The Talc Lake prospect outcrops north and south of an unnamed lake atop a ridge west of the Fraser River, 19.5 kilometres south-southwest of Lytton.
Significant talc occurrences were first reported in this area in the early 1950s by Geological Survey of Canada geologists. In 1973, talc was first reported in the Talc Lake prospect area by J. A. Chamberlain Consultants while conducting surveys for nickel, chromite and talc. Low-grade nickel (0.2 per cent) was identified over a wide area and a zone of talc-magnesite mineralization was outlined. The zone is now referred to as the Talc Lake deposit. Between 1986 and 1988, 3000 hectares of ground was staked to cover potential talc (magnesite) lenses. In 1989 and 1990, Highland Talc Minerals Ltd. began systematic geological mapping of the Talc Lake deposit. Late in 1990, a second talc zone referred to as the South Talc deposit was defined. Four exploratory drillholes were completed in 1990. Between 1991 and 1992, detailed geological surveys, surface stripping, and four follow-up drillholes were completed. In 1992, the North Talc deposit and five smaller satellite lenses were discovered. In 1993, a 100-kilogram bulk sample taken from the South Talc deposit and a 120-tonne bulk sample taken from the North Talc deposit were shipped to Finland for pilot scale tests. In 1994, an additional 10 drillholes were completed on the South Talc deposit.
The area is underlain by phyllite, schist and foliated greenstone of the Permian(?) to Lower Cretaceous Bridge River Complex (Group) and by phyllite, schist and local conglomerate of the Upper Jurassic to Lower Cretaceous Relay Mountain Group. Pods of serpentinized ultramafics of the Bridge River Complex occur in fault and normal contact with both units. All units are intruded by stocks of Late Cretaceous quartz monzonite and granodiorite.
The Bridge River Complex and Relay Mountain Group are separated along the ridge by an intervening fault-bounded mass of serpentinite striking northwest for 5.9 kilometres, generally following the crest of the ridge, and varying up to 900 metres in width. The ultramafic rock is dark-green to black and weathers buff to reddish-brown. The serpentinite consists of fine-grained, massive serpentine with minor carbonate and 5 per cent magnetite.
Since 1990, several systematic programs have been completed on the Talc Lake deposit, including geological surveys, bulldozer stripping, trenching and drilling. The deposit consists of a lens of talc on the north side of the lake that has been exposed over a length of 800 metres and a width of 25 to 100 metres, near the north end of the serpentinite mass. The talc lens strikes 110 degrees and dips 55 degrees south. The zone continues southeast beneath the lake for an additional 300 metres, for a total strike length of up to 800 metres.
The talc is pale-green to white with a creamy buff weathered surface and contains small quantities of disseminated magnetite. Thin sections show the rock to be composed of 50 per cent talc and 50 per cent carbonate and magnesite. Although strongly schistose in outcrop, the talc does not appear so in thin section. Trenches show a homogeneous admixture of talc and magnesite. Ten-metre continuous chip samples were collected from each trench and analysed by X-ray diffraction. They yielded an average of 57 per cent talc, 41 per cent magnesite, 1 per cent chlorite and less than 1 per cent siderite (Assessment Report 22665). Previous sampling in 1973 yielded 62 per cent talc, 30 per cent magnesite, 8 per cent chlorite and 6 per cent iron oxide (Assessment Report 22665). A bulk sample taken from the north side of the lake showed the talc to be very high grade, but the iron content makes it unsuitable for whitener or for a refractory base. The percentages given are:
-------------------------- Talc – 62 per cent Magnesite – 30 per cent Chlorite – 8 per cent Fe2O3 - 5.8 per cent Brightness factor - 63.1 per cent -------------------------- |
The Talc Lake deposit reserve calculation is based solely on surface exposures and thus categorized as geologically inferred reserves. Total geologically inferred reserves are 5 231 600 tonnes, using a depth of 80 metres (Assessment Report 22665).
In 2015, Dan Cardinal conducted systemic 1:4000 scale mapping over two zones as part of exploration on the Dot-Apex claim group (MINFILE 092ISW055). The Talc Lake prospect was covered by the southernmost map zone.
