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!
Occurs very sparingly, generally as clear to white grains in (white) mendipite. Laurionite may be more common than realised, as it is very unobtrusive in this environment.