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Montreal Mine (Ottawa; 33 Company Mine; Trimble; Odanah; Moore; Jupiter; Bourne; Sec. 33 Mine), Montreal, Gogebic Range, Iron Co., Wisconsin, USA

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Latitude & Longitude (WGS84): 46° 25' 40'' North , 90° 14' 45'' West
Latitude & Longitude (decimal): 46.42778,-90.24583
Köppen climate type:Dfb : Warm-summer humid continental climate

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 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."

Mineral List

30 valid minerals.

Regional Geology

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

1600 - 2500 Ma

ID: 2882702
Baraga Group; Tyler Formation

Age: Proterozoic (1600 - 2500 Ma)

Stratigraphic Name: Tyler Formation

Description: 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

Comments: Continental margin assemblage (north of Niagara Fault)

Lithology: Major:{sandstone,siltstone}, Minor:{banded iron formation}

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. [133]

1600 - 2500 Ma

ID: 3241842
Marquette Range Supergroup: Tyler Formation

Age: Proterozoic (1600 - 2500 Ma)

Stratigraphic Name: Tyler Formation

Description: Quartz-rich graywacke and argillite. Gray, greenish-gray, and brown. Thin- to thick-bedded, commonly graded-bedded. Ripple marks and cross laminations also common. Ferruginous black chert, black pyritic slate, and feruginous conglomerate near base.

Comments: Penokean province; marine; foreland basin

Lithology: Major:: {metagraywacke},Minor:: {argillite,slate}

Reference: Cannon, W.F., L.G. Woodruff, S.W. Nicholson, C.A. Hedgman, and R.D. Barber-Delach. Digital Bedrock Geologic Map of the Ashland and Northern Part of the Ironwood 30' x 60' Quadrangles, Wisconsin and Michigan. U.S. Geological Survey Open-File Report 99-546. [162]

2500 - 4000 Ma

ID: 3192109
Archean volcanic rocks

Age: Archean (2500 - 4000 Ma)

Lithology: 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. [154]

Data and map coding provided by Macrostrat.org, used under Creative Commons Attribution 4.0 License

This page contains all mineral locality references listed on mindat.org. This does not claim to be a complete list. If you know of more minerals from this site, please register so you can add to our database. This locality information is for reference purposes only. You should never attempt to visit any sites listed in mindat.org without first ensuring that you have the permission of the land and/or mineral rights holders for access and that you are aware of all safety precautions necessary.


Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Dickey, R. M. (1938): Manganese in the Montreal Mine, Montreal, Wisconsin: Economic Geology, 33: 600-624.
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.

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