Beryl: a mineral that is chemically a beryllium aluminum silicate, with the formula Be₃Al₂(Si₆O₁₈). It ranges from transparent to opaque, has a vitreous luster, and varies in color from colorless to different hues. It crystallizes in the Hexagonal System and typically forms elongated prismatic crystals, more rarely tabular ones. It is found in Pegmatite veins associated with granitic rocks and, more rarely, in alluvial deposits. Depending on the chromophore (the element that substitutes for Aluminum in the crystal lattice and imparts color), the varieties include: green (Emerald), blue green (Aquamarine), yellow (Heliodor), colorless (Goshenite), light pink–violet (Morganite), and red (Bixbite).
