Vote for your favorite mineral in #MinCup26! - Sphalerite vs. Anorthite Both zinc ore Sphalerite and calcium plagioclase feldspar Anorthite have perfect cleavage that will split cleanly if you hit them with a hammer, but only one can claim a larger split of your votes!
Meikle (1989): "Chalcopyrite is only rarely found. It is present in a single occurrence in a cavity, forming a 1 - 1.5 mm thick layer, coating botryoidal surfaces of reddish-brown ash-impregnated prehnite. Also, it forms small, <3 mm, tarnished groups of complexly twinned crystals distributed over the surface of small prehnite botryoids and is coated by chrysocolla or goethite. Rarely, it is found altering to earthy chalcocite and/or covellite."
