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!
Meikle (1989): "Cuprite occurs with native copper and malachite in a mixture of prehnite, calcite, and analcime, which fills joints (<25 mm) in dense, fine-grained lava , as well as in small (2-3 mm), infrequent cavities. The cuprite form ranges from blood-red adamantine, transparent, cubo-octahedral crystals (<0.3 mm), through to crimson transparent elongated bladed crystals (<0.03 x 0.25 mm). In addition, it is also present as hair-like masses (variety chalcotrichite) (<11 x 13 mm), as well as metallic deep-red or dull-grey (<1 x 3 mm), or dull, earthy, brick-red to orange masses (<15 x 35 x 75 mm). The latter often include small bright hackly masses and crystals (<0.5 mm) of native copper and are frequently bordered by a layer of malachite."
Boyleston Quarry, Barrhead, East Renfrewshire, Scotland, UK