Ref.: U.S.G.S. PP144, "Copper Mines of Keweenaw", by Clarke.
The Manganese Mine is one of the more interesting mines of the Keweenaw. Manganese minerals were discovered south of Copper Harbor by geologist Douglass Houghton in the 1830's. In 1881, an open cut to a depth of 75 ft. was mined by the Cambria Iron Co. and approx. 800 tons of material was removed. In 1883, a shaft was sunk and another 400 tons of manganese ore was removed for assay. It was determined that the ore was unsuitable for steel production, and the mine was abandoned.
The piles, if found through 120 years of overgrowth, can produce some excellent micro-minerals. It is the only site on the Keweenaw where specimens such as orientite, braunite, and macfallite are found.
Mineral List:17 entries listed. 17 valid minerals. 1 type locality (valid mineral).
The above list contains all mineral locality references listed on mindat.org. 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!
