Image Credit: Malcolm Southwood
Image Credit: Malcolm Southwood
Specimen Title
Smithsonite (w. mimetite)
Associated Minerals
aurichalcite (?); goethite; malachite; mimetite; undetermined
Principal Mineral
Size
Cabinet; 77mm
Location in the Mine
Provenance
Bruce, I.
Collection
Southwood, M.; MS2015.107
Entry Number
Specimen; TSNB791
Associated Minerals
aurichalcite (?); goethite; malachite; mimetite; undetermined
Description
Sheaves of smithsonite (to 8 mm), made up of almost acicular individual crystallites consisting of steep rhombohedral forms and ranging from colourless-white to an intense but pale green colour, and composite aggregates of ivory-white mimetite crystals (to 2.5 mm) some of which are stained orange by iron oxides (?). The matrix is a heavily mineralised dolostone, with a thin veneer of goethite on which the smithsonite and mimetite have crystallised. A narrow vug at one margin of the specimen is lined with an unidentified yellow mineral, a few whispy aggregates of pale blue aurichalcite (?) and sparse micro-botryoidal malachite.
The specimen was purchased from Ian Bruce (Crystal Classics) in 2015 but with no 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). They hypothesised that the principal chromophore is Cu (22972 ppm) which is in solid solution in the smithsonite lattice. Analytical data is presented in Exhibit 2.
