“…The minerals in a coal sample are therefore usually isolated and identified by low-temperature oxygenplasma ashing (Gluskoter, 1965;Standards Australia, 2000), during which the coal is exposed, under vacuum, to a stream of electronically activated oxygen, which destroys the organic matter at a temperature of around 120°C, leaving a residue consisting of the essentially unaltered mineral components. The organic sulphur in the coal macerals may, however, interact with organically-associated inorganic elements to form mineral artefacts in the plasma-ashing process (Frazer and Belcher, 1973). Non-mineral calcium, for example, may react with sulphur released from the coal to form bassanite (CaSO 4 .½H 2 O) in the low-temperature ash residues of South African coal samples (Matjie et al, , 2011(Matjie et al, , 2012a(Matjie et al, , 2012bHlatshwayo et al, 2009).…”