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These white tailings are the leftovers from the cyanidation process. It is one of the oldest methods (created in the 1890s and opposed to more modern (trial) methods as, say, using bacteria in the effort to find a more environmentally friendly method of leaching) of removing gold and silver from ore and, while the most inexpensive and productive method, also arguably the most toxic.

In the modern era, the most common method of cyanidation used is the heap method. Cyanide is mixed with water and then sprayed on a carefully designed heap of ore to maximize oxygenation, as the rate of gold dissolution in the cyanide solution is directly proportional to the amount of oxygen present. Calcium oxide or some other alkali is added to prevent the cyanide from decomposing into hydrogen cyanide gas. The presence of other minerals, such as naturally-occuring arsenic in the form of arsenopyrite, pose special problems during the leaching process and require special consideration. In the case of arsenic, it reacts with the cyanide and uses up the available oxygen, thus slowing down the leaching process. The cyanide-metal solution is then further processed to remove the gold and/or other metals. Although the composition of the post-leach tailings varies depending on the ore, it is usually composed of calcium carbonate. Due to the age of the Techatticup Mine, the ore was probably processed using vat or agitated leaching.

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