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!
Kingsbury reference. Cooper & Stanley (1990): "Traces of bayldonite were found in material 'from an old cross-cut at, or near, the junction of the east-west lead veins with the Emerson vein at the foot of Brandy Gill (Kingsbury & Hartley, MS; Hartley, 1984: 36)."