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!
Re-analysis by SXRD (Uwe Kolitsch) showed the twinned "leiteites" (Schebesta, 1992) to be valentinites (Kolitsch, 2013; see also http://www.mindat.org/mesg-7-128482.html).