smithsonite

Closely intergrown crystals (to 12 mm) of brown to grey-brown smithsonite on a matrix of black, partly oxidised galena-rich sulphide ore. The smithsonite is weakly fluorescent in SW ultraviolet (orange) and in LW ultraviolet (pale yellow).

The specimen was purchased from Australian collector George Stacey in 2007, but with no record of either its earlier provenance or location in the mine. The specimen has been analysed by EMPA-WDS and LA-ICP-MS as part of a study of the causes of colour in smithsonite (Weall 2022; Southwood et al. 2025). They hypothesised that the brown colouration is due to partial oxidation of Fe²⁺ in solid solution in the smithsonite. Analytical data is presented in Exhibit 2.

galena