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Knowlton Mine, Mass City, Ontonagon Co., Michigan, USA
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Knowlton Mine, Mass City, Ontonagon Co., Michigan, USA

Photo: Dan & Diana Weinrich Minerals
An underground copper mine consisting of three shafts located near Mass City, MI. The Knowlton Mining Co. was organized in 1860 but exploration work started in 1853. The mine officially closed in 1867, but work continued on tribute until 1885. The mine produced approx. 992,000 lbs. of refined copper. Minerals that can be found include copper, silver, datolite, and other micro minerals.

Mineral List


3 entries listed. 3 valid minerals.

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Butler, B.S., and Burbank, W.S., 1929, The Copper Deposits of Michigan. U.S. Geological Survey. Professional Paper 144. 238 pp.

The Copper Country Rock & Mineral Club, 2001, Red Gold and Tarnished Silver, 2nd Ed., 44 pp.

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Copyright © Jolyon Ralph and Ida Chau 1993-2014. Site Map. Locality, mineral & photograph data are the copyright of the individuals who submitted them. Site hosted & developed by Jolyon Ralph. Mindat.org is an online information resource dedicated to providing free mineralogical information to all. Mindat relies on the contributions of thousands of members and supporters. Mindat does not offer minerals for sale. If you would like to add information to improve the quality of our database, then click here to register.
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