olivine

olivine (ŏlĭv`ēn), an iron-magnesium silicate mineral, (Mg,Fe)₂SiO₄, crystallizing in the orthorhombic system. It is a common constituent of magnesium-rich, silica-poor igneous rocks; metamorphism of some high magnesium sediments also can form olivine. Dunite consists almost entirely of olivine. It also occurs in lunar rocks and meteorites. Olivine has a characteristic yellow-green to olive-green color, hence the name. Transparent olivine of good color can be cut into gemstones; the gem form is known as peridot. Sources of gem-quality olivine are St. John's Island in the Red Sea, Myanmar, and Arizona. Magnesium-rich olivine has a high melting point and is used in the manufacture of refractories. It was formerly called chrysolite.

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olivine

Any member of a group of common magnesium, iron silicate minerals. Olivines occur in many igneous rocks and are a major constituent of the Earth's upper mantle. They also have been found in some lunar rocks and in many meteorites. Olivine forms yellow to greenish yellow crystals and is sometimes used in making bricks. Transparent green olivine (precious olivine) is called peridot.