Trimountain Mine, Trimountain, Houghton Co., Michigan, USA
|Latitude & Longitude (WGS84):||47° 3' 19'' North , 88° 39' 38'' West|
|Latitude & Longitude (decimal):||47.05528,-88.66056|
|Other regions containing this locality:||Keweenaw Peninsula, Michigan, USA|
|Köppen climate type:||Dfb : Warm-summer humid continental climate|
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.
Commodity ListThis is a list of exploitable or exploited mineral commodities recorded at this locality.
6 valid minerals.
Rock Types Recorded
Select Rock List TypeAlphabetical List Tree Diagram
Entries shown in red are rocks recorded for this region.
This geological map and associated information on rock units at or nearby to the coordinates given for this locality is based on relatively small scale geological maps provided by various national Geological Surveys. This does not necessarily represent the complete geology at this locality but it gives a background for the region in which it is found.
Click on geological units on the map for more information. Click here to view full-screen map on Macrostrat.org
1000 - 1200 Ma
|Portage Lake Volcanics|
Age: Stenian (1000 - 1200 Ma)
Stratigraphic Name: Portage Lake Volcanics
Comments: This unit is the same as unit Yp on paper map of Sims (1992). Description is taken from that unit description.
Reference: Horton, J.D., C.A. San Juan, and D.B. Stoeser. The State Geologic Map Compilation (SGMC) geodatabase of the conterminous United States. doi: 10.3133/ds1052. U.S. Geological Survey Data Series 1052.