Magnesite claims have been pegged in South Australia as early as 1913 by D.Calder of Tumby Bay. The first production of this mineral also came from Tumby Bay where W.P. Cormack produced about eighty tons in 1915. By 1921 a total of 1466 tons had been mined from various locations in South Australia. Five years later this had increased to 5234 tons. Since then more than 43,000 tons have been mined, most of it in the Flinders Ranges. Beds of magnesite range in average thickness from five centimetres to five metres. Some of these deposits can be found in the Torrens Gorge and near Copley, Myrtle Springs and Witchelina.
Small amounts of magnesite have also been mined near Robertstown where J.Baker produced nearly a hundred tons in 1915. Another 5620 tons were mined between 1916-1953 and from 1980-1983 by Jomoco Pty. In 1918 J.Dyer, J.Bottom and H.Ridgeway produced some sixty tons from an outcrop at Copley but lack of a market and the isolation forced them to stop their venture. Samples from this area were analysed by W.S.Chapman who found a magnesium carbonate content of between 87 and 95 per cent.
During the 1940s magnesite was mined in the Northern Flinders Ranges, at Mundallio and near Johnburg. About two hundred tons were mined at Witchelina, north of Farina, during 1964 and twenty years later 10,000 tons were produced from a large deposit at Myrtle Springs, near Leigh Creek.
Magnesite is an ore used for the production of Magnesium. Pure magnesite can contain as much as 47.8 per cent magnesium oxide. Magnesium is the lightest of all structural metals. Its low weight and high strength make it ideal for many different purposes. It has, and still is, used in the production of fire bricks for furnaces, cement killns, floors, fertilizer, vacuum cleaners, wall boards, mouldings, lawn mowers, cameras, aircraft, acoustic tiles, alloys, paper pulp, glass, paint, rubber and mag wheels.
The largest use now is for aluminium alloying, particularly in the automotive industry. With all major motor manufacturers planning to use more magnesium in the production of their new models, mining companies have been searching for first class deposits to meet the increase in demand.
Between 1997 and early 1998 both airborne and ground surveys were made to the west of the Willouran Ranges. They established large high grade deposits of magnesite, particularly at Screechowl Creek where some beds are up to five metres thick and can be traced for more than ten kilometres.
During 1998 Pima established South Australian Magnesium Project (SAMAG) to test the magnesite deposits situated between Leigh Creek and Lyndhurst. It acquired leases over the Mount Hutton, Witchelina and Screechowl Creek areas. The Mount Hutton ore is virtually free of any impurities. Diamond drilling of more than hundred holes provided some 8000 metres of cores. In the Witchelina area magnesite beds of more than ten metres in thickness were located. It has now been proven that a world class magnesite deposit of more than half a billion tons can be mined.