Beryllium is named from the Greek beryllos, beryl and was discovered as the oxide vauquelin in beryl and in emeralds in 1798. The metal was isolated in 1828. Beryllium is found in some 30 mineral species, the most important of which are bertrandite, beryl, chrysoberyl and phenacite. Aquamarine and emerald are precious forms of beryl. Beryl and bertrandite are the most important commercial sources of the element and its compounds. Beryllium is one of the lightest metals and has one of the highest melting points of the light metals. It resists attack from concentrated nitric acid, has excellent thermal conductivity and is nonmagnetic. Beryllium is used as an alloying agent in producing beryllium copper which is extensively used for springs, electrical contacts, spot welding electrodes and for non sparking tools. It is also used as a structural material in high speed aircraft, missiles, spacecraft and communication satellites. It is being used in the windshield frame, brake discs, support beams and other structural components of the space shuttle.