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!
Green et al. (2009): "Although pyrolusite was claimed in Kingsbury’s manuscript notes, no specimen has been traced in his collection and in view of the difficulties involved in characterising manganese oxide minerals to species level, the record should be regarded as unsubstantiated."
