Cerussite

Cerussite from Blackwood Opencut, Broken Hill, New South Wales, Australia, measuring 72 × 26 × 11 mm and weighing 13 grams. The narrow proportions distinguish this piece within the group of Broken Hill specimens offered here. Its precise opencut attribution is a useful feature for collectors who follow the district through its individual workings rather than by mineral species alone.

Cerussite is lead carbonate, commonly produced as lead-bearing minerals alter in an oxidising environment. It belongs to the Aragonite structural group, despite being chemically quite different from calcium carbonate. That connection is one of the pleasures of systematic mineral collecting: familiar-looking crystal families can accommodate very different elements, and the same broad process of weathering can produce a wide range of species.

The cream-coloured blades spread into an open, uneven jackstraw spray with a smaller spray at its base, giving this slender specimen a surprisingly animated outline. Individual elongated forms can be followed through the group, rather than disappearing into a solid mass. The light build of the cluster is part of its charm; a supported position that leaves the projecting blades clear will show it to advantage. This example comes from the Anne McDonald Collection. At 72 mm long but only 11 mm in its smallest recorded dimension, it deserves a carefully supported position in a tray or display. The combination of those distinctive proportions, the named working and the collection provenance gives the next collector several concrete points of interest to preserve with the piece.