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): "Hartley (1984) lists sphalerite as occurring on material from the 60 fathom level, claimed to have been collected by Kingsbury, but the specimen could not be found in the NHM. In this study, sphalerite is uncommon, but has been found mainly as brown cleavage fragments, a few millimetres across, in the matrix of specimens of supergene minerals such as hemimorphite and smithsonite. One specimen in the Tim Neall Collection consists of a layer 10 mm thick, with a crystalline surface, on wallrock and partly coated with 2 to 3 mm nailhead calcite crystals. Minor oxidation to hemimorphite is evident on this specimen."
