Ontario Geological Survey
Permanent Link to this Record:
MDI000000002230
| Record Name(s) | Superior Shoal Copper - 1980 |
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| Related Record Type | |
| Related Record(s) | |
| Record Status | Discretionary Occurrence |
| Date Created | 2018-Oct-09 |
| Date Last Modified | 2022-Apr-12 |
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| Revised By |
Primary Commodities: Copper
Latitude: 48° 3' 48.17" Longitude: -87° 8' 18.56"
UTM Zone: 16 Easting: 489682 Northing: 5323354 UTM Datum: NAD83
Resident Geologist District: Thunder Bay South
NTS Grid: 42D03SE
Point Location Description: Point from Kirkham and Franklin, 1980
Location Method: Data Compilation
Access Description: By boat
Late 1970s: D. King, a retired fisherman from Rossport, reported recovering pieces of native copper in his nets while fishing on the shoal. 1980: The Cousteau Expedition visited the site and collected a dredge sample.
| Rock Type | Rank | Composition | Texture | Relationship | Mafic lava flow-unsubdivided | 1 | Amygdaloidal Basalt | Host |
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Oct 09, 2018 (Therese Pettigrew) - At a depth of approximately 18 m (10 fathoms), a single, angular block, weighing 2.65 kg was recovered by a dredge from a steep, rocky slope. The sample has a dark grey surface, and is slightly porphyrytic amygdaloidal basalt with a pronounced weathered rim 1-1.5 cm thick. The fresh interior is purple-grey. The rock is ophitic and contains approximately 20% of 0.5 to 2 mm long plagioclase laths, and about 20% of irregular 0.1 to 12 mm diameter amygdules.
| Rank | Mineral Name | Class | Economic Mineral Type | Alteration Mineral Type | Alteration Ranking | Alteration Intensity | Alteration Style |
|---|---|---|---|---|---|---|---|
| 1 | Copper | Economic | Ore | ||||
| 2 | Chalcocite | Economic | Ore | ||||
| 3 | Digenite | Economic | Ore | ||||
| 1 | Calcite | Economic | Gangue | ||||
| 2 | Chlorite | Economic | Gangue |
Oct 09, 2018 (Therese Pettigrew) - Most of the large amygdules are filled with white sparry calcite. The outer rims of the large amygdules and most small amygdules contain dark green, Fe-rich chlorite, and subround grains of native copper, 0.1 to 1 mm in diameter. Trace amounts of chalcocite and digenite were identified by x-ray. The copper is most common in small amydules and near the walls of large amydules, and is clearly and early cavity filling. A representative sample was assayed and found to contain 0.23% Cu (Kirkham and Franklin, 1980).
Publication - Native Copper on Superior Shoal, Ontario; In: Current Research Part C, Paper 80-1C
Publication Number: Paper 80-1C Date: 1980
Author: Kirkham, R.V. and Franklin, J.M.
Publisher Name: Geological Survey of Canada
Location: https://doi.org/10.4095/102243
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