Ontario Mineral Inventory

Ontario Geological Survey
Permanent Link to this Record: MDI52B13SE00005

Record: MDI52B13SE00005

General

Commodities

Primary Commodities: Iron

Secondary Commodities: Manganese

Location

Township or Area: Freeborn

Latitude: 48° 47' 36.3"    Longitude: -91° 38' 17.61"

UTM Zone: 15    Easting: 600013.77   Northing: 5405385.56    UTM Datum: NAD83

Resident Geologist District: Thunder Bay South

NTS Grid: 52B13SE

Point Location Description: Pit wall, south end of Errington Pit.

Location Method: Conversion from MDI

Access Description: Along Middle Arm of the former Steeprock Lake and the north part of the West Arm. Access via Steep Rock Lake road north and NW from Atikokan.

Exploration History

1891: H.L. Smyth noted the presence of hematite boulders in the vicinity of Steep Rock Lake. 1930-31: dip needle surveys were conducted by J.E. Marks and J. Cross. 1937-38: Steerola Exploration Ltd. carried out drilling. 1938-39: magnetometer and EM surveys were carried out. 1945: full-scale mining operations began by open pit from the Errington Mine and continued until 1952. 1953: Underground mining began from the Errington shafts. Open-pit mining began from the Hogarth Mine and continued until 1962. 1955-1961: Dredging operations at the Roberts mine, to establish the pit. 1958: Hogarth shaft was sunk, but has been on a standby basis since 1961. 1962: Open-pit mining began from the Roberts Mine, located between the Errington and Hogarth Mines. 1966: Steep Rock Iron Mines Ltd. entered into a joint venture agreement with The Algoma Steel Corporation Ltd., whereby Algoma acquired title to open-pit or in the Roberts and Hogarth Mines to a depth of 350 feet, with Steep Rock Iron Mines to deliver 22 million gross tons of pellets at a minimum annual rate of 1,100,000 gross tons. 1967: pellet plant was completed. 1972: Roberts pit was closed. Open pit mining resumed at Hogarth. 1973: underground operations at Errington ceased. 1979: Steep Rock mine closed.

Geology

Province: Superior

Subprovince: Wabigoon

Geological Age: Archean  

Lithology

Lithology Comments

Jun 21, 2018 (Therese Pettigrew) - The pre-Steep Rock complex is mainly granitic and dioritic gneiss. Above the gneiss, conglomerate occurs at intervals at the base of the Steep Rock Group. The greatest thicknesses of the gravel exceed 183 m and coincide with depressions in the pre-Steep Rock surface. Above the conglomerate is a dolomite formation up to 457 m thick. The ore zone is comprised of a lower Manganiferous Paint Member (non-ore) and the upper Goethite member (ore). The Manganiferous Paint Member is made up largely of incoherent to unctuous, rudely-banded to fragmental material that is commonly below ore grade. In places it holds more or less continuous highly siliceous bands which include massive chert, disconnected chert fragments, as well as white powdery siliceous material. The member is extremely variable in thickness, ranging from 1-305 m. The boundary between the Manganiferous Paint and the Goethite Members is quite abroupt. The Paint has more than 0.5% manganese and has iron/manganese ratios of less than 70 whereas the Goethite Member rarely has more than 0.3% manganese and the iron/manganese ratios are commonly greater than 200. Most of the Goethite Member is ore grade. Goethite is usually 2-5 times as abundant as hematite. The most characteristic feature of the ore is a ubiquitous breccia structure with hard, dark, angular lumps set in a lighter-coloured, porous, friable matrix. An irregular, stock-like body of material locally termed “Buckshot” occurs near the top of the Goethite Member at the Errington Mine. This rock is made up of dark pisolites and fragments of hematite in a lighter-coloured matrix containing kaolinite and gibbsite. Above the Goethite Member is the Pyrite Member, which has pyrite occurring in conformable lenses sporadically distributed along and near the contact between the ore zone and the overlying Ashrock Formation. The uppermost formation of the Steep Rock Group is the Ashrock Formation, which is nearly 275 m thick at the Errington Mine and contains pyroclastic rock and one or more basaltic lava flows (Shklanka, 1972).

Mineralization

Mineralization Comments

Jun 21, 2018 (Therese Pettigrew) - The mineral content from the ore zone has been calculated at 71.09% goethite, 20.98% hematite, 3.73% kaolin, 2.90% quartz, 0.36% pyrolusite, 0.24% vivianite, 0.19% magnesite, 0.18% calcite, and 0.06% pyrite (Shklanka, 1972). The goethite-hematite ore has a strike length of 6.1 km and is up to 91.4 m thick. Average of 1963 shipments yielded 59.6% Fe, 4.63% SiO2, and 0.03% S. Pyritic lenses occur over a strike length of 4.3 km and are up to 76 m wide and 510 m long. A weighted average of 600 m of drill intersections gave 38.6% Fe, 14.6% SiO2, and 24.3% S (Shklanka, 1968).

Mineral Record Details

References

Book - Canadian Mines Handbook 1980-1981

Publication Number: CMH 1980 Page: 256-257  Date: 1980

Author:

Publisher Name: Northern Miner Press

Location: Thunder Bay RGP office

Map - Steep Rock Lake area, Rainy River District

Publication Number: M2217 Scale: 1:12,000    Date: 1972

Author: Shklanka R.

Publisher Name: Ontario Dept. of Mines and Northern Affairs

Location:

Mono - Iron deposits of Ontario

Publication Number: MDC011 Page: 297  Date: 1968

Author: Shklanka R.

Publisher Name: Ontario Dept. of Mines

Location:

MonoMap - Geology of the Steep Rock Lake Area, District of Rainy River

Publication Number: R093 Page: 72-79  Date: 1972

Author: Shklanka R., McIntosh J.R.

Publisher Name: Ontario Dept. of Mines and Northern Affairs

Location:

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For detailed information regarding this mineral record please contact the Thunder Bay South Resident Geologist District Office