Lightest rigid metal. From the mineral beryl. Its ability to absorb large amounts of heat makes it useful in spacecraft, missiles, aircraft, etc. Emeralds are beryl crystals with chromium traces giving them their green color. Also used in light weight metal alloys, X-ray tube windows, watch springs and sparkless tools.
Beryllium comes from Greek beryllos, beryl.
Beryllum is found in beryl, chrysoberyl and phenacite. It has a high melting point for a light metal and is more elastic than steel. It is used in computer parts, gyroscopes and for construction. Beryllium and its salts are toxic and should be handled with great care. Do not taste it to confirm that it is sweet.