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!
fine crystals tapering from a point at one end to a larger, curved, somewhat hemispherical crystallization at the other end of the crystal. It appears to have grown in wedge shaped areas between interlocking crystal plates of cleavelandite. Some of the hemispherical terminations may be as much as two or three inches across at the large end. They are noted in cross section to be made up of many curved crystalline plates of lepidolite all curved over each other, so that in pealing off layers of this mica, they would all appear with hemispherically curved surfaces.
Walden Gem Quarry, Portland, Middlesex County, Connecticut, USA