Beryl
A mineral of great hardness occurring in green and bluish-green six-sided prisms. It is ranked among the gems, and is nearly identical with emerald, but is not so brilliant in color. It is infusible; with borax it fuses into a transparent glass. Its composition is: silex 68, alumina 15, glucine 14, lime 2, oxide of iron 1. See EMERALD; PRECIOUS STONES.