Peridot is the gem-quality variety of the mineral OLIVINE. A rock- forming mineral, olivine occurs in silica-poor igneous rocks, such as basalts, gabbro, troctolite, and peridotite. The crystals mostly project as granular olivines, but also in tabular forms. Peridot's shades of green are caused by the presence of iron, and it often has a greasy lustre. The mineral is named for the French word peritotmeaning ‘gold’ because the mineral can vary towards this colour.
Peridot crystals are fashioned in the trap-cut style, and also faceted as cabochon, pendeloque, step, table, brilliant, rose, and mixed cuts. Peridot is too soft to be used as gemstones in rings or bracelets, but is popular for earrings, pendants, clasps, and brooches. Small crystals are relatively common, but large, good quality ones are rare. In some locations, finding a stone of five carats causes excitement. The Smithsonian Institution in Washington, D.C., has a cut stone of 310 carats.
The main source of peridot in the ancient world was Topazos Island (now Zebirget or St John's Island) in the Egyptian Red Sea, and the stones were called topazios. They were used for carved talismans in ancient Egypt. In the Middle Ages, Europeans brought the crystals back from the Crusades to decorate church plates and robes. In the 19th century, the mines on Zebirget Island produced millions of dollars worth of peridot, today they lie almost silent. United States' sources include the San Carlos Apache Reservation, Arizona, Kilbourne Hole, New Mexico, and Salt Lake Crater, Hawaii (beach pebbles). Other sources include Pyaung gaung, Mogok, Burma (Myanmar) and Northwest Frontier Province, Pakistan.
pronunciation (1878) : any of a group of granular igneous rocks composed of ferromagnesian minerals and esp. olivine pe•ri•do•tit•ic \pə-॑ri-də-॑ti
n 1 a dark coarse-grained ultrabasic plutonic igneous rock consisting principally of olivine [C19: from French, from peridot] › peridotitic (ˌpɛrɪd
ONE OF THE MOST ECONOMICALLY important rocks, peridotite is the ultimate source of all chromium ore, and its variety kimberlite is the...