Grain Coarsening of Hematite in the Gushan Iron Deposit,Anhui Province,China

The iron ores of the Gushan mine occur in the contact zone of a Mesozoic dioriteintrusion and are composed primarily of hematite microcrystallites and chalcedony. Thehematite microcrystallites have undergone post-mineralization recrystallization and coarseningwith resultant formation of lath-shaped hematite porphyroblasts. Microscopic investigation reveals that recrystallization and coarsening of the hematite ores of the Gushan mine took placewithout the formation of new nuclei, due to the coalescence of the microcrystallites. The wholeprocess could have begun with the mutual approach of the microcrystallites, followed by grainrotation to realize parallelism and ending by the welding of these grains to form optically homogeneous porphyroblastic hematite.