The Park (Indian Creek, Hassel) district, on the east side of the Elkhorn Mountains between WinÂ¬ston and Radersburg, has produced lode and placer gold, silver, and a little lead and zinc. Placer deÂ¬posits were discovered about 1860 along Indian Creek near Hassel, and gold veins were discovered later (Stone, 1911, p. 90). The placers yielded about $50,000 (2,370 ounces) in 1871, but little else is known of the early placer operations (Lyden, 1948, p. 19). There was placer mining in 1911-15, 1933-43, and again in 1945-49.
Records of the early lode mining are meager. According to Stone (1911, p. 90), tunnels and open-pit mining along some large mineralized zones produced about $500,000 (23,690 ounces) in gold, probably prior to 1908. With few exceptions there was some production every year from 1908 through 1957. The district was idle from 1957 through 1959. M. R. Klepper (written commun., 1962) summarized gold production as follows: 1864-1904, $850,000; 1905-28, $50,000; 1929-56, $1,250,000. Production from 1864 to 1904 was mainly from placers and from some lode mines in the Hassel area. From 1929 to 1956, production was mainly lode gold from the Marietta mine. Total production for all three periods was about 80,300 ounces of gold valued at $2,150,000.
Most of the lode deposits in the Park district are quartz veins in andesite which is intruded by quartz monzonite. The ore consists chiefly of auriferous pyrite accompanied by arsenopyrite and galena; the principal value is in gold (Stone, 1911, p. 89-91).
The Radersburg (Cedar Plains, Crow Creek) district, on the east side of the Elkhorn Mountains in southern Broadwater County, was the largest producer of lode gold in the county; it also produced some placer gold and significant amounts of silver, copper, lead, and a small amount of zinc.
Placer and lode deposits were discovered in 1866 (Winchell, 1914a, p. 173, 182). By the late 1870's the easily worked oxidized gold ores were depleted, and most of the mines closed. In 1883 railroad connections were made with the large smelters at Butte and Helena that treated sulfide ores at low costs. The mines at Radersburg were reactivated and continued in operation through 1956. The district was idle from 1956 through 1959.
Placer deposits are found for several miles along Crow Creek and Johnny Gulch near Radersburg. Old residents of the district estimated the placer production from 1866 to 1904 at $500,000 (24,380 ounces) to $1 million (48,379 ounces) (Winchell, 1914a, p. 182). Placer production after 1904 was about 850 ounces. The total gold production of the district through 1959, including both lode and placer, was about 325,000 ounces.
The principal gold deposits in the Radersburg district are in veins in andesitic volcanic rocks and associated intrusive diorite porphyry of Late Cretaceous age (M. R. Klepper, written commun., 1962). A stock of monzonite cuts these rocks about a mile south of the major mines. Ore deposits, which are valued mainly for silver, lead, and zinc, are along or near contacts of intrusive rocks with Paleozoic and Mesozoic sedimentary rocks. The most valuable deposits are gold-bearing pyrite veins containing a very small amount of chalcopyrite and very little quartz or other gangue material. A few veins contain quartz and small amounts of sphalerite, arsenopyrite, chalcopyrite, and galena. The ore along or near the igneous contacts is accompanied locally by calcite, siderite or ankerite, limonite, and pyrolusite. Cerussite, wulfenite, and hematite are in the oxidized parts of a few deposits.
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