscovered 

native copper deposits is possible but seems less likely 

here than it is in zone Cu6 .

is ranked class A because it shows geophysical 

anomalies and contains favorable rock types and also 

subeconomic copper and zinc mineralization.

IRON

Undiscovered deposits of iron ore could exist in any 

of zones Fe, through Fe7 , which are all within or are 

extensions of past mining districts. Such ores are of 

limited importance in the short term and are not likely 

to be explored for in the foreseeable future.

SPECULATIVE RESOURCES

Speculative resources are those that possibly exist 

but that, if found, would be a new type of deposit for 

the region. Several genetic types of speculative 

resources are discussed here. They are the ones judged 

most likely to occur. Other types, not discussed, could 

also occur but, at present, are judged either to have insufficient potential to enter into near-term resource 

considerations or to have not yet been recognized as 

possible resources.

VOLCANOGENIC MASSIVE SULFIDE DEPOSITS

Volcanogenic massive sulfide deposits occur in submarine volcanic rocks and generally near centers of 

volcanic activity. Massive sulfides are generally polymetallic ores that may be mined for copper, lead, zinc, 

silver, and gold. Areas designated Msi in figure 2 are 

zones where ancient submarine volcanic rocks are at 

the bedrock surface and are considered favorable for 

massive sulfides. In most areas, however, the bedrock 

is so poorly exposed that few details of the volcanic 

rocks are known; the belts are defined as class C areas 

and cannot be further subdivided.

Zone Ms2 is a thick unit of submarine volcanic 

rocks that is considered to be a class B area because it 

appears to have formed near a volcanic center and, in 

addition, because it causes several distinctive geophysical anomalies (electromagnetic conductors) that could 

result from massive sulfide deposits in the subsurface.

Zone Ms3 is a belt of submarine volcanic rocks 

about which few details are known, but that is ranked 

class B because geophysical anomalies there could be 

caused by massive sulfide deposits in the subsurface.

Zone Ms4 is a small belt west of Lake Gogebic that

SEDIMENT-HOSTED SULFIDE DEPOSITS

Several types of sediment-hosted sulfide deposits 

are possible in the quadrangle and could contain ores 

of copper, zinc, lead, silver, or gold.

CARBONATE-SHALE HOSTED DEPOSITS

About 30 miles (48 kilometers) east of the 

quadrangle, near Marquette, Midi., a large subeconomic copper sulfide deposit, estimated to contain 1 

billion tons (0.9 billion tonnes) of mineralized rock 

(Wilband, 1978), occurs in shale beds in a generally 

dolomitic rock unit. Extensions of the dolomite unit 

are known in several parts of the quadrangle. Areas 

containing the dolomite are ranked class C and shown 

as zones Ssi on the map. Zone Ss2 is ranked class B 

because geophysical anomalies indicate that subsurface rocks contain either extensive shale beds within 

the dolomite or possibly sulfide-rich beds. Zone Ss3 is 

a small area ranked class A because it contains an outcrop of mineralized bedrock. Copper sulfide minerals 

occur in quartzite beds that are interlayered with 

dolomite. Grades are locally as high as 1 percent copper (Cannon, 1980).

SHALE AND IRON-FORMATION HOSTED DEPOSITS

Several areas contain shale and interbeds of ironformation, zones Ss4 in figure 2. Many of these areas 

are poorly known because of the scarcity of bedrock 

exposures but are judged to be potential hosts for 

sulfide deposits of copper, zinc, and lead. Some lowgrade mineralization (generally less than 0.1 percent 

copper plus zinc) is known locally, and undocumented 

verbal reports from mining companies indicate discoveries of subeconomic sulfide deposits. Some 

carbonate-hosted deposits such as those of zones Ssi 

are also possible within the Ss4 zones.

VOLCANIC-SEDIMENT ASSOCIATION

Massive and disseminated sulfide deposits 

sometimes occur at the fringes of submarine volcanic

12
zones where the volanic rocks are interlayered with 

submarine sedimentary rocks. Zone Sss is assigned 

class C favorability because it contains interlayered 

volcanic rocks, shale, graywacke, and iron-formation. 

No direct signs of mineralization are known. Zone Ss* 

is given class A favorability. It contains rocks similar 

to those in zone Sss but, in addition, is known to contain sulfide-rich rock units that have subeconomic 

concentrations of copper and zinc.

the fringes of iron-ore bodies in the Sherwood and 

James mines (James and others, 1968). These deposits 

are of small size and subeconomic grade. Consequently, the belts in which the iron ores of the district 

occur (zones Fe4 and Fe7) are considered to have class 

C favorability for uranium.

URANIFEROUS PHOSPHATE DEPOSITS

DEPOSITS ASSOCIATED WITH MAFIC INTRUSIVE ROCKS

Igneous rocks that have undergone strong chemical 

fractionation as they crystallized from a molten state 

to solid state may contain concentrations of copper, 

nickel, cobalt, chromium, or platinum. Such strongly 

fractionated mafic rocks exist in a few places in the 

quadrangle, but no mineralization is known in them. 

Zones Mi, are areas where such rocks are known. 

Zones Mi2 contain rocks formed in that part of the 

mafic fractionation sequence in which mineral 

deposits are most likely to occur. They are assigned 

class B favorability.

UNCONFORMITY URANIUM DEPOSITS

During the 1970's, some very rich uranium deposits, 

some of which also contain nickel and gold, were discovered along ancient erosion surfaces (unconformities) in Australia and Canada. The unconformity extending across the Iron River quadrangle from near 

the northeast corner to Wakefield has many features 

in common with those uranium-bearing unconformities. In the late 1970's, many mining companies explored for uranium along the unconformity in the 

quadrangle. A broad belt parallel to and including the 

unconformity Uiii is given class C favorability because 

of similarities between the geology there and that of 

mineralized unconformities. A zone east of Lake 

Gogebic (Uu2) is given class B favorability because it 

contains some of the specific features directly associated with mineralization elsewhere (as noted in the 

explanation, fig. 2).

URANIUM-IRON ASSOCIATION

In the Iron River-Crystal Falls district, concentrations of uranium were discovered in several places at

In 1976, small deposits of phosphate-rich rock, 

some with small concentrations of uranium, were discovered at several localities in the northeast part of the 

quadrangle (Cannon and Klasner, 1976b). Since then, 

additional low-grade occurrences have been found in 

the Gogebic Range. All known deposits are very near 

(within a few hundred feet) the unconformity separating very ancient crystalline rocks from somewhat 

younger metasedimentary rocks. That unconformity is 

shown, wherever it is known to exist, in figure 2, and a 

class C favorability belt is considered to exist along it, 

although that belt is too narrow to show at this scale.

SILVER-BEARING SHALE

A belt of black shale and slate in the northeast part 

of the quadrangle (zone Ag) contains unusually high 

concentrations of silver, which, in places, are accompanied by molybdenum. Soil overlying these rocks 

commonly is also silver rich. Although these rocks are 

far from being economically exploitable for silver or 

molybdenum, they are considered to have class C 

favorability for silver or molybdenum deposits 

because, within the shale belt, some process locally 

might have further concentrated the widespread high 

silver and molybdenum values to potentially economic 

levels.

DIAMOND

About 15 miles (24 kilometers) northeast of Crystal 

Falls, a small body of kimberlite was discovered recently (Cannon and Mudrey, 1981). Kimberlite is a rare 

type of rock and is the only natural source of diamonds. About 1 kimberlite body in 10 contains diamonds. Only one kimberlite occurrence is known in the 

quadrangle, but it is likely that others exist nearby, so 

diamond-bearing rocks may exist in the quadrangle.

13
CONCLUSIONS

The Iron River quadrangle is part of a mineral-rich 

region that contains large identified deposits that are 

currently or potentially economic to mine. In addition, 

large areas of promising ground for exploration exist, 

and future discoveries of presently unknown deposits 

are possible. Despite the relatively low level of mining 

in the quadrangle in 1980, the Iron River quadrangle 

has the potential to produce large amounts of minerals 

in the future.

Within the quadrangle, about 12.2 billion pounds 

(5.5 billion kilograms) of copper are known to exist in 

well-studied deposits. Material that is presently 

economic includes 9.2 billion pounds (4.2 billion 

kilograms) of copper in the White Pine orebody. At 

least several billion additional pounds are likely to 

occur in known mineralized rocks in areas where data 

do not allow quantification.

About 13.25 billion tons (12.02 billion tonnes) of 

banded iron-formation are estimated to exist within 

500 feet (152.4 meters) of the surface in three principal 

mining districts the Marquette, the Gogebic, and the 

Iron River-Crystal Falls districts. A small percentage 

of that material might someday be minable as taconite 

if improved mining or metallurgical technology or increased iron prices permit profitable extraction of 

iron.

Possibly, parts of the quadrangle contain undiscovered deposits of copper, zinc, lead, silver, uranium, 

phosphate, nickel, chromium, cobalt, platinum, gold, 

and diamonds. Future exploration seems likely to find 

some of these and add to the known mineral wealth of 

the region.

BIBLIOGRAPHY

The following references were selected from many publications 

on the Iron River region because they are considered principal 

references on the geology of certain areas or certain problems or 

bear directly on ore deposits and mineral resources of the 

quadrangle. Each reference includes a brief annotation that indicates the nature of material presented in the publication. 

Alien, R. C., 1910, The Iron River iron-bearing district of Michigan: Michigan Geological and Biological Survey Publication 

3, Geological Series 2, 151 p. Discussion of the iron resources 

in the Iron River district of Michigan, including maps of individual mines. Also discussion of geology of this district, inchiding a geologic map at 1:31,250 scale (2 inches = 1 mile). 

___1912, Mineral resources of Michigan with statistical tables 

of production and value of mineral products for 1910 and 

prior years: Michigan Geological and Biological Survey Publication 8, Geological Series 6, 456 p. Discussion of mineral 

resources of Michigan, statistics of mining industry, and production, including copper and iron. Includes maps of mine 

locations and yearly production of individual mines. 

_1920, Mineral resources of Michigan with statistical tables

of production and value of mineral products for 1918 and 

prior years: Michigan Geological and Biological Survey Publication 29, Geological Series 24, 200 p. Discussion of metallic 

mineral resources (copper and iron) and a statistical review of 

iron ore shipments by districts from 1905 to 1918. Discussion 

of nonmetallic minerals, including production tables.

Alien, R. C., and Barrett, L. P., 1915, Contributions to the Precambrian geology of northern Michigan and Wisconsin: 

Michigan Geological and Biological Survey Publication 18, 

Geological Series 15, p. 13-164. Geologic descriptions of 

and magnetic data on the eastern part of the Gogebic Iron 

range and several other iron-bearing areas in the western part 

of the Iron River quadrangle.

Alminas, H. V., Hoffman, J. D., and Hopkins, R. I., 1983a, 

Copper distribution in B-horizon soils in the Iron River 

I°x2° quadrangle, Michigan and Wisconsin: U.S. Geological Survey Miscellaneous Investigations Map I-1360-H, scale 

1:250,000. Map showing soil-sample localities and copper 

contents, in parts per million. Brief text.

___1983b, Chromium distribution in B-horizon soils in the 

Iron River 1° x2° quadrangle, Michigan and Wisconsin: U.S. 

Geological Survey Miscellaneous Investigations Map 

I-1360-I, scale 1:250,000. Map showing soil-sample localities 

and chromium contents, in parts per million. Brief text. 

_1983c, Interpretive geochemical map of the Iron River

I°x2° quadrangle, Michigan and Wisconsin: U.S. Geological Survey Miscellaneous Investigations Map I-1360-N, scale 

1:250,000. Map showing variations in soil compositions derived from multielement correlation of metal contents. Brief 

text.

Anderson, G. J., 1968, The Marquette district, Michigan, in Ore 

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

volume): New York, American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc., v. 1, p. 507-517. 

Discussion of the mining history of the area, the physiographic and geologic history, the economic geology, and the 

genesis of the ores. Generalized maps and sections, stratigraphic table.

Bailey, S. W., and Tyler, S. A., 1960, Clay minerals associated 

with the Lake Superior iron ores: Economic Geology, v. 55, 

no. 1, p. 150-175. Discussion of the accessory clay-sized 

minerals found in the Marquette, Gogebic, and Iron River 

districts in Michigan. Differences in assemblages between 

these and the Mesabi, Cuyuna, and Vermillion district of 

Minnesota indicate different environments of formation. No 

maps.

Balsley, J. R., Jr., Davis, F. J., Nelson, R. A., Reinhardt, P. W., 

and Stead, F. W., 1950, Airborne radioactivity survey of 

parts of Marquette, Dickinson, and Baraga Counties, 

Michigan: U.S. Geological Survey Geophysical Investigations 

Map, scale 1:126,720. Map showing the approximate locations of radioactive anomalies over an area of about 1,600 

mi2 indicating areas in which uranium and thorium may occur. 

Brief text.

Barghoorn, E. S., Meinschein, W. G., and Schopf, J. W., 1965, 

Paleobiology of a Precambrian shale: Science, v. 148, no. 

3669, p. 461-472. Studies on the geology, organic geochemistry, and paleontology of the White Pine area in Michigan to 

investigate the problem of detection of ancient life. Deals 

mostly with the Nonesuch Shale.

14
Barrett, L. P., 1953, A sampling and radiation analysis of the 

pre-Cambrian rocks of Michigan, Minnesota, and Wisconsin: 

U.S. Atomic Energy Commission RME-3032, 15 p. Brief description of the general geology of the area and a summary of 

the results of a scintillometer survey and radiologic sampling 

of the Precambrian formations. Some indications of uranium 

and thorium were found. Generalized map.

Bayley, R. W., 1959, Geology of the Lake Mary quadrangle, 

Iron County, Michigan: U.S. Geological Survey Bulletin 

1077, 112 p., 7 pis., scale 1:24,000. Detailed geology of a 

7'/2-min quadrangle, including descriptions of stratigraphy, 

structure, magnetic surveys, and economic geology. Geologic 

and magnetic maps, photographs.

Bayley, R. W., Dutton, C. E., and Lamey, C. A., 1966, Geology 

of the Menominee iron-bearing district, Dickinson County, 

Michigan, and Florence and Marinette Counties, Wisconsin: 

U.S. Geological Survey Professional Paper 513, 96 p. Major 

references on the geology, structure, and economic geology of 

an area slightly larger than three 7'/2-min quadrangles. Geologic maps and sections, photographs.

Bayley, W. S., 1904, The Menominee iron-bearing district of 

Michigan: U.S. Geological Survey Monograph 46, 513 p. Major reference on an area of 112 mi2 that was one of the major 

iron ore producers in Michigan. Detailed geology and description of iron ore. Many geologic maps, cross sections, and 

diagrams.

Bodwell, W. A., 1972, Geologic compilation and nonferrous 

metal potential, Precambrian section, northern Michigan: 

Houghton, Mich., Michigan Technological University, M.Sc. 

thesis, 106 p. General geology of area and detailed discussions 

of locations of nonferrous metal occurrences, especially copper, pyrite, uranium, and gold. Geologic map and numerous 

tables.

Books, K. G., 1968, Magnetization of the lowermost Keweenawan 

lava flows in the Lake Superior area: U.S. Geological Survey 

Professional Paper 600-D, p. D248-D254. Discusses correlation of magnetization in the lowermost Keweenawan lava 

flows on opposite sides of Lake Superior. Uses paleomagnetic 

data and 145 drill core samples. Includes general geologic 

map, summary of paleomagnetic data, and diagrams of directions of magnetization.

___1972, Paleomagnetism of some Lake Superior Keweenawan 

rocks: U.S. Geological Survey Professional Paper 760, 42 p. 

Discusses natural remanent magnetization of rocks. Paleomagnetic studies were conducted at the Keweenaw Peninsula, 

Ironwood-Mellen area, and north shore of Lake Superior. Includes many equal-area diagrams showing direction of remanent magnetizations.

Brecke, E. A., 1968, Copper mineralization in the upper part 

of the Copper Harbor Conglomerate at White Pine, Michigan: Economic Geology, v. 63, no. 3, p. 294. Discussion of 

color change in shale and limestone and alteration of ferric 

iron. Attributes change to hydrothermal activity.

Broderick, T. M., 1929a, Zoning in Michigan copper deposits 

and its significance, part I: Economic Geology, v. 24, no. 2, 

p. 149-162. Arsenic occurs in small quantities in all known 

Michigan copper deposits. The ratio of arsenic to copper increases with depth. One very generalized map and two graphs 

of arsenic ratios.

___1929b, Zoning in Michigan copper deposits and its significance, part II: Economic Geology, v. 24, no. 3, p. 311-326. 

Study of the changes of the ratio of arsenic to copper with 

depth makes it possible to group formations and predict mineralogical changes likely to occur in mining. It is also possible 

to extend zones beyond known lode deposits. No map.

___1931, Fissure vein and lode relations in Michigan copper 

deposits: Economic Geology, v. 26, no. 8, p. 840-856. Discussion of the relation of fissure veins to lode formation and 

application of this relation to exploration for new lode 

deposits of copper.

_____1952, The origin of Michigan copper deposits: Economic 

Geology, v. 47, no. 2, p. 215-219. Brief discussion of the differences of opinion on origin of copper held by author and 

H. R. Cornwall. See other references by these two authors for 

more details.

___1956, Copper deposits of the Lake Superior region: Economic Geology, v. 51, no. 3, p. 285-287. Letter in the "Discussion" section comments on author's view that a theory, to 

be acceptable, must explain all deposits of a district studied. 

Refers to work done by a USGS team in the Lake Superior 

region and their proposal of varied modes of origin.

Broderick, T. M., and Hohl, C. D., 1935, Differentiation in traps 

and ore deposition: Economic Geology, v. 30, no. 3, 

p. 301-312. Study of differentiation in Keweenawan lava 

flows of the Michigan copper district furnishes new data concerning the amounts of copper and its distribution in the 

traps. No map; a table of sulfur and copper percentages in 

various rock types.

Broderick, T. M., Hohl, C. D., and Eidemiller, H. N., 1946, 

Recent contributions to the geology of the Michigan copper 

district: Economic Geology, v. 41, no. 7, p. 675-725. Discussion of general geology of the area, internal features of 

orebodies, geologic relations as guides to exploration, and 

origin of deposits. Very generalized map and cross section and 

a stratigraphic column.

Brown, A. C., 1968, Zoning in the White Pine copper deposit, 

Ontonagon County, Michigan: Ann Arbor, Mich., University 

of Michigan, Ph.D. thesis, 194 p. Entertainment of the proposal that mineralization of the basal Nonesuch Formation 

was accomplished by the introduction of copper from Copper 

Harbor Formation after burial of Nonesuch sediments. Uses 

infiltration and diffusion models.

___1974, An epigenetic origin for stratiform Cd-Pb-Zn, sulfides in the lower Nonesuch Shale, White Pine, Michigan: 

Economic Geology, v. 69, no. 2, p. 271-274. Proposes an epigenetic origin for layers of Cd-Pb-Zn, which requires the 

metals to be pulsed to a higher level by an influx of cupriferous solution from the underlying strata.

Burnie, S. W., Schwarcz, H. P., and Crocket, J. H., 1972, A 

sulfur isotopic study of the White Pine mine, Michigan: Economic Geology, v. 67, no. 7, p. 895-914. Discussion on the 

Nonesuch Shale, including analysis by sulfur extraction, isotopic analysis, carbon analysis, and boron analysis.

Butler, B. S., and Burbank, W. S., 1929, The copper deposits of 

Michigan: U.S. Geological Survey Professional Paper 144, 

238 p. Detailed study of copper deposits in northern Michigan. Includes 27 geologic maps and 16 longitudinal sections. 

Sections include general features, ore deposits, and detailed 

descriptions of lodes and fissures.

Cannon, W. F., 1973, The Penokean orogeny in northern Michigan, in Young, G. M., ed., Huronian stratigraphy and sedimentation: Geological Association of Canada Special Paper 

12, p. 251-271. Discussion of the structural style and orogenic 

sequence of the event known as the Penokean orogeny. Geologic sketch map and numerous cross sections.

15
_1976, Hard iron ore of the Marquette Range, Michigan: 

Economic Geology, v. 71, no. 6, p. 1012-1028. Discussion of 

petrology and origin of specularite and clastic and magnetite 

ores found in the Marquette Range, Michigan. General geologic map, isometric maps, stratigraphic sections, and photographs included.

_1977, Map showing Precambrian geology in parts of the 

Baraga, Dead River, and Clark Creek basins, Marquette and 

Baraga Counties, Michigan: U.S. Geological Survey OpenFile Report 77-467, 1 pi., scale 1:62,500. Detailed geologic 

map of the area, no text.

_1980, Copper-bearing quartzite near Watersmeet, Michigan: U.S. Geological Survey Open-File Report 80-390, 7 p. 

Brief description of a copper occurrence in Precambrian 

quartzite. Includes assays and two maps.

_1983a, Mineral resources map of the Iron River I°x2° 

quadrangle, Michigan and Wisconsin: U.S. Geological Survey 

Miscellaneous investigations Map I-1360-A, scale 1:250,000. 

Map showing location of known mineral resources of the 

quadrangle and zones of potential for undiscovered deposits. 

Brief text and tables.

_1983b, Bedrock geologic map of the Iron River I°x2° 

quadrangle, Michigan and Wisconsin: U.S. Geological Survey 

Miscellaneous Investigations Map I-1360-B, scale 1:250,000. 

Map showing bedrock geology of the area. Brief text and 

cross sections.

_1983c, Structural and tectonic map of the Iron River 1° x 2°

quadrangle, Michigan and Wisconsin: U.S. Geological Survey 

Miscellaneous Investigations Map I-1360-D, scale 1:250,000. 

Map showing lithotectonic units and major structures of the 

quadrangle.

Cannon, W. F., and Gair, J. E., 1970, A revision of stratigraphic 

nomenclature for middle Precambrian rocks in northern 

Michigan: Geological Society of America Bulletin, v. 81, 

no. 9, p. 2843-2846. Proposal to introduce the name Marquette Range Supergroup to supplant the term Animikie 

Series for the middle Precambrian sequence of the Northern 

Peninsula and areas in Wisconsin. Includes sketch map and 

stratigraphic correlation chart.

Cannon, W. F., King, E. R., Hill, J. J., and Mory, P. C., 1980, 

Mineral resources of the Sturgeon River Wilderness Study 

Area, Houghton and Baraga Counties, Michigan: U.S. Geological Survey Bulletin 1465, 49 p. Discussion of geology and 

geophysical interpretations and investigation of known and 

potential mineral deposits. General geologic maps, aeromagnetic maps, and partial chemical analysis of samples.

Cannon, W. F., and Klasner, J. S., 1975, Stratigraphic relationships within the Baraga Group of Precambrian age, central 

upper peninsula, Michigan: U.S. Geological Survey Journal 

of Research, v. 3, no. 1, p. 47-51. Correlation of units between geographically separated areas has been greatly aided 

by mapping in the Witch Lake 15-min quadrangle. Various 

iron-formation units can now be correlated. Generalized geologic map and section.

___1976a, Geologic map and geophysical interpretation of the 

Witch Lake quadrangle, Marquette, Iron, and Baraga Counties, Michigan: U.S. Geological Survey Miscellaneous Investigations Map 1-987, scale 1:62,500. Detailed geologic map of 

the area, also showing available geophysical information. 

Brief text on map.

___1976b, Phosphorite and other apatite-bearing sedimentary 

rocks in the Precambrian of northern Michigan: U.S. Geological Survey Circular 746, 6 p. Brief discussion of occurrences

of phosphate with sedimentary rocks in the Precambrian of 

northern Michigan. Includes a geologic sketch map.

Cannon, W. F., and Mudrey, M. G., Jr., 1981, The potential for 

diamond-bearing kimberlite in northern Michigan and Wisconsin: U.S. Geological Survey Circular 842, 15 p. Describes 

kimberlite pipe in northern Michigan and historic discoveries 

of diamonds in glacial drift in Wisconsin. Proposes that 

diamond-bearing kimberlites exist in Michigan or Wisconsin.

Cannon, W. F., Powers, S. L., and Wright, N. A., 1978, 

Computer-aided estimates of concentrating-grade iron 

resources in the Negaunee iron-formation, Marquette 

District, Michigan: U.S. Geological Survey Professional 

Paper 1045, 21 p. Analysis of resource potential and estimation of the maximum amount of recoverable iron through a 

statistical simulation model. Includes generalized geologic 

map, numerous histograms, graphs, and charts.

Carpenter, R. H., 1963, Some vein-wall rock relationships in the 

White Pine mine, Ontonagon County, Michigan: Economic 

Geology, v. 58, no. 5, p. 643-666. The dominant facies of 

copper mineralization at White Pine is characterized by the 

relationship of copper to sedimentary features and by its 

restriction to the base of the Nonesuch Shale. A second minor 

facies is fracture controlled and of two types: fracture-filled 

veins and halos.

Chaudhuri, Sambhudas, and Faure, Gunter, 1967, Geochronology 

of the Keweenawan rocks, White Pine, Michigan: Economic 

Geology, v. 62, no. 8, p. 1011-1033. Report deals with age 

determinations made by the Rb-Sr method applied to suites of 

total-rock specimens and isotope analyses of lead from the 

White Pine copper mine.

Clements, J. M., and Smyth, H. L., 1899, The Crystal Falls ironbearing district of Michigan: U.S. Geological Survey Monograph 36, 512 p., scale 1:125,000. Comprehensive report on 

an area of 1,300 mi2 in northern Michigan describing the geography, geology, and mining history. Many detailed geologic 

maps, cross sections, diagrams, and photographs.

Cornwall, H. R., 1951, Ilmenite, magnetite, hematite, and copper 

in lavas of the Keweenawan series: Economic Geology, v. 46, 

no. 1, p. 51-67. Opaque minerals in 10 lava flows were studied microscopically, and two groups of minerals and their 

alteration production were distinguished to provide an index 

to the degree of differentiation of basaltic lavas of the area. 

No map.

Dutton, C. E., 1949, Geology of the central part of the Iron River 

district, Iron County, Michigan: U.S. Geological Survey Circular 43, 9 p. General geology of an area of 5 mi2 . Description 

of iron-formation, past and present mining, and future possibilities. Geologic maps and sections, mine level maps, magnetic 

data.

___1969, Geology and magnetic data for central Iron River 

area, Michigan: Michigan Geological Survey Division Report 

of Investigation 5, 17 p., maps, scale 1:6,000. Supplements 

USGS Professional Paper 570 with detailed geology, descriptions of mines and exploration, and magnetic surveys of the 

area.

Dutton, C. E., and Bradley, R. E., 1970, Lithologic, geophysical, 

and mineral commodity maps of Precambrian rocks in Wisconsin: U.S. Geological Survey Miscellaneous Investigations 

Map 1-631, 6 shts., scale 1:500,000, 15-p. text. Six maps plus 

text. Text discusses lithology, aeromagnetic and gravity data, 

and geology of specific areas as it relates to mineral deposits. 

Tables show geochronological data and mineral occurrences. 

Maps show geology, lithology, and geophysical data. One

16
map shows mineral localities and metamorphic zones extending into northern Michigan.

Dutton, C. E., and Linebaugh, R. E., 1967, Map showing Precambrian geology of the Menominee iron-bearing district and 

vicinity, Michigan and Wisconsin: U.S. Geological Survey 

Miscellaneous Investigations Map 1-466, scale 1:125,000. 

Map of an area of about 1,000 mi2 showing geology and ironbearing formations. No text.

Ensign, C. O., Jr., White, W. S., Wright, J. C., Patrick, J. L., 

Leone, R. J., Hathaway, D. J., Trammell, J. W., Fritts, 

J. J., and Wright, T. L., 1968, Copper deposits in the Nonesuch Shale, White Pine, Michigan, in Ore deposits of the 

United States, 1933-1967 (Graton-Sales volume): New York, 

American Institute of Mining, Metallurgical, and Petroleum 

Engineers, Inc., v. 1, p. 460-488. Discussion of mining and 

exploration, physiographic history, general geology, and 

structure of area. Extensive descriptions of stratigraphy, mineralogy, and form of orebodies as well as their origin and time 

of mineralization. Sketch maps of geology, structure, and 

thickness of beds.

Fritts, C. E., 1969, Bedrock geologic map of the MareniscoWatersmeet area, Gogebic and Ontonagon Counties, Michigan: U.S. Geological Survey Miscellaneous Investigations 

Map 1-576, scale 1:48,000, 5-p. text. Detailed geologic map 

of three 15-min quadrangles, four cross sections, some aeromagnetic data, and locations of mineralized areas.

Gair, J. E., and Wier, K. L., 1956, Geology of the Kiernan quadrangle, Iron County, Michigan: U.S. Geological Survey Bulletin 1044, 88 p., 5 pis., scale 1:24,000. Detailed geology of a 

7!/2-min quadrangle, including stratigraphy, structure, magnetic surveys, and economic geology. Geologic maps and sections, magnetic maps, diagrams, tables, and photographs.

Good, S. E., and Pettijohn, F. J., 1949, Magnetic survey and 

geology of the Stager area, Iron County, Michigan: U.S. 

Geological Survey Circular 55, 4 p. Very generalized geology 

of an area of 4 mi2 and more detailed magnetic data. Brief 

description of mining possibilities. Geologic map and 

magnetic data map.

Hamblin, W. K., 1958, The Cambrian sandstones of northern 

Michigan: Michigan Geological Survey Division Publication 

51, 149 p. Comprehensive study of the Cambrian sediments, 

by means of area! mapping, and a detailed study of stratigraphy, sedimentation, and paleontology. Geologic maps, sections, tables, stratigraphic charts, and many photographs.

Hamilton, S. K., 1967, Copper mineralization in the upper part 

of the Copper Harbor Conglomerate at White Pine, Michigan: Economic Geology, v. 62, no. 7, p. 885-904. Nature and 

distribution of copper mineralization in the upper parts of the 

Copper Harbor Conglomerate. Controls of copper distribution and mode of origin are discussed.

Heran, W. D., and Smith, B. D., 1980, Description and preliminary map, airborne electromagnetic survey of parts of 

Iron, Baraga, and Dickinson Counties, Michigan: U.S. Geological Survey Open-File Report 80-297, 13 p., 1 sht., scale 

1:62,500. Map showing location and magnitude of electromagnetic anomalies. Brief text describing method of survey.

Hobbs, W. H., 1899, The diamond field of the Great Lakes: 

Journal of Geology, v. 7, p. 375-388. Text covers physical 

characteristics of the lake diamonds, their distribution, and 

their origin.

Hoffman, J. D., Alminas, H. V., and Hopkins, T. R., 1983a, 

Cobalt distribution in B-horizon soils in the Iron River 1° x 2° 

quadrangle, Michigan and Wisconsin: U.S. Geological Survey

Miscellaneous Investigations Map I-1360-J, Scale 1:250,000. 

Map showing soil-sample localities and cobalt contents, in 

parts per million. Brief text. 

_1983b, Nickel distribution in B-horizon soils in the Iron

River I°x2° quadrangle, Michigan and Wisconsin: U.S. 

Geological Survey Miscellaneous Investigations Map 

I-1360-K, scale 1:250,000. Map showing soil-sample localities 

and nickel contents, in parts per million. Brief text.

Hopkins, T. R., Alminas, H. V., and Hoffman, J. D., 1983a, 

Silver distribution in B-horizon soils in the Iron River 1° x 2° 

quadrangle, Michigan and Wisconsin: U.S. Geological Survey 

Miscellaneous Investigations Map I-1360-L, scale 1:250,000. 

Map showing soil-sample localities and silver contents, in 

parts per million. Brief text.

___1983b, Molybdenum distribution in B-horizon soils in the 

Iron River 1° x2° quadrangle, Michigan and Wisconsin: U.S. 

Geological Survey Miscellaneous Investigations Map 

I-1360-M, scale 1:250,000. Map showing soil-sample localities and molybdenum in parts per million. Brief text.

Hubbard, H. A., 1974, Bedrock geology of the Porcupine Mountains, Michigan: U.S. Geological Survey Open-File map, scale 

1:62,500. Detailed geologic map of the area. No text.

___1975a, Geology of Porcupine Mountains in Carp River and 

White Pine quadrangles, Michigan: U.S. Geological Survey 

Journal of Research, v. 3, no. 5, p. 519-528. Detailed geology 

of an area of 75 mi2 and descriptions of stratigraphy and structure. Geologic map and cross sections and stratigraphic correlation table.

___1975b, Lower Keweenawan volcanic rocks of Michigan and

Wisconsin: U.S. Geological Survey Journal of Research, v. 3, 

no. 5, p. 529-541. Detailed geology of an area of about 70 mi2 

showing new correlations and stratigraphic nomenclature between rocks of unconformable sequences of Keweenawan volcanic rocks. Geologic map, chemical analyses, and stratigraphic table.

Irving, R. D., and Van Hise, C. R., 1890, The Penokee ironbearing series of Michigan and Wisconsin: U.S. Geological 

Survey Monograph 19, 534 p. A summary of previous work 

on the area and a detailed description of the current geology, 

with emphasis on the iron-bearing formations. Geologic 

maps, diagrams, and sections.

James, H. L., 1951, Iron formation and associated rocks in the 

Iron River district, Michigan: Geological Society of America 

Bulletin, v. 62, no. 3, p. 251-266. Discussion of origin of ironformation linking climate with other factors. Includes tables 

showing stratigraphic succession in the Iron River district and 

chemical analysis of graphite slate, iron-formation, graywacke, and magnetic ironstone.

___1953, Origin of the soft iron ores of Michigan: Economic 

Geology, v. 48, no. 8, p. 726-728. A letter in the 

"Discussion" section on the theory of soft iron ore formation 

in Michigan as proposed by V. I. Mann versus other ideas as 

proposed by USGS.

___1955, Zones of regional metamorphism in the Precambrian 

of northern Michigan: Geological Society of America Bulletin 

v. 66, no. 12, pt. 1, p. 1455-1487. General discussion of 

geology of the area of 7,500 mi2 . Detailed discussion of the 

metamorphism of the rocks and its relationship to intrusive 

rocks and structure. Tables and diagrams.

___1958, Stratigraphy of pre-Keweenawan rocks in parts of 

northern Michigan: U.S. Geological Survey Professional 

Paper 314-C, p. C27-C44. Discussion of stratigraphic 

nomenclature used for lower and middle Precambrian rocks

17
in Iron and Dickinson Counties and detailed description of 

various lithologies. Proposes correlation of layered rock sequence containing the iron-formations with Animikie series. 

Generalized geologic map and stratigraphic tables.

James, H. L., Clark, L. D., Lamey, C. A., and Pettijohn, F. J., 

1961, Geology of central Dickinson County, Michigan: U.S. 

Geological Survey Professional Paper 310, 176 p., 1 pi., scale 

1:24,000. Extensive summary of the geology of an area of 

250 mi2 and detailed discussions of stratigraphy, structure, 

and economic geology. Iron ore is principal mineral resource. 

Other minerals are dolomite and uranium. Geological and 

geophysical maps and stratigraphic and chemical analysis 

tables.

James, H. L., and Dutton, C. E., 1951, Geology of the northern part of the Iron River district, Iron County, Michigan: 

U.S. Geological Survey Circular 120, 12 p. General geology of 

an area of 12 mi2 . Description of stratigraphy and brief discussion of iron-formation and future mining possibilities. 

Geologic maps and cross sections, stratigraphic chart, and 

magnetic data.

James, H. L., Dutton, C. E., Pettijohn, F. J., and Wier, K. L., 

1968, Geology and ore deposits of the Iron River-Crystal 

Falls district, Iron County, Michigan: U.S. Geological Survey 

Professional Paper 570, 134 p., 4 pis., scale 1:24,000. Detailed discussion of geology of an area of 300 mi2 . Stratigraphy, structure, and ore deposits described, as well as ore 

mineralogy. Iron is chief ore. Uranium present. Geologic 

maps, stratigraphic charts, chemical analyses, and production 

data.

James, H. L., Dutton, C. E., and Wier, K. L., 1967, Geologic 

and magnetic data for northern Iron River area, Michigan: 

Michigan Geological Survey Division Report of Investigation 

4, 46 p., maps, scale 1:6,000. Supplements USGS Professional Paper 570 with detailed geology, descriptions of mines 

and explorations, and magnetic surveys of the area.

James, H. L., Pettijohn, F. J., and Clark, L. D., 1970, Geology 

and magnetic data between Iron River and Crystal Falls, 

Michigan: Michigan Geological Survey Division Report of Investigation 7, 17 p., maps, scale 1:6,000. Supplements USGS 

Professional Paper 570 with detailed geology, descriptions of 

mines and explorations, and magnetic surveys of the area.

James, H. L., and Wier, K. L., 1948, Magnetic survey and geology 

of the eastern and southeastern parts of the Iron River 

district, Iron County, Michigan: U.S. Geological Survey Circular 26, 18 p., 4 pis. Discussion of geology in the eastern and 

southeastern parts of the Iron River district and detailed 

section-by-section descriptions. Includes a stratigraphic chart 

of characteristics of the iron-formation. Maps include: 

(1) Geologic cross section in eastern and southeastern parts of 

the Iron River District, scale 1:2,400. (2) Inferred geology in 

southeastern part of Iron River district, scale 1":6,000. 

(3) Magnetic data in southeastern part of Iron River District, 

scale 1:6,000. (4) Magnetic data and inferred geology in eastern part of the Iron River district, scale 1:6,000.

___1969, Geology and magnetic data for the southeastern 

Iron River area, Michigan: Michigan Geological Survey Division Report of Investigation 6, 30 p., maps, scale 1:6,000. 

Supplements USGS Professional Paper 570 with detailed 

geology, descriptions of mines and explorations, and magnetic surveys of the area.

Johnson, R. F., and White, W. S., 1969, Preliminary report on 

the bedrock geology and copper deposits of the Matchwood 

quadrangle, Ontonagon County, Michigan: U.S. Geological

Survey Open-File Report, 29 p., I pi. scale 1:62,500. Discussion of general geology, stratigraphy, structure, and economic 

geology of a 15-min quadrangle. Black and white geologic 

map.

Jolly, W. T., 1974, Behavior of Cu, Zn, and Ni during prehnitepumpellyite rank metamorphism of Keweenawan basalts, 

northern Michigan: Economic Geology, v. 69, no. 7, 

p. 118-1125. Study of metamorphic zonation and its affect on 

metal distribution. Native copper deposits appear to be 

formed by leaching of copper in higher temperature zones and 

reprecipitation in lower temperature zones.

Kalliokoski, J. O. K., 1976, Uranium and thorium occurrences 

in Precambrian rocks, Upper Peninsula of Michigan and 

northern Wisconsin: Houghton, Mich., Michigan Technological University, 274 p. Regional geologic setting and detailed 

geologic descriptions of known occurrences of uranium and 

thorium. Contains detailed maps of most occurrences and 

assay data for most.

King, Elizabeth, 1983, Aeromagnetic map of the Iron River 

1° x2° quadrangle, Michigan and Wisconsin: U.S. Geological 

Survey Miscellaneous Investigations Map I-1360-F, scale 

1:250,000. Map showing variations in magnetic field of the 

area.

Klasner, J. S., and Cannon, W. F., 1974, Geologic interpretation 

of gravity profiles in the western Marquette district, northern 

Michigan: Geological Society of America Bulletin, v. 85, 

no. 2, p. 213-218. Interpretation of gravity profiles, specifically of the Marquette Trough near Humboldt, Mich., the 

Marquette Trough near Michigamme, Mich., the Republic 

Trough, and the Michigan River Trough. Includes gravity 

profiles, geologic sections, stratigraphic column, and gravity 

models.

___1978, Bedrock geologic map of the southern part of the 

Michigamme and Three Lakes quadrangles, Marquette and 

Baraga Counties, Michigan: U.S. Geological Survey Miscellaneous Investigations Map 1-1078, scale 1:24,000. Detailed 

geologic map and text covering stratigraphy, structure, metamorphism, and iron resources. Includes table of mine production from the Negaunee Iron-formation and the Bijiki Ironformation Member of the Michigamme Formation.

Klasner, J. S., and Jones, W. J., 1983, Bouguer gravity anomaly 

map and geologic interpretation of the Iron River I°x2° 

quadrangle, Michigan and Wisconsin: U.S. Geological Survey 

Miscellaneous Investigations Map I-1360-F, scale 1:250,000, 

2 shts. Map showing variations in gravitative attraction. Includes additional maps of computer-filtered data. Brief text.

Klein, Ira, 1939, Microcline in the native copper deposits of 

Michigan: American Mineralogist, v. 24, no. 10, p. 643-650. 

Studies of the distribution, nature, and paragenesis of an 

unusual variety of microcline found in copper-rich areas of 

Michigan.

Lane, A. C., 1911, The Keweenaw Series of Michigan: Michigan 

Geological and Biological Survey Publication 6, Geological 

Series 4, v. 1 and 2, 984 p. Major references on geology and 

copper deposits of area and detailed descriptions of stratigraphy of each deposit. Geologic maps and sections, diagrams, 

and tables.

___1924, Native Silver in an iron mine [abs.]: Geological Society of America Bulletin, v. 35, no. 1, p. 127-128. Brief abstract discussing origin and inclusion of silver in Michigan 

iron-formations.

Leith, C. K., Lund, R. J., and Leith, Andrew, 1935, PreCambrian rocks of the Lake Superior region: U.S. Geological

18
Survey Professonal Paper 184, 34 p. Revised Precambrian 

geology of the area surrounding Lake Superior, approximately 550x350 mi. Discussion of stratigraphy and origin of 

the iron-formation. Geologic map, structure sections, and 

stratigraphic chart.

Mancuso, J. J., Lougheed, M. S., and Shaw, R., 1975, Carbonateapatite in Precambrian cherty iron-formation, Baraga County, Michigan: Economic Geology, v. 70, no. 3, p. 583-586. 

Report on the occurrence of carbonate-apatite from ironformations in the Upper Peninsula of Michigan. Infers that 

this occurrence lends credibility to hypothesis that biota were 

present during deposition of Precambrian cherty ironformations. Includes two pages of photographs.

Mann, V. I., 1953, The relation of oxidation to the origin of soft 

iron ores of Michigan: Economic Geology, v. 48, no. 4, 

p. 251-281. Discussion of views regarding soft iron-ore 

development in the Marquette and Gogebic Ranges, the major 

and minor minerals of the iron-formation and their alteration, and the thermodynamics of the system. Generalized map 

of Marquette Range.

Marsden, R. W., 1968, Geology of the iron ores of the Lake 

Superior region in the United States, in Ore deposits of the 

United States, 1933-1967 (Graton-Sales volume): New York, 

American Institute of Mining, Metallurgical, and Petroleum 

Engineers, Inc., v. I p. 489-506. Discussion of mining 

history, physiography, geologic history, and stratigraphy of 

region. Description of various types of Lake Superior iron 

ores and their origin. Generalized geologic and locality maps 

and production table.

Peterson, W. L., 1983, Surficial geologic map of the Iron River 

I°x2° quadrangle, Michigan and Wisconsin: U.S. Geological Survey Miscellaneous Investigations Map I-1360-C, scale 

1:250,000. Map showing distribution of unconsolidated surficial deposits. Brief text outlining glacial history of the area.

Pettijohn, F. J., 1970, Geology and magnetic data for northern 

Crystal Falls area, Michigan: Michigan Geological Survey 

Division Report of Investigation 8, 23 p., scale 1:4,750. Supplements USGS Professional Paper 570 with detailed geology, 

descriptions of mines and explorations, and magnetic surveys 

of the area.

___1972, Geology and magnetic data for southern Crystal 

Falls area, Michigan. Michigan Geological Survey Division 

Report of Investigation 9, 31 p., maps, scale 1:4,500. Supplements USGS Professional Paper 570 with detailed geology, 

descriptions of mines and explorations, and magnetic surveys 

of the area.

Pettijohn, F. J., Gair, J. E., Wier, K. L., and Prinz, W. C., 1969, 

Geology and magnetic data for Alpha-Brule River and Panola 

Plains areas, Michigan: Michigan Geological Survey Division 

Report of Investigation 10, 12 p., maps, scale 1:6,000. Supplements USGS Professional Paper 570 with detailed geology, 

description of mines and explorations, and magnetic surveys 

of the area.

Prinz, W. C., 1967, Pre-quaternary geologic and magnetic map 

and sections of part of the eastern Gogebic Iron Range, 

Michigan: U.S. Geological Survey Miscellaneous Investigations Map 1-497, scale 1:10,000. Map of an area of about 

6 mi2 showing geology and magnetic data and cross sections. 

Map text describes past exploration and future possibilities 

for iron mining.

Prinz, W. C., and Hubbard, H. A., 1975, Preliminary geologic 

map of the Wakefield quadrangle, Gogebic County, 

Michigan: U.S. Geological Survey Open-File Report 75-119,

12 p., 1 pi., scale 1:24,000. Detailed geologic map of 

7'/2-min quadrangle in black and white. No text.

Pumpelly, Raphael, 1871, The paragenesis and derivation of 

copper and its associates on Lake Superior: American Journal 

of Science, 3d ser., v. 2, no. 10, p. 188-198, 243-258, 

347-355. List of mines and description of their contents.

Schmidt, R. G., 1980, The Marquette Range Supergroup in the 

Gogebic iron district, Michigan and Wisconsin: U.S. Geological Survey Bulletin 1460, 96 p. Detailed petrographic descriptions of Proterozoic X strata including the Ironwood Ironformation. Generalized geologic map.

Snelgrove, A. K., Seaman, W. A., and Ayres, V. L., 1943, 

Strategic minerals investigations in Marquette and Baraga 

Counties: Michiganm Geological Survey Progress Report 10, 

p. 1-67. Studies of the Marquette iron range, the Lake Michigamme area, the Republic area, and the Ishpeming gold 

range for locating strategic and rare minerals. Includes a 

geologic column for the Lake Superior region in general and 

the Marquette iron range in particular.

Snider, D. C., compiler, 1976, General geologic map of the 

Keweenawan copper range and adjacent areas of Michigan: 

Michigan Geological Survey Division Map 3867, scale 

1:250,000. Generalized geologic map in black and white. No 

text.

Stoiber, R. E., and Davidson, E. S., 1959, Amygdule mineralzoning in the Portage Lake Lava Series, Michigan copper district, pt. 2: Economic Geology, v. 54, no. 8, p. 1444-1460. 

Discussion of the origin and location of copper deposits with 

respect to amygdule minerals formed by regional hydrothermal alteration of basaltic lava flows. Supports metamorphic 

origin of copper rather than a magmatic origin. Studied 

mineralogy of amygdaloidal rock from mine dumps and the 

mineralogy of the Kearsarge Flow. Concludes that copper will 

be found at the outer limit of the regional quartz zone owing 

to pumpellyitization of basalts.

Trent, V. A., 1973, Geologic map of the Marenisco and Wakefield NE quadrangles, Gogebic County, Michigan: U.S. Geological Survey Open-File map, 4 shts., scale 1:20,000. Detailed geologic map of the area. Brief text.

Tyler, S. A., 1949, Development of Lake Superior soft iron ores 

from metamorphosed iron formation: Geologic Society of 

America Bulletin, v. 60, no. 7, p. 1101-1124. Review of two 

theories of the origin of Lake Superior soft ores. Reexamines 

the character and distribution of the metamorphic facies of 

the iron-formations and the nature of ferruginous cherts and 

the ore.

Tyler, S. A., Barghoorn, E. S., and Barrett, L. P., 1957, Anthracitic coal from the Precambrian upper Huronian black shale 

of the Iron River district, northern Michigan: Geological 

Society of America Bulletin, v. 68, no. 10, p. 1293-1304. Discussion of carbonaceous shale, anthracitic carbon, and evidence for biogenic origin of graphitic coal.

Tyler, S. A., Marsden, R. W., Grout, F. F., and Thiel, G. A., 

1940, Studies of the Lake Superior pre-Cambrian by 

accessory-mineral methods: Geological Society of America 

Bulletin, v. 51, no. 10, p. 1429-1537. Generalized geology and 

detailed descriptions of the accessory minerals found in each 

of the various Precambrian units of the area around Lake 

Superior. Generalized or sketch geologic maps and tables of 

mineral analyses.

U.S. Bureau of Mines and U.S. Geological Survey, 1980, Principles of a resource/reserve classification for minerals: U.S. 

Geological Survey Circular 831, 5 p. Discussion of the

19
philosophy of mineral-resource classification and definitions 

of resource terminology.

Van Hise, C. R., and Bayley, W. S., 1897, The Marquette ironbearing district of Michigan, with atlas: U.S. Geological 

Survey Monograph 28, 608 p., atlas of 39 shts. folio. Major 

reference on geology of an area of about 100 mi2 . Detailed 

descriptions of geology. Maps, diagrams, and photographs.

Van Hise, C. R., and Leith, C. K., 1911, The geology of the Lake 

Superior region: U.S. Geological Survey Monograph 52, 

641 p. Major reference on geology of entire area around Lake 

Superior. Detailed discussion of geology and mineral 

deposits. Many geologic maps, cross sections, and diagrams.

Vickers, R. C., 1953, Reconnaissance for uranium in the United 

States, north-central district, in Geologic investigations of 

radioactive deposits, semiannual program report, June 1 to 

November 30, 1953: U.S. Geological Survey Trace Elements 

Investigations TEI-390, p. 202-205. Brief descriptions of 

radioactive deposits in Baraga and Marquette Counties, 

Michigan. Uranium minerals and monazite were found. No 

map.

___1956, Origin and occurrences of uranium in northern 

Michigan: U.S. Geological Survey Open-File Report, 76 PJ, 

7 figs. A comprehensive report describing the occurrences of 

uranium in northern Michigan. Generalized geologic map 

showing locations of occurrences, cross sections, and tables.

White, W. S., 1950, Radiometric scanning of collections of. 

Keweenawan rocks of the Michigan copper-district: U.S. 

Geological Survey Trace Elements Memorandum TEM-37, 

7 p. Geiger-counter tests run on drill cores and rocks and 

mineral specimens from the surface, mine dumps, and underground did not indicate any significant radioactivity. The 

most promising material is from the Nonesuch Shale.

___1960a, The Keweenawan lavas of Lake Superior, an example of flood basalts: American Journal of Science, v. 258-A, 

p. 367-374. Discussion of lava flows of Keweenawan age in 

the Lake Superior Basin compared to lava flows from shield 

volcanoes. Uses volume, slope, and direction of flow for basis 

of comparison. Includes longitudinal stratigraphic section.

___1960b, The White Pine copper district: Economic Geology, 

v. 55, no. 2, p. 402-409. Letter discussing different theories of 

ore formation in the White Pine district as argued by the 

author versus Reno Sales.

___1966, Tectonics of the Keweenawan basin, western Lake 

Superior region: U.S. Geological Survey Professional Paper 

524-E, 23 p. Discussion of subsurface structure in the Keweenawan Basin includes information on surface geology. 

General geologic map, two gravity maps, general aeromagnetic map, gravity map, gravity and aeromagnetic profile, and 

map of major tectonic elements.

___1968, The native-copper deposits of Northern Michigan, 

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

Volume): New York, American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc., v. 1, p. 303-325. 

Discussion of geologic and mining history of the area and the 

genesis of ore. Three generalized geologic maps, cross sections, and tables.

___1971, A paleohydrologic model for mineralization of the 

White Pine copper deposit, northern Michigan: Economic 

Geology, v. 66, no. 1, p. 1-13. Discussion of a quantitative 

view of lateral migrations of fluids to the White Pine copper 

deposit through the subjacent Copper Harbor Conglomerate.

___1972, The base of the Upper Keweenawan, Michigan and 

Wisconsin; U.S. Geological Survey Bulletin 1354-F, 23 p. 

Proposal that the top of the Copper Harbor Conglomerate be 

adopted as the base of the upper Keweenawan and the Oronto 

Group. Uses paleomagnetic and seismic data. Includes two 

stratigraphic sections and a diagram of mean directions of 

magnetization for some Keweenawan rocks.

White, W. S., and Wright, J. C., 1950, Radioactivity of the Nonesuch Shale, White Pine Mine, Ontonagon County, Michigan: 

U.S. Geological Survey Trace Elements Memorandum 

TEM-158, 4 p. Beta-gamma counts were made on the Nonesuch Shale in the Bill Schacht shaft of the White Pine mine. 

Discussion of the stratigraphy of the mine, methods of sampling, and findings. Shaft map and several figures and tables.

___1960, Lithofacies of the Copper Harbor Conglomerate, 

Northern Michigan: U.S. Geological Survey Professional 

Paper 400-B, p. B5-B8. Brief discussion of the Copper Harbor Conglomerate accompanied by (1) a map of the distribution of Copper Harbor Conglomerate and its oriented sedimentary structures and (2) a stratigraphic cross section of the 

Copper Harbor Conglomerate.

___1966, Sulfide-mineral zoning in the basal Nonesuch Shale,

northern Michigan: Economic Geology, v. 61, no. 7, 

p. 1171-1190. Description of the mineral zoning of the Nonesuch Shale, including discussion of copper.

Whitelow, J. W., 1974, Geologic map of the Greenland and 

Rockland quadrangles, Ontonogan County, Michigan: U.S. 

Geological Survey Miscellaneous Field Studies Map MF-596, 

scale 1:62,500. Detailed geologic map of the area. Brief text 

on map.

Wier, K. L., 1967, Geology of the Kelso Junction quadrangle, 

Iron County Michigan: U.S. Geological Survey Bulletin 1226, 

47 p., 3 pis., scale 1:24,000. Detailed geology of 7 1/2-min 

quadrangle. Brief description of iron-bearing strata and mention of cobalt, copper, and nickel. Geologic map of magnetic 

data, aeromagnetic profiles, and rock analyses.

___1971, Geology and magnetic data for northeastern Crystal 

Falls area, Michigan: Michigan Geological Survey Division 

Report of Investigation 11, 14 p., maps, scale 1:6,000. Discussion of geology, stratigraphy, structure of an area of 9 mi2 , 

descriptions of the mines, and magnetic data collected by section. Two geologic sketch maps. Supplements USGS Professional Paper 570.

Wier, Karen, 1983, Metamorphic map of the Iron River I°x2° 

quadrangle, Michigan and Wisconsin: U.S. Geological Survey 

Miscellaneous Investigations Map I-1360-G, scale 1:250,000. 

Map showing the distribution of zones of metamorphic intensity developed during three periods of regional metamorphism. Brief text.

Wilband, J. T., 1978, The copper resources of northern Michigan: East Lansing, Mich., Michigan State University 

Geology Department, 66 p. Discussion of known and potential reserves of copper in northern Michigan. Includes nine 

tables of production by lode and mine, exploration diamonddrill data, and production figures. Maps and stratigraphic sections are also included.

Zietz, Isidore, Karl, J. H., and Ostrom, M. E., 1977, Preliminary 

aeromagnetic map covering most of the exposed Precambrian 

terrane in Wisconsin: U.S. Geological Survey Miscellaneous 

Field Studies Map MF-888, scale 1:250,000. Contoured map 

showing variations in total intensity magnetic field of the 

Earth in gammas.

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Zietz, Isidore, and Kirby, J. R., 1971, Aeromagnetic map of the 

western part of the northern peninsula, Michigan, and part of 

northern Wisconsin: U.S. Geological Survey Geophysical Investigations Map GP-750, scale 1:250,000. Spectrally colored 

contoured map showing variations in total intensity magnetic 

field of the Earth in gammas.

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