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!
Bridges et al. (2011): "Early specimens of leadhillite, attributed to Roughton Gill Mine, may well have originated from Higher Roughton Gill or Red Gill. In the present study, it is very rare, but has been found as thin hexagonal plates reaching 2.5 mm across on quartz with small crystals of linarite and cerussite in association."
Roughton Gill Mine, Roughton Gill, Caldbeck, Allerdale, Cumbria, England, UK