Ontario Mineral Inventory

Ontario Geological Survey
Permanent Link to this Record: MDI52B13SE00009

Record: MDI52B13SE00009

General

Commodities

Primary Commodities: Iron

Location

Township or Area: Schwenger

Latitude: 48° 48' 54.71"    Longitude: -91° 36' 18.18"

UTM Zone: 15    Easting: 602405.78   Northing: 5407850.58    UTM Datum: NAD83

Resident Geologist District: Thunder Bay South

NTS Grid: 52B13SE

Point Location Description: West side of North Mink Pit.

Location Method: Conversion from MDI

Access Description: Access via mine roads north from Atikokan.

Exploration History

1891: H.L. Smyth first recognized the possibilities of iron ore at Steep Rock Lake. 1930: J.E. Marks and J. Cross carried out two dip needle surveys. 1937: Steerola Exploration Ltd. was formed and drilled in the Steep Rock Lake area. 1938-40: Steerola Exploration Ltd. drilled in Falls Bay, completing 41 DDH for a total of 5255.67 m. 1949: Caland Ore Company Ltd. was formed as a wholly-owned subsidiary of Inland Steel Company and obtained an option from Steep Rock Iron Mines Ltd. to lease the orebody under Falls Bay. 1949-53: Exploratory drilling was conducted. 1953: Caland Ore signed a 99 year lease with Steep Rock Iron Mines, allowing Caland to proceed with development and mining. 1959: Caland began open-pit mining in the Lime Bay zone. 1960: first ore was shipped. 1964-66: pelletizing processing plant was constructed. 1979: mining operations ceased.

Geology

Province: Superior

Subprovince: Wabigoon

Geological Age: Archean  

Lithology

Lithology Comments

Jun 21, 2018 (Therese Pettigrew) - The Caland ore zone is a faulted extension of the Steep Rock Iron Range and, as such, is similar in lithology and structure to the ore zone of Steep Rock Iron Mines. The uppermost member of the Steep Rock Group consists of intermediate to felsic lava flows, which commonly are extensively carbonatized and locally pillowed. An ultramafic black "ashrock", invaded by mafic intrusions, underlies these volcanics and overlies the ore zone. The "ashrock" has a well-developed pyroclastic texture and locally maybe pyritic in the immediate vicinity of the ore. A narrow hematitic selvage zone, several feet in width, may be present at the ore-"ashrock" contact, indicating the introduction of ferric iron. Underlying the ore is a grey to yellowish brown porcelaneous chert. It is discontinuous and is regarded as a direct chemical precipitate. Below the chert lies the manganiferous "paint rock," which is not a true stratigraphic member, but rather is believed to be the result of weathering and alteration, in situ, of a siliceous, manganiferous, and ferruginous carbonate. The poorly developed sorting and banding is indicative of little or no transportation during decomposition. This incoherent mixture of iron and manganese oxides, quartz, carbonate, and kaolinite protrudes into the underlying carbonate and may penetrate as far as the granite. Contact with the overlying ore is sharp, whereas with the chert and carbonate the boundaries are commonly gradational. There does not appear to be any discordance with the overlying rocks. The carbonate is well banded to massive, ranges from a calcitic limestone to an ankeritic dolomite, and at several locations is well brecciated. This breccia is believed to be of tectonic origin. The upper surface of the carbonate is regarded by some geologists to be a karst topographical profile and the "paint rock" to be residual soil derived from the erosional decomposition of a much greater thickness of carbonate. Two narrow conglomerate bands within the Falls Bay area are believed to be of different ages. The conglomerate at the base of the carbonate is of limited extent and is believed to be derived from the underlying granite inasmuch as it contains quartz and granite-like pebbles. The second conglomerate because of its impurities and more angular quartz pebbles is regarded as younger. The leucocratic granite contains numerous mafic dikes that display chilled margins. Where the alteration has penetrated into the granite, the granite is very soft and kaolinized (McIntosh, 1972).

Mineralization

Mineralization Comments

Jun 21, 2018 (Therese Pettigrew) - The S-shaped ore deposit is 8,600 feet long, conformable with the bordering volcanics and sediments of the Steep Rock Group and is centred in an alteration aureole in which the rocks have been decarbonatized, desilicified, and oxidized. Contacts with the overlying "ashrock" and underlying chert or "paint rock" are generally sharp and well defined. The ore deposit passes into a well-banded chert and goethite iron formation, grading 30 to 40 percent iron, which in turn grades into a thinly banded, carbonaceous hematite-silicate iron formation. The six ore zones of Bessemer grade consist of a porous and friable mixture of goethite and hematite with small percentages of silica and kaolin as waste constituents. There is no visible bedding within the ore and little evidence of any appreciable slumping. The goethite ranges from a hard, very fine grained, metallic bluish black lump, most commonly occurring at the perimeters of the orebody, to fragments less than an inch across of the same hard fine texture in a matrix of earthy reddish hematite and brown limonitic goethite. Locally, goethite is found in acicular and colloform habits. Stalactitic and botryoidal goethite with an internal concentric or radial structure, is seldom present except as fracture fillings. Hematite is very erratic in occurrence, forming from 0 to 85 percent of the mineral content of the ore. No stratigraphic or other geological control for its distribution is apparent. There is no evidence of increase in hematite with depth. It occurs mainly as a red earthy coating on the harder fragments in the brecciated ore. Locally, however, the hematite may be hard, very fine grained, bluish lump grading up to 65 percent in iron. This type was found in the northwestern end of the North Mink zone as a narrow selvage zone in the hanging-wall of the ore against the "ashrock" (McIntosh, 1972). The ore consists of 67% goethite, 21% hematite, 5% kaolin, and 5% quartz (Shklanka, 1968).

Mineral Record Details

References

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 Scale:     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 Scale:     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