Watson Lake hydromagnesite deposit, Watson Lake, 105 Mile House, Clinton Mining Division, British Columbia, Canadai

Regional Level Types
Watson Lake hydromagnesite deposit	Deposit
Watson Lake	Lake
105 Mile House	Village
Clinton Mining Division	Division
British Columbia	Province
Canada	Country

The Watson Lake hydromagnesite deposit is located immediately west of Watson Lake, 2 kilometres west of the old stopping-place of 105 Mile House on Highway 97, or about 75 kilometres south-east of Williams Lake, British Columbia, in the Clinton Mining Division.
There is a good description of the deposit on the British Columbia “Minfile” site, current to 2003, part of which is quoted below:
“The Watson Lake hydromagnesite deposits are located about 500 metres southwest of Watson Lake and about 1.5 metres above the lake level. Watson Lake is a small lake covering about 1.2 hectares about 1.5 kilometres west of 105 Mile House on Highway 97.
Physiographically, it is in the Cariboo Plateau, a semi-arid plateau area averaging 1130 metres elevation which is host to several playa lakes. The area is underlain by alkaline plateau basalt flows of the Miocene to Pleistocene Chilcotin Group, mantled by a thin cover of glacial till and glaciofluvial sediments. Annual precipitation averages between 300 and 400 millimetres [Renaut and Stead, 1991].
Several deposits of hydromagnesite, some associated with impure hydromagnesite are located in a swampy depression to the southwest of Watson Lake.
The larger area, to the west, is about 200 by 60 metres along a northeast trend. It has a variable depth, to an underlying dark grey mud, up to about 2.16 metres. The hydromagnesite has a white surficial layer which varies between 50 and 100 centimetres in thickness with an average of about 58 centimetres. Underlying the upper layer is a cream to brown hydromagnesite in the order of 1.5 metres thick but with a higher calcium content. ”
Giles Peatfield comments:
This is one of several small hydromagnesite occurrences in the general region: (Robertson (1919); (Reinecke, (1920); Cummings, (1940); Grant, (1987); Renaut and Stead, (1991); Renaut et al. (1994). I have chosen the Watson Lake occurrence for its historical significance. None of these occurrences have recorded serious commercial production. Note – do not confuse this Watson Lake with the well-known town in Yukon.
Analyses of the Watson Lake hydromagnesite, as reported by Reinecke (1920) and Cummings (1940) and listed in the Minfile report, average (for the major components): MgO - 40.08; CaO - 1.60; CO2 - 40.82; total H2O - 17.79. These figures are in good agreement with those quoted by Hoffmann (1900), and with what Traill (1983) reported as done by R. A. A. Johnston, which curiously are very slightly different from those reported in Hoffmann (1900) for the same material. Detailed examination of this issue is beyond the scope of this review.
One point of interest is a comment by Robertson (1919), that when drilling with a post-hole auger to sample the hydromagnesite, “At a depth of 5 feet water is struck, and this water appears to be very full of gas, but is most palatable.”
Comment on the Mineral Reported:
Hydromagnesite: This is the only mineral specifically reported for the occurrence. It is noteworthy that it was first reported here by Hoffmann (1900), who wrote that “This species, now for the first time identified as occurring in Canada, has been met with in considerable abundance in the immediate vicinity of the 108-mile House on the Cariboo road, . . . .” Hoffmann probably referred it to 108 Mile, as that stopping place was perhaps better known than 105 Mile – from his description this is clearly the Watson Lake occurrence. Subsequent workers have not reported any other minerals.
Further comments on minerals that may or may not be present: Although Renaut et al. (1994) do not provide mineralogical data specific to the Watson Lake occurrence, they imply that the following minerals might well be present and should be looked for: calcite, aragonite, magnesite, nesquehonite (uncommon), huntite (uncommon), gypsum and possibly others.

Giles Peatfield
BASc. (Geological Engineering) University of British Columbia 1966.
PhD Queen's University at Kingston 1978.
Worked for Texas Gulf Sulphur / Texasgulf Inc. / Kidd Creek Mines - 1966 to 1985.
Vancouver based consultant 1982 to retirement in 2016.
Presently totally retired and happily living in Courtenay, B.C. (Vancouver Island) - preparing postings for Mindat, mostly on B.C. deposits / occurrences.

Other Databases

Link to British Columbia Minfile:	092P 077

Other Regions, Features and Areas containing this locality

References