igneous
Olivine (Peridotite)
(Mg,Fe)2SiO4 (Magnesium Iron Silicate)
Hardness: 6.5–7.0 (Mohs scale), Color: Olive-green to yellowish-green, Luster: Vitreous, Crystal Structure: Orthorhombic, Cleavage: Poor, Specific Gravity: 3.27–4.37.
- Hardness
- 6
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Physical properties
Hardness: 6.5–7.0 (Mohs scale), Color: Olive-green to yellowish-green, Luster: Vitreous, Crystal Structure: Orthorhombic, Cleavage: Poor, Specific Gravity: 3.27–4.37.
Formation & geological history
Formed in the Earth's upper mantle through slow cooling of mafic and ultramafic magmas. It is a primary component of the mantle and can be brought to the surface through volcanic activity or tectonic uplift.
Uses & applications
Used as a refractory material in steel making, as an abrasive (sandblasting), and high-quality specimens are cut into the gemstone Peridot.
Geological facts
Olivine is one of the first minerals to crystallize from a cooling magma. It has also been discovered in meteorites (Pallasites) and on the surface of Mars and the Moon.
Field identification & locations
Identify by its distinctive pistachio to olive green color and granular texture. Found commonly in basaltic lava flows, ophiolites, and magnesium-rich igneous rocks. Collectors look for translucent green crystals within darker volcanic rock.
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