Ontario Geological Survey
Permanent Link to this Record:
MDI52E09SE00012
| Record Name(s) | Graphic Lake Rare Earths - 1982 |
|---|---|
| Related Record Type | Simple |
| Related Record(s) | |
| Record Status | Discretionary Occurrence |
| Date Created | 1991-Jan-23 |
| Date Last Modified | 2023-Jun-16 |
| Created By | |
| Revised By |
Primary Commodities: Lithium, Beryllium
Secondary Commodities: Cesium, Rare Earth Elements, Rubidium, Gallium, Tantalum, Niobium
Township or Area: Work
Latitude: 49° 36' 10.68" Longitude: -94° 4' 32.64"
UTM Zone: 15 Easting: 422273 Northing: 5495044 UTM Datum: NAD83
Resident Geologist District: Kenora
NTS Grid: 52E09SE
Point Location Description: From OFR6099, p. 66
Location Method: Conversion from MDI
Access Description: The pegmatites are crossed by Highway 71; further access is provided by Graphic Lake and old logging roads.
Based on old claim posts, the area was apparently staked and explored around 1980, but no information on this work is available. 2004: Property was staked by J.D. Resky, who conducted prospecting, stripping and sampling.
| Office File Number | Online Assessment File Identifier | Online Assessment File Directory |
|---|---|---|
| 2.27148 | 52E09SE2007 | 52E09SE2007 |
Province: Superior
Subprovince: Wabigoon
Geological Age: Archean
| Rock Type | Rank | Composition | Texture | Relationship | Pegmatite | 1 | Host |
|---|---|---|---|---|
| Terrigenous-Clastic-Unsubdivided | 2 | Adjacent | ||
| Mafic lava flow-unsubdivided | 3 | Adjacent |
Jul 26, 2017 (Therese Pettigrew) - A large number of white to pale pink pegmatites intrude the metasediments and metavolcanics in this area. They are roughly parallel to the foliation of the host rocks (040 to 050 degrees). Rudimentary zoning is evident in one pegmatite observed near the south end of Graphic Lake, where small quartz segregations were observed. The remainder of the pegmatites are homogeneous but some of the large ones have minor replacement or fracture filling zones. The major minerals present are pale green muscovite, biotite, quartz, white to pale pink microcline and microcline graphic granite. Trowell (1979) tentatively identified beryl from some of these pegmatites. Xenoliths of the host rocks are common (Storey, 1990). The beryl-bearing pegmatites are hosted in the Royal Island group metasedimentary rocks that are possibly correlative with nearby Warclub group metasedimentary rocks (Breaks et al., 2003).
| Rank | Mineral Name | Class | Economic Mineral Type | Alteration Mineral Type | Alteration Ranking | Alteration Intensity | Alteration Style |
|---|---|---|---|---|---|---|---|
| 1 | Beryl | Economic | Ore | ||||
| 2 | Ferrocolumbite | Economic | Ore | ||||
| 1 | Quartz | Economic | Gangue | ||||
| 2 | Microcline | Economic | Gangue | ||||
| 3 | Muscovite | Economic | Gangue | ||||
| 4 | Biotite | Economic | Gangue | ||||
| 5 | Garnet | Economic | Gangue |
Jul 26, 2017 (Therese Pettigrew) - Samples of the metavolcanic host rock show elevated lithium values. One sample near the main dyke contains 158 ppm Li and one at the south end of Graphic Lake contains 860 ppm Li (Storey, 1990). The pegmatites comprise a swarm with a breadth of least 300 m as delineated northward along Highway 71 from Graphic Lake. The strike length of the swarm has not been determined, although mapping by Trowell (1986) suggests at least a 5.5 km strike length. At Graphic Lake, dykes between 20 cm and 8 m in width, are mainly controlled by the foliation of host rocks (metawacke of medium metamorphic grade). These dykes are massive, garnet-muscovite white potassic pegmatite with subordinate sodic aplite and medium-grained garnet-muscovite granite. Muscovite is quite common and is typically lime green. Beryl appears as sparse, faint green crystals up to 2 by 4 cm. The pegmatite dykes hosted in clastic metasedimentary rocks near Graphic Lake were sampled at 3 different sites along Highway 71. These beryl-type pegmatites are mildly to strongly peraluminous (A/CNK = 1.092-1.598), depending upon the abundance of green muscovite. A significant degree of fractionation is evident in the low K/Rb (mean 44; range 32-52), K/Cs (mean 1488; range 754-2412) and Nb/Ta (mean 4.3; range 2.4-6.9) ratios derived from bulk samples. Anomalous levels of all the rare-elements were detected: Rb (mean 763 ppm; range 672-991 ppm), Be (mean 21 ppm; 4-50 ppm), Cs (mean 27 ppm; range 14-42 ppm), Ga (mean 60 ppm; range 54-64 ppm), Sn (mean 32 ppm; 10-69 ppm), Nb (mean 89 ppm; range 66-109 ppm) and Ta (mean 23 ppm; range 16-28 ppm). Local black grains of ferrocolumbite were documented in garnet-muscovite leucogranite in the midpart of the largest dike (on Graphic Lake), and specifically within a quartz-rich pod that also contains blue-grey, blocky potassium feldspar crystals up to 25 cm in diameter. An average of 9.56 weight % Ta2O5 was determined from 20 electron microprobe analyses of the ferrocolumbite grains. The ferrocolumbite is associated with iron-rich garnet with a composition of almandine (60-66% almandine, 31-36% spessartine, 2-3% pyrope). Ferrocolumbite (12-19 weight % Ta2O5) also occurs in the centre of a muscovite potassic pegmatite dike hosted by Gibi metasedimentary sequence rocks at Graphic Lake on Highway 71 (locality 01-FWB-123: UTM 422185E, 5495553N, Zone 15) (Breaks et al., 2003).
| Rank | Classification |
|---|---|
| 1 | Pegmatite |
| Rank | Characteristic |
|---|---|
| 1 | Intrusive |
Map - Precambrian geology, Gibi Lake area, District of Kenora
Publication Number: P3076 Scale: 1:15,840 Date: 1987
Author: Trowell N.F., Logothetis J., Caldwell G.F., Webb J.R.
Publisher Name: Ontario Geological Survey
Location:
Mono - Fertile Peraluminous Granites and Related Rare-Element Mineralization in Pegmatites, Superior Province, Northwest and Northeast Ontario: Operation Treasure Hunt
Publication Number: OFR6099 Page: 65-68 Date: 2003
Author: Breaks F.W., Selway J.B., Tindle A.G.
Publisher Name: Ontario Geological Survey
Location:
Part - Geology of the area from Minaki to Sidney Lake, District of Kenora
Publication Number: ARV39-03.002 Page: 35-40 Date: 1998
Author: Derry D.R.
Publisher Name: Ontario Dept. of Mines
Location:
Article - Gibi Lake area, District of Kenora
Publication Number: MP090.007 Page: 33 Date: 1997
Author: Trowell N.F.
Publisher Name: Ontario Geological Survey
Location:
Article - Gibi Lake area, District of Kenora
Publication Number: MP096.004 Page: 19 Date: 1997
Author: Trowell N.F., Logothetis J., Caldwell G.F.
Publisher Name: Ontario Geological Survey
Location:
Mono - An evaluation of the industrial mineral potential of parts of the districts of Kenora and Rainy River
Publication Number: OFR5718 Date: 1990
Author: Storey C.C.
Publisher Name: Ontario Geological Survey
Location:
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