Broadwater County Montana Gold Production
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By A. H. KOSCHMANN and M. H. BERGENDAHL - USGS 1968
Broadwater County, in west-central Montana, was noted for its gold placers, which were among the most productive in the State. Though production before 1904 was not recorded, it was large. The estimated placer gold production of Confederate Gulch alone was about $12 million (580,550 ounces) (Pardee and Schrader, 1933, p. 172-173), and significant production has also come from placers along White, Avalanche, Beaver, Indian, and Crow Creeks (Lyden, 1948, p. 17-20). Early lode production is also unrecorded, but it probably was small. Total gold production for the county from 1901 through 1959 was approximately 362,000 ounces - about 327,500 ounces from lodes and 34,500 ounces from placers; from the beginning of mining through 1959 the total probably was about 1 million ounces.
CONFEDERATE GULCH DISTRICT
The Confederate Gulch (Backer) district is along Confederate Gulch, a tributary of the Missouri River in northern Broad water County, about 11 miles north of Townsend. Gold has been mined chiefly from placer deposits along Confederate Gulch and its tributaries; only a little production has come from lode deposits. The placers along Confederate Gulch were discovered in 1864 and proved to be exceedingly rich; they were higher in grade, though lower in tonnage, than the well-known placers along Alder Gulch in Madison County and along Last Chance Gulch in Lewis and Clark County. The total yield is estimated to be worth about $12 million (580,550 ounces), most of which was achieved in the first 5 years of mining. After 1869 placer mining declined rapidly and by 1880 only a few miners remained in the district (Pardee and Schrader, 1933, p. 171-173). Lode production in the early years was of little consequence, but from 1908 through 1951 lodes were worked continuously on a small scale, except during World War II. No activity was reported in either lodes or placers from 1953 through 1959.
The total gold production of the district through 1959 was "between 550,000 and 600,000 ounces; all but about 10,000 ounces was from placers.
The placers are in stream terrace gravels believed to be Pleistocene in age (Pardee and Schrader, 1933, p. 174-175). They were deposited at several levels by streams during the process of excavating the Confederate Gulch drainage basin. Pardee concluded that the distribution of the gold-bearing gravel indicates that the chief, if not the only, source of the gold is the quartz lodes on Miller Mountain at the head of Montana Gulch.
Most of the district is underlain by Precambrian shaly, slaty, and calcareous rocks of the Belt Series. These are disconformably overlain by Paleozoic sedimentary rocks that include the Flathead Quartzite, Wolsey Shale, and unnamed limestone and shale, all of Cambrian age; limestone and shale of Devonian age; and the Madison Limestone, Quadrant Quartzite, and Phosphoria Formation, all of Carboniferous age. These rocks were folded into a large northwest-trending anticline, exposing the Precambrian rocks in the eastern part of the district and steeply dipping bands of Paleozoic rocks in the western part. The rocks were also cut by prominent thrust faults and were intruded during Late Cretaceous or early Tertiary time by sills, dikes, and small stocks of quartz diorite and quartz monzonite (Pardee and Schrader, 1933, p. 123-132). Gold-quartz veins are along fractures in the quartz diorite and bedding planes in adjacent Precambrian shale. A few lodes are replacement bodies in the quartz diorite. Quartz, pyrite, and galena are characteristic minerals of both types of lodes. The oxidized parts of the deposits contained quartz, iron oxides, and small specks of native gold (Pardee and Schrader, 1933, p. 139-146).