Madison County Montana Gold Production
The Virginia City-Alder Gulch district, which includes the Summit area, is in central Madison County at the south end of the Tobacco Root Mountains. It is the leading producer of placer gold in Montana and has also produced a small amount of lode gold. The discovery of rich gold placer deposits in Alder Gulch in 1863 marked the beginning of mining activity in Madison County. Gold-quartz veins were discovered in the district later in the year (Winchell, 1914a, p. 159). The richness of the placers attracted hordes of prospectors to the area, and within 18 months Virginia City boomed to a town of 10,000 population. Within 3 years, placer gold valued at $30 million was recovered from Alder Gulch and its tributaries (Knopf, 1913, p. 15). The Alder Creek placers, extending for about 20 miles, were the longest and most productive ever discovered in Montana. From 1863 until 1899 the gravels were worked by sluice boxes, pans, and rockers. In 1899 the Conrey Placer Mining Co. began dredging operations that lasted until 1922, when the gravels were considered mined out. The peak year of dredging, 1915, resulted in more than $800,000 in gold recovered from 6 million cubic yards of gravel (Lyden, 1948, p. 80-82). During the 14 years following 1922 only small-scale sluicing operations were undertaken. In 1935 dryland dredges were installed (Lyden, 1948, p. 82) and were successfully operated through 1942, when operations closed for the duration of World War II. Dredging was resumed in 1946 but was suspended in late 1948.
The gold-bearing gravel in Alder Gulch is 30 to 50 feet deep; the most valuable gravel is about 6 feet above the soft, plastic bedrock (Kirk, 1908, p. 330). The placer gold probably was weathered directly from the thousands of veins of the district (Lyden, 1948, p. 83).
Various estimates have been made regarding production of the Alder Gulch placers before 1904. In addition to the $30 million produced during the first 3 years (1863-66), Hart (in Tansley and others, 1933, p. 46) estimated that Alder Gulch and its tributaries yielded $42.75 million from 1867 through 1903. The Montana Bureau of Agriculture, Labor,and Industry (1900, p. 188) estimated production at $150 to $200 million in gold through 1899. Kirk (1908, p. 330) estimated the output by 1908 at $125 million. Lyden (1948, p. 80) believed that Hart's estimate was low and Kirk's was high. Almost certainly Hart's figure of $42.75 million (2,068,215 ounces) is a conservative estimate for the period 1863-1903. From 1904 through 1930 the production was 380,351 ounces (Hart, in Transley and others, 1933, p. 46), and from 1932 through 1959, about 24,500 ounces. Therefore the total production through 1959 was at least 2,475,000 ounces.
Lodes also were productive in the Virginia City district. The first lode deposits were developed soon after 1864, and by 1871 at least 8 mills had been erected to treat the gold-quartz ores (Winchell, 1914a, p. 159). Much of the early lode production came from the Oro Cache and Kearsarge mines, in the Summit camp, which produced an estimated $500,000 and $150,000 in gold, respectively by 1881 (Winchell, 1914a, p. 159). Hart (in Tansley and others, 1933, p. 46) estimated the lode production during 1867-90 at $1 million (48,379 ounces), and during 1891-1903, at $269,256 (13,026 ounces). Lode production fluctuated but continued at a moderate scale through 1914 and ranged from $131,000 in 1910 to only $12,856 in 1912 (Hart, in Tansley and others, 1933, p. 46). Thereafter, production was sporadic and it declined sharply until the price of gold was raised in 1934. Annual production after 1934, except during World War II, ranged from about 1,300 to 4,500 ounces. Very small amounts of lode gold were mined in the 1950's. Total lode production of the district was about 142,000 ounces, and the minimum total placer and lode production through 1959 was about 2,617,000 ounces.
The following brief summary of the geology and ore deposits has been abstracted from reports by Winchell (1914a, p. 159-165) and Hart (in Tansley and others, 1933, p. 47-50).
The district is underlain by gneiss and schist of Precambrian age and intrusions of aplite and andesite porphyry of Cretaceous or Tertiary age. East of Virginia City the uplands are capped by basalt flows of Tertiary age. The lode deposits are chiefly in the gneiss and schist, but one vein system is in aplite. The lodes are quartz veins and stringers that contain auriferous pyrite, galena, sphalerite, and chalcopyrite and lesser amounts of gold tellurides, tetrahedrite, argentite, and stibnite. Most of the ore shipped was oxidized and consisted of gold and free silver in quartz, iron oxides, manganese oxides, and a little locally occurring copper stain.