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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.
This entry comes from Encyclopædia Britannica Concise. For the full entry on olivine, visit Britannica.com.