Mimetite (w. cuprite)

cuprite; malachite

cuprite; malachite

A sliver of altered dolostone (?) supports a thick crust of mimetite comprising numerous narrow, radiating sprays of closely sub-parallel slender crystals (individually to 11 mm in length). The mimetite crystals are orange-yellow near the matrix contact, transitioning to straw-yellow at the terminations. Two incomplete octahedral cuprite crystals (to 11 mm) are associate at the upper margin of the specimen (as photographed). Malachite microcrystals are present on some faces of the cuprite.

Mark Feinglos acquired the specimen from Cal Graeber in 1980 but with no record of earlier provenance or location in the mine.