Plagioclase: belonging to the Feldspar group, which includes silicates with common characteristics such as Potassium Feldspars (Orthoclase, Adularia Moonstone, Microcline, Amazonite) and, specifically, Plagioclases (Albite, Oligoclase Sunstone, Andesine, Labradorite, Bytownite, Anorthite). Plagioclases form an isomorphic series between the pure end-members Albite and Anorthite. The intermediate members (Oligoclase, Andesine, Labradorite, Bytownite) vary according to the percentage of Albite and Anorthite. Their chemical composition is expressed as: nNa[AlSi₃O₈] – nCa[Al₂Si₂O₈]. They range from translucent to opaque, with luster from vitreous to pearly, and colors from gray to greenish, bluish, reddish, white, or colorless. They generally occur as rare single crystals with prismatic or tabular shapes, often twinned, but also in compact granular aggregates. Found in igneous and metamorphic rocks.
