Latitude: 47°3'19"N
Longitude: 88°39'38"W
Commodities (Major) - Copper
Deposit Type: Lode
Development Status: Past Producer
Deposit Model: 96: Native Cu
Host Rock Unit: Baltic Amygdaloid, Portage Lake Volcanics
Host Rock: Basalt
An underground copper mine consisting of 4 shafts near the community of Trimountain. The Trimountain Mining Co. was organized in 1899 and worked the Baltic Lode. Shafts at this mine were some of the steepest in the Keweenaw at 70 degrees from horizontal to follow the orebodies. The mine opereated under Trimountain until 1923, when the company was dissolved. Copper Range Consolidated Co. took over operations in 1925 and operated the mine until 1930 when it was closed permanantly. The Trimountain Mine produced approx. 144 million lbs. of refined copper. Some minerals that can be found on the piles include copper, epidote, datolite, and rarely chalcocite.
References
Rocks & Min.: 58:109.
Kilpela, T, 1995, The Hard Rock Mining Era in the Copper Country. 89 pp.
BUTLER, B.S., AND BURBANK, W.S., 1929, THE COPPER DEPOSITS OF MICHIGAN: USGS PROF PAPER NO. 144, 238 PP.
WHITE, W.S., AND WRIGHT, J.C., 1956, GEOLOGIC MAP OF THE SOUTH RANGE QUADRANGLE, MICHIGAN: USGS MAP MF-48, SCALE 1:24000.
Mineral List
6 entries listed. 5 valid minerals.
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