Chalcostibite altering to Azurite and Malachite
Bar-el-Anz, near Casablanca, Morocco
Thumbnail, 2.5 x 2.0 x 2.0 cm
This seemingly humble specimen is actually quite significant as it is a mostly UNALTERED crystal of this species, whereas the common sort from this locality is almost completely altered to azurite and malachite as a mixture. This very stout, well-formed crystal instead is still almost entirely CHALCOSTIBITE, though it has a thin alteration skin on parts of the surface. Old and rare material!