smithsonite

Sharp, highly translucent rhombohedral crystals (to 20 mm) of smithsonite, intergrown, and lining a large vug in a ferruginous, gossan-like matrix with some residual sulphide. The smithsonite is nearly colourless in visible light, but with a subtle yellow-brown tint; in long wavelength UV radiation it shows a strong blue-white fluorescence (Exhibit 2).

The specimen is from the collection of Clement Victor Latz which was donated to the Australian Bureau of Mineral Resources (now Geoscience Australia) in 1976. 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 2023; Southwood et al. 2025). Analytical data is presented in Exhibit 2. The slight yellow-brown tint of the specimen is probably due to the partial oxidation of iron (2599 ppm) in solid solution in the smithsonite, but the colour perception is also influenced by the presence of goethite in the specimen matrix.

goethite