smithsonite (on tennantite)

Intergrown tetrahedrons (to 25 mm on edge) of tennantite are directionally encrusted with colourless-grey smithsonite. Striated crystals of galena and a little quartz are evident locally (exhibits 1 and 2). The tennantite has not been analysed, but is almost certainly tennantite-(Zn).

The specimen was purchased from Australian dealer Cyril Kovac in 2004, but with no record of its earlier provenance.

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) who hypothesised that likely chromophore elements are present in insufficient quantity, either individually or in combination, to colour the mineral. Analytical data is presented in Exhibit 3. The high EMPA total (103.947 wt %) indicates a poor quality analysis, possibly due to the presence of anglesite or galena inclusions as implied by the high Pb (31377 ppm) and S (5424 ppm) values.

galena; quartz; tennantite-(Zn) (?)