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Olivine:
Neosilicates (A series consisting of two end members, forsterite and fayalite, which occur as separate species; when chemically combined they form the magnesium iron silicate that is commonly called olivine) Mg2SiO4(forsterite) (Mg,Fe)2SiO4(olivine) Fe2SiO4 (fayalite) AKA: Chrysolite, Fayalite, Forsterite, Peridot |
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System: Orthorhombic; crystals rare; usually in rounded grains, granular masses. Appearance: Yellowish green (peridot), yellowish brown, reddish; vitreous; streak colorless. Physical Properties: Hardness: (6.5 - 7.0); Specific gravity: (3.2 - 4.3). Cleavage: indistinct, two directions at 90o; fracture, conchoidal, uneven; transparent to translucent; brittle. Similar species: Apatite is softer and is fluorescent; green tourmaline is not found in volcanic rocks or gabbros, and green garnet lacks cleavage. Occurrence: Olivine is a rock-forming mineral and occurs as an essential mineral in gabbro, peridotite and basalt. The finest olivine (peridot) comes from St. Johns Island in the Red Sea. Olivine is widespread in various rocks in North America, but there are not many places one can collect specimens much larger than grains. In North America olivine has been found in British Columbia Canada, Arizona and California. Miscellaneous: Transparent gem-quality olivine is called peridot, and ranges in color from yellowish-green to olive green. Dark yellowish-green stones are most valuable, and flawless stones are common. Olivine is named for its olive-green color; fayalite after Fayal, an island in the Azores; and forsterite after Johann R. Forster (1729-1798), a German naturalist who sailed with the great explorer Captain James Cook. Conventional Wisdom: Olivine can be used to magnify the inner aspects of any situation or circumstance. It furthers the understanding of those changes which are occurring in ones life and assists one in the recognition of the detrimental patterns which have been the basis for iimpairmentin attaining that which is necessary for growth. Belongs to the Astrological Signs of Virgo, Leo, Scorpio and Sagittarius. |