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 diorite intrusion and are composed primarily of hematite microcrystallites and chalcedony. The hematite microcrystallites have undergone post-mineralization recrystallization and coarsening with resultant formation of lath-shaped hematite porphyroblasts. Microscopic investigation reveals that recrystallization and coarsening of the hematite ores of the Gushan mine took place without the formation of new nuclei, due to the coalescence of the microcrystallites. The whole process could have begun with the mutual approach of the microcrystallites, followed by grain rotation to realize parallelism and ending by the welding of these grains to form optically homogeneous porphyroblastic hematite.
Key wordsiron ore hematite recrystallization annealing grain coarsening coalescence
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