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!
Crystals commonly show the forms m(110), q(011), e(101), k(021), t(013). "Certain crystals ...recently acquired by the Harvard Museum, are somewhat complex and show, in addition to the above, the forms: g(111), o(112), i(312), n(012), Φ(023), τ(031), x(321), B(514)." (Hitchen, 1935)
Rollstone Hill Quarries, Fitchburg, Worcester County, Massachusetts, USA