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!
From Schooner (circa 1985): "Mary E. Mrose [USGS] studied some exceptional material collected at the Strickland quarry by Charles Thomas, when the last sporadic work was done in the non-flooded pit. Lacroixite formed rather granular pale yellow areas in a mixture of augelite, brazilianite, and hydroxylapatite (?), replacing natromontebrasite. Her paper redefined the species, which had been in question." Natromontebrasite was discredited in 2007, being a mixture of montebrasite, lacroixite, and wardite.