The mine was originally worked for gold by Western Mining Corporation in 1932. Drummond Gold, the current (mid-2011) holders of the property state "The historic Koala mine produced more than 226,000 oz of gold from 1914-1939 and in the 1990’s. Koala currently has an estimated Measured, Indicated and Inferred Resource of 604,000 tonnes @ 3.5 g/t gold (67,200 oz gold). The currently known resources at Mt Coolon (Koala) occur around the periphery of the underground workings, below the open pit and in the old tailings."