smithsonite (on galena)

Weakly translucent crystals of dark, yellowish-brown to chocolate-bown smithsonite (to 11 mm) on a galena-rich sulphide matrix. Some of the smithsonite crystals are complete and free-standing, while others appear to have grown interstitially between and as coatings over galena crystals that form part of the matrix.

There is no record of provenance or of 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 2023; Southwood et al. 2025). Analytical data is presented in Exhibit 2. Co (102 ppm) and Mn (1015 ppm) are both at levels that could cause a pink colouration. Their influence, however, is overwhelmed by the oxidation of ferrous iron in solid solution in this Fe-enriched (12113 ppm) smithsonite. Cd (583 ppm) and S (121 ppm) are present at relatively low concentrations but the crystals show no sign of inclusions of either CdS or Fe oxides.

galena