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. Kingsbury and Hartley (1957): "in some massive, intergrown chalcopyrite and blende, derived from the 30-fathom level, serpierite occurs in narrow veinlets or coating surfaces of joints; it forms aggregates of tiny, pale blue, lath-like crystals, with a pearly lustre, and at first sight could be confused with aurichalcite. Its identity was confirmed by powder photographs which exactly match that of authenticated serpierite from Laurium. On some of the specimens from Driggith mine, the serpierite is intimately associated with another pale-blue, pearly mineral, in minute hexagonal plates, which gives an entirely different but well-defined powder-pattern but has so far remained unidentified."
