Commodities
PrimaryCopper
SecondarySilver
Commodity typeM
Deposit
Deposit typeLode
Model96: Native Cu
Deposit sizeM
Orebody formTABULAR
Ore controlAmygdaloidal basalt flow top
Materials
Ore mineralsCopper
GangueFeldspar, Epidote, Quartz, Calcite, Sericite, Pumpellyite-(Mg)
Geology
Host rockBasalt · "Isle Royale Amygdaloid", "Portage Lake Volcanics"
StructureSyncline, Isle Royale syncline--the largest structure seen in the mine. The only fau
AlterationEarly oxidation followed by epidotization/pumpellitization associated with copper mineralization
Economic & production
Development statusPast Producer
Production years1853-1885; 1901-1925 AND POSSIBLY LATER.
First production1853
Last production1885
Identification
Deposit ID10082868
MRDS IDW062231
Alternate namesOld Isle Royale Mine, Dodge Exploration Formation
RegionNA
Data scoreB
Coordinates47.09778, -88.58033
References
BUTLER, B.S., AND BURBANK, W.S., 1929, THE COPPER DEPOSITS OF MICHIGAN: USGS PROF PAPER NO. 144, 238 PP.WHITE, W.S., 1956, GEOLOGIC MAP OF THE CHASSELL QUADRANGLE, MICHIGAN: USGS MAP MF-43, SCALE 1:24000.JOHNSON, A.M. AND GROTH, E.H., 1998, INVENTORY OF UNDERGROUND MINES, HOUGHTON COUNTY, SITE ID 310016, MICHIGAN DEPARTMENT OF NATURAL RESOURCES.BUTLER, B.S., AND BURBANK, W.S., 1929, P. 87.