Brochantite

Brochantite from Mount Oxide Mine, Mount Isa District, Queensland, Australia, measuring 68 × 55 × 21 mm and weighing 77 grams. This locality specimen brings a copper sulphate into the collection, adding a different chemical family to the better-known copper carbonates. The named mine is a central part of the piece's interest within a Queensland mineral group.

Brochantite is a copper sulphate hydroxide and is associated with the alteration of copper-bearing deposits. Its chemistry gives it a useful place in a systematic display alongside minerals such as Malachite and Atacamite, whose carbonate and chloride components represent different pathways in secondary mineral formation. Such comparisons make the diversity of copper mineralogy particularly easy to appreciate.

A bright green, finely textured coating spreads across the broad face of a shallow brown matrix piece. The contrast makes the distribution of the copper mineral easy to follow, especially around the irregular edges. A face-on display gives the colour room to work, while closer examination brings out the smaller variations within the coated surface. The specimen comes from the David Vince Collection. Its strongest collecting theme is the connection between a defined mine locality and a less familiar copper compound. That gives the next owner a clear reason to retain it within a locality or systematic group, while the collection provenance adds the personal history that accompanies the mineral from one cabinet to another.