Smithsonite

Smithsonite from BHP Mine, Broken Hill, New South Wales, Australia, measuring 72 × 51 × 37 mm and weighing 144 grams. This specimen represents the zinc-carbonate side of Broken Hill mineralogy. It provides a useful counterpoint to the district's lead minerals, allowing a collector to consider how two important ore metals appear in different secondary mineral species.

Smithsonite is zinc carbonate, a member of the Calcite structural group. It commonly develops where zinc-bearing minerals are altered and carbonate is available in the surrounding fluids. The result is a secondary mineral rather than the original zinc sulphide ore, and that distinction adds geological interest when Smithsonite is displayed alongside Sphalerite or other minerals from the same mining district.

A pale grey-white mineral surface spreads unevenly across the piece, interrupted by darker matrix patches. That contrast helps the eye follow the contours and small openings instead of reading it as a single flat coating. The restrained colour suits close examination, where variations in surface texture and the distribution of the pale material become the main attraction. The provenance records the Anne McDonald Collection. That association connects the specimen with an established collection of Australian material and gives the next owner a name to retain with the mine label. The interest here is a clear one: zinc-carbonate mineralogy, a specific Broken Hill attribution and a specimen of useful display size brought together in a single documented piece.