Umangite with Malachite

This rare copper selenide, Umangite, is from its type locality at the Tumiñico mine at Sierra de Cacho in north western Argentina.  Fine-grained granular crystals of silvery-blue-grey Umangite are scattered amongst cryptocrystalline layers and smudges of bluish-green Malachite in a Calcite rich carbonate veinstone.  Priced at just US$ 100, this is a rare opportunity to acquire an extremely rare selenium species.