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!
In the 'antimony vein' as grains up to 20 µm in quartz (Fortey et al., 1984). The same authors (op. cit.: 61) also observed '... minute inclusions of a possible Sb-As alloy ... in a berthierite prism.'
Wet Swine Gill, Coombe Height, Caldbeck, Allerdale, Cumbria, England, UK