STATUS OF MINERAL RESOURCE INFORMATION FOR THE 

BLACKFEET INDIAN RESERVATION, MONTANA 

By 

C. A. Balster Michael Sokaski 

Billings, Montana George McIntyre 

R. B. Berg U.S. Bureau of Mines 

H. G. McClernan 

Miller Hansen 

Montana Bureau of Mines and Geology 

Administrative Report BIA-24 

1976 
CONTENTS

SUMMARY AND CONCLUSIONS ................................................. 1

INTRODUCTION ................................................................ 1

General ................................................................... 1

Geography ................................................................ 1

Physiography .............................................................. 2

GEOLOGY ..................................................................... 3

Stratigraphy ............................................................... 3

Structure .................................................................. 5

MINERAL RESOURCES .......................................................... 6

Energy Resources ........................................................... 6

Petroleum and Natural Gas ............................................. 6

General ....................................................... 6

Production and Reserves ......................................... 7

Cut Bank Oil and Gas Field ................................. 7

Reagan Oil and Gas Field .................................. 9

Blackfoot Oil Field ...................................... 10

Red Creek Oil Field ...................................... 12

Graben Coulee Oil Field .................................. 12

Landslide Butte Field ..................................... 14

Other Fields ............................................ 14

Future Possibilities ............................................. 14

Exploration Techniques ................................... 14

Probability Areas ........................................ 16

Exploration Costs ........................................ 17

Recommendations ............................................. 17

Exploration Philosophies .................................. 17

Leasing Philosophies ..................................... 18

Potential Resources ............................................ 18

Transportation and Markets ...................................... 19

Environmental and Social Effects ................................. 19

Oil Shale ........................................................... 19

Coal .............................................................. 20

General ...................................................... 20

Valier Coal Field .............................................. 20

Blackfeet Coal Field ............................................ 20
Coal Characteristics ............................................ 21

Coal Preparation ............................................... 23

Potential Resources ............................................ 23

Mining Methods ............................................... 23

Underground Mining ..................................... 23

Surface Mining .......................................... 24

Markets ..................................................... 26

Local .................................................. 26

Electrical Power Generation ............................... 27

Metallurgical Applications ................................. 28

Cement ................................................ 28

Uranium and Thorium ................................................ 28

Metallic Mineral Resources .................................................. 29

Titaniferous Magnetite ................................................ 29

Geology ..................................................... 29

Deposits ..................................................... 29

Lower Milk River District ................................. 29

Rimrock Butte District .................................... 30

Kiowa Junction District ................................... 30

Milk River Ridge District ................................. 30

Potential Resources ............................................ 30

Beneficiation ................................................. 31

Smelting ..................................................... 33

Iron ................................................... 33

Titanium ............................................... 34

Nonmetallic Mineral Resources ............................................... 34

General ............................................................ 34

Bentonite .......................................................... 34

Clay .............................................................. 34

Sand and Gravel ..................................................... 35

Transportation ...................................................... 35

SOCIAL EFFECTS FROM MINERAL RESOURCE DEVELOPMENT .................... 35

RECOMMENDATIONS .......................................................... 35

General .................................................................. 35

Oil and Gas .............................................................. 36

Coal .................................................................... 36

Titaniferous Magnetite ...................................................... 37

Nonmetallic Minerals ....................................................... 37
REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
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Status of Mineral Resource Information for The Blackfeet Indian Reservation, Montana 

C. A. Balster, Michael Sokaski, George McIntyre, R. B. Berg, H. G. McClernan, and Miller Hansen 

SUMMARY AND CONCLUSIONS 

The most important mineral resources on the 

Blackfeet Indian Reservation are oil and natural 

gas. Several productive fields occur on and near 

the reservation and continuing exploration will 

almost certainly discover others. Probabilities for 

new discoveries appear to be greater in the western 

and eastern parts of the reservation than in the 

central section. The expected costs for new discoveries in the western part of the reservation will be 

many times that for new discoveries in the eastern 

part, mainly because of the complex geology and 

depth to potentially producing formations. Gathering of additional surface and subsurface data, by 

geological mapping and geophysical surveys, is 

necessary to fully evaluate areas of greatest potential. 

Thin beds of bituminous coal are in the northcentral and southeastern part of the reservation. 

Coal for local consumption can be produced from 

these but they cannot be considered a source of 

large reserves that might compete with the thicker, 

more extensive coal beds in eastern Montana and 

elsewhere. 

Titaniferous magnetite deposits occur in Cretaceous sandstones and might be sources of titanium 

metal in the distant future. Problems in their 

development as resources include beneficiation, 

smelting, and marketing. Further study of these 

deposits is recommended, even though their current value is very limited. 

Large deposits of sand and gravel are along the 

drainages throughout the reservation. These are 

adequate for local usage but costs of transportation 

precludes their competing in markets distant from 

the reservation. 

Some clays associated with coal beds might 

find local usages in pottery making or similar 

industries but none are known to have unique 

qualities to compete successfully in markets distant 

from the reservation. 

INTRODUCTION 

General 

This report was prepared for the U.S. Bureau of 

Indian Affairs by the U.S. Geological Survey and 

the U.S. Bureau of Mines under an agreement to 

compile and summarize available information on 

the geology, mineral and energy resources, and 

potential for economic development of certain 

lands. Sources of information were published and 

unpublished reports as well as personal communication with various individuals. No field work was 

done. 

Geography 

The Blackfeet Indian Reservation includes 

about 2,400 square miles in Glacier and Pondera 

Counties, Montana (Figure 1). Of the total area, 81 

percent is allotted, 13 percent is privately owned, 

5 percent is non-Indian, and 1 percent is government owned (U.S. Department of Commerce, 

1974, p. 269). 

The reservation is bounded on the north by 

Canada, and on the west by Glacier National Park. 

The southern and eastern boundary is defined in 

part by Birch and Cut Bank Creeks. 

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Status of Mineral Resource Information for The Blackfeet Indian Reservation, Montana 

C. A. Balster, Michael Sokaski, George McIntyre, R. B. Berg, H. G. McClernan, and Miller Hansen 

The terrain slopes gently upward toward the 

west and is partly dissected, grassy, and nearly 

without a forest cover. The Rocky Mountains rise 

abruptly along the western edge without marked 

foothills. Elevations range from 3,800 feet along 

the eastern edge to about 9,000 feet on the northwestern boundary (Figure 2). Topographic relief of 

some lower valleys in the eastern area is as much 

as 350 feet; in the mountain foothills about 1,500 

feet; and near the highest point about 4,000 feet. 

The climate is typical of the Northern Great 

Plains with severe, cold winters, and warm-hot 

summers. Freezing temperatures are common from 

November to April. Precipitation averages about 

15-20 inches. 

The reservation drains north and east into two 

major geographic basins. Most of the drainage is 

into the Missouri River Basin by the Milk River, 

Cut Bank Creek, Two Medicine Creek and Birch 

Creek. The St. Mary River flows north from the 

northwestern corner of the reservation into Canada. 

The Indian population consists of about 6,200 

who reside on or adjacent to the reservation. 

Browning (population 1,700) (1970), the largest 

town and principal reservation supply center, 

contains the tribal headquarters. 

The reservation is served by the Burlington 

Northern Inc. railroad which passes east-west 

through Cut Bank, Browning and East Glacier 

Park. A Burlington Northern spur heading is at 

Valier southeast of the reservation. U.S. Highway 

2 is the main east-west route and U.S. Highway 89 

is a major north-south route through the area. 

Secondary roads afford access to most of the other 

sections of the reservation. 

Physiography 

The reservation's west boundary crosses Chief 

Mountain, about 4 miles south of the Canadian 

border, then veers southeasterly toward St. Mary; 

from St. Mary the boundary trends generally south 

for about 4 miles, then southeasterly again to Heart 

Butte, then due south to Birch Creek (Figure 2).

For this entire distance the boundary lies on or very 

nearly to the dividing line between the Great Plains 

on the east and the Rocky Mountains on the west. 

According to Stebinger (1916, p. 120-121), "The 

front range of the mountains rises with wall-like 

abruptness from the plains without marked foothills. . . . . the plains appear to extend indefinitely 

eastward as a single surface with monotonous 

regularity. On closer examination, however, the 

part of the plains in the area here treated proves to 

have considerable relief, with low plateau-like 

areas in places, together with extensive dissected 

tracts along the principal streams. . . the topographic types that give a distinctive character to the 

surface features in different parts of the region are 

1) high-level plains, 2) low-level plains, 3) escarpments, two of which are continuous across the 

entire area, 4) badlands, 5) glacial moraines of 

considerable extent." To this group we might add 

the extensive area of glacial lake deposits of Lake 

Cut Bank (Colton, Lemke, and Lindvall, 1961). 

Figure 3 shows the western limits of the advances 

of the continental glaciers, portions of the eastern 

limits of the mountain glaciers, and the unglaciated 

areas. This entire area is shown in greater detail by 

Alden (1932, Plate 1). In the vicinity of Cut Bank 

the glacial lake deposits border the ground moraine 

and terminal moraines of the continental glaciers. 

BIA Administrative Report 24 (1976) 2 
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Status of Mineral Resource Information for The Blackfeet Indian Reservation, Montana 

C. A. Balster, Michael Sokaski, George McIntyre, R. B. Berg, H. G. McClernan, and Miller Hansen 

To the north of Cut Bank a distinct melt-water 

channel drains across an otherwise unglaciated 

area into Lake Cut Bank from a lobe of terminal 

moraine. Southwest of Cut Bank is a larger area of 

glacial deposits left by the mountain glaciers, as 

well as remnants of the three alluvial terraces that 

formerly maintained a continuous slope back 

toward the mountain front. In the northwest corner 

of the reservation are remnants of terminal moraines, ground moraines, and several stream-cut 

terraces. Remnants of early mountain glacial 

deposits partly cemented to tillite, lie on top of the 

number one terrace remnants. 

With few exceptions, main streams on the 

Blackfeet Reservation flow east and northeast. 

Rocky Coulee and Little Rocky Coulee, north of 

Cut Bank, flow southeast into the Cut Bank to its 

junction with the Marias River a few miles to the 

south. 

The Continental Divide lies a few miles west 

of the reservation in Glacier Park. The Hudson Bay 

Divide crosses the reservation in the northwest 

corner, and trends generally north, east of the St. 

Mary Lakes and Duck Lake, west of Goose Lake, 

and finally trending generally northeast into 

Canada on the ridge between St. Mary River and 

the North Fork of the Milk River. 

GEOLOGY 

Stratigraphy 

The stratigraphic units exposed at the surface 

and known from oil wells are listed in Table 1. 

Figure 4 is a generalized geologic map showing 

outcrop areas of formations in the east half of the 

reservation. 

In the unglaciated portions of the Blackfeet 

Indian Reservation, and in areas where erosion has 

removed the glacial deposits or alluvial terraces, 

the underlying Cretaceous formations are exposed. 

Surface exposures of the Virgelle Sandstone are 

limited to small areas along streams in T. 31 and 

32 N., R. 5 W., south of Cut Bank in both Glacier 

and Pondera Counties. 

Exposures of the Two Medicine Formation on 

the east side of the reservation are bordered by 

glacial deposits. The Two Medicine is succeeded 

toward the west by the Bearpaw Shale, the 

Horsethief Sandstone, the St. Mary River Formation, all of Cretaceous age and the Willow Creek 

Formation (Tertiary). West of the Willow Creek is 

the area called the "disturbed belt" with repeated 

exposures of Cretaceous formations. 

From the eastern boundary of the "disturbed 

belt," westward to the Belt rocks of the Rocky 

Mountain Front, the Cretaceous formations are so 

disturbed that they are not differentiated on the 

geologic map. Not shown on the geologic map are 

small areas of the Cretaceous Colorado Group, the 

Kootenai, and Paleozoic rocks in the southwest 

part of the reservation near Heart Butte. 

The formation descriptions for bedrock units 

on the Blackfeet Reservation are adapted from 

Stebinger (1914, 1916), Cobban (1955), and 

Weimer (1955). 

The Virgelle is light gray, fine to medium 

grained, and commonly crossbedded. Over wide 

areas the formation contains large brown weathering calcareous sandstone concretions. At many 

places the top of the Virgelle is titaniferous-magBIA Administrative Report 24 (1976) 3 
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Status of Mineral Resource Information for The Blackfeet Indian Reservation, Montana 

C. A. Balster, Michael Sokaski, George McIntyre, R. B. Berg, H. G. McClernan, and Miller Hansen 

netite sandstone. Near the mouth of Birch Creek 

there is a sharp contact between the Virgelle and 

the Two Medicine next above. 

The Two Medicine Formation is exposed at the 

surface in the northeast and southeast parts of the 

reservation and in the disturbed belt. This formation is almost entirely nonmarine and is about 

2,125 feet thick at the south end of the reservation. 

The formation is composed of soft, calcareous 

mudstone containing hard calcareous nodules. 

Carbonaceous beds and sandstone layers occur 

within the formation, and thin coal beds are found 

near the base. The Two Medicine covers the 

greatest area of the Cretaceous formations exposed 

on the Blackfeet Reservation. 

Above the Two Medicine are exposures of the 

Bearpaw Shale, a dark-gray marine shale containing clay-ironstone concretions, bentonite, and thin 

sandstone beds. In the south-central part of the 

reservation the Bearpaw is about 400 feet thick. 

Overlying the Bearpaw is the Horsethief Sandstone, consisting of about 360 feet of gray to buff 

coarse sandstone, massive and cross bedded, and a 

lower part grading from slabby sandstone to shaly 

sandstone toward the base. The Horsethief is a 

marine and brackish-water formation. The sandstone layers near the top carry heavy concentrations of detrital magnetite. 

Next above is the St. Mary River Formation, 

consisting mainly of greenish-gray clay and sand 

and thin, discontinuous, buff-weathering sandstone. Thin beds of red clay and a few lenticular 

beds of limestone are common, and coal beds 

occur both at the base and at the top of the formation. The St. Mary River Formation is about 980 

feet thick on the Blackfeet Indian Reservation. 

The youngest bedrock unit on the reservation is 

the Tertiary Willow Creek Formation, consisting 

of about 700 feet of clay and soft sandstone. The 

contact between the Willow Creek and the underlying St. Mary River Formation is placed on the 

color change from the grayish rocks to the dominantly red sediments of the Willow Creek Formation. The red Willow Creek rocks give rise to 

reddish soils that are easily recognized in tracing 

the limits of the formation. 

On the west side of the reservation the boundary line crosses mostly Cretaceous rocks but 

occasionally the boundary crosses outliers of rocks 

of the Belt Series (Figure 4) over thrust toward the

east over the Cretaceous formations. The Belt 

rocks in this area consist of as much as 10,000 feet 

of argillite, quartzite, and limestone beds. 

In the southwest part of the reservation are 

exposures of the Colorado Group, the Kootenai 

Formation, and even a few small exposures of 

Mississippian, Devonian and Cambrian rocks (not 

shown on Figure 4). The Colorado Group consists

of 1,500 to 2,000 feet of dark-gray shale and a few 

layers of concretionary limestone. The lower 600 

feet is made up of dark marine shale alternating 

with gray siliceous sandstone layers 20 to 50 feet 

thick. 

The Kootenai Formation consists of 900 to 

1,200 feet of red and green shale and siltstone and 

lenticular beds of sandstone. At the base is a 

conglomeratic sandstone 90 feet thick, called the 

Cut Bank sand. The Kootenai Formation is mainly 

a continental deposit. 

The Mississippian rocks are represented by the 

Madison Group, consisting of about 1,500 feet of 

limestone and dolomite. 

BIA Administrative Report 24 (1976) 4 
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Status of Mineral Resource Information for The Blackfeet Indian Reservation, Montana 

C. A. Balster, Michael Sokaski, George McIntyre, R. B. Berg, H. G. McClernan, and Miller Hansen 

The Devonian rocks consist of about 1,000 feet 

of limestone, dolomite, and shale, and the Cambrian is represented by between 1,000 and 1,500 

feet of sandstone, limestone, and shale. 

Structure 

The regional structure of the Blackfeet Reservation is influenced by the Sweetgrass Arch (Figure 5) to the east and the Lewis Overthrust on the 

west. The shallow synclinal structure that underlies 

the central part of the reservation broadens into a 

more extensive feature to the north, where it is 

referred to as the Alberta Syncline. On the south 

the syncline flattens out and is not distinguishable 

beyond Cut Bank Creek. The Cretaceous beds dip 

gently to the west off the Sweetgrass Arch, then 

dip more steeply into the synclinal area. Complex 

folding and faulting mark the eastern boundary of 

the so-called disturbed belt. At the Rocky Mountain Front, Paleozoic rocks as well as rocks of the 

Belt Series are thrust over the Cretaceous rocks of 

the disturbed belt to the east and northeast. More 

details of the structure of the Blackfeet Reservation 

are discussed in the section on petroleum geology. 

On the structure map (Figure 6) the contours

depict the generally westward dip of the beds on 

the west flank of the Sweetgrass Arch. Several 

modifications of that generality appear; one of the 

most significant is the Reagan structure, which is 

a small closure in T. 37 N., R. 7 W. It has produced both oil and gas for many years and is 

indicative of the importance that local modifications of the regional structure may have. Close 

attention to the structure map shows several 

northwest-trending plunging noses (anticlinal 

features without closure). All of these may be 

important, if they continue to the depth of the 

potentially productive rocks. One large synclinal 

area is indicated between the disturbed belt and the 

contoured area in the northern part of the reservation. 

It should be noted that the contours on the map 

were modified from the cited publications. Much 

of the information available was either shallow 

well data or surface information. The contours, 

therefore, reflect only the general structural picture 

at or near the ground surface. Typically, structural 

configuration at depth is only approximately 

followed by surface structure and may turn out to 

be much more complex. 

The large area in the western half of the reservation that is labeled as having "sharp surface folds 

underlain by thrust faults" is in the disturbed belt. 

Geologic structure is much too complex to represent on a small scale map and is often difficult to 

show on a large-scale map. (For details see 

Weimer, 1955). In a broad way, the area represents 

the eastward "dying-out" of the overthrust faulting 

of the Glacier Park area. At depth, thrust faults and 

recumbent folds are commonly encountered in 

wells drilled for oil or gas. As many as 50 or 60 

faults may be identifiable in a well before any 

Paleozoic rocks are reached. 

Very important to an understanding of the 

structural geology is the fact that folded and 

faulted potentially productive Paleozoic rocks 

underlie structurally complex Cretaceous rocks. 

The very complexity of the Cretaceous structure 

adds to the difficulty of exploring for the underlying features that may contain oil or natural 

gasfields. 

BIA Administrative Report 24 (1976) 5 
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Status of Mineral Resource Information for The Blackfeet Indian Reservation, Montana 

C. A. Balster, Michael Sokaski, George McIntyre, R. B. Berg, H. G. McClernan, and Miller Hansen 

MINERAL RESOURCES Montana's first commercial oil production. Most 

significant to this report is the fact that Somes' 

Energy Resources discovery was only a few miles from the Blackfeet 

Indian Reservation and is now covered by the 


	���	��
�	� waters of Sherburne Lake. 

Although production from that oil field in the 

�� Swift Current valley didn't last, it marked the 

beginning of the development of an oil and gas 

Before Glacier National Park was established, industry of major importance to the state's econa prospector named Sand D. Somes was looking omy. Since 1903, several fields have been discovfor copper along Swift Current Creek near what is ered on the Blackfeet Indian Reservation, and it 

now Many Glaciers Lodge (Douma, 1953). While seems likely that several more fields will be found 

cleaning out his workings after blasting, he found (Figure 7).

pools of oil. Those pools of oil soon became more A summary of past drilling activity on or near 

exciting than rocks with no copper shows, and by the reservation is given in Table 2, which lists both 

1902 Mr. Somes had started drilling. By the spring wildcat and developmental drilling in Glacier 

of 1903, he had drilled to a depth of 500 feet and County, Montana, from 1962 to 1974. 

found oil. He is thus credited with finding 

TABLE 2 

Summary of Drilling in Glacier County, Montana 

Wildcat wells Development wells Total Footage

Year Dry Oil Gas Dry Oil Gas wells drilled

1962 3 0 0 3 21 27 83,273 

1963 0 0 1 5 10 2 18 59,912 

1964 3 1 0 12 13 0 29 104,939 

1965 4 2 0 14 19 0 39 124,671 

1966 11 1 0 12 37 2 63 205,135 

1967 5 0 0 9 12 2 28 87,028 

1968 1 2 2 5 3 0 13 38,923 

1969 3 0 0 3 35 0 41 133,826 

1970 3 0 2 2 11 3 21 87,503 

1971 8 0 0 4 16 1 29 108,740 

1972 2 0 0 6 27 4 39 120,832 

1973 2 1 0 2 13 1 19 52,978 

1974 2 0 0 9 10 2 23 69,697 

Source: Department of Natural Resources and Conservation of the State of Montana, Oil and Gas Conservation 

Division. 

BIA Administrative Report 24 (1976) 6 
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Status of Mineral Resource Information for The Blackfeet Indian Reservation, Montana 

C. A. Balster, Michael Sokaski, George McIntyre, R. B. Berg, H. G. McClernan, and Miller Hansen 

Stratigraphic units on the reservation that are 

productive of hydrocarbons include the carbonate 

rocks of the Madison Group (Table 1), sandstone

beds of the Kootenai Formation, and to a small 

extent, sandstone beds of the Blackleaf Formation. 

These units are not the only potentially productive 

rocks, as significant shows have been found in 

additional zones on or near the reservation, and 

these zones should be regarded as prospective. In 

January 1976, for example, it seems that production from Devonian rocks has been established 

from a well only about 30 miles from the reservation. Oil shows were first seen in Devonian rocks 

of the area in the early 1930's, but production did 

not occur until more than 40 years later. Shows 

have also been found in Cambrian rocks (Flathead 

Quartzite) in the area, but production has never 

been established. 

Each of the porous and permeable rock units of 

the area should be regarded as potentially productive of oil or natural gas. Units of particular importance are the Blackleaf Formation, Kootenai 

Formation, Madison Group, and Jefferson Group. 

As exploration proceeds, the increased geologic 

knowledge will permit a better evaluation of the 

characteristics of these units. 

Stratigraphy of the Blackfeet Indian Reservation is moderately complex in detail but relatively 

simple in general. Most of the thick units as shown 

in the stratigraphy sequence (Table 1) are continuous throughout the area, but many of the thinner 

units are markedly lenticular. In some areas thickness variations take place over very short distances. If such short-range variations can be found 

in the proper structural attitudes, they may form 

stratigraphic traps for hydrocarbons, which should 

be one of the major objectives of the search for oil 

and gas on the reservation. 

Two cross sections (Figure 8) show, in a

general way, the major stratigraphic relations in the 

area. The wells for the cross sections were chosen 

to show the stratigraphy to as great a depth as 

possible and across areas of typical variability. The 

cross sections do not show details of stratigraphic 

variation, but they indicate typical thickness and 

structural variations. 

�
��	���	��

Three oil, and two oil and gas fields have been 

discovered on or near the Blackfeet Reservation; 

and additional discoveries are probable (Figure 7).

Several one-well and two-well pools that failed to 

develop into commercial ventures are not included 

in these fields. 

�
	���	��	���	�	���

The Cut Bank oil and gas field (Figure 1 and 

Figure 7) is about 30 miles long, 5 to 10 miles 

wide, and extends north and south of the town of 

Cut Bank. Most of this oil field is east of the 

reservation. In 1960, production was 2,077,933 

barrels of oil, of which 438,957 barrels was from 

Indian land (Hubbard and Henkes, 1962, p. 27). 

Since that time oil may have been produced on the 

reservation, but specific production records have 

not been found. 

Production through 1974 was 141,286,000 

barrels. Yearly production, including present 

reserves, are listed in Table 3. Gas production from

this and the Reagan field is listed in Table 4. 

BIA Administrative Report 24 (1976) 7 
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Status of Mineral Resource Information for The Blackfeet Indian Reservation, Montana 

C. A. Balster, Michael Sokaski, George McIntyre, R. B. Berg, H. G. McClernan, and Miller Hansen 

TABLE 3 

Oil Production from the Cut Bank Field 

Production from Kootenai Formation

 Producing Oil 

Year wells (barrels) 

Production from Madison Group

Producing Oil

wells (barrels) Shut-in

1966 1,139 3,902,643 

1967 1,139 3,259,049 

1968 729 3,673,177 

1969 714 4,837,708 

1970 727 5,300,919 

1971 830 5,441,493 

1972 926 4,669,512 

1973 844 3,916,348 

1974 863 3,303,815 

39 135,908

39 133,374

31 118,313

33 115,756

28 114,332 29

27 99,568 29

27 88,985 29

27 89,256 29

28 89,423 29

Kootenai cumulative production to 1-1-75 was 134,953,000 barrels. Madison cumulative production to 1-1-75 was 6,333,000 barrels.

Kootenai reserves as of 1-1-75 were estimated to be 45,047,000 barrels. Madison reserves as of 1-1-75 were estimated to be 967,000 barrels.

Note: Cumulative production and reserves are given to closest 1000 barrels.

Source: Dept. of Natural Resources and Conservation of the State of Montana, Oil and Gas Conservation Div., Annual Reviews, 1966-1974.

The production peaks in 1970 and 1971 were due to water flooding the Kootenai Formation (Dept. of Natural Resources and Conservation

of the State of Montana, annual reviews, 1966 to 1973 inc.)

TABLE 4 

Gas Production from the Cut Bank and Reagan Gas Fields 

Production Producing 

Year (Mcf) formation 

Producing wells

 Kootenai Formation Madison Group

Cut Bank Reagan Cut Bank Reagan

field field field field

1960 11,231,488 Kootenai* 

1961 12,377,473 Kootenai 

1962 8,618,812 Kootenai 

1963 7,198,429 Kootenai 

1964 7,484,591 Kootenai 

1965 8,292,024 Cut Bank & Sun River 

1966 8,253,797 Cut Bank & Sun River 

1967 9,497,010 Cut Bank & Sun River N.A.*** N.A. N.A. 

1968 7,811,914 Cut Bank & Sun River 170 0 2 1 

1969 7,308,722 Cut Bank & Sun River 133 0 2 1 

1970 6,696,872 Cut Bank & Sun River 135 0 Shut-in 1 

1971 11,072,365 Cut Bank & Sun River 135 0 Shut-in 1

 & Blackleaf** 

1972 4,068,780 Cut Bank & Sun River 129 0 Shut-in 1 

1973 3,274,900 Cut Bank & Sun River 129 0 Shut-in 1 

1974 2,350,799 Cut Bank & Sun River 139 0 Shut-in 0 

*Kootenai Formation includes Moulton, Sunburst, and Cut Bank sands.

**Blackleaf production is from West Reagan. Discovered in 1970. The gas is injected into the Reagan oil field as a secondary recovery

agent. In 1971, there were eight Blackleaf gas wells.

***The number of wells producing gas before 1968 is not available(N.A.).

Source: Department of Natural Resources and Conservation of the State of Montana, Oil and Gas Conservation Division, Annual Rev iew,

1960-1974.

BIA Administrative Report 24 (1976) 8 
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Status of Mineral Resource Information for The Blackfeet Indian Reservation, Montana 

C. A. Balster, Michael Sokaski, George McIntyre, R. B. Berg, H. G. McClernan, and Miller Hansen 

According to Perry (1960, p. 38), the Cut Bank 

gas field was discovered in 1926 by a well drilled 

in sec. 1, T. 35 N., R. 5 W. Initial production was 

about 8 million cubic feet of gas per day from a 

depth of 2,780 feet. Since no pipeline was available, the well was plugged and abandoned. In 

1929, a second well, 81⁄2 miles to the southwest, 

found oil and gas in the same formation, although 

it was structurally 250 feet lower. Productive zones 

were found in the Cut Bank Sandstone at the base 

of the Kootenai Formation. Intensive drilling did 

not begin until 1931 when 20 wells were drilled 

northeast of Cut Bank. Only one hole was dry. 

Each well averaged 12,700,000 cubic feet of gas 

per day. 

In 1932, the presence of oil in one of the wells 

(Drumheller-Yunck) led to downdip drilling and 

the Cut Bank oil field was discovered (Perry, 1960, 

p. 38 and 39). As of January 1936, development 

drilling had proven a gas-producing area 18 miles 

long and 3 to 5 miles wide, and an oil-producing 

area 20 miles long and 3 to 22 miles wide. Oil 

production peaked during 1942, 1943, and 1944 at 

about 51⁄2 million barrels of oil annually (about 

15,000 barrels daily). In December 1950, there 

were 1,171 oil wells and 162 gas wells. 

The Carter-Brindley well No. 1 (sec. 12, T. 36 

N., R. 6 W.) discovered oil and gas in the upper 

part of the Madison Group at a depth of about 

3,090 feet in the summer of 1945. Within two 

years approximately one-tenth of the Cut Bank oil 

production was from the Madison Group (Sun 

River Dolomite) (Perry, 1960, p. 39). 

Now that several hundred wells have been 

drilled, it is known that the Cut Bank field is a 

stratigraphic trap. The oil and gas were trapped in 

sandstone bodies and in limestone layers that 

showed distinctly limited areas of porosity and 

permeability. Structure contributes to the trap only 

because it tilts the limited sand bodies and affords 

a completed trapping mechanism. 

The main producing zone at Cut Bank is at or 

near the base of the Kootenai Formation. The 

Kootenai has a total thickness of about 500 feet on 

the east side of the field and as much as 650 feet on 

the west, within a horizontal distance of about 10 

miles. The formation is an intermingled series of 

river-laid, flood-plain, and near-shore deposits 

consisting of mudstones and shales with lenticular 

siltstones and sandstones. Most of the sandstones 

are in the lower third of the formation. 

The three producing sandstone zones, in the 

lower 150 to 200 feet of the Kootenai Formation, 

are the upper Moulton, the middle Sunburst, and 

the basal Cut Bank zones, with the latter being the 

most important oil and gas reservoir (Perry, 1960, 

p. 40).

The Cut Bank sand zone is present throughout 

the field. The thickness averages about 45 feet, the 

porosity about 15 percent, and the permeability 

about 115 millidarcys. However, the characteristics 

of the sand vary from well to well, and dry holes 

and poor wells are found throughout the field. 

Initial production of the wells was as much as 300 

barrels of oil per day (Perry, 1960, p. 40, 41) 

�����	��	���	�	���

The Reagan oil and gas field lies about 10 

miles northwest of the north end of the Cut Bank 

field and 1 mile south of the Canadian border 

(Figure 1 and Figure 7). It is about 5 miles long 

BIA Administrative Report 24 (1976) 9 
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Status of Mineral Resource Information for The Blackfeet Indian Reservation, Montana 

C. A. Balster, Michael Sokaski, George McIntyre, R. B. Berg, H. G. McClernan, and Miller Hansen 

and 1 mile wide (Perry, 1960, p. 43) and is completely within the reservation. 

Surface geologic mapping provided the basic 

information for locating the discovery well of 

Reagan field. Core drilling was used to supplement 

and verify the presence of the small anticlinal 

closure that forms the trapping mechanism. Later, 

seismic information showing that the structure 

extended northward encouraged the drilling that 

expanded the field almost to the Canadian border. 

The Reagan field is recognized as an accumulation of oil and gas that is trapped in an anticlinal 

closure. The eastern edge of the anticline, however, 

is modified by a normal fault, and the field seemingly is bounded by the fault. 

The discovery well, Reagan Associates Tribal 

194-1 in sec. 22, T. 37 N., R. 7 W., was completed 

March 29, 1941. Initially it produced 6 million 

cubic feet of gas per day from a total depth of 

3,869 feet. One of the deepest wells in the field 

penetrated Cambrian strata. No production was 

found below the Madison Group. The Cambrian 

test well (Figure 8--Blackfeet Tribal 194-12) was 

drilled to a depth of 6,258 feet by the Union Oil 

Co. The field has a combination gas and water 

drive. A pressure maintenance project was started 

in August 1961 by injecting gas into the oil reservoir (Dept. of Natural Resources and Conservation 

of the State of Montana, 1965, p. 32). 

The following field data are from Perry (1960, 

p. 43): "An active drilling campaign got underway 

in 1947 after the Montana Power Company Tribal 

335 No. 1 (sec. 10, T. 37 N., R. 7 W.) flowed 50 

barrels of oil and 12 million cubic feet of sulfurous 

gas per day. By the end of 1948, eight more wells 

had been drilled. After being acidized, each flowed 

from 25 to more than 400 barrels of oil per day. 

Gas pressure was about 1,100 pounds per square 

inch. Depths varied between 3,745 feet and 3,810 

feet. The producing zone, about 20 feet of porous 

limestone or dolomite, is from 30 to 60 feet below 

the top of the Madison Group. Sulfurous water 

occurs beneath the productive zone. Total production in 1950 was 182,334 barrels of oil from 18 

wells. Production peaked in 1953 at 250,890 

barrels of oil per year. In 1958, 45 wells produced 

only 166,634 barrels of oil. The specific gravity of 

the oil is from 31o to 36o A.P.I." 

Production from the Reagan field through 1974 

was 5,666,364 barrels of oil. Yearly production 

and estimated present reserves, are given in Table 

5. With the help of secondary repressuring, ultimate recovery is estimated to be about 7 million 

barrels. In other words, there should be about 1.3 

million barrels of oil remaining to be produced 

from the Reagan field after 1974. 

���	��	���

The Blackfoot field is in T. 37 N., R. 6 W. and 

covers all or part of secs. 2, 3, 10, 11, and 14 

(Figure 1). The field is east of the reservation and 

underlies about 480 acres (Hubbard and Henkes, 

1962, p. 29). 

Surface mapping checked by detailed seismic 

mapping led to the discovery of the Blackfeet field 

in October 1956. Union Oil No. 1 Muntzing was 

completed at a depth of 3,542 feet, producing 15 

barrels of oil per day from the uppermost part of 

the Madison Group. It was recompleted about a 

year later, producing 55 barrels of oil per day from 

the Cut Bank Sandstone. 

BIA Administrative Report 24 (1976) 10 
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Status of Mineral Resource Information for The Blackfeet Indian Reservation, Montana 

C. A. Balster, Michael Sokaski, George McIntyre, R. B. Berg, H. G. McClernan, and Miller Hansen 

A dozen or more wells were drilled in a square 

mile area. Ten were producers from either the Cut 

Bank sand or the Madison Group (Sun River 

Dolomite). Initial flows from the wells in the 

Madison were about 100 barrels of oil per day with 

rapid declines to about 30 barrels per day. Initial 

production of wells in the Cut Bank was about 40 

barrels per day and slowly declined to about 30 

barrels per day. In 1958, 11 Madison Group wells 

and four Cut Bank sand wells produced 97,781 

barrels of oil (Perry, 1960, p. 43). 

The Cut Bank pay zone is about 18 feet thick 

with a porosity of about 15 percent. The Madison 

zone averages about 10 feet thick with a porosity 

of about 14 percent (Dept. of Natural Resources 

and Conservation of the State of Montana, 1974). 

Cumulative production from the Blackfoot 

field through 1974 was 1,026,547 barrels of oil. 

Yearly production, including present reserves are 

given in Table 6. 

The Blackfoot field is another example of an 

accumulation trapped by a faulted anticlinal closure, but either stratigraphic characteristics of the 

Madison Group or hydrodynamic components 

cause the oil field to the displaced northward from 

the top of the closure. Both the Cut Bank sandstone and the Madison Group show great variation 

in porosity and permeability, and the field should 

probably be regarded as a combination 

stratigraphic-structural trap. 

The Blackfoot field is small, only 160 acres 

productive from the Cut Bank Sandstone and 480 

acres productive from the Madison Limestone. Oil 

from the Cut Bank Sandstone is 30o A.P.I. gravity; 

and that from the Madison Limestone, 25o A.P.I. 

gravity. Estimated ultimate recovery is about 1.2 

million barrels; more than a million barrels having 

been produced since 1956, a little less than 

130,000 barrels of oil probably remains to be 

produced. It must be concluded that the field is 

about depleted. 

TABLE 5 

Oil Production from the Reagan Field, Madison Group Production 

Oil Producing Oil Producing wells

Year (barrels) Wells Year (barrels) Oil Shut-in

1960 190,334 50 1968 266,539 48 ? 

1961 152,764 50 1969 270,257 48 ? 

1962 210,584 43 1970 255,426 50 ? 

1963 231,624 47 1971 223,986 46 19 

1964 223,451 48 1972 212,167 44 19 

1965 208,110 51 1973 186,958 44 19 

1966 208,668 46 1974 170,261 44 19 

1967 250,923 47 

Cumulative production to 1-1-75 was 5,666,364 barrels. 

Reserves as of 1-1-75 were estimated to be 1,335,000 barrels. 

Source: Department of Natural Resources and Conservation of the State of Montana, Oil and Gas Conservation Division,

Annual Reviews, 1960-1973.

BIA Administrative Report 24 (1976) 11 
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Status of Mineral Resource Information for The Blackfeet Indian Reservation, Montana 

C. A. Balster, Michael Sokaski, George McIntyre, R. B. Berg, H. G. McClernan, and Miller Hansen 

TABLE 6 

Oil Production from the Blackfoot Oil Field 

Production Cut Bank Formation Sun River Formation

Year (barrels) producing wells producing wells

1966 50,278 5 7 

1967 41,849 5 8 

1968 33,423 Shut-in 6 

1969 29,653 Shut-in 7 

1970 29,212 Shut-in 6 

1971 25,218 6 Shut-in 

1972 19,812 5 Shut-in 

1973 16,217 3 Shut-in 

1974 13,509 4 Shut-in 

Cumulative production to 1-1-75 was 1,026,547 barrels.

Reserves as of 1-1-75 were estimated to be 123,000 barrels.

Source: Department of Natural Resources and Conservation of the State of Montana, Oil and Gas Conservation Division,

Annual Reviews 1966-1974. 

��	��	��	���

The Red Creek oil field, near the Canadian 

border, is about 7 miles east of the reservation 

(Figure 1). Production is from a stratigraphic trap 

in the Cut Bank sand and a structural trap in the 

Madison Group (Sun River Dolomite) (Dept. of 

Natural Resources and Conservation of the State of 

Montana, 1974, p. 23). 

The discovery well, G. S. Frary #1 Morberly, 

was completed in January 1958, in sec. 1, T. 37 N., 

R. 5 W. The wells initially produced 1,500,000 

cubic feet of gas per day from a total depth of 

2,656 feet. 

In June 1965, a waterflood project was started 

in the Cut Bank sand using water from Madison 

strata which has a natural water drive (Dept. of 

Natural Resources and Conservation of the State of 

Montana, 1965, p. 32). The waterflood started 

yielding results in 1967 (Table 7).

Cumulative production from the Red Creek 

field through 1974 was 4,742,000 barrels. Yearly 

production, including present reserves, are given in 

Table 7. 

��	�
	��	���

The Graben Coulee oil field, near the Canadian 

border, is about 6 miles east of the reservation 

(Figure 1). Production is from the Sunburst, Cut

Bank Formations, and the Madison Group. All the 

reservoirs are structural-stratigraphic traps and 

have depletion drives (Dept. of Natural Resources 

and Conservation of the State of Montana, 1974, p. 

15). The discovery well, Cardinal Petroleum #1 

McAlpine, was completed December 7, 1961 in 

sec. 3, T. 37 N., R. 5 W. Initial production of 56 

barrels of oil per day was from the Sunburst Formation at a total depth of 2,816 feet (Dept. of 

BIA Administrative Report 24 (1976) 12 
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Status of Mineral Resource Information for The Blackfeet Indian Reservation, Montana 

C. A. Balster, Michael Sokaski, George McIntyre, R. B. Berg, H. G. McClernan, and Miller Hansen 

Natural Resources of the State of Montana, 1965, 

p. 22).

Cumulative production from the Graben 

Coulee field through 1974 was 1,043,092 barrels 

of oil. Yearly production, including estimated 

present reserves, are given in Table 8. 

TABLE 7 

Oil Production from the Red Creek Field 

Cut Bank Formation

 Production Number of wells

Year (barrels) Producing Shut-in 

Sun River Formation

 Production Number of wells

(barrels) Producing Shut-in

1963 165,648 N.A. N.A. 343,789 N.A. N.A. 

1964 150,710 N.A. N.A. 322,282 N.A. N.A. 

1965 127,534 N.A. N A. 216,224 N.A. N.A. 

1966 121,473 16 N.A. 178,629 20 N.A. 

1967 151,162 10 N.A. 175,106 20 N.A. 

1968 152,622 9 N.A. 153,348 17 N.A. 

1969 139,648 9 N.A. 114,967 14 N.A. 

1970 117,977 9 N.A. 97,877 12 N.A. 

1971 94,866 8 2 98,328 12 9 

1972 60,649 7 2 105,181 12 9 

1973 64,790 7 2 111,252 12 9 

1974 64,935 7 2 83,600 12 9 

Cut Bank cumulative production to 1-1-75 was 1,983,000 barrels.

Madison cumulative production to 1-1-75 was 2, 759, 000 barrels.

Cut Bank reserves as of 1-1-75 were estimated to be 1,017,000 barrels.

Madison reserves as of 1-1-75 were estimated to be 741,000 barrels.

Note: Cumulative production and reserves are given to closest 1000 barrels. N.A. (information not available).

Source: Department of Natural Resources and Conservation of the State of Montana, Oil and Gas Conservation

Division, Annual Reviews.

BIA Administrative Report 24 (1976) 13 
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Status of Mineral Resource Information for The Blackfeet Indian Reservation, Montana 

C. A. Balster, Michael Sokaski, George McIntyre, R. B. Berg, H. G. McClernan, and Miller Hansen 

TABLE 8 

Oil Production from the Graben Coulee Oil Field 

Number of wells, formation

 Production Cut Bank Sunburst 

Year (barrels) Formation Formation 

Dual wells,

Madison Cut Bank-Madison

Group

1966 190,100 20 0 22 0 

1967 139,266 20 0 22 0 

1968 100,394 20 1 7 17 

1969 68,800 18 2 7 17 

1970 53,061 18 2 7 2 

1971 45,628 23 1 0 3 

1972 45,729 17 1 0 3 

1973 80,188 17 1 0 3 

1974 101,386 28 1 0 3 

Cumulative production to 1-1-75 was 1,043,092 barrels. 

Reserves as of 1-1-75 were estimated to be 1,457,000 barrels.

Note: No secondary recovery has been attempted.

Source: Department of Natural Resources and Conservation of the State of Montana, Oil and Gas Conservation Division, Annual Reviews. 

�����	
	��� (Figure 7) 

Early in 1968, the Montana Power Company 

completed the No. 1 Thelen as an oil well at a 

depth of 4,725 feet in the Sun River Dolomite. It is 

in sec. 13, T. 37 N., R. 9 W., and is the discovery 

well for Landslide Butte field. The field has had 

only two productive wells, and records of production and reserves are not readily available. The oil 

is 41o A.P.I. gravity, and productivity of the wells 

is small. 

�	���

A one-well gas field located in T. 31 N., R. 11 

W., has never been named. It is capable of gas 

production from rocks of the Madison Group but 

has never been extended. No reserve or production 

data are available. 

�

	����

����	��


Modern technology is capable of marvelous 

accomplishments, but it has never developed a 

method of successfully finding oil or gas with a 

high rate of success. This fact is not surprising if 

we realize the complexity of the subsurface structure and lithologic characteristics of the rocks 

involved. 

Basically, a hydrocarbon trap is composed of 

(1) a porous reservoir rock, (2) a structural position 

that allows the oil and gas to rise to a position of 

BIA Administrative Report 24 (1976) 14 
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Status of Mineral Resource Information for The Blackfeet Indian Reservation, Montana 

C. A. Balster, Michael Sokaski, George McIntyre, R. B. Berg, H. G. McClernan, and Miller Hansen 

higher elevation (lower pressure environment), and 

(3) a nonpermeable barrier having a configuration 

that prevents escape of the hydrocarbons upward. 

Structural configuration may be mapped by various 

methods, and the lithologic character of the rocks 

may be predicted to a degree, but errors in both 

techniques lead to many failures when the exploratory test is drilled. 

Geologic structure may be mapped by using 

surface geologic information, well data, or seismic 

data. Each method has limitations. Structure as 

expressed in surface beds may not extend to the 

depth of the prospective zones and cannot be relied 

upon to define accurately structural conditions 

where the explorationist needs to know them. 

Information from wells already drilled is obviously 

a hindsight method because when the information 

is available the presence or absence of hydrocarbons is already known. Subsurface data are very 

useful, but accurate interpretation between control 

points is usually difficult. Seismic data are often 

useful, but it must be remembered that the method 

is an indirect one and involves the measurement of 

travel times of energy through the rock complex 

and does not show the rock configuration directly. 

When someone prepares to spend money to drill an 

exploratory well, he is usually well advised to use 

all the data available to him at a reasonable cost. 

"Reasonable cost" is usually defined by the degree 

of risk that the explorationist is willing to take. 

The search for prospective hydrocarbon traps is 

tempered by the characteristics of the area under 

study. If the prospective trap is mostly likely to be 

of a purely stratigraphic nature, well data, regional 

trends, and drilling are used in exploration. If the 

conjectured trap is estimated to be entirely of the 

structural type, surface geology and seismic information are usually used. Very often the evidence 

suggests that traps may be combination stratigraphic and structural, and all methods are used. 

On the reservation, stratigraphic, structural, and 

combination traps are known to exist. The Cut 

Bank field is a good example of a stratigraphic 

trap, the Reagan field is a structural trap, and the 

Blackfoot field seems to be a combination type of 

accumulation. 

As a generalization, some parts of the reservation are more likely to have a particular type of 

trap. By no means should such a generalization be 

taken to mean that the other type of traps are not 

likely to be found in an area characterized as being 

a likely environment for one type of trap. The 

western part of the reservation, for example, is 

most likely to have strictly structural traps. Figure 

9 illustrates the structural configuration that develops where an overthrust fault displaces beds and 

results in what is known as "drag folding." Distortion of the bed probably begins as a fold 

(anticline), which increases in displacement as 

compressional stress results in deformation. Ultimately, the deformation becomes so great that the 

beds are no longer competent to withstand breaking, and a fault occurs. The result is folding along 

the fault surface that gives the appearance of being 

caused by dragging along the broken surface. 

After an overthrust fault occurs, subsequent 

folding is very likely to cause deformation of the 

displaced beds as shown in Figure 10. In a sense 

such a structure is an anticlinal trap but not a 

simple one. In this situation multiple traps may 

develop in the same formation because the thrust 

faulting causes repetition of beds, which the drill 

BIA Administrative Report 24 (1976) 15 
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Status of Mineral Resource Information for The Blackfeet Indian Reservation, Montana 

C. A. Balster, Michael Sokaski, George McIntyre, R. B. Berg, H. G. McClernan, and Miller Hansen 

penetrates vertically. These types of folding are 

important in the western part of the Blackfeet 

Reservation because they are the most likely type 

of trap in the disturbed belt. The large gas fields of 

the disturbed belt of Alberta are in traps of these 

types, and it is worthy of note that fields such as 

Waterton Lakes and Pincher Creek in Canada 

contain more recoverable gas than Montana's entire 

proven gas reserves. Those fields should indicate 

the great potential for finding gas in Montana's 

disturbed belt. 

Although the disturbed belt is most likely to be 

characterized by structural type accumulations, the 

probability is great that some stratigraphic influences will be apparent in many of the traps. Carbonate reservoirs such as in the Madison Group 

typically have variable porosity and permeability. 

It may be that many of the traps, when discovered 

and analyzed, will have stratigraphic changes as 

part of the trapping mechanism. 

Most of the rest of the reservation (other than 

the disturbed belt) will be likely to have both 

stratigraphic traps and combination structuralstratigraphic traps. The area just southwest of the 

Cut Bank field is likely to be dominated by stratigraphic accumulations. It is fairly certain that all of 

the purely structural traps have been found, but 

there may be unknown structures in Devonian or 

Cambrian rocks. Updip porosity "pinchouts" will 

probably account for most of the oil and gas found 

on the reservation outside of the disturbed belt. 

It must be pointed out that exploration for new 

hydrocarbon reserves is no longer a simple and 

easy task. The brief, and consequently simplified, 

discussion of the probable trapping situations on 

the reservation should serve to illustrate the point. 

Additional discoveries are almost a certainty, 

however, if exploration continues. 

���	�

Any attempt to assign probabilities of discovering significant reserves of oil or gas must be 

subjective. Such probabilities are someone's 

educated evaluation, and only a means of transferring integrated information beyond that which can 

be put on a few printed pages. 

Figure 11 attempts to rate the various areas of 

the reservation as to the probability of discovering 

significant hydrocarbon reserves. Probability of 

directional porosity and permeability changes and 

structural conditions throughout the entire section 

of sedimentary rocks were considered. Much of the 

area is characterized by scarcity of data, so interpretation of trends must be utilized. The resulting 

map shows five categories, of which category "1" 

represents the greatest probability of discovery, 

and category "5" represents the least. 

Nationally, the success rate in wildcat drilling 

is about one discovery in 13 attempts, and one 

discovery of economic reserves in about 22 attempts. This means that only a little more than half 

of the discoveries pay out. These success rates may 

be used to consider the probability ratings on the 

map in this way. If the area rated "3" is about 

equivalent to the national average for discovery 

rates, one might expect that 22 exploratory wells 

would need to be drilled (on the average) before an 

economic discovery was made. By the same reasoning, the areas rated as "1" should have a considerably higher probability of a significant discovery, 

but there is no way of putting an accurate number 

BIA Administrative Report 24 (1976) 16 
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Status of Mineral Resource Information for The Blackfeet Indian Reservation, Montana 

C. A. Balster, Michael Sokaski, George McIntyre, R. B. Berg, H. G. McClernan, and Miller Hansen 

on that likelihood. It may be in the vicinity of one 

discovery in about 15 attempts. On the other end of 

the scale, wells in the areas rated "5" may have 

about one chance in 40 of being successful. In the 

final analysis, the actual numbers are unimportant, 

it is the relative chance of success that is meaningful for this report. 

����	�

There are many ways of calculating exploration 

costs. The map showing relative exploration costs 

does not reflect dollars and cents per barrel of oil, 

but is only an attempt to rate each part of the 

reservation as related to other parts (Figure 12).

It is obvious that some types of traps should be 

easier to find than others. Structural traps, for 

example, in a structurally simple province, are 

relatively easy to identify. As the structures become more complex, they become harder to find. 

Stratigraphic variations that lead to trapping of 

hydrocarbons are typically difficult to find and 

require more exploratory holes to discover a new 

accumulation of hydrocarbons. 

Let us assume that exploration investigations 

were begun by mapping surface geology, supplemented with all of the subsurface data available 

from previous drilling, then progressed through 

seismic work, and resulted in the decision to drill 

a test well. Total investment to that point would be 

different across the reservation by a factor of, 

perhaps, two. Investigations up to the point of 

drilling a test well in the disturbed belt might cost 

twice as much as the same techniques would cost 

in the vicinity of the Cut Bank field. The cost of 

drilling the test well, however, is vastly different. 

A well drilled to test the Madison Limestone in the 

vicinity of the Cut Bank field may cost only about 

one percent of the cost of a well in parts of the 

disturbed belt. 

These factors were all considered in constructing the map of relative exploration costs (Figure 

12). No actual costs should be applied to the areas, 

but the area rated as "1" should be least expensive 

to explore and the area rated as "5" should be the 

most expensive. 

������

����	���

Generally speaking, exploration is governed by 

many factors. Availability of funds, governmental 

attitudes, marketing considerations, taxation, 

personnel, and other factors need not be extensively considered here. Of particular importance 

here is the relationship of the prospector to the 

land-owner and holder of the mineral rights. 

Investment of money in a risk venture such as 

the search for oil or gas is a type of business totally 

unfamiliar to most people. For someone to be 

willing to spend large sums of money in hopes of 

a one in 20, or less, chance of receiving any return 

seems totally unreasonable to most people. It is the 

chance of a very large return that encourages such 

an investment. At the same time the investor can 

scarcely be careless in considering all factors 

involved or he would be foolish and would rapidly 

be reduced to the state of no longer having money 

to invest. 

When it is considered that the cost of drilling 

an exploratory test to the Madison Limestone in 

BIA Administrative Report 24 (1976) 17 
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Status of Mineral Resource Information for The Blackfeet Indian Reservation, Montana 

C. A. Balster, Michael Sokaski, George McIntyre, R. B. Berg, H. G. McClernan, and Miller Hansen 

the disturbed belt may cost a million to several 

million dollars, it quickly becomes apparent that 

large companies, with large financial resources will 

be involved. The shallower areas with less structural complexity will more likely be the area in 

which the smaller investor will be willing to 

explore. 

Whoever the explorationist may be, large 

company or small independent, he must be able to 

see the possibility of a satisfactory return on his 

investment. 

����	���

When a lease is issued for oil or gas exploration, there may be no implication that a test well 

will be drilled on any particular tract, because 

leases are usually purchased to cover, as completely as possible, all of the probable producing 

area if a discovery is made. More often than not, 

there are no discoveries and many leases remain 

undrilled. 

Any owner may include such provisions as he 

desires when the lease is purchased, but he should 

be careful that what he requires does not unreasonably discourage exploration. The real income from 

a lease comes when oil is discovered, not from the 

rentals or bonuses on the lease itself, and dollars 

spent for bonuses cannot be spent for drilling. In 

general, it is desirable to append clauses that will 

assure (1) satisfactory care and reclamation of the 

land surface both at the well site and on all access 

roads; (2) satisfactory care of the well site if a 

discovery is made; and (3) provision for the landowner to acquire information that may be useful to 

him, such as ground-water data or information on 

other mineral resources not included in the lease. 

Some companies are willing to assist the landowner in the completion of a well as a water well 

if it is not capable of hydrocarbon production. 

An operator should always be willing to discuss and negotiate with the landowner on any 

points that may be questionable. It is important that 

both parties understand the desires of the other and 

attempt to reach an agreement that is satisfactory to 

both that will lead to exploration. Oil or gas can be 

found only by drilling and does not become a 

resource until discovered. 

When a lease is executed, the rate of the landowner's royalty is usually established. In the past, 

it has almost universally been a constant rate, with 

no change throughout the productive life of the 

wells. This practice may make a productive well 

uneconomic during the last years that it is capable 

of giving up oil or gas. 

Whenever a landowner has the opportunity, he 

should use his efforts to encourage wise production 

practices. Secondary recovery practices can sometimes be encouraged or discouraged by the landowner. On the other hand, he should be careful that 

water disposal problems, or use of water for injection do not jeopardize his water resources. 

���	�


A new oil field similar to the Cut Bank field 

would produce about 200 million barrels of oil. A 

new oil field similar to the Reagan field would 

produce about 7 million barrels and one similar to 

the Blackfoot field would net about 1.25 million 

barrels. The discovery of a Cut Bank-sized field on 

the reservation is unlikely, but immense volumes 

BIA Administrative Report 24 (1976) 18 
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Status of Mineral Resource Information for The Blackfeet Indian Reservation, Montana 

C. A. Balster, Michael Sokaski, George McIntyre, R. B. Berg, H. G. McClernan, and Miller Hansen 

of oil may be in small and subtle stratigraphic traps 

sandwiched between otherwise undistinguished 

layers of impervious rock (Gillette, R., 1974, p. 

68). Five-to 25-million-barrel fields will likely be 

discovered in relatively small traps on the reservation. 

������	���	��

The reservation is adequately served by pipelines, and refineries are nearby. There is both a 

local and a national market for oil and gas. Westco 

Refining Co. and Big West Oil Co. have refineries 

in the immediate area. The Reagan and Cut Bank 

fields have pipeline connections for oil. Continental Oil Co. has two oil pipelines (8 and 12 inches in 

diameter) crossing the reservation from the northwest to the southeast (Figure 1). Montana Power 

has a 16-inch diameter gas pipeline crossing the 

reservation from the northwest to the southeast and 

an 8-inch gas pipeline crossing the reservation 

from the southwest to the northeast. 

������	���	��	��

Oil and natural gas are closely associated 

natural resources occurring in sandstone and 

limestone reservoirs below the surface of the earth. 

Both are in short supply and can be obtained 

without adversely affecting the environment. 

Government and private experts have warned 

that the domestic effort to solve the energy shortage may trigger an even worse national water crisis 

(Tulsa Daily World, 1975, p. 20). Virtually every 

proposed method for boosting domestic energy 

production places heavy demands on local water 

supplies. Most synthetic fuels require great quantities of water in their production. However, finding 

and producing oil and gas require very little water. 

Oil and gas production could downgrade the 

local environment, but proper planning can hold 

decline in living space, wildlife, vegetation, topsoil, water resources, and air quality to a minimum. 

Royalty payments will help improve the economic base of the reservation. Also, employment 

possibilities will be enhanced if additional oil and 

gas resources were discovered and developed. 

��	�

Oil shale is known to occur within the lower 

150 feet of the Colorado Group which underlies 

the entire reservation east of the Disturbed Belt 

(Alpha, 1955, p. 137). An oil shale bed has been 

reported about 10 miles south of the reservation on 

Dupuyer Creek (Stebinger, 1918, p. 162, 163). 

This bed, about 10 feet thick, is described as 

"highly bituminous." Whether this or other oil 

shale beds extend laterally onto the reservation is 

not known. 

No significant amount of oil is expected to be 

extracted from oil shale deposits before 1985, but 

by the year 2000 oil shale is expected to supply 2 

million barrels of oil per day (Dupree and 

Corsentino, 1975, p. 45). Initially the highest-grade 

and more easily mined deposits will be developed. 

Oil shale on the reservation may eventually be a 

valuable future source of oil. 

BIA Administrative Report 24 (1976) 19 
_________________________________________________________________________________________________ 

Status of Mineral Resource Information for The Blackfeet Indian Reservation, Montana 

C. A. Balster, Michael Sokaski, George McIntyre, R. B. Berg, H. G. McClernan, and Miller Hansen 

��

��

Coal deposits of bituminous rank on the Blackfeet Reservation were examined by Stebinger 

(1916) and the discussion given here is from his 

work. 

Coal is found at three levels in the Two Medicine Formation--at the base, about 250 feet above 

the base, and at the top, below the overlying 

Bearpaw Shale (Figure 13). The coal at the base of 

the Two Medicine Formation was mined in the 

Valier coal field (Figure 13). The coal in the bed 

250 feet above the base was prospected but seemingly never successfully mined because the coal is 

either too thin (little more than 1 foot thick) or too 

dirty (as much as 30% ash). The coal at the top of 

the Two Medicine was investigated at three sites in 

and near T. 37 N., R. 8 W., and, although the coal 

is clean, it is only about 1 foot thick and is not 

minable. 

Coal also is found at two levels in the St. Mary 

River Formation--at the base and at the top. The 

coal at the base is the only coal mined in the 

Blackfeet coal field (Figure 14 and Figure 15). The

coal at the top of the St. Mary River Formation is 

known from one locality only where it is reported 

as 10 inches thick and therefore unworkable. These 

brief descriptions show that of the five coal zones 

in the two coal-bearing formations only two seams 

are of any real significance, the coal at the base of 

the Two Medicine, above the Virgelle Sandstone, 

and the coal at the base of the St. Mary River 

Formation, overlying the Horsethief Sandstone. 

	��	��	���

The Valier coal field lies in T. 31 N., R. 5 W., 

about 6 miles north of Valier (Figure 14 and Figure 

7). Several underground mines formerly were 

worked in this area. Stebinger referred to a coal 

bed 2 ft. 10 in. thick, but this measurement includes one bed of coal 1 ft. 6 in. thick, one 2 in. 

thick, and one 4 in. thick, and two partings of clay 

8 in. thick and 2 in. thick. It would probably be 

best not to plan on salvaging any of the 2 in. or 4 

in. layers of coal, and perhaps only a part of the 1 

ft. 6 in. layer. A lower coal bed in this field is 

judged too dirty to be worked, consisting of two 

layers of dirty coal more than 1 foot thick and an 8 

in. layer of good coal. The coal in the Valier field 

thins out to the north and does not extend beyond 

the south line of sec. 21, T. 31 N., R. 5 W. To the 

south the coal goes below creek level in section 31 

of the same township. No other significant coal 

deposits are known from this zone. In T. 35 N., R. 

4 W., about 12 miles north and 11 miles east of 

Cut Bank, exposures of the coal near the top of the 

Virgelle, and thus from the same zone as that of 

the Valier coal field, show as much as 9 inches of 

dirty coal. 

���	��	���

The Blackfeet field (Figure 7 and Figure 15) 

lies north and west of Browning in Townships 35 

to 36 North, Ranges 11 to 12 West. The field is 

about 12 miles long and 1 mile wide and the coal 

lies mainly in a northwest-trending syncline. On 

the west a reverse fault has carried Two Medicine 

rocks up against the coal at the base of the St. 

BIA Administrative Report 24 (1976) 20 
_________________________________________________________________________________________________ 

Status of Mineral Resource Information for The Blackfeet Indian Reservation, Montana 

C. A. Balster, Michael Sokaski, George McIntyre, R. B. Berg, H. G. McClernan, and Miller Hansen 

Mary River, thus limiting the field to the west. The 

field is limited on the east by the steep dip of the 

coal-bearing beds, which carries the coal below 

minable depth in sec. 15, T. 34 N., R. 11 W., 31⁄2 ft. 

of good clean coal is exposed. This is the thickest 

bed of coal known in the field. In section 9 of the 

same township, an exposure of 21⁄2 ft. of good coal 

was measured. In section 4 of the same township, 

a coal bed about 2 ft. thick dips east, parallel to the 

slope of the ground. Stebinger reported many 

exposures of coal in this area, and a thick layer of 

coal smut over many acres. These last two localities lie on the south slope of the Milk River Ridge, 

a gravel-covered divide between Milk River and 

Cut Bank Creek. Gravel deposits obscure the 

bedrock formations in this area. 

On the north side of the Milk River Ridge in 

sec. 18, T. 35 N., R. 11 W., two good beds of coal 

2 ft. 4 in. and 1 ft. 10 in. thick are exposed, separated by about 10 ft. of clay and sandstone. Other 

exposures to the north show coal thicknesses of l1⁄2 

to 2 ft. of clean coal, but one exposure shows only 

7 in. to 1 ft. 4 in. of dirty coal. In sec. 35, T. 36 N., 

R. 12 E., a seam of coal about 2 ft. 6 in. thick was 

mined for many years by a rancher for his own use. 

This coal has been somewhat crushed because of 

its location in the disturbed belt, and a large percentage of the coal is reduced to small fragments. 

Coal at the base of the St. Mary River Formation is exposed at numerous locations just west of 

the main outcrop of Horsethief Sandstone, which 

lies almost entirely in Townships 28 to 37 North, 

Range 9 West. These deposits are generally flat 

lying but are either too thin or too dirty to be 

workable. Several of the deposits contained 9 to 11 

in. of clean coal or 2 to 5 ft. of dirty coal. Farther 

west in the disturbed belt, coal from this same zone 

is the only coal mined in the Blackfeet field. 

Numerous other exposures of coal are known 

in the disturbed belt but they are generally too 

fractured and crushed to warrant development. 

The coal deposit in sec. 4, T. 34 N., R. 11 W., 

may well be worthy of further investigation. Concerning the coal exposure Stebinger stated, "The 

dip of the bed parallels the slope of the ground 

wherever the coal is exposed at this point, and the 

surface is therefore covered with a thick layer of 

coal smut over many acres." An area such as this 

one may be amenable to stripping, and other 

similar areas may be found through field examination. This area, Stebinger added, is on the south 

slope of Milk River Ridge, the divide between 

Milk River and Cut Bank Creek. Stebinger suggested that it was not improbable that at least a part 

of this ridge is coal land. A similar feature exists 

farther north in the southeast corner of T. 36 N., R. 

12 W., where a gravel-covered plain is at the same 

altitude as the Milk River Ridge. All three of these 

areas deserve field examination, and a follow-up 

program involving some test drilling may be in 

order. 

��	�����

The rank of the reservation coal is high-volatile 

bituminous C. Heat values range between 11,500 

and 13,000 Btu on an air-dried, mineral-matter-free 

basis. Analyses of two samples, one from the 

Blackfeet field and the other from the Valier field, 

are listed in Table 9. Although the moisture contents of 5 to 6 percent are high for bituminous 

coals (typically 1 to 3 percent), reservation coal is 

BIA Administrative Report 24 (1976) 21 
_________________________________________________________________________________________________ 

_________________________________________________________________________________

______________________________________________________________________________________________________ 

_____________________________________________________________________________________________________ 

Status of Mineral Resource Information for The Blackfeet Indian Reservation, Montana 

C. A. Balster, Michael Sokaski, George McIntyre, R. B. Berg, H. G. McClernan, and Miller Hansen 

reported not to slack or disintegrate when exposed 

to the weather (Stebinger, 1916, p. 137, 153). Coal 

from the Valier field is hard and blocky whereas 

coal from the Blackfeet field is extensively fractured and will produce a large proportion of finesized coal. The fractured nature of the coal from 

the Blackfeet field is a consequence of the extensive tectonic action that has occurred to the west of 

the reservation. 

The ash and sulfur contents are moderate to 

high; the sulfur content of the sample from the 

Valier 

field is particularly high. Coal from the reservation 

would generally require extensive upgrading to 

meet market requirements. 

TABLE 9 

Analyses of Coal from the Blackfeet Indian Reservation, Montana 

(From Stebinger, 1916, p. 138) 

Proximate 

Volatile Fixed

Locality Moist.* matter carbon Ash 

(%) (%) (%) (%) 

Ultimate Heat Content

Sulfur Hydrogen Carbon Nitrogen Oxygen Calories Btu.

(%) (%) (%) (%) (%) per lb. per lb.

Stone prospect, 5.8 36.2 45.3 12.74 1.02 5.03 64.40 1.49 15.32 6,280 11,310 

Blackfeet field 

Blair mine, 5.3 40.9 39.7 14.07 3.12 5.09 61.51 1.14 15.07 6,150 11,070 

Valier field 

*Analyses were made after the sample had been dried at a temperature a little above normal until its weight 

became constant. 

Moist, mineral-matter-free heat content is 12,960 Btu/lb. for coal from the Stone prospect and 12,880 Btu/lb. for 

coal from the Blair mine. 

BIA Administrative Report 24 (1976) 22 
_________________________________________________________________________________________________ 

Status of Mineral Resource Information for The Blackfeet Indian Reservation, Montana 

C. A. Balster, Michael Sokaski, George McIntyre, R. B. Berg, H. G. McClernan, and Miller Hansen 

��	�����

Reservation coal is not suitable for most markets (with the possible exception of the cement 

industry) unless the ash and sulfur contents are 

reduced. Modern coal preparation techniques can 

lower the ash and sulfur contents of run-of-mine 

coal by removing non-combustibles such as rock, 

shale partings, sandstone inclusions, pyrite lenses, 

sulfur balls, and other high density materials. 

Neither finely disseminated pyrite nor organic 

sulfur can be removed by mechanical cleaning. 

Coarse pyrite is easily removed. 

Costs range from about $1.20 to $2.50 per ton 

for cleaning both the coarse (plus one-fourth to 

three-eighths inches) and fine sizes of coal. These 

costs assume that the cleaning plant operates two 

shifts a day and five days a week. This operating 

schedule is rarely attained and therefore coal 

cleaning costs are more realistically estimated to 

range from $2.50 to $3.50 per ton. 

���	�


The coal resources on the reservation are 

estimated to range from 30 to 50 million tons 

(Hubbard and Henkes, 1962, p. 25). Most are in 

the Blackfeet field. The Valier field contains at 

least 2 million tons and possibly 5 million tons of 

minable coal, although the lateral extent of the 

beds in the southwestern direction is unknown. 

The Kootenai Formation is exposed only in the 

disturbed belt, and although the rocks are severely 

folded and faulted, exposures are good and the 

formation is reportedly noncoal-bearing (Stebinger, 

1916, p. 125). However, it does contain significant 

coal resources north of the reservation in British 

Columbia and Alberta as well as in the Great Falls 

region to the southeast. According to Zubovic and 

others (1961, p. A40), the coal beds in Montana 

were deposited in many small shallow basins 

rather than large basins as is common in the Eastern United States. Hence, the Kootenai Formation, 

which underlies the remainder of the reservation 

where the rocks are essentially flat-lying, could 

contain significant coal resources. This possibility 

can be explored by a drilling program, or possibly 

by examining oil and gas well logs and geophysical 

surveys of oil and gas wells that penetrate the 

Kootenai Formation. However, a hole drilled 15 

miles off the east edge of the reservation in the 

NW1⁄4 sec. 25, T. 34 N., R. 4 W. penetrated the 

entire Kootenai Formation and did not intersect 

any coal beds (Stebinger, 1917, p. 305). 

�����	�

����
��	�����

Most of the coal that has been mined in the 

United States has been mined by underground 

methods--particularly by room and pillar. Coal is 

also mined by the longwall method, with the 

retreating longwall the most popular in the United 

States. 

Underground mining in the Blackfeet field will 

present more formidable problems. The coal beds 

are thin, steeply inclined, folded, and faulted. 

Continuous mining machines and other mobile 

equipment are not practical for beds that are inclined more than 10 to 14 percent (5.7o to 8.0o). 

BIA Administrative Report 24 (1976) 23 
_________________________________________________________________________________________________ 

Status of Mineral Resource Information for The Blackfeet Indian Reservation, Montana 

C. A. Balster, Michael Sokaski, George McIntyre, R. B. Berg, H. G. McClernan, and Miller Hansen 

Consequently, much of the coal in the Blackfeet 

field cannot be mined using equipment and mining 

techniques that have been developed for flat-lying 

coal beds. However, coal beds dipping as much as 

50o are being mined in the Lorraine basin, France, 

by using a modified longwall system (Coates, et 

al., 1972, p. 97). 

Steeply inclined coal beds in the Blackfeet field 

might be mined by cutting the working face with 

high pressure water jets. The efficacy of water jets 

in breaking coal from the working face has been 

demonstrated on a limited scale in the United 

States by the Bureau of Mines, but detailed plans 

for hydraulic mining were not developed (Price 

and Bada, 1965). The shortwall mining method, a 

modification of the longwall method, has recently 

been introduced into the United States by the U.S. 

Bureau of Mines (Palowitch and Brisky, 1973, p. 

16-22). 

The general thinness of the coal beds on the 

reservation limits the applicability of underground 

mining. For example, the best minable coal bed in 

the Valier field averages only about 38 inches 

thick. Coal beds as thin as 36 inches and under the 

most favorable conditions as low as 30 inches 

(Coal Age, 1975, p. 250) can be mined. Conventional mobile mining equipment (loading machines, cutting machines, drills, and shuttle cars) as 

well as longwall equipment are available for 

mining thin beds. 

Mining costs in the Valier field can be roughly 

estimated from a recent Bureau of Mines cost 

study (Katell and Hemingway, 1975, p. 5). The 

coal selling price from a mine with an annual 

capacity of 1.03 million tons per year from a 48­

inch bed is estimated to be $14.83 per ton. The life 

of the mine is assumed to be 20 years and require 

254 employees. The coal resources in the Valier 

field now appear insufficient to support a mine of 

this size although an exploratory drilling program 

could increase resources if additional deposits are 

found in the Two Medicine and Kootenai Formations. Known resources will only support smaller 

mines. Therefore, mining costs will be higher 

because many of the economies associated with 

large-scale production will be lost. 


��	�����

An advantage of surface mining is that the 

mining cost is only one-fourth to one-third that of 

underground mining. Furthermore, coal recovery is 

high, i.e., about 90 percent. This method is applicable only to shallow coal beds. The ratio of overburden thickness to coal thickness averages about 11 

to 1 in the United States. By using this stripping 

ratio as a guide, the depth of overburden for the 

best coal bed in the Valier field would be limited 

to about 33 feet. Stripping ratios as high as 30 to 1 

are technically feasible but are practical only under 

specially favorable mining and economic conditions. 

Some flat-lying coal beds on the reservation 

might be mined by the area method. It is applicable 

to the gently rolling and relatively flat topography 

on the reservation. At an area surface mine, the 

overburden is drilled and broken by explosives. It 

is then removed and deposited in an adjacent cut 

where the coal has been removed. Next, the coal is 

drilled, blasted, loaded into trucks, and removed 

from the pit. 

BIA Administrative Report 24 (1976) 24 
_________________________________________________________________________________________________ 

Status of Mineral Resource Information for The Blackfeet Indian Reservation, Montana 

C. A. Balster, Michael Sokaski, George McIntyre, R. B. Berg, H. G. McClernan, and Miller Hansen 

Contour surface mining may find some application where the coal beds crop out on the sides of 

ravines and valleys. Mining proceeds along the 

side of a valley or hill at the elevation of the outcrop. The width of coal that is mined extends from 

the outcrop into the hillside to where the overburden thickness becomes excessive. As originally 

practiced, the spoil was simply cast downhill to 

uncover the coal. This method of overburden 

removal is now prohibited in most states, including 

Montana. To overcome the shortcomings of this 

overburden disposal method, a haulback system 

has recently been developed in which the overburden is trucked to areas where the coal has been 

removed. This method of controlled overburden 

placement greatly reduces the adverse effects of 

contour surface mining. 

Auger mining has gained wide acceptance in 

the Eastern United States. With it an auger machine bores horizontal holes as small as 19-inches 

in diameter and up to 250 feet deep into the exposed coal bed. Capital costs are low and productivity is high, but recovery is low, about a maximum of about 50 to 60 percent. Auger mining may 

find some application on the reservation where 

flat-lying beds of sufficient thickness are readily 

exposed. 

An interesting adaptation of a fine grading 

machine has been successfully applied to mining 

an 18-inch-thick coal bed in Oklahoma (Coal 

Mining and Processing, 1975, p. 58-60). A rotating 

toothed auger cuts the coal from the bed and 

transports it to a central conveyor. This conveyor 

discharges the coal into trucks. Thus the machine 

acts as an excavator/crusher/loader. It makes cuts 

6 inches deep and 10 feet wide as it moves along 

the coal bed. The production rate is about 100 tons 

per hour. It is particularly adaptable to mining thin 

beds and therefore may find some application on 

the reservation. 

The reservation's coal resources are insufficient 

to support large-scale surface mining as practiced 

in the thick subbituminous coal beds in eastern 

Montana. Small-scale surface mining would be 

applicable for the thin flat-lying coal beds on the 

reservation if suitable areas can be found where the 

overburden thickness is not excessive. 

The applicability of surface mining on the 

steeply inclined coal beds in the Blackfeet field is 

less definite. Techniques have been developed for 

surface mining in inclined beds, but only an extensive field study will reveal whether suitable areas 

are present here (Phelps, 1973, p. 390-392). 

Environmental Aspects.--The environmental 

aspects of surface mining, especially the rehabilitation of mined land, recently has received a large 

amount of attention from scientists and engineers 

as well as the general public. Much of this concern 

originated from past practices, particularly in the 

Eastern United States. Objections have centered 

mainly around contour surface mining where the 

spoil was cast over the hillside and caused stream 

silting and acid drainage from the exposed pyritebearing rocks. Much more acceptable methods for 

overburden disposal have been developed, and 

technology for rehabilitating mined lands has 

progressed remarkably in the past few years. 

A study by the National Academy of Sciences 

(1974, p. 53) concluded there "presently exists 

technology for rehabilitating certain western sites 

with a high probability of success."These include 

BIA Administrative Report 24 (1976) 25 
_________________________________________________________________________________________________ 

Status of Mineral Resource Information for The Blackfeet Indian Reservation, Montana 

C. A. Balster, Michael Sokaski, George McIntyre, R. B. Berg, H. G. McClernan, and Miller Hansen 

sites with over 10 inches of annual precipitation. 

The annual precipitation at Browning is about 15 

inches, and therefore rainfall should not be a 

limiting factor in rehabilitating mined areas on the 

reservation. However, the rehabilitation of surface 

mined lands is essentially site specific and depends 

on many factors other than precipitation; some of 

which are soil composition, topography, vegetation, and projected land use. 

Rehabilitation of surface mined land includes 

top soil removal, spoil grading, top soil placement, 

surface manipulation to trap rain and snow, 

revegetation, and possibly fertilizing and irrigation. 

The cost of rehabilitation at a mine in eastern 

Montana according to a recent Bureau of Mines 

study is about $4,300 per acre (Bitler and others, 

1976). 

Coal beds in Montana are commonly aquifers 

and often used by farmers and ranchers as underground sources of water. Surface mining may 

disrupt flow patterns. Fortunately, the amount of 

disturbed land at any time will be small so only 

local dislocations will occur. Therefore, no extensive or long term damage to the water resources on 

the reservation is expected. Furthermore, the small 

quantity of water required by a mining operation, 

e.g., for coal processing, road sprinkling, sanitary 

purposes, etc., should not seriously deplete present 

aquifers. 

Radioactive elements in coal remain in the ash 

after combustion. Uranium has been recovered 

from the ash of some "dirty" North Dakota lignites, 

but uranium in economically recoverable quantities 

has not been reported in reservation coals. Smaller 

quantities of radioactive elements in the ash may 

require attention to prevent possible human health 

hazards from some forms of ash disposal, e.g., 

concrete admixtures, construction fill material, etc. 

Any future investigations of reservation coals 

should include checks for radioactive elements. 

Some trace elements in coal may also cause a 

health hazard by their liberation during combustion. Arsenic and mercury, for example, are exceptionally dangerous pollutants highly toxic to 

humans and animals. The volatility of both is 

relatively high in the elemental and combined 

forms. Mercury and arsenic would therefore be 

mobilized into the atmosphere by combustion 

(Bertine and Goldberg, 1971, p. 234). New arsenic 

standards have been proposed by the Occupational 

Safety and Health Administration. These will 

reduce the minimum permissible concentration 

from the present level of 0.5 mg to 0.004 mg per 

cubic meter of air averaged over an 8-hour period. 

It has been reported that samples of coal from 

Montana and Wyoming contained 33 ppm and 18.6 

ppm of mercury, respectively (Joensuu, 1971, p. 

1027). These values are unusually high and were 

among the highest of 36 coal samples analyzed. 

Clearly, future investigations of reservation coals 

must include analyses for mercury and arsenic as 

well as other elements, e.g., lead, that could possibly cause a health hazard. 

��

�

Small quantities of coal have been mined on or 

near the reservation to supply local needs. However, the local market has been largely captured by 

BIA Administrative Report 24 (1976) 26 
_________________________________________________________________________________________________ 

Status of Mineral Resource Information for The Blackfeet Indian Reservation, Montana 

C. A. Balster, Michael Sokaski, George McIntyre, R. B. Berg, H. G. McClernan, and Miller Hansen 

oil and natural gas. The recent rising costs and 

shortages of these fuels may stimulate a return to 

coal for domestic heating and as a fuel for small 

local industries. Nevertheless, the local market for 

coal will probably be small and would not support 

any large-scale development of the resources on 

the reservation. 

��	�	����

The electric utility industry is the largest user 

of coal in the United States, consuming about 419 

million tons or 70 percent of production in 1973. 

The electrical power generated in the United States 

has been increasing by almost 7 percent a year 

while the rate of increase of all forms of energy is 

about 4 percent a year. Nearly all of the coal that is 

currently mined in Montana is used for generating 

electrical power. The electric utility industry could 

form a large and viable market for coal from the 

reservation if it met their specifications. 

Generally, contracts for the sale of coal to 

electrical power plants specify limits on moisture, 

ash, and sulfur contents; penalties are assessed for 

exceeding these limits. Similarly, a minimum heat 

content is specified. Ash and sulfur can usually be 

reduced and the heat content increased by mechanical cleaning. Assuming the heat content of clean 

coal is about 12,000 Btu per pound, the maximum 

allowable sulfur permitted by present Environmental Protection Agency regulations is 0.8 percent. 

Therefore, the sulfur content of reservation coal 

must be reduced to this level, but coal with a 

higher sulfur content could be blended with low 

sulfur coal from an off-reservation source. Low 

sulfur coal from eastern Montana is the most likely 

candidate for this purpose. 

Additional coal characteristics important in 

power plants are related to the ash composition. 

The fluidity of the ash is an important factor in the 

design of boilers particularly with regard to ash 

removal equipment. For example, coal with an ash 

softening temperature above 2,600oF cannot be 

used in cyclone furnaces (Slicer and Leonard, 

1968, p. 3-22). 

Coal commonly contains trace elements which 

may have future resource importance. These are 

gallium, germanium, selenium, tellurium, thallium, 

and vanadium. The reservation coals should be 

analyzed for them. 

Each boiler manufacturer through experience 

has developed empirical methods for evaluating 

coal ash fluidity characteristics. These have not 

been standardized between manufacturers. They 

commonly depend on the amount of Fe2O3, CaO, 

MgO, Na2O, K2O, SiO2, A12O3, and TiO2 in the 

ash. 

Most modern power plants are designed to 

operate with steam temperatures above 1,000oF. 

This recent development has caused a new type of 

fouling deposit to occasionally form on the boiler 

tubes. The source of these deposits are some 

sodium and potassium compounds in the coal, 

particularly the chlorides. Coal ashes containing 2 

to 5 percent Na2O are considered medium fouling 

for Western coals; higher Na2O contents may cause 

severe fouling (Winegartner and Ubbens, 1974, p. 

6). Some boiler manufacturers, recognizing that 

most of the alkali associated with fouling problems 

is in the form of chlorides, evaluate fouling potential by analyzing the coal for total chlorine content. 

BIA Administrative Report 24 (1976) 27 
_________________________________________________________________________________________________ 

Status of Mineral Resource Information for The Blackfeet Indian Reservation, Montana 

C. A. Balster, Michael Sokaski, George McIntyre, R. B. Berg, H. G. McClernan, and Miller Hansen 

Grindability is an important physical property 

in pulverized coal firing, and is dependent on 

specific properties such as hardness, toughness, 

strength, tenacity, and fracture. It is measured by 

the Hargrove grindability test which is a standard 

of the American Society for Testing Materials. 

Coal from the Blackfeet field should be easy to 

grind because of its friable nature. 

Modern power plants are commonly rated at 

about 1,000 Mw with an expected life of 35 years. 

The reservation's coal resources, estimated to be 30 

to 50 million tons, would supply the power plant 

for only 10 to 20 years; it is unlikely that a power 

plant will be built on the reservation. 

�
���	������

Coke has been manufactured from Montana 

coal in the past and used in local copper smelters. 

Modern copper smelting methods, however, do not 

require coke as a reducing agent. However, it is the 

most common reducing agent for the manufacture 

of steel. A resource investigation by the Bureau of 

Mines has established that substantial but low 

grade iron ore resources are present in southwestern Montana (Roby and Kingston, 1966), which 

can be upgraded to meet industry requirements. 

Coal from the reservation could be used in the 

future development of a local iron and steel industry. 

If reservation coal is to be used by the iron and 

steel industry, it must be upgraded to not more than 

8 percent ash and 1.2 percent sulfur. Washability 

tests are required to determine the degree of upgrading that is possible. If used in blast furnaces, 

blending with low volatile bituminous coal will 

probably be required. The blend must form a 

strong, well fused coke. Carbonization tests are 

necessary to determine coking characteristics. If 

the coal can be upgraded to satisfy the ash and 

sulfur limits but cannot be made into suitable coke, 

it can still be used by the iron and steel industry in 

the form of carbonized coal briquettes (formed 

coke) or as material for direct reduction processing. 

��

Shortages of fuel oil and natural gas, as well as 

the sharp increase in their costs have forced nearly 

all cement manufacturers to consider coal as a 

primary fuel. Many manufacturers have acquired 

coal reserves or signed long-term contracts to 

assure a reliable fuel supply. 

The amount of Portland cement consumed in 

Montana in 1972 was 241,720 tons (Minerals 

Yearbook, 1972, p. 432). Two plants are currently 

operating near Helena. High volatile bituminous 

coal with a heat content above 10,000 Btu per 

pound and with an ash content ranging from 6 to 

22 percent is commonly used in cement plants 

(Leonard and McCurdy, 1968, p. 3-25). Reservation coal would readily meet these specifications. 

����
	���	�


Both the Virgelle Sandstone and the Horsethief 

Sandstone are possible sources of radioactive 

minerals which are associated with the magnetite 

and titaniferous magnetite beds. Both formations 

appear favorable for the occurrence of uranium, 

but the abnormal radioactivity of one sample from 

BIA Administrative Report 24 (1976) 28 
_________________________________________________________________________________________________ 

Status of Mineral Resource Information for The Blackfeet Indian Reservation, Montana 

C. A. Balster, Michael Sokaski, George McIntyre, R. B. Berg, H. G. McClernan, and Miller Hansen 

the Virgelle Sandstone was thought to be due to 

thorium in the associated monazite (Armstrong, 

1957, p. 215, 222). 

Metallic Mineral Resources 

�����
	����

�

Concentrations of titaniferous magnetite 

formed as beach deposits during deposition of the 

Horsethief and Virgelle Formations. Although the 

host rocks for the deposits are relatively widespread on the reservation, the deposits are more 

restricted geographically. 

Three deposits on the reservation were examined by the Burlington Northern Company (1970). 

The location of these deposits is shown in Figure 

7, and the following description is condensed from 

the Company's 1970 report. 

On the Blackfeet Indian Reservation, many 

exposures near the top of the Horsethief Sandstone 

are rich in iron and titanium. In these areas the rock 

is dark greenish brown to black on fresh exposures 

and dark reddish brown to black when weathered. 

The titaniferous magnetite deposits originated 

as beach placer concentrations. They are hard, 

lenticular sandstones, medium to coarse grained, 

generally with calcareous cementing material. 

Normally the deposits consist of two to four 

zones, rich in titaniferous magnetite intercalated 

with lean sandstone layers. 

The individual rich zones range from a few 

inches to about 20 feet in thickness. The rich zones 

are commonly finely banded with distinct layers of 

rich material alternating with layers of lean material consisting chiefly of quartz and feldspar. Most 

layers are less than 1⁄4 inch thick. 

The most obvious effect of this banding is to 

make sampling difficult, and the most truly representative samples have been obtained from test 

pits. Core drilling recovers a greater proportion of 

either the rich or the lean, depending on which 

layer is harder at a particular site. 

The samples of the iron-titanium beds all 

contained the same suite of minerals, but with 

differences in the proportions. The titanium content is greater than can be accounted for by the 

ilmenite, indicating that in much of the magnetite, 

titanium has replaced iron in the crystal lattice. 

The opaque minerals consist of magnetite, 

hematite, magnetite-ilmenite intergrowths, 

hematite-ilmenite, and magnetite-hematite, and 

usually minor amounts of hematite-goethite-limonite. The samples also contain iron-stained quartz 

and feldspar and minor carbonates and silicates. 

���

The reservation's titaniferous magnetite deposits were first described in 1914 (Stebinger, p. 329­

337). Twenty-one titaniferous magnetite deposits 

have been identified (Hubbard and Henkes, 1962, 

p. 9-19) and are listed in Table 10. 

�	��	���	���

The Kennedy Coulee deposit (Figure 16) is

exposed for 1,000 feet along the upper edge of the 

bluff on the north side of Kennedy Coulee. AverBIA Administrative Report 24 (1976) 29 
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Status of Mineral Resource Information for The Blackfeet Indian Reservation, Montana 

C. A. Balster, Michael Sokaski, George McIntyre, R. B. Berg, H. G. McClernan, and Miller Hansen 

age thickness is about 8 feet. About 130,000 tons 

of titaniferous magnetite are estimated to be 

minable at a stripping ratio of 3 to 1. The deposit 

may extend beneath the southeast end of the bluff. 

The Radar Station deposit is exposed for 21⁄2 

miles south-southeast from the Milk River. It 

contains about 330,000 tons of titaniferous magnetite in a bed averaging 10 feet thick. An additional 

1,500,000 tons is inferred and it could be more. 

This may be the largest minable deposit on the 

reservation. 

The Buffalo Lake deposits are about 2 miles 

northwest of Buffalo Lake. Outcrops average about 

3 feet thick. An estimated 60,000 tons are minable 

at a stripping ratio of 3 to 1 but the deposit may be 

substantially larger. 

���	
	���

The Rimrock Butte district (Figure 17) contains 

three deposits that lie along two low parallel ridges 

on top of a butte. The beds average about 2 feet 

thick. About 1 million tons of titaniferous magnetite are present with little or no overburden. 

����	�
���	���

Seven small deposits are present in the Kiowa 

Junction district (Figure 18). These are the Lower 

Kiowa, East Kiowa No. 2 extension, Kiowa Junction, South Fork, High Knob, Two Medicine, and 

Cut Bank Ridge. They are relatively small. The 

two largest are the Two Medicine with estimated 

minable resources of 50,000 tons and the Kiowa 

Junction with 44,000 tons. Each of the remaining 

deposits contain minable resources of 16,500 tons 

or less. 

��	���	����	���

The Milk River Ridge district (Figure 19) 

contains several widely scattered deposits 10 to 20 

miles northwest of Browning. These are the 

Livermore Creek, Horse Lake, North Browning, 

and Star School. The Star School deposits are the 

most important; about 60,900 tons of titaniferous 

magnetite are minable by surface methods. The 

Livermore Creek and Horse Lake each contain 

about 10,000 tons of indicated resources. 

���	�


The potential resources of titaniferous magnetite in the Horsethief Sandstone suitable for surface 

mining have been estimated to range from 10 to 15 

million tons (Hubbard and Henkes, 1962, p. 18). 

These deposits vary from a few thousand tons to a 

million or more. 

The Virgelle Sandstone underlies the entire 

reservation to the east of the Disturbed Belt and is 

reported to contain locally abundant magnetite and 

titaniferous magnetite as well as small amounts of 

zircon, monazite, and garnet (Armstrong, 1957, p. 

125). The extent of the iron resources in the 

Virgelle Sandstone on the reservation is not 

known. 

An aeromagnetic survey indicates the presence 

of a large mass of magnetic material in the southwestern part of the reservation at a depth of 8,000 

feet (±4,000 feet) (Mudge and others, 1966, p. 

B133). The magnetic anomaly is believed to be 

BIA Administrative Report 24 (1976) 30 
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Status of Mineral Resource Information for The Blackfeet Indian Reservation, Montana 

C. A. Balster, Michael Sokaski, George McIntyre, R. B. Berg, H. G. McClernan, and Miller Hansen 

caused by a mass of iron-rich rock of moderate 

density and regional extent. Even if the magnetic 

anomaly is caused by an iron deposit, its depth 

probably rules out any possibility of being mined 

economically at this time. 

�������

The iron content of the titaniferous magnetite 

samples listed in Table 10 ranges from 10.6 percent to 55.6 percent. Therefore, ore from the 

reservation will not be "direct shipping ore" because the iron content is too low and consequently 

beneficiation will be necessary. 

Titaniferous magnetite from the Choteau area 

approximately 30 miles southeast of the reservation, which is probably similar to that on the 

reservation, has been investigated at the Albany 

Metallurgy Research Center of the U.S. Bureau of 

Mines (Wilmer, 1946, 12 p.). 

The results of this test, Table 11, indicate that 

a concentrate with an iron content of 61.3 percent 

was obtainable (Holmes and Stickney, 1969, p. 3, 

4). This is of sufficient grade to satisfy industry 

requirements. 

Results of a Davis Tube magnetic beneficiation 

test of the titaniferous magnetite sands from the 

Kennedy Coulee deposit are as follows (Burlington 

Northern Inc., 1970, table 2):

 Crude Ore Davis Tube Test products at -150 mesh

Fe% Ti02% Product Weight% Fe% Ti02% SiO2% Al203%

36.19 10.71 Conc. 27.0 51.10 20.48 2.28 1.22

 Tails 73.0 30.68 7.11

BIA Administrative Report 24 (1976) 31 
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-- 

-- 

-- 

-- 

-- 

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Status of Mineral Resource Information for The Blackfeet Indian Reservation, Montana 

C. A. Balster, Michael Sokaski, George McIntyre, R. B. Berg, H. G. McClernan, and Miller Hansen 

TABLE 10 

Analyses of Titaniferous Magnetite (Hubbard and Henkes, 1962, p. 11, 12) 

Sample Thickness 

No. Deposit / Location (feet) 

Average grade

Iron TiO2

(%) (%) Remarks

1 Kennedy Coulee, NE1⁄4 8.0 29.1 8.77 Channel sample

 sec. 30, T. 37 N., R. 9 W. 

2 Radar station, SW1⁄4 sec. 29, 8.8 37.4 12.6 Do.

 T. 37 N., R. 9 W. 

3 Radar station, SW1⁄4 sec. 29 11.3 32.9 10.2 Do.

 T. 37 N., R. 9 W. 

4 Radar station, NW1⁄4 sec. 3 19.0 33.7 10.31 Do.

 T. 37 N., R. 9 W. 

5 Buffalo Lake, SE1⁄4 sec. 16, 19.0 35.9 5.47 Do.

 T. 36 N., R. 9 W. 

6 Buffalo Lake, NE1⁄4 sec. 27, 1.1 29.5 9.30 Do.

 T. 36 N., R. 9 W. 

7 Rimrock Butte, SW1⁄4 sec. 4, 1.9 37.7 12.7 Do.

 T. 34 N., R. 9 W. 

8 Rimrock Butte, NW1⁄4 sec. 15, 2.1 45.5 14.5 Do.

 T. 34 N., R. 9 W. 

9 Lower Kiowa, SW1⁄4 sec. 1, 4.0 10.6 2.30 Channel sample

 T. 32 N., R. 13 W. bottom section of bed 

10 Lower Kiowa, SW1⁄4 sec. 1, 3.0 46.4 9.14 Channel sample

 T. 32 N., R. 13 W. top section of bed 

11 East Kiowa No. 2 Ext., 2.0 31.5 5.46 Channel sample

 NE1⁄4 sec. 1, T. 32 N., R. 13 W. 

12 Kiowa Junction, NW1⁄4 sec 10, 4.0 33.4 5.03 Do.

 T. 32 N., R. 13 W. 

13 South Fork, NE1⁄4 sec. 12, 1.8 19.4 4.16 Do.

 T. 32 N., R. 13 W. 

14 High Knob, NE1⁄4 sec. 18, 5* 50.8 Character sample

 T. 32 N., R. 12 W. of outcrop 

15 Two Medicine Ridge, NE1⁄4 3* 47.8 Character sample

 sec. 21, T. 32 N., R. 12 W. of float 

16 Cut Bank Ridge, SE1⁄4 sec. 31, 1* 54.5 Grab sample 

T. 33 N., R. 12 W. of high-grade float 

17 Livermore Creek, SE1⁄4 sec. 30, 2* 36.2 Chip sample

 T. 35 N., R. 12 W. 

18 Horse Lake, SE1⁄4 sec. 1, 2.5 55.6 Channel sample

 T. 34 N., R. 13 W. of best outcrop 

19 North Browning, SE1⁄4 sec. 18, 1.0 10.5 2.01 Chip sample

 T. 34 N., R. 11 W. 

20 Star School, NE1⁄4 sec. 11, 3.4 25.2 4.86 Channel sample

 T. 33 N., R. 12 W. 

21 Star School, SW1⁄4 sec. 13, 7.5 37.0 5.86 Do.

 T. 33 N., R. 12 W.

*Estimated 

BIA Administrative Report 24 (1976) 32 
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Status of Mineral Resource Information for The Blackfeet Indian Reservation, Montana 

C. A. Balster, Michael Sokaski, George McIntyre, R. B. Berg, H. G. McClernan, and Miller Hansen 

TABLE 11 

Analysis of Concentrate from Beneficiated Choteau Titaniferous Magnetite 

(from Holmes and Stickney, 1969, p. 4) 

Element or compound Percent

Iron 61.3 

Ti02 5.6 

Al203 1.4 

Si02 4.3 

CaO .4 

MgO 1.0 

Chromium .3 

Vanadium .3 

Manganese .2 

Sulfur .05 

Phosphorous .03 

Note: Concentrate yield was 75 percent of the ore. 

���

��

Titaniferous magnetite is not a source of iron in 

the United States at the present time although iron 

was made from New York deposits in the 1800's 

(Rossi, 1892-93, p. 835). The objections to smelting titaniferous magnetite ores in a blast furnace 

are that the fuel requirements are excessive, the 

slag is pasty and not free flowing, and accretions 

form which cause scaffolding in the furnace and 

clogging in the hearth. 

The problem of high-fuel consumption originates in part from the dilution effect of the titanium 

in the ore--the higher the titanium content, the 

lower the iron content. Furthermore, magnetite ore 

is characteristically hard, dense, and resistant to 

reduction which in turn causes high-fuel consumption. However, titaniferous magnetite ore is amenable to magnetic concentration, and a large part of 

the non-iron-bearing material can be removed. If 

the magnetic concentrate is pelletized, attack by 

the reducing gasses in the furnace is greatly facilitated. By adopting modern beneficiating methods, 

the underlying factors leading to high-fuel consumption are largely eliminated. 

The Albany Metallurgy Research Center has 

demonstrated that a free flowing slag can be 

obtained when smelting Choteau titaniferous 

magnetite concentrate by proper manipulation of 

the slag composition (Holmes and Stickney, 1969, 

p. 21.) Unfortunately, titaniferous magnetite ore 

and concentrate are best smelted under acid conditions to promote the formation of a fluid slag. The 

sulfur content of iron ore is characteristically low, 

but coke used as a reducing agent commonly 

contains a much higher sulfur content. If the sulfur 

content of the iron obtained from reservation 

titaniferous magnetite is excessive, additional 

BIA Administrative Report 24 (1976) 33 
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Status of Mineral Resource Information for The Blackfeet Indian Reservation, Montana 

C. A. Balster, Michael Sokaski, George McIntyre, R. B. Berg, H. G. McClernan, and Miller Hansen 

desulfurization will be necessary. The technology 

for smelting under acid conditions followed by 

external desulfurization of hot metal is well established; but if this additional treatment is necessary, 

an additional expense will be added (Ross, 1958, 

p. 410, 411).

Titaniferous magnetite ore has been smelted 

successfully in an electric furnace at the Salt Lake 

City Metallurgy Research Center of the U.S. 

Bureau of Mines (Fuller and Edlund, 1960, 11 p.). 

Coal was a more satisfactory reducing agent than 

coke because coal promoted a more fluid and less 

foamy slag. Power requirements are estimated to 

range from 1,300 to 1,500 kilowatt hours per ton of 

ore. 

The recent emphasis on the elimination of 

pollution from smelters has caused renewed interest in hydrometallurgical processes. A soda sinter 

process for treating low-grade titaniferous magnetite ore has been developed by the College Park 

Metallurgy Research Center, U.S. Bureau of 

Mines, College Park, Md. (MacMillan, et al., 1952, 

62 p.). 

����


About 90 percent of the titanium that is used in 

the United States is imported. The price of rutile, 

a major source of titanium, has been rising sharply 

because of decreased world supply. Attention is 

now being directed to other sources including 

titaniferous magnetite ores. Titanium or titania can 

be recovered from blast furnace slag, electric 

furnace slag, or directly by hydrometallurgical 

processes. In 1974, about 250,000 tons of titanium 

slag were imported into the United States, largely 

from Canada by titania pigment producers (Commodity Data Summaries, 1975, p. 74). Electric 

furnace slag obtained from smelting Choteau 

titaniferous magnetite concentrate contained about 

40 percent TiO2 (Hubbard and Henkes, 1962, p. 

13). The titaniferous magnetite on the reservation 

could become an important future source of titanium. 

Nonmetallic Mineral Resources 

��

The Bearpaw Shale, exposed along a narrow 

belt extending in a north-south direction across the 

entire reservation (Figure 4), commonly contains a 

bentonite zone. Also, the clay and shale may be 

suitable for the manufacture of common brick, tile, 

and sewer pipe (Hubbard, et al., 1966, p. 84). 

���

No commercial beds of bentonite are known 

within this area. The Bearpaw Shale contains 

bentonite, but impurities in bentonite from this 

area are more abundant than in the beds farther east 

where bentonite is being mined from the Bearpaw 

(Berg, 1969, p. 28). It is unlikely that bentonite 

from the reservation is of commercial quality. 

��

Clays that are associated with coal beds in the 

Two Medicine Formation and the Saint Mary 

River Formation are often suitable for the manufacture of ceramic products. Also, the shale associated with coal beds has been used for the manufacBIA Administrative Report 24 (1976) 34 
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Status of Mineral Resource Information for The Blackfeet Indian Reservation, Montana 

C. A. Balster, Michael Sokaski, George McIntyre, R. B. Berg, H. G. McClernan, and Miller Hansen 

ture of expanded aggregate (Harris, et al., 1962, p. 

2-32). 

���	���	��

The extensive deposits of sand and gravel on 

the reservation (Figure 20) indicate they are sufficient to supply future local needs. About 58 gravel 

pits are located on the reservation but only four or 

five are operated. Most of the gravel is used for 

road construction and repair. 

������

The Burlington Northern railroad crosses the 

central part of the reservation in an approximately 

east-west direction. In addition, rail service is 

available at Valier, about 4 miles southeast of the 

reservation. The cost of transporting large quantities of coal or other bulk solids for long distances 

(over 400 miles) by unit train ranges from 0.4 to 

0.9 cents per ton mile (Campbell and Katell, 1975, 

p. 24). The freight cost for shipping smaller quantities, i.e., smaller than full train loads, is about 30 

percent higher (Zachar and Gilbert, 1968, p. 5-8). 

Trucking costs depend on volume hauled, the 

nature of the terrain, and the capacity of the trucks. 

Transportation of coal by truck over 100 miles is 

considered impractical (Zachar and Gilbert, 1968, 

p. 5-9). The cost of shipment by truck for a one 

way haul and empty return ranges from 5.0 to 8.0 

cents per-ton-mile (Campbell and Katell, 1975, p. 

24). 

SOCIAL EFFECTS FROM MINERAL RESOURCE DEVELOPMENT 

The coal resources appear at this time to be of 

insufficient size to support large-scale development such as those now underway in eastern 

Montana, Wyoming, and Arizona. Consequently, 

no large industrial complexes are likely to be built 

on the reservation, and thus no serious disruptions 

to the traditional life style of the residents is expected. On the other hand, the coal resources are 

adequate to support relatively small-scale development with the attendant advantages of providing 

income as well as employment. The social impact 

from development of the iron resources, insofar as 

can be predicted at this time, would probably also 

be similar. If the mineral resources are developed 

by surface mining, relatively short-term training 

for mine employees would be required. However, 

underground mining would require the employment of highly skilled personnel and a comprehensive training program. 

RECOMMENDATIONS 

General 

The disturbed belt of the Blackfeet Indian 

Reservation has a petroleum and titaniferous iron 

potential, but surface and subsurface geologic data 

are necessary to assist in evaluating the areas of 

greatest potential. Such data have not been compiled for all of the area. 

BIA Administrative Report 24 (1976) 35 
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Status of Mineral Resource Information for The Blackfeet Indian Reservation, Montana 

C. A. Balster, Michael Sokaski, George McIntyre, R. B. Berg, H. G. McClernan, and Miller Hansen 

Oil and Gas 

Geologic and geophysical studies of the reservation are recommended to locate areas favorable 

for oil and gas. 

The disturbed (faulted and folded) belt encompasses the western part of the Blackfeet Indian 

Reservation (Figure 4). At the International border 

it is about 181⁄2 miles wide and maintains its width 

south to Browning. South of Browning the width 

of the belt thins to about 101⁄2 miles at Birch Creek, 

the southern boundary of the reservation. Thus in 

the reservation, the belt encompasses about 1,113.5 

sq mi (712,640 acres). 

Petroleum, mainly gas, is potentially present in 

the disturbed belt. The belt is a southern extension 

of the Alberta foothills of which there are 4 major 

gas fields. It is also in a geologic setting similar to 

part of the Wyoming disturbed belt where large 

quantities of gas were recently discovered. Past 

petroleum exploration in this part of the reservation consisted mostly of seismic surveys. A few 

test wells have been drilled in the northern and 

southern parts of the area but vast areas remain 

unexplored. Some wells in the vicinity of East 

Glacier Park contain some gas. 

Most of the area has not been mapped or 

studied geologically. Geologic studies were completed in 1976 in the foothills south of East Glacier 

Park along the western boundary of the reservation. Some broad reconnaissance geologic data are 

available in Two Medicine, Badger Creek, and 

Milk River drainages. Modern topographic maps 

(1:24,000 scale) cover the area. 

The belt consists of closely spaced, westerly 

dipping thrust faults that repeat Upper Cretaceous 

strata. Much of the area is covered by glacial debris 

and stream gavels. Bedrock exposures, therefore, 

are sparse except along some major stream 

drainages. Detailed geologic knowledge of the 

Cretaceous strata are necessary to interpret the 

surface structure in the area. Geophysical studies 

(gravity and ground magnetometer) are necessary 

to aid in interpreting subsurface structures. Truck 

mounted magnetometer traverses would locate any 

titaniferous iron deposits beneath glacial debris and 

extensive gravel deposits. 

A geologic and geophysical study of the disturbed belt in the reservation should consist of: 

1. Geologically map the area at a scale of 

1:125,000, depicting structure and formations, and 

where applicable, members of formations. 

2. Geophysical studies (gravity and magnetometer) of the area. Gravity stations to be on 3 to 6 

mile spacings depending on elevation control 

points. The spacing of truck mounted magnetometer traverses will be determined by northeasterly 

access roads or trails. Detailed geophysical traverses will be conducted in areas where anomalies 

are located. 

3. A petroleum evaluation should be made for 

the area, based on all available surface and subsurface data. 

Coal 

Surface mining would be the best method for 

the initial development of coal resources on the 

reservation largely because of low mining costs; 

this applies to the Valier field, Blackfeet field, and 

possibly to some thinner beds outside of these 

fields. A comprehensive and systematic exploraBIA Administrative Report 24 (1976) 36 
_________________________________________________________________________________________________ 

Status of Mineral Resource Information for The Blackfeet Indian Reservation, Montana 

C. A. Balster, Michael Sokaski, George McIntyre, R. B. Berg, H. G. McClernan, and Miller Hansen 

tion program is recommended to determine the 

location and extent of the areas suitable for surface 

mining. The two most important technical factors 

in determining such areas are coal bed and overburden thickness. 

An essential part of any investigation would be 

the determination of coal quality. This requires a 

complete analysis of representative samples including trace elements as well as ash analyses and ash 

fusion characteristics. Grindability, washability, 

and carbonization tests are also recommended. 

Titaniferous Magnetite 

Numerous small titaniferous iron deposits are 

known in sedimentary strata in parts of the belt. 

Together the deposits constitute a large tonnage of 

titaniferous iron. Geological and geophysical 

studies should determine the extent of these deposits under moderate cover of Quaternary deposits, 

and locate any buried deposits. 

Beneficiation tests of the ores are recommended to determine the degree of upgrading that 

can be expected from established methods. The 

possible recovery of vanadium, uranium, thorium, 

and rare earth elements should be investigated. 

Nonmetallic Minerals 

The reservation contains clays and shales that 

might be used by the ceramic industry. A survey of 

the reservation to determine the extent and suitability of these deposits is recommended. 

BIA Administrative Report 24 (1976) 37 
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Status of Mineral Resource Information for The Blackfeet Indian Reservation, Montana 

C. A. Balster, Michael Sokaski, George McIntyre, R. B. Berg, H. G. McClernan, and Miller Hansen 

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BIA Administrative Report 24 (1976) 38 
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Status of Mineral Resource Information for The Blackfeet Indian Reservation, Montana 

C. A. Balster, Michael Sokaski, George McIntyre, R. B. Berg, H. G. McClernan, and Miller Hansen 

Cannon, J. L., Jr., 1971, Petroleum potential of 

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BIA Administrative Report 24 (1976) 39 
_________________________________________________________________________________________________ 

Status of Mineral Resource Information for The Blackfeet Indian Reservation, Montana 

C. A. Balster, Michael Sokaski, George McIntyre, R. B. Berg, H. G. McClernan, and Miller Hansen 

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23-32. 

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___1955, Structure contour map of the Montana 

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Erdmann, C. E., Beer, W. M., and Nordquist, J. 

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BIA Administrative Report 24 (1976) 40 
_________________________________________________________________________________________________ 

Status of Mineral Resource Information for The Blackfeet Indian Reservation, Montana 

C. A. Balster, Michael Sokaski, George McIntyre, R. B. Berg, H. G. McClernan, and Miller Hansen 

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Montana Bur. Mines and Geology, Mineral and 

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Liquidus temperatures of titaniferous slags: 

U.S. Bur. Mines Rept. Inv. 7232, 21 p. 

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___1962, Distribution and correlation of Upper 

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23-32. 

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BIA Administrative Report 24 (1976) 41 
_________________________________________________________________________________________________ 

Status of Mineral Resource Information for The Blackfeet Indian Reservation, Montana 

C. A. Balster, Michael Sokaski, George McIntyre, R. B. Berg, H. G. McClernan, and Miller Hansen 

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Montana Oil and Gas Conservation Division, 

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Montana Water Resources Board, 1964, Water 

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National Academy of Sciences, 1974, Rehabilitation potential of western coal lands: Ballinger, 

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Oil and Gas Journal, 1942, Typical oil-field structures: Sedimentation trap, Cut Bank, Montana: 

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Geology and ground water resources of the 

Two Medicine unit and adjacent areas, Blackfeet Indian Reservation, Montana, with a 

section on chemical quality of water by R. H. 

Langford: U.S. Geol. Survey Open-file Rept., 

126 p. 

BIA Administrative Report 24 (1976) 42 
_________________________________________________________________________________________________ 

Status of Mineral Resource Information for The Blackfeet Indian Reservation, Montana 

C. A. Balster, Michael Sokaski, George McIntyre, R. B. Berg, H. G. McClernan, and Miller Hansen 

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___1937, Natural gas in Montana: Montana Bur. 

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___1953, Oil and gas in Montana: Montana Bur. 

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___1975, Origin and significance of natural gases 

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___1916, Geology and coal resources of northern 

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___1917, Anticlines in the Blackfeet Indian Reservation, Montana: U.S. Geol. Survey Bull. 641, 

p. 281-305.

BIA Administrative Report 24 (1976) 43 
_________________________________________________________________________________________________ 

Status of Mineral Resource Information for The Blackfeet Indian Reservation, Montana 

C. A. Balster, Michael Sokaski, George McIntyre, R. B. Berg, H. G. McClernan, and Miller Hansen 

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BIA Administrative Report 24 (1976) 44 

Figure 1. Index map of Blackfeet Indian Reservation, Montana (adapted from Hubbard and Henkes, 1962).
Figure 2. Topographic map of the Blackfeet Indian Reservation, Montana

 (from U.S. Geological Survey State of Montana Map, 1966). 
Figure 3. Map showing glacial deposits in eastern part of the Blackfeet Indian Reservation,

 Montana (adapted from Colton and Lemke, 1961). 
Figure 4. Generalized geologic map showing bedrock units on the Blackfeet Indian

 Reservation, Montana (adapted from Stebinger, 1916, pl XV).
Figure 5. Map showing regional geologic structures of parts of northwestern Montana and southern Alberta, Canada.
Figure 6. Map showing structure contours in eastern part of the Blackfeet Indian Reservation,

 Montana (adapted from Erdmann and others, 1946, and Dobbin and Erdmann, 1955). 
Figure 7. Map showing oil and gas fields, coal fields, and magnetite-bearing sandstone and

 magnetite deposits, Blackfeet Indian Reservation, Montana (adapted from

 Stebinger, 1914 and 1916). 
Figure 8. Cross sections through drill holes showing general structure and stratigraphic 

 relations in parts of the Blackfeet Indian Reservation, Montana (for location 

of sections, see Figure 7).
Figure 9. Diagram showing drag folds.
Figure 10. Diagram showing complex anticlinal traps.
Figure 11. Map showing areas rated according to the probability of discoveries of

 significant oil and gas reserves, Blackfeet Indian Reservation. 
Figure 12. Map showing areas rated according to the probable costs of finding significant

 discoveries of oil and gas, Blackfeet Indian Reservation, Montana.
Figure 13. Partial stratigraphic section showing position of known coal beds,

 Blackfeet Indian Reservation, Montana. 
Figure 14. Map showing Valier coal field and sections through coal beds, Blackfeet 

 Indian Reservation, Montana (adapted from Hubbard and Henkes, 1962); 

see index map (Figure 1) inset B for location.
Figure 15. Map showing Blackfeet Coal Field, Blackfeet Indian Reservation, Montana 

 (adapted from Hubbard and Henkes, 1962); see index map (Figure 1) 

inset A for location.
Figure 16. Map showing titaniferous magnetite deposits in the Lower Milk River 

 district, Blackfeet Indian Reservation (adapted from Hubbard and 

Henkes, 1962). See index map (Figure 1) inset C for location.
Figure 17. Map showing Rimrock Butte titaniferous magnetite deposits, 

 Blackfeet Indian Reservation (adapted from Hubbard and Henkes, 

1962). See index map (Figure 1) inset D for location.
Figure 18. Map showing Kiowa Junction titaniferous magnetite deposits, Blackfeet 

 Indian Reservation (adapted from Hubbard and Henkes, 1962). See 

index map (Figure 1) inset E for location.
Figure 19. Map showing Milk River Ridge titaniferous magnetite deposits, Blackfeet 

 Indian Reservation (adapted from Hubbard and Henkes, 1962). See 

index map (Figure 1) inset F for location.
Figure 20. Map showing location of sand and gravel deposits, Blackfeet Indian

 Reservation (adapted from Larrabee and Shride, 1946).