smithsonite

Closely intergrown, modified rhombs of smithsonite (to 6 mm) on a dark grey sulphide matrix of which galena is a prominent constituent. The smithsonite crystals are striated, highly transparent and, for the most part, colourless. However, inclusions of orange-brown iron oxides, possibly goethite (?), at the cores of the crystals create an overall orange-brown colour impression.

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. This is essentially colorless smithsonite, with localised zones in the cores of the crystals with inclusions of orange-colored Fe oxides which contribute to the perception of an orange-brown colour.

galena; goethite (?)