Bulletin 166
Franklin K. Lane, Secretary
Bureau of Mines
Van H. Manning, Director

(In cooperation with the University of Idaho)

(page 49-51)
Adams and Washington counties lie along the Oregon boundary, on the western edge of the State. The topography is varied with a considerable range in elevations. The greatest relief is where the Seven Devils Mountains rise abruptly from the Snake River, With elevations varying from about 1,800 feet at the river over 5,000 feet on the mountain summits.

The geologic structure is complex and is not very well known; rocks representing almost all the geologic eras occur.

The Black Lake distrist lies on the east slope of the Seven Devils range on the drainage area of Rapid River. The district is about 50 miles north of Council on the Pacific & Idaho Northern Railroad, and can also be reached by trail from Pollock on the Little Salmon River or from Homestead on the Snake River.

There is practically no published information in regard to this district, except in the State mine inspector's reports. Local reports on former operations are not promising, and the outlook does not appear to be very bright.

Tbe Seven Devils district embraces the south end of the Seven Devils range and is about 13 miles north of Council. There is a fairly good Wagon road into the district, with a tri-weekly auto Stage from Council during the summer months. The nearest railroad point is Homestead, the terminus of a branch line of the Oregon Short Line Railroad from Huntington, Oreg. The distance from Homestead by wagon road is only about 15 miles, but the rise in elevation is nearly 4,000 feet.

Copper ore, consisting chiefly of bornite, occurs as contact metamorphic deposits in crystalline limestone, which hea been intruded by diorite.

The area of mineralization is of considerable extent and over 20,000 tons of ore, running 10 to 40 per cent copper, have shipped, principally from the Peacock mine. There are a number of claims following a belt of altered limestone for a distance of about 7 miles, all of which show more or less ore of the same kind; that is, bornite and oxidized copper minerals, in a gangue of garnet, epidote, and specular iron.

A different type of deposit occurs in the north end of the district on Deep Creek, a deep and rugged canyon, about 2 miles from the Snake River. This is known as the Red Ledge. The ore deposit is in red and yellow stained porphyry, and is about 80 feet wide. It contains values in gold and copper reported as $4 or $5 to the ton in gold and 1 to 4 per cent copper. Diamond drilling was being done in 1917, and has shown this body of ore to be continuous in depth though somewhat low in grade.

This district will undoubtedly become an important producer of copper when transportation is less expensive than at present, as the distance from the railroads, and the heavy grades to be overcome on the Snake River side are a great handicap.


The Heath district is situated 24 miles northwest of Cambridge on the Pacific & Idaho Northern Railway.

Copper deposits, similar to those of the Seven Devils district are reported as well as lead-silver deposits. Little definite information about the district is available, and the extent and value of the deposits is not known.

The Hornet Creek, or Galena, district lies at the top of the Cuddy Mountains near the head of Hornet Creek, and is 22 miles northwest of Council. A rough road leaves the main road to the Seven Devils about 14 miles from Council, and most of the distance has to be traveled on horseback.

Lead-silver ore occurs on one property in irregular bunches in limestone.

On the Freese property a flat-dipping quartz vein in diorite or monzonite rock has been exposed for several hundred feet by open cuts and a small shaft. The exact width of the vein was hard to determine, but will probably average 3 or 4 feet. Seemingly several hundred tons of material that will run $10 to the ton and can be mined by open cut, are available.

The Mineral district is situated about 4 miles east of the Snake River and about 29 miles from Huntington, Oreg. The railroad follows the Oregon side of the Snake River from Huntington to Homestead, and the district is reached by ferry and by wagon road from the Mineral ferry.

The geologic structure is somewhat complex. The country rock is slate and limestone, which has been intruded by porphyry, diorite, and basalt. The ore deposits consist of veins and replacements. The values are principally in silver, with copper in subordinate amounts, the silver being associated with pyrite, chalcopyrite, tetrahedrite, and a little sphalerite in a calcareous gangue.

Formerly the ore was smelted on the ground, and at one time there were two small furnaces in the district. The district became idle when silver dropped in price and has remained so up to the present time. Recently some parties from Idaho Falls have been working a small vein, and have taken out about a carload of shipping ore from near the surface.

At Iron Mountain, 6 miles east of the Snake River, large bodies of magnetite and hematite are reported to occur as contact metamorphic deposits in limestone. Very little is known of the extent or quality of the ore.

The Meadows district lies about 4 miles east of Meadows, on Goose Creek.

Placer deposits, containing much corundum and other uncommon minerals, occur at the Rock Flat placers. A small amount of gold has been produced.

The Monroe Creek district is situated 10 miles north of Weiser. The Modoc mine contains gold occurring in a network of quartz seams in a volcanic breccia.

Fuller's earth also occurs in the district.



Engineering AND Mining Journal. The Seven Devils and the Snake River District Vol. 84, Aug. 81, 1907, p. 401.

LINDGREN, WADEMAR. The copper deposits of the Seven Devils, Idaho. Min. and SM. Press, vol. 78, 1890, p. 126.

WEED, W. H. The copper mines of the United States in 3905. Bull. 285, U. S. Geol. Survey, 1900, pp. 108-109.


LINDGREN, W. The gold and silver veins of Silver City, De Lamar, and other districts in Idaho. Twentieth Ann. Rept., U. S. Geol. Survey, pt. 3, 1900, pp. 75-256.

——The gold belt of the Blue Mountains of Oregon. Twenty-second Ann. Rept., U. S. Geol. Survey, pt. 2,1901, pp. 754-756.

RusseLL, I. C. Geology and water resources of the Snake River Plains of Idaho. Bull. 199. U. S. Geol. Survey. 1902.192 pp.

TURNER. H. W. The ore deposits of Mineral, Idaho. Econ. GeoL, voL 8, 1908, pp. 492-502.

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