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Ontario Geological Survey
Permanent Link to this Record:
MDI52A07SW00002
| Record Name(s) | Silver Islet - 1868 |
|---|---|
| Related Record Type | Simple |
| Related Record(s) | |
| Record Status | Past Producing Mine With Reserves or Resources |
| Date Created | 1980-Jan-23 |
| Date Last Modified | 2022-Apr-26 |
| Created By | |
| Revised By |
Primary Commodities: Silver
Secondary Commodities: Copper, Lead, Zinc, Barite, Nickel, Cobalt
Township or Area: Porphyry Island Area
Latitude: 48° 19' 17.43" Longitude: -88° 48' 43.03"
UTM Zone: 16 Easting: 365681 Northing: 5353622 UTM Datum: NAD83
Resident Geologist District: Thunder Bay South
NTS Grid: 52A07SW
Point Location Description: AMIS Shaft location
Location Method: Other
1846: staked by J. Woods. 1868: J. Morgan discovered the vein. Montreal Mining Co. began surface exploration. 1869: shaft sinking began. 1870-73: Ontario Mineral Lands Syndicate of Detroit built cribwork around the islet, mined to 360 foot level, with 2 million ounces of silver produced. 1873-78: Silver Islet Mining Co. conducted mostly underground exploration. Southerly drifting on 3rd level (150 foot depth) in 1878 encountered rich ore that produced 800,000 oz of silver. 1878-1883: workings developed to 1230 foot depth. 1920: Islet Exploration Co. pumped out the mine to the fourth level and carried out sampling. 1921: Islet Exploration Co. carried out an exploration drift on the 4th level driven southwest for 783 feet; diamond drill hole extended it a further 431 feet. 1922: mining carried out above the 60 foot level. 1974: Q.C. Explorations Ltd. optioned the property and carried out sampling of the dump.
Province: Southern
Formation Group: Animikie Group
Geological Age: Paleoproterozoic
| Rock Type | Rank | Composition | Texture | Relationship | Diabase | 1 | Diabase Dyke | Adjacent |
|---|---|---|---|---|
| Mudstone | 2 | Shale | Adjacent | |
| Vein | 3 | Carbonate And Quartz | Host |
| Rank | Mineral Name | Class | Economic Mineral Type | Alteration Mineral Type | Alteration Ranking | Alteration Intensity | Alteration Style |
|---|---|---|---|---|---|---|---|
| 1 | Argentite | Economic | Ore | ||||
| 2 | Chalcopyrite | Economic | Ore | ||||
| 3 | Galena | Economic | Ore | ||||
| 4 | Pyrrhotite | Economic | Ore | ||||
| 5 | Silver | Economic | Ore | ||||
| 6 | Sphalerite | Economic | Ore | ||||
| 1 | Dolomite | Economic | Gangue | ||||
| 2 | Quartz | Economic | Gangue | ||||
| 3 | Barite | Economic | Gangue |
Mar 28, 2018 (Therese Pettigrew) - Silver Islet is formed by a NE-striking Keweenawan diabase dyke of 350' width that intruded Animikie sediments. The dyke and sediments are crossed by a NW-striking fault that caused excessive brecciation of the dyke but little in the sediments. The productive silver vein lies within the brecciated fault zone in the dyke and parallel to the fault. Native silver occurs in a gangue of dolomite and quartz; other minerals include: argentite, niccolite, galena, sphalerite, marcasite, cobaltite, smaltite, domeykite, chalcopyrite and tetrahedrite. Locally above 360' level, rich secondary silver in vugs and fissures occurs as wires, leaves and nuggets of native silver (Sergiades, 1968). The vein system is distributed through a mass of rock 1800 feet long, 1230 feet deep, and with widths varying from a few inches up to 50 feet. Individual veins are less than a foot wide and the majority of them are less than one inch wide and the majority of them are less than one inch wide; masses of breccia cement, however, have been observed with dimensions up to 3 feet (Tanton, 1931).
| Zone | Year | Category | Tonnes | Reference | Comments | Commodities |
|---|---|---|---|---|---|---|
| Silver Islet | 1974 | Unclassified | 104326 | Fenwick and Scott, 1977, p. 44 | An examination of records and the dump surrounding Silver Islet, combined with systematic sampling, revealed a recoverable 115,000 tons grading 40 opt Ag. |
| Year | Tonnes | Commodities | Reference | Comment |
|---|---|---|---|---|
| 1922 | 999 |
Silver 2870000 Ounces |
Tanton T.L, 1931, Memoir 167 p.89, MDC010 p. 74 | 1870s-1922: 2,870,000 oz of Ag produced worth $3,261,000; 1869-70: about 13.5 tons graded approx. 2,200 opt Ag, 1870-73: Ore shoot of about 350’ depth by 200’ length produced 2,000,000 opt Ag, 1878: ore shoot of about 100’ depth by 50’ length produced 800,000 opt Ag, 1921: Silver content of roof pillar estimated at 300,000 oz Ag. |
Mono - Silver cobalt calcite vein deposits of Ontario
Publication Number: MDC010 Page: 74 Date: 1968
Author: Sergiades A.O.
Publisher Name: Ontario Dept. of Mines
Location:
Article - 1976 report of the North Central Regional Geologist
Publication Number: MP071.004 Page: 44 Date: 1997
Author: Fenwick K.G., Scott J.F.
Publisher Name: Ontario Geological Survey
Location:
Publication - Fort William and Port Arthur, and Thunder Cape Map-area, Thunder Bay District, Ontario; Geological Survey of Canada, Memoir 167
Publication Number: GSC Memoir 167 Page: 92-104 Date: 1931
Author: Tanton, T.L.
Publisher Name: Geological Survey of Canada
Location: https://doi.org/10.4095/100799
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