Montreal Mine (Ottawa; 33 Company Mine; Trimble; Odanah; Moore; Jupiter; Bourne; Sec. 33 Mine), Montreal, Gogebic Range, Iron Co., Wisconsin, USA
|Latitude & Longitude (WGS84):||46° 25' 40'' North , 90° 14' 45'' West|
|Latitude & Longitude (decimal):||46.4277777778, -90.2458333333|
An iron mine located near Montreal, just west of Hurley (Sec 33 T46N R2E). Test pits were first dug in the deposit and the first shaft sunk in 1882. The mine was predominantly an open pit operation until 1886. At the height of mining, it employed over 400 workers. As the mine grew, it engulfed a number of adjacent operations. The last ore was shipped in 1963. Workings featured the #4, #5 & #6 shafts; 20th., 37th., 38th. & 42nd. levels. The workings extended to a depth of 4,518 feet. It holds the record still for deepest underground iron mine in the world. It is in a classic Proterozoic banded iron formation (the Ironwood Formation) that forms the Gogebic Iron Range. The iron formation strikes NE-SW and dips north. It is cross-cut by diabasic dikes, which have localized a number of oxidized zone in the iron formation with large open pockets filled with a variety of minerals.
Excerpt from a AIME Report published 1/1/1940:
"The Montreal mine, operated by the Montreal Mining Co., is four miles west of Ironwood, Mich., in Iron County, Wisconsin. It is the westernmost producing property on the Gogebic Iron Range of the Lake Superior district. Its production is 4000 tons of hematite per day from an average depth of 2300 ft. This tonnage is hoisted through a five-compartment vertical shaft. Several mining methods are in use but in the larger orebodies the method is sublevel caving. … The main orebodies of the Montreal mine lie in eastward-pitching troughs formed by the intersections of intrusive dikes with impervious members of the iron formation. The formation has an average width of 425 ft., strikes east and west and dips north at approximately 62. The dikes dip south at 45° and bear north 20' from the strike of the formation, making the intersections with various members pitch east at 16°. The dikes are not continuous across the formation but are interrupted by a longitudinal bedding fault, which has a throw of 380 ft. vertically and 885 ft. horizontally. North of the fault zone the formation is called "hanging," south it is called "footwall" formation. The faulting has created two ore-bearing horizons; viz., at the intersection of hanging dikes with the slate members and the foot dikes with the quartzite footwall. In each formation the main ore-bearing member consists of wavy beds of hard chert interlaid with hematite. In the most productive part of the mine, where the sublevel caving method is employed, a hanging-formation dike lies in juxtaposition with a footwall dike and the iron formation carries ore in certain sections from the quartzite footwall to the hanging dike. Here a horizontal section of the orebody may be 300 to 400 ft. wide for a length of 150 ft. or more and tail out lengthwise in both the foot and hanging formations. The footwall ore section is much longer than the hanging wall because of the orebody's greater height above the "pitching dike."
30 valid minerals.
This 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 data will improve over time as more accurate maps and data sets are added.
|Paleoproterozoic1600 - 2500 Ma||Baraga Group; Tyler Formation|
Baraga Group; Tyler Formation - Light- to dark-gray, feldspathic, fine-grained sandstone, argillaceous siltstone, and argillite. Near base, ferruginous argillite contains beds of cherty sideritic and pyritic iron-formation
Continental margin assemblage (north of Niagara Fault)
|Paleoproterozoic1600 - 2500 Ma||Paleoproterozoic volcanic rocks|
May include hypabyssal intrusions.
|Paleoarchean3200 - 3600 Ma||Paleoarchean plutonic: tonalite|
References for regional geology:
Data provided by Macrostrat.org
Garrity, C.P., and Soller, D.R.,. Database of the Geologic Map of North America: adapted from the map by J.C. Reed, Jr. and others (2005). U.S. Geological Survey Data Series 424 .
USGS compilers. State geologic map data. State Maps.
Geological Survey of Canada. Generalized geological map of the world and linked databases. doi:10.4095/195142. Open File 2915d.
Lake Superior Iron Ore Association (1952), Lake Superior iron ores: mining directory and statistics: 56-57.
La Berge, G. (1984) The Geologic History of Wisconsin: Rocks and Minerals 59 (2), 60-73.
Schmidt, R G. (1980): The Marquette Range Supergroup in the Gogebic iron district, Michigan and Wisconsin: U. S. Geological Survey Bulletin 1460, 96 p.
Cox, B. (2005) Mines of the Pewabic Country of Michigan and Wisconsin: vol. 3 Wisconsin Iron: Agogebic Press: 88-91.
Robinson, G. & G. LaBerge (2013) Minerals of the Lake Superior Iron Ranges: A. E. Seaman Mineral Museum: Michigan Technological University, 52 p.