Sodium Sulfate Deposits in Alberta

Sodium sulfate is found as solid salt beds and brines in undrained or poorly drained basins in Manitoba, Saskatchewan, Alberta and British Columbia. The salt waters generally give an alkaline reaction and they are commonly referred to as alkali lakes. Those of Saskatchewan are better known than the others as sodium sulfate has been extracted from them with varying degrees of economic success during the past 40 years. A reconnaissance investigation of naturally occurring sodium sulfate in Alberta was carried out during the summer of l958 and, on the whole, the general character of the alkali lakes of Alberta seems to be similar to that of the Saskatchewan lakes originally described by Cole (l926) and recently reviewed by Tomkins (l954). The aim of the survey was to locate potentially economic deposits for subsequent more detailed investigation. To this end over 250 lakes were visited in the area from Edmonton eastwards to the Alberta Saskatchewan border, and southwards to the Alberta-Montana border. The concentration of sodium sulfate and other salts in lakes in Alberta shows great variation, some lakes are virtually fresh whilst others are saturated with various salts. Lakes containing high concentrations of salts were found to be present only in depressions in glacial drift within areas of rolling topography. The depth of brine in different lakes varies from a few inches to nearly seven feet, and some of the shallower lakes dry up completely during the summer.

According to Cole (l926) two types of crystal beds may be present in the Saskatchewan deposits: (1) a permanent bed which forms the source of the sodium sulfate in most of the economic deposits, and (2) an intermittent bed which crystallizes or dissolves according to prevailing temperatures and moisture conditions. Intermittent crystals may even form during a cold night, and go back into solution consequent upon a rise in temperature the next day. An intermittent crystal bed was observed forming in several lakes in Alberta during the summer months, but in the absence of drilling data it is not possible to determine with certainty whether a permanent crystal bed is present in any of these lakes.

The methods adopted for the routine investigation of the lakes consisted of measuring the specific gravity and temperature of the lake waters with hydrometer and thermometer (all specific gravity results have been corrected to l5 degrees Celsius). Samples of brine, and in some cases salt, were collected from the lakes of high salt concentration for chemical analyses in the laboratory. In an effort to determine whether crystal beds were present, the bottom of some of the lakes were probed with a pipe.