Beryl, a mineral used as a gem-stone; the chief ore of the metal beryllium; and an important ceramic material. Beryl is beryllium aluminum silicate, consisting of beryllium, aluminum, silicon, and oxygen. It is harder than quartz, and usually forms large crystals that are shaped like a six-sided prism. Beryl may be colorless, white, pink, pale yellow to golden yellow, blue, or blue-green to dark green. It has a glasslike luster, and is either transparent or translucent.

Beryl gemstones include most transparent varieties, regardless of their color. They are widely used in jewelry. The most highly prized beryl is emerald, a rich green variety. Blue-green beryl is known as aquamarine. Other beryl gemstones include pink morganite, golden yellow heliodor, and colorless goshenite.

Common beryl is translucent, and usually blue-green or pale yellow. It is the primary ore of beryllium, and is widely used by the ceramics industry in making spark plugs and high-voltage electrical porcelains.

Beryl is usually found in pegmatite granites, in mica schists, and near tin-bearing ores.

Chemical formula: Be3Al2Si6O18. Specific gravity: 2.75 to 2.8. Hardness: 7.5 to 8.