By A. H. KOSCHMANN and M. H. BERGENDAHL - USGS 1968
The important mineral deposits of Shoshone County are in the Coeur d'Alene Mountains, along its northeast boundary. This mineralized area covers about 500 square miles and includes about eight mining districts, known collectively as the Coeur d'Alene region.
The county's gold production from 1881 through 1942 was 393,088 ounces (Staley, 1946, p. 27) ; from 1943 through 1959 it was 41,113 ounces a total of 434,201 ounces for 1881-1959.
COEUR D'ALENE REGION
The Coeur d'Alene region is in northeastern Shoshone County between lat 47Â°25' and 47Â°40' N. and long 115Â°40' and 116Â°10' W., and includes the districts of Beaver, Eagle, Evolution, Hunter or Mullan, Lelande or Burke, Placer Center or Wallace, Summit, and Yreka. Wallace is its principal town.
The first mineral discoveries were lodes in 1878, but it was not until rich placers were discovered along Prichard and Eagle Creeks in the early 1880's that any concentrated interest was shown in the area. The town of Murray was founded in the placer area, and it soon became the county seat of Shoshone County. In 1885 rich deposits of lead and silver were discovered along the South Fork of the Coeur d'Alene River; at the same time the placers at Murray began to decline (Ransome and Calkins, 1908, p. 78-80). A railway into the region was completed in 1887, and by that time many propertiesâ€”among them the Bunker Hill and Sullivan, Mammoth, Tiger, Morning, Poorman, and Granite â€”were producing substantial amounts of ore. The succeeding decade was marked by strife between the miners' unions and the mine owners, and several times troops were called in to restore order (Ransome and Calkins, 1908, p. 81). Meanwhile the Murray placers experienced a revival. The bench gravels were worked, and several new lode properties began producing. By 1911 the lead-zinc mines at Murray reached their peak, and many continued operating until 1933, when all of them closed (Shenon, 1938, p. 15). The region became slightly active again in the mid-1930's and remained so through 1959.
Most of the early gold production of the region was from placers and gold-quartz veins near Murray; the lead-zinc ores at Murray contained only negligible amounts of gold. A total of 227,890 ounces of gold was produced in the region from 1884 to 1905 (Ransome and Calkins, 1908, p. 82). From 1906 through 1934 the Murray area produced 66,092 ounces of placer and 3,154 ounces of lode gold (Shenon, 1938, p. 17), and from 1935 through 1951 a total of 16,275 ounces of placer and lode gold was produced (Hosterman, 1956, p. 740). Mines in the Coeur d'Alene region, including the Murray district, produced a total of $7,180,151 (348,550 ounces) in gold from 1884 through 1931 (Ross, 1941, p. 85). Total gold production of the region through 1960 was about 439,000 ounces (Shenon, 1961, p. 1).
The geology of the region was described in detail by Ransome and Calkins (1908, p. 23-77), and the following was abstracted from their report. The oldest and most abundant rocks underlying the district are Precambrian sedimentary rocks of the Belt Series. These are subdivided into six formations, from the oldest to youngest: Prichard Formation, Burke Formation, Revett Quartzite, St. Regis Formation, Wallace Formation, and Striped Peak Formation. All these formations, except the Striped Peak, are intruded along a northeast-trending belt by bodies of quartz monzonite. The intruded rocks, especially the calcareous types, are metamorphosed extensively along the contacts. In addition to quartz monzonite, other igneous rocks of the district are dikes of diabase and lamprophyre.
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