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Northwestern Mine, Central, Keweenaw Co., Michigan, USA
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Photo: DMM
Latitude: 47°24'32"N
Longitude: 88°11'29"W
 
 
The Northwestern Mine consists of 4 shafts and at least 1 adit. The Northwestern Mining Company was organized in 1845 and then reorganized in 1848. Work continued until 1857 and resumed again in 1863. All work ceased in 1865 and was absorbed by the Central Mining Company shortly after. 313,000 lbs. of refined copper was recovered from the mine. Copper, silver, analcime, and prehnite can be found on the poor-rock piles.

Mineral List

Analcime
'Apophyllite'
Calcite
Chalcocite
'Chlorite Group'
Chrysocolla
Copper
Datolite
'K Feldspar
var: Adularia'

Microcline
Prehnite
'Pumpellyite'
Pumpellyite-(Mg)
var: Chlorastrolite

Quartz
Saponite
Silver


16 entries listed. 11 valid minerals.

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References

Henwood, W.J. (1871): Observations on Metalliferous Deposits: On the Native Copper of Lake Superior. Transactions of the Royal Geological Society of Cornwall 8(1), 385-489.

Tschernich, R. (1992): Zeolites of the World, 66

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