smithsonite

conichalcite-duftite (?); goethite

Curvilinear "teardrop" aggregates (to 10 mm) of vitreous, translucent green smithsonite, comprising rhombohedral crystals in close parallel growth with the composites preserving a hint of trigonal symmetry.The matrix is mineralised feldspathic sandstone (?) with fractures filled with massive smithsonite and a subordinate yellow-green copper arsenate, probably conichalcite-duftite (?); a little goethite is present locally.

The specimen was purchased from the Crystal Circle dealership in 2016, but with no record of 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 principal chromophore is Cu (13209 ppm) which is almost certainly in solid solution in the smithsonite lattice. Analytical data is presented in Exhibit 2.