calcite

Pearly-white rhombs of calcite (to 55mm), with an unusual silky lustre and etched surfaces, possibly indicative of recrystallisation (?). Broken surfaces on the base of the specimen indicate that the "recrystallised" layer is about 4 mm thick. Some "spots" of a undetermined dark grey-black mineral are noted as near-surface inclusions in some of the calcite crystals. On the reverse of the specimen (Exhibit 2) some of this same (?) undetermined mineral is exposed between the calcite crystals and its powdery, blue-black soot-like nature suggests Mn oxides, but analysis is required. A very little matrix material adheres to the base of the specimen - apparently consisting of chalcocite (?), malachite and calcite.

The specimen was acquired from Scott Werschky in 2014 who was dispersing calcite specimens from the collection of Tsumeb miner Eric Louw which he had received from South African collector Ronnie McKenzie. The location in the mine is not recorded.

chalcocite (?); malachite; undetermined