The rare copper bismuth arsenate hydroxide hydrate species Mixite is one of a remarkable 53 species first discovered from the Jáchymov District (St. Joachimsthal) in the Krušné Hory Mts (Erzgebirge), Karlovy Vary, Bohemia, Czech Republic. Recognized in 1875, it was formally named Mixite in 1880 but specimens from Jáchymov are so rarely seen, even within museums. This very rich and fairly large (for a rare species) specimen heralds from the amazing systematic collection assembled by the brothers Martin and Michael Günther (1951-2007 & 1956-2021) who were renowned for finding historically important specimens from classic localities. The specimen consist of a somewhat porous mass of green supergene copper mineralization much of which is probably Mixite although several other species are likely to be present based on the different shades in colour. Under magnification the Mixite is seen as typical tiny acicular silky blue-green crystal sprays, with probable Brochantite as the darker emerald-green crystals. Slight desiccation (cracking) of the surface can be seen, but this does not appear to affect the stability of the specimen.
