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!
Found on red tourmaline. Re-examination by Pekov et al (2010) of old rhodizite samples (from co-type locality) showed that these are Cs-dominant and are londonite according to IMA nomenclature.
Habit:
small crystals; dodecahedra {110} in combination with tetrahedron{111}