Goodenough Lake natron occurrence, Meadow Lake, Clinton Mining Division, British Columbia, Canadai

Regional Level Types
Goodenough Lake natron occurrence	Occurrence
Meadow Lake	Lake
Clinton Mining Division	Division
British Columbia	Province
Canada	Country

The Goodenough Lake natron occurrence is located just south of the west end of Meadow Lake, about 30 kilometres west-northwest of the small community of 70 Mile House, or about 90 kilometres south of Williams Lake, British Columbia, in the Clinton Mining Division.
There is a description of the geological setting for this property, with details of the occurrence, on the British Columbia “Minfile” site, current to 2003, as quoted below:
“The lake is a semi-evaporitic playa lake. It is located in the "Green Timber Plateau" area [Cummings, 1940], 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 [Renaut and Stead, 1991].
Goodenough Lake contains sodium carbonate-rich brine and "Winter and Permanent Crystal" (natron or hydrated sodium carbonate). At the end of the dry season in 1937 [Cummings, 1940] the lake was completely dry and the surface of the lake was covered with a white encrustation from 5 millimetres to 2.5 centimetres thick [Cummings, 1940] approximately 6.5 hectares in size. The surface encrustation at Goodenough Lake is underlain by 20 centimetres of greenish muddy material containing 50 to 75 per cent natron crystals underlain by black oozy mud. An analysis of "fresh winter crystal" [Cummings, 1940] yielded: 35.54 per cent sodium carbonate, 1.34 per cent sodium bicarbonate and 62.89 per cent water. Between 2700 and 4500 tonnes are estimated to be present on the surface of Goodenough Lake [Cummings, 1940]).”
Giles Peatfield comments:
Goodenough Lake is one of a large number of saline lakes with carbonates in the “Cariboo Plateau” region of British Columbia, roughly between Clinton and 100 Mile House (Renaut et al., 1994). A few of these had some minor production of various sodium carbonate products. The mineralogy is complex and not fully reported – the following is an attempt to rationalize the published information.
Comments on Minerals Reported:
Amphibole supergroup: In his description of the mud in the lake bottom, Hoffmann (1900) reported “minute crystals of hornblende.”
Feldspar group: In his description of the mud in the lake bottom, Hoffmann (1900) reported “. . . some few [grains] of felspar [sic], . . . .”
Halite: Reported by Goudge (1926) as “sodium chloride.”
Kaolinite Subgroup: In his description of the mud in the lake bottom, Hoffmann (1900) reported “. . . a highly plastic clay, containing a large proportion of exceedingly fine scaly kaolinite, . . . .”
Mica Group: In his description of the mud in the lake bottom, Hoffmann (1900) reported “. . . a few scales of mica.”
Mirabilite: This was reported by Goudge (1926) as “Glauber’s salt.”
Natron: This was first reported by Hoffmann (1900), who wrote that “A very considerable deposit of natron, a mineral not previously recognized as occurring in Canada, has been met with in Goodenough Lake, about twenty-eight miles due north of Clinton, Lillooet district, in the province of British Columbia.” Refer also to Johnston (1915), Reinecke (1920), Goudge (1926), Walker and Parsons (1927), Cummings (1940), Traill (1970 and 1983) and Renaut et al. (1994).
Quartz: In his description of the mud in the lake bottom, Hoffmann (1900) reported “. . . small quantities of grit consisting, for the most part, of minute grains of translucent quartz, . . . .”
Thermonatrite: Reinecke (1920) described material “. . . collected from the surface of the pile [of natron] which after exposure for a few winter months in a heated building had been converted into a fine white powder. The analysis . . . probably represents the salt in an intermediate stage in the conversion from natron to a carbonate with less water, thermonatrite, Na2CO3.H2O and this is said to be the composition of the white efflorescence on the shores of all the soda lakes in this area.”
In addition to the minerals listed above, Renaut et al. described several others as occurring in carbonate saline lakes in the general region, viz trona, nahcolite, gaylussite and pirssonite, although they did not specifically mention these as being from Goodenough lake.
Other comments that may be germane include: Walker and Parsons (1927) in describing the natron stated that “The material for the present study, when broken, is nearly colourless and exhibits a good vitreous lustre, but on the surface, which has been exposed for some time to the air, it has become white and chalky, as it is converted into one of the lower hydrates.” Goudge (1926) described the natron, or as he called it “winter crystal” on account of its formation in freezing conditions and shows several good photos of the material. Reinecke (1920) wrote at some length regarding the possible change from the decahydrate (natron) to other sodium carbonate species with less contained water. This whole topic is complex, and beyond the scope of this review.

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Link to British Columbia Minfile:	092P 057

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References