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Ontario Geological Survey
Permanent Link to this Record:
MDI42D14SW00034
| Record Name(s) | Three Mile Garnet - 1922 |
|---|---|
| Related Record Type | Simple |
| Related Record(s) | |
| Record Status | Discretionary Occurrence |
| Date Created | 1997-Feb-07 |
| Date Last Modified | 2022-Feb-17 |
| Created By | |
| Revised By |
Primary Commodities: Garnet (Nonmetals), Sulphur/Pyrite
Secondary Commodities: Zinc
Township or Area: Killraine
Latitude: 48° 48' 36.2" Longitude: -87° 19' 44.34"
UTM Zone: 16 Easting: 475846 Northing: 5406393 UTM Datum: NAD83
Resident Geologist District: Thunder Bay South
NTS Grid: 42D14SW
Point Location Description: Railway rock cut.
Location Method: Field Visit
Access Description: The occurrence is located in Killraine Twp. approximately 4.4 km west of Schreiber on the Canadian Pacific Railway, at a point approximately 400 m east of Mileage 3 on the railway. The occurrence is accessible by walking the CPR tracks west of Schreiber.
1922: Geological mapping; OBM (Hopkins 1922). Hopkins (1922) noted the presence of garnet in the vicinity of the occurrence. 1991: Lithogeochemical sampling and thin section analysis; SH Resident/Staff Geologist (OGS). J. Courtney and G. Daniels conducted stripping and sampling.
| Office File Number | Online Assessment File Identifier | Online Assessment File Directory |
|---|---|---|
| OP91-081 | 42D15NW0006 | 42D15NW0006 |
Province: Superior
Geological Age: Archean
Dec 07, 2005 (D McKay) - Schnieders et al. (1992) described the occurrence as follows: Local rocks consist mainly of heterolithic lapilli tuff and tuff breccia in which mafic, feldspar-phyric clasts predominate over light grey, feldspar- and amphibole-phyric clasts. The clasts are fine-grained to aphanitic and occur in an aphanitic, light grey, feldspar- and amphibole-phyric matrix. Quartz phenocrysts are notably absent and plagioclase phenocrysts are locally saussuritized. The rocks are not strongly foliated, but the subangular clasts are slightly flattened at 280 degrees/56 degrees north. Clasts vary in length up to 10 cm, but average 3 to 7 cm.
| Rock Type | Rank | Composition | Texture | Relationship | Schist-Unsubdivided | 1 | Fel-Bio Schist | Host |
|---|---|---|---|---|
| Mafic lava flow-unsubdivided | 2 | Amphibolitic | Massive To Tuffaceous | Host |
| Intermediate Tuff-Breccia | 3 | Heterolithic | Lapilli Tuff And Tuff-Breccia | Host |
Dec 07, 2005 (D McKay) - Schneiders et al. (1992) described the lithologies present as follows: In the vicinity of the garnetiferous rocks, the plagioclase- and amphibole-phyric tuffs are white- to light-grey-weathering. Plagioclase may locally form foliation-parallel bands 2 mm wide. Garnets up to 1 cm in diameter are exposed as protruding knobs on the south side of the railway rock cut. They may comprise up to 50% of the host rock locally. The host rock varies from a rusty weathering, dark grey feldspar-biotite schist to a massive, dark green amphibolite. Garnets occur as lenticular masses and euhedral crystals occuring with magnetite and quartz in bands 0.5 to 3.5 cm wide. These bands define a foliation at 284 degrees/ 52 degrees north and occur within a light green-gray groundmass in which 1 to 2mm amphibole phenocrysts are developed. The garnetiferous portion of the metavolcanic rocks has an exposed thickness of approximately 3 m and outcrops on the north side of the tracks.
| Rank | Mineral Name | Class | Economic Mineral Type | Alteration Mineral Type | Alteration Ranking | Alteration Intensity | Alteration Style |
|---|---|---|---|---|---|---|---|
| 1 | Garnet | Economic | Ore | ||||
| 2 | Pyrite | Economic | Ore | ||||
| Epidote | Alteration | Saussuritization | 1 | Unknown | Disseminated |
Dec 07, 2005 (D McKay) - Minor pyrite occurs on joints and with garnets as fine-grained blebs and aggregates. In thin section, the rock consists dominantly of euhedral, poikiloblastic garnet, rimmed by finer grained, decussate biotite and amphibole, which also tend to concentrate in the strain shadows of the porphyroblasts of garnet. Some biotite has been altered to secondary amphiboles. Quartz and lessor plagioclase comprise the felsic mineral assemblage, largely interstitial to the mafic constituents. Opaque minerals, dominantly magnetite, are fine grained and disseminated or occur as somewhat foliation-parallel trains in the garnet porphyroblasts. No other minerals characteristic of hydrothermal alteration associatd with volcanogenic massive sulphide deposits were noted. A grab sample collected by MNDM staff in 1991 returned assay results of trace Au and Ag, 147 ppm Cu and 117 ppm Zn.
Map - Nipigon-Schreiber, geological compilation series, Thunder Bay District
Publication Number: M2232 Scale: 1:253,440 Date: 1973
Author: Carter M.W., McIlwaine W.H., Wisbey P.A.
Publisher Name: Ontario Division of Mines
Location:
Mono - Mineral Occurrences in the Nipigon-Marathon Area, Volumes 1 and 2.
Publication Number: OFR5951 Scale: Date: 1996
Author: Schnieders B.R., Smyk M.C., Speed A.A., McKay D.B.
Publisher Name: Ontario Geological Survey
Location:
Book - ASSESSMENT FILES
Publication Number: AF Scale: Date:
Author:
Publisher Name:
Location: Thunder Bay RGP
Map - Geological series, Precambrian geology of the Schreiber area, east part, Thunder Bay District
Publication Number: P2391 Scale: 1:15,840 Date: 1981
Author: Carter M.W.
Publisher Name: Ontario Geological Survey
Location:
Map - Schreiber area, District of Thunder Bay, Ontario
Publication Number: ARM47J Scale: 1:31,680 Date: 1997
Author: Bartley M.W., Harcourt G.A.
Publisher Name: Ontario Dept. of Mines
Location:
Part - Schreiber-Duck Lake area
Publication Number: ARV30-04.001 Scale: Date: 1998
Author: Hopkins P.E.
Publisher Name: Ontario Dept. of Mines
Location:
Map - Schreiber-Duck Lake area, District of Thunder Bay
Publication Number: ARM30A Scale: 1:63,360 Date: 1998
Author: Hopkins P.E., Tanton T.L.
Publisher Name: Ontario Dept. of Mines
Location:
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For detailed information regarding this mineral record please contact the Thunder Bay South Resident Geologist District Office