Ontario Geological Survey
Permanent Link to this Record:
MDI42E01NW00007
| Record Name(s) | Blank Lake - 1968, Kentron Lake - 1968 |
|---|---|
| Related Record Type | Simple |
| Related Record(s) | |
| Record Status | Occurrence |
| Date Created | 1983-May-26 |
| Date Last Modified | 2023-May-26 |
| Created By | |
| Revised By |
Primary Commodities: Niobium
Secondary Commodities: Rare Earth Elements
Township or Area: Vein Lake Area
Latitude: 49° 10' 44.99" Longitude: -86° 27' 18.57"
UTM Zone: 16 Easting: 539707.834 Northing: 5447515.678 UTM Datum: NAD83
Resident Geologist District: Thunder Bay South
NTS Grid: 42E01NW
Point Location Description: General
Location Method: Conversion from MDI
| Rock Type | Rank | Composition | Texture | Relationship | Pegmatite | 1 | nepheline syenite |
|---|
May 26, 2023 (Therese Pettigrew) - The pegmatites have two modes of occurrence; regular dike-like bodies and irregular, sinuous veins. A dike, situated on a narrow isthmus between two islands in Blank Lake, is about 2 feet wide and is exposed over a strike length of 30 feet. Nepheline syenite pegmatite replaces both the syenite and a dike of "olivine-nepheline syenite" which intersects the zone obliquely. No offsetting of the "olivine-nepheline syenite" dike contacts has taken place; in fact, vestiges of the replaced dike can be traced through the pegmatitic material to a continuation in the opposite wall. The dike is buff coloured, with a tone similar to that of the enclosing syenites. The surface is deeply pitted; circular to oval pock-marks 2 to 15 cm in diameter are caused by the recessive weathering of rose-coloured nepheline. Zircon in octahedral (1 mm) crystals is an abundant (2 to 3 percent) accessory mineral in the dike. Most of the pegmatites are coarse-grained, although, in some places, aphanitic syenitic material with sugary texture encloses or intermingles with the coarser parts (Coates, 1970).
| Rank | Mineral Name | Class | Economic Mineral Type | Alteration Mineral Type | Alteration Ranking | Alteration Intensity | Alteration Style |
|---|---|---|---|---|---|---|---|
| 5 | Pyrochlore | Economic | Ore | ||||
| 1 | Nepheline | Economic | Gangue | ||||
| 2 | Feldspar | Economic | Gangue | ||||
| 3 | Zircon | Economic | Gangue | ||||
| 4 | Magnetite | Economic | Gangue | ||||
| 5 | Tourmaline | Economic | Gangue | ||||
| 6 | Apatite | Economic | Gangue | ||||
| 7 | Calcite | Economic | Gangue |
May 26, 2023 (Therese Pettigrew) - Essentially the rock is composed of feldspar and nepheline with minor amounts of aegirine in a 3 to 1 ratio. Accessory minerals are zircon, magnetite, tourmaline, apatite, calcite, and pyrochlore. Feldspar occurs in felted masses of blade-like crystals (0.25 mm to 0.5 mm) with sutured rims and the feldspar masses are enclosed in larger grains of nepheline. The feldspar grains possess properties of the orthoclase-microperthite-low albite series (optically negative; 2V 450 to 500). Nepheline is present as irregular percrystalline masses of subhedral to anhedral grains (2 to 3 mm) which in some sections show zoning. Zircon crystals (0.5 mm to 1.5 mm) show strong zoning and irregular distribution throughout the rock. Tourmaline, biotite, and magnetite occur in trace amounts interstitial to nepheline. Aegirine is a common accessory mineral in the pegmatite veins. Pyrochlore, in small cubic or octahedral grains (0.1 mm in diameter), is honey yellow to golden brown in thin section and occurs as irregular clusters, randomly distributed throughout the feldspathic portions. The niobium mineralization occurred as a late stage in the evolution of the complex. Large quantities of volatiles escaped and reached higher levels along zones of weakness: joints, fissures, faults, and dikes. The nepheline syenite pegmatites represent a period of pneumatolysis in which the principal components were H2O, CO2, F, CL, B, and minor amounts of Th and the rare earths. Radioactive mineral content was low in the pegmatites sampled. Sample 66-KC-31-5E returned 0.35% Nb2O5 and trace Y, Yb, and La. Samples 66-KC-31-23E returned 0.05% Nb2O5 (Coates, 1970).
Map - Mineral deposits series, Ontario mineral potential, Longlac sheet, districts of Thunder Bay and Cochrane
Publication Number: P1527 Scale: 1:250,000 Date: 1978
Author: Springer J.S.
Publisher Name: Ontario Geological Survey
Location:
MonoMap - Geology of the Killala-Vein lakes area, District of Thunder Bay
Publication Number: R081 Page: 18-20 Date: 1970
Author: Coates M.E.
Publisher Name: Ontario Dept. of Mines
Location:
Map - Manitouwadge-Wawa sheet, geological compilation series, Algoma, Cochrane, Sudbury and Thunder Bay districts
Publication Number: M2220 Scale: 1:253,440 Date: 1972
Author: Milne V.G., Giblin P.E., Bennett G., Thurston P.C., Wolfe W.J., Giguere J.F., Leahy E.J., Rupert R.J.
Publisher Name: Ontario Division of Mines
Location:
Mono - Industrial minerals of northern Ontario-supplement 2
Publication Number: OFR5439 Page: 390 Date: 1983
Author: Vos M.A., Smith V.
Publisher Name: Ontario Geological Survey
Location:
MonoMap - Geology of Stevens-Kagiano Lake area, District of Thunder Bay
Publication Number: R068 Date: 1968
Author: Coates M.E.
Publisher Name: Ontario Dept. of Mines
Location:
Map - Moosonee sheet, geological compilation series, Cochrane District
Publication Number: M2171 Scale: 1:253,440 Date: 1969
Author: Bennett G., Brown D.D., George P.T., Guillet G.R.
Publisher Name: Ontario Dept. of Mines
Location:
Map - Killala-Vein lakes area, District of Thunder Bay
Publication Number: P0382 Scale: 1:63,360 Date: 1997
Author: Coates M.E.
Publisher Name: Ontario Dept. of Mines
Location:
Map - Stevens sheet, Thunder Bay District
Publication Number: M2141 Scale: 1:63,360 Date: 1967
Author: Coates M.E.
Publisher Name: Ontario Dept. of Mines
Location:
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