Ropes Gold Mine, Ishpeming Greenstone belt (Marquette Greenstone belt), Marquette Co., Michigan, USA
|Latitude & Longitude (WGS84):||46° 31' 47'' North , 87° 42' 57'' West|
|Latitude & Longitude (decimal):||46.52972,-87.71583|
|Köppen climate type:||Dfb : Warm-summer humid continental climate|
S/2 NW/4 Section 29 T48N R27W
A gold mine north of Ishpeming.
In 1881, former druggist, postmaster, and school board member Julius Ropes discovered gold among the serpentine rocks north of the town of Ishpeming, which prompted him to form the Ropes Gold and Silver Company to exploit that discovery. Mining and stamp-milling operations began in earnest in 1883 with the sinking of the Curry shaft and continued until financial troubles forced closure of the mine in 1897. Fifteen levels had been developed to 813 feet depth. $645,792 worth of gold (period values) was shipped during this period, extracted by the mercury amalgamation process and gravity separation.
Corrigan, McKinney and Co. purchased the mine property and, using the newly-developed cyanide leaching process, reclaimed nearly $200,000 in gold from the tailings during 1900 - 1901. Additional gold was gleaned from scraps of mercury amalgam recovered throughout the mill buildings.
The mine changed hands numerous times without further production until the inflation of the 1970s drove up gold prices enough to prompt Callahan Mining Co. to purchase the property and invest in exploration and rehabilitation of the mine. Mining resumed in 1983 with the sinking of a truck decline to 900 feet depth, and a new shaft was sunk in 1984, with workings reaching 1548 feet depth. Ore rock was trucked to the ore dressing plant of the retired Humboldt Iron Mine for gold extraction. Operations continued despite the collapse of the uppermost levels into a huge stope in 1987. The hole was filled with sand and mining carried on until expensive repairs and falling gold prices prompted closure in 1991 of the only profitable gold mine in Michigan's history.
Commodity ListThis is a list of exploitable or exploited mineral commodities recorded at this locality.
27 valid minerals.
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 Macrostrat.org
2500 - 2800 Ma
Age: Neoarchean (2500 - 2800 Ma)
Description: Derived from mafic to intermediate pyroclastic rocks and massive to pillowed lava flows. Unit mapped as Ramsey Formation by Prinz (1981) south of Gogebic Range; mapped as Mona Schist and Kitchi Schist in northern complex of Marquette District.
Comments: Continental margin assemblage (north of Niagara Fault). Prinz, W. C., 1981, Geologic map of the Gogebic Range-Watersmeet area, Gogebic and Ontonagon Counties, Michigan: U.S. Geological Survey Miscellaneous Investigations Series Map I-1365, scale= 1:125,000
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. 
2500 - 4000 Ma
|Archean volcanic rocks|
Age: Archean (2500 - 4000 Ma)
Lithology: Mafic volcanic rocks
Reference: Chorlton, L.B. Generalized geology of the world: bedrock domains and major faults in GIS format: a small-scale world geology map with an extended geological attribute database. doi: 10.4095/223767. Geological Survey of Canada, Open File 5529.