The Meadow Lake hydromagnesite deposits are located immediately east of the east end of Meadow Lake, 25 kilometres west-northwest of 70 Mile House. The main deposits occur in swampy areas adjacent to two small lakes in a west-trending zone approximately 2 kilometres long.
The lakes are semi-evaporitic playa lakes. They are located in the "Green Timber Plateau" area (EMPR Bulletin 4), a semi-arid plateau area averaging 1130 metres elevation which is part of the Cariboo Plateau and 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 (EMPR Paper 1991-1).
The deposits comprises two main occurrences with numerous smaller patches of pure hydromagnesite and impure hydromagnesite. The largest occurence, Area B covers an area of approximately 12 hectares and the smaller deposit covers approximately 6 hectares. Area A is about 300 metres east of Meadow Lake, while Area A is an additional 1.5 kilometres east of that. All occurrences have irregular outlines and a typical cauliflower-like surface which is raised 10 to 60 centimetres above the surrounding swamp. The impure hydromagnesite occurrences have a flat, cracked surface of dense, grey material. They occur both east and west of Meadow Lake and the individual deposits vary widely in composition but generally contain elevated values for calcium and silica.
A sample (Sample No. 6) of "grey earth" was taken from the northeast end of Meadow Lake. It was collected 0 to 70 centimetres from the surface where impure hydromagnesite is about 70 centimetres thick (Geological Survey of Canada Memoir 118, pages 25-46).
The pure hydromagnesite consists of two or more distinct layers in overall sheet-like deposits. The surface horizon is usually white, massive and has a low calcium content. Usually a horizon of creamy yellow, loosely granular hydromagnesite, which contains an increasing proportion of calcium toward the base, underlies the surface layer of 60 to 90 centimetres. This creamy hydromagnesite usually overlies a layer of impure hydromagnesite. One sample (Geological Survey of Canada Memoir 118, pp. 25-46, Sample No. 7) represents a composite of white hydromagnesite from a number of the Meadow Lake occurrences. Sample No. 8 is a similar composite, but is limited to white material from drill holes in area A and B as described below. The two main deposits and the numerous smaller occurrences of pure or white hydromagnesite are estimated to cover about 20 hectares.
Area A, the second largest occurrence, consists of white hydromagnesite covering about 6 hectares of swampy terrain, roughly 325 metres southeast of Area B, the main deposit. In Area A, the hydromagnesite is 30 to 90 centimetres thick with an average thickness of 41 centimetres.
Area B, on Lot 4878, is about 1.5 kilometres east of Meadow Lake. Drilling confirmed that the 12 hectares of white hydromagnesite has a thickness of 20 to 81 centimetres with an average of about 46 centimetres. Creamy yellow granular material underlies the white hydromagnesite in a layer which is in the order of 90 to 125 centimetres thick and is underlain in turn by impure hydromagnesite. Sample No. 1 is of material from 0 to 38 centimetres depth within the white hydromagnesite at the centre of the main deposit. Sample 2 is from 38 to 130 centimetres, below sample 1, and consists of cream coloured hydromagnesite. Sample 3 is cemented soil taken from 130 to 168 centimetres depth. Sample 4 was collected near Sample 1 and is from 0 to 99 centimetres but includes some yellow hydromagnesite. Sample 5, taken below sample 4, is from 99 to 153 centimetres and is entirely within yellow, granular hydromagnesite. The results are as follows:
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Samp. From To MgO CaO CO2 SiO2 Al2O3 Fe2O3 FeO H2O H2O
cm cm +105 -105
1 0 38 41.38 1.32 37.67 4.00 1.36 0.14 0.23 12.12 1.80
2 38 130 35.68 6.38 36.63 11.33 2.88 0.24 0.20 4.15 2.29
3 130 168 20.34 25.55 - 7.60 - - 0.22 - -
4 0 99 36.63 2.86 35.64 13.10 1.34 0.11 0.17 7.00 2.58
5 99 153 24.32 20.12 38.64 10.32 1.35 0.49 - 2.93 1.45
6 0 30 20.14 9.20 20.24 36.78 1.54 0.84 0.59 6.80 3.52
7 composite 40.56 1.26 35.96 1.22 0.67 0.18 0.63 18.00 1.45
8 composite 38.80 0.80 38.70 7.40 ->2.50<- - 11.50 -
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Energy Mines and Petroleum Resources Bulletin No. 4 (page 105) has estimated that 104,000 tonnes of white hyromagnesite is contained in the Meadow Lake deposits.
Canadian Occidental Petroleum staked the Soda 55 claim in 1989 and collected a water sample in 1989 and completed analyses for sodium carbonate and other alkalai salts (Assessment Report 20080). Canoxy also completed an airborne infrared survey to test for dissolved solids in the lakewaters.
