By A. H. KOSCHMANN and M. H. BERGENDAHL - USGS 1968
Many districts throughout Idaho County - such as Buffalo Hump, Dixie, Elk City, Orogrande, Simpson, Tenmile, and Warren-Marshall - have made the county the second largest producer of gold in the State.
The first gold discoveries in this general area were made in 1857 along Orofino Creek, in what is now Clearwater County, by Jean deLassier, a trapper. Later, E. D. Pierce made the well-known discoveries at Pierce, and a rush to the region followed. By 1861 a group from the Orofino area explored the unknown country to the south and found placer gold along the South Fork of the Clearwater River at Elk City, in what is now Idaho County. In a few months more than 2,000 people rushed to the new area. Other discoveries were made in 1861 at Florence by another group from Orofino, and at almost the same time placers were found at New-some, Dixie, and along the Salmon River. By 1872 the richest placers were depleted, and the Chinese took over most of the workings. After 1900, low-grade placers were worked at several localities, but it was not until the 1930's that a real revival of the placers was made possible by higher prices, development of new mining equipment, and improved transportation facilities (Lorain and Metzger, 1938, p. 6-8, Thomson and Ballard, 1924, p. 13-14).
Gold-bearing veins were worked as early as 1866 in the Warren district (Ross, 1941, p. 62), but the important lode mines at Elk City, Dixie, and Buffalo Hump were developed in the 1880's and 1890's. After a few years of intense activity, lode mining declined in Idaho County and reached a low in 1920 (Lorain, 1938, p. 7). Activity increased in the 1930's because of higher prices and improved transportation, but a general decline in both lode and placer activity was again dominant from 1950 through 1959.
Total gold production before 1904 was estimated at from $35 to $55 million by Lindgren (1900, p. 233, 238; 1904, p. 84) and at $47 million by Thomson and Ballard (1924, p. 13). Production from 1905 through 1936 was 101,354 ounces of placer and 122,008 ounces of lode gold (Lorain and Metzger, 1938, p. 9). From 1905 through 1959 a total of 455,554 ounces of gold was produced in Idaho County. Staley (1946, p. 20, 21) presented yearly production data from 1862 through 1942 that totaled 2,176,550 ounces.
In general the oldest rocks in Idaho County are gneisses, schists, quartzites, and limestones of the Belt Series of Precambrian age (Shenon and Reed, 1934, p. 10). These were intruded by the Idaho batholith, a granodiorite and quartz monzonite body that underlies much of central Idaho and most of Idaho County. Unconformably overlying these rocks at low altitudes are remnants of the Columbia River Basalt, basaltic lavas which were poured out on a mature erosion surface during Tertiary time. Gold-bearing fissure veins occur in both the metasedi-mentary rocks of the Belt Series and in the granitic rocks of the Idaho batholith near intrusive contacts (Shenon and Reed, 1934, p. 24).
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