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Star Mine, Copper Harbor, Keweenaw Co., Michigan, USA

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Latitude & Longitude (WGS84): 47° 28' North , 87° 53' West
Latitude & Longitude (decimal): 47.46667,-87.88333
Other regions containing this locality:Keweenaw Peninsula, Michigan, USA
Köppen climate type:Dfb : Warm-summer humid continental climate

An underground copper mine consisting of four shafts and two adits located southeast of Copper Harbor, or one mile south of the Clark Mine. The Star Copper Company was organized in 1851 nad began producing copper in 1855. Work was suspended in 1859, but resumed in 1864 due to rising copper prices. Prices dropped again in 1865, forcing the mine to close once again. The mine reopened briefly in 1872 and again in 1881 but closed permanently in 1882. The company remained organized in hopes of reopening the mine, but never did. The property was sold around 1908 to Calumet & Hecla Mining Co.
As with Clark Mine, datolite is the main attraction here, and some very nice specimens can still be found on the rock piles. Prehnite and copper can also be found here. Beware however, that the piles are covered with 120+ years of overgrowth, so finding them can be tricky.

Mineral List

4 valid minerals.

Regional Geology

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

1000 - 1600 Ma

ID: 2871548
Copper Harbor Conglomerate

Age: Mesoproterozoic (1000 - 1600 Ma)

Stratigraphic Name: Copper Harbor Conglomerate

Description: Red lithic conglomerate and sandstone; mafic to felsic volcanic flows similar to those of the unnamed formation (unit Yu) are interlayered with the sedimentary rocks.

Comments: Note: The unnamed formation has since been named the Porcupine Volcanics (Ypv).

Lithology: Major:{conglomerate,sandstone}, Minor:{mafic volcanic}

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. [133]

Data and map coding provided by, used under Creative Commons Attribution 4.0 License

This page contains all mineral locality references listed on This does not claim to be a complete list. If you know of more minerals from this site, please register so you can add to our database. This locality information is for reference purposes only. You should never attempt to visit any sites listed in without first ensuring that you have the permission of the land and/or mineral rights holders for access and that you are aware of all safety precautions necessary.


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Rocks & Minerals: 58:111.
Clarke, D.H., 1973, Copper Mines of Keweenaw; Star Mining Company, No. 2, 11 pp.

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