This study reports on a project to establish a magnesium oxide derivatives business in South Australia, by exploiting a resource of sedimentary magnesite held by Commercial Minerals Ltd (a member of the Normandy Poseidon Group of companies). Aspects of the project which were investigated to permit effective reporting on its viability include the magnesite resource, mining, infrastructure, transportation logistics, magnesite processing, electrofusion practice and the magnesia market. A current inferred resource of 16 million tonnes of magnesite, containing a possible 6.5 million tons of high grade refractory material, has been costed for open pit mining, local beneficiation by caustic calcination or electrofusion methods to produce high purity magnesia, and local and overseas product marketing, using a target initial magnesite production rate of 35,000 tonnes per annum. This study has confirmed the potential for profitable development of the South Australian Magnesite resource, and concludes that a further study is justified.