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!
Cooper & Stanley (1990): "In debris below Iron Crag, probably originating from the outcrop of the Roughton Gill (South) vein: as minute translucent pistachio green rounded crystals on goethite and quartz (D. Middleton Collection); and as greasy lustred brown rounded crystals encrusting quartz with pyromorphite (N. Thomson Collection). Both occurrences det. BM(NH): XRD."