43 491 tonnes of magnesite have been mined. The location, geology, tenement history, mining production, reserves and references are summarised for all deposits. The most important have been :Myrtle Springs - 19 625 tonnes in 1947 - 84Robertstown - 8 198 tonnes in 1916 - 53 and 1980 - 1984 Copley - 6 031 tonnes in 1918 - 55Witchelina - 2 778 tonnes in 1964 - 74 Mundallio - 2 554 tonnes in 1940 - 53Port Germein - 1 466 tonnes in 1925 - 25 and 1947 - 50. Sedimentary magnesite from Skillogalee Dolomite totalled 36 499 tonnes from Myrtle Springs, Copley, Witchelina, Mundallio, Port Germein, Johnburgh, Beetaloo, Saddleworth, Torrens Gorge and from 1980 - 84, Robertstown. Secondary residual magnesite derived from magnesium - rich rocks totalled 6 382 tonnes from Robertstown (1916 - 53), Paratoo, Clare, Clinton, Tumby Bay, Koppio and Mangalo. Only 660 tonnes of metasomatic replacement magnesite has been mined from Balcanoona. In late 1984, new large scale operation began at Myrtle Springs to supply 40 000 - 60 000 tonnes per year to the aluminium refinery industry to filter treatment water.