Lake Khiluk (Spotted Lake), Osoyoos, Osoyoos Mining Division, British Columbia, Canadai

Regional Level Types
Lake Khiluk (Spotted Lake)	Lake (Active)
Osoyoos	Town
Osoyoos Mining Division	Division
British Columbia	Province
Canada	Country

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The Spotted Lake evaporite occurrence is located immediately west of the Crowsnest Highway (British Columbia Provincial Highway No. 3), just south-east of Richter Pass, about 9.8 kilometres north-west of Osoyoos, British Columbia, in the Osoyoos Mining Division.
There is a brief description of the geological setting for this occurrence on the British Columbia “Minfile” site, current to 2012. A portion of this description is quoted below:
“The showing is underlain by metasediments and metavolcanics of the Carboniferous to Permian Kobau Group. Schist, chlorite schist, quartzite, amphibolite and minor limestone comprise major lithologies of the Kobau Group. To the immediate south, granite and granodiorite of the Similkameen intrusions intrude the Kobau Group.
Spotted Lake covers approximately 8 hectares. When examined in 1938, the lake was covered with 15 to 20 centimetres of brine. The brine crystals form a bowl-like shape covering 50 to 60 per cent of the lake. The bowl-like shapes are 6 to 24 metres diameter, averaging 1.07 metres depth. The encircling mud rings are raised 10 to 46 centimetres above the crystal level, containing gypsum. The mud was determined to contain 70 to 80 per cent calcium sulphate.”
Giles Peatfield comments:
The geology of the region surrounding Spotted Lake is somewhat complex, and has had several interpretations over the years. A relatively recent compilation (Tempelman-Kluit, 1989) shows the lake to be surrounded by rocks of the Carboniferous or Older Kobau Group, described as undivided amphibolite, greenschist, quartzite, mica schist, greenstone, minor marble. Immediately to the south are exposures of the Cretaceous and/or Jurassic Osoyoos Granodiorite.
For more information on the history and social significance of the lake, refer to Wikipedia “Spotted Lake”.
Official records of production from Spotted Lake (see “Minfile”) show that in 1915 (Cummings, (1940) reports 1915-1919), a total of 1,500 tons (1,361 tonnes) of material was mined, with production of 707,720 kilograms of what was described as “Magnesium Sulphate”. Cummings’ report also states that “Crude epsomite from Spotted Lake, Clinton Lake and Epsom Lake [probably Hot Lake, see Google Earth], a small lake on Kruger Mountain, 2 ½ miles north of Oroville [in Washington State], were treated at this plant [in Oroville]. It is understood that the use of Spotted Lake material was largely restricted to the tanning industry owing to its relatively high content of sodium sulphate.”
Comment on Minerals Reported:
Blödite: Reported by Renaut and Stead (1994), as a component of soft, muddy material with epsomite from a nearshore pool. All their identifications were apparently by X-ray diffraction analysis.
Calcite: Renaut and Stead (1994) described both calcite and “Mg-calcite” (a variety with elevated magnesium carbonate content).
Epsomite: Goudge (1926) described “crystal” which one assumes was epsomite. Renaut and Stead wrote that “Clear salts from a nearshore pool were mainly epsomite, . . . .”
Gypsum: Goudge (1926) reported gypsum in the muds surrounding the salt pools. Renaut and Stead reported gypsum in nearshore muds.
Hexahydrite: Renaut and Stead (1994) reported that “Efflorescent gypsum, thenardite [sic] and hexahydrite crusts occur along the shore zone and on interpool muds.”
Mirabilite?: Renaut and Stead (1994) commented that “Mirabilite probably freezes out during autumn and winter.”
Thénardite: see comment above for hexahydrite.
Comment on Rock types Reported:
These rock types were reported variously, by several workers. The best summary is that provided by Tempelman-Kluit (1989) – see his description of the Kobau Group above.

Mineral List

6 valid minerals.

Rock Types Recorded