By A. H. KOSCHMANN and M. H. BERGENDAHL - USGS 1968
The gold production of Madison County is exceeded in Montana only by that of Silver Bow and Lewis and Clark Counties. Most of its gold was produced before 1904 from the placer deposits of Alder Gulch, by far the richest placers in the State. About 40 other gulches in the county produced placer gold, but only in small amounts (Lyden, 1948, p. 80-95). After 1904, lodes became increasingly important gold sources.
Most of the gold lodes and other auriferous deposits are near the contacts of Precambrian metamorphic and Paleozoic sedimentary rocks with the Tobacco Root batholith and other smaller intrusives and satellite stocks that are probably related to the Boulder batholith (Hart, in Tansley and others, 1933, p. 23-55). Some deposits are in the igneous rocks. The more productive lode areas are the Norris, Pony, Renova, Sheridan, Silver Star-Rochester, Tidal Wave, and Virginia City districts.
The total gold production of the county through 1959 was at least 3,746,000 ounces - 2,605,000 from placers and 1,141,000 from lodes. This must be considered a conservative figure, for as Lyden noted (1948, p. 80), estimates of the Alder Gulch placer production ranged from $50,612,000 to $125 million.
Located in the northeastern part of Madison County, the Norris district, which includes Norwegian, Lower Hot Springs, and Washington, has produced chiefly gold and smaller amounts of silver, copper, and lead.
Placer deposits along Norwegian Gulch and South Meadow Creek were discovered in early 1864, and Norwegian Gulch yielded $150,000 in gold by 1874 (Winchell, 1914a, p. 111). By 1902 the district had produced at least $300,000 (14,514 ounces) in placer gold (Winchell, 1914a, p. 118), and the placers were worked on a fairly large scale from 1936 through 1942.
Quartz lodes also were discovered in 1864, and within 5 years the district had at least 8 mills (Winchell, 1914a, p. 111). Production fluctuated but was almost continuous through 1953.
Winchell (1914a, p. 118) estimated that the total lode output to 1902 exceeded $3 million in combined metals. From 1902 through 1912 gold accounted for about 90 percent of the value of mine production; if the same ratio was applicable before 1902, the lode mines of the district produced about $2,700,000 (130,600 ounces) during that period. The total lode production of the district was about 235,000 ounces and the total minimum production of both lodes and placers through 1959 was about 265,000 ounces.
The geology and ore deposits were described by Winchell (1914a, p. 111-118) and by Hart (in Tansley and others, 1933).
The Norris district is on the northeast side of the Tobacco Root batholith of Late Cretaceous age. The batholith consists chiefly of quartz monzonite and is intrusive into gneiss and schist of Precambrian age. Small remnants of rhyolite and basalt of Late Cretaceous or Tertiary age intrude and cap the older rocks.
Most of the ore deposits occur in the quartz monzonite but some are in gneiss near the intrusive contact. The ore occurs in quartz veins, which are oxidized in the upper part, and contains iron oxide, gold, and silver. In the Revenue mine, the most productive in the district, the zone of oxidation extends to the 200-foot level. Some oxidized ore also carries copper carbonate and silicate minerals. Below the zone of oxidation the most common ore mineral is auriferous pyrite, but some ore also contains galena, sphalerite, chalcopyrite, bornite, and chalcocite (Hart, in Tansley and others, 1933, p. 52).
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