The origin of normal Merensky Reef Impala Mines, Bushveld Complex.

Three models are considered for the origin of normal Meresky reef: a) PGE are collected by a sulphide liquid; b) PGE are collected by clusters of PGE ions; c) PGE are collected by volatiles. No model can explain all the aspects of the reef. A new model involving sulphide collection of the PGE followed by re-equilibration of the sulphides with chromite resulting in PGM crystallization from the sulphide liquid is proposed.