igneous
Olivine (Peridotite)
(Mg, Fe)2SiO4 (Magnesium Iron Silicate)
Hardness: 6.5–7.0 on Mohs scale; Color: Olive-green, yellow-green, or brownish; Luster: Vitreous (glassy); Crystal Structure: Orthorhombic; Cleavage: Poor; Specific Gravity: 3.2–4.4.
- Hardness
- 6
- Color
- Olive-green, yellow-green, or brownish
- Luster
- Vitreous (glassy)
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Physical properties
Hardness: 6.5–7.0 on Mohs scale; Color: Olive-green, yellow-green, or brownish; Luster: Vitreous (glassy); Crystal Structure: Orthorhombic; Cleavage: Poor; Specific Gravity: 3.2–4.4.
Formation & geological history
Formed deep in the Earth's mantle and brought to the surface via volcanic activity. It is the primary component of the upper mantle and constitutes intrusive igneous rocks like peridotite and extrusive basalt.
Uses & applications
Industrial uses include blast furnace flux for steel making and sand blasting. High-quality transparent specimens (Peridot) are used in jewelry.
Geological facts
Olivine is one of the first minerals to crystallize from magma (Bowen's Reaction Series). It has also been discovered in meteorites (Pallasites) and on the surface of Mars and the Moon.
Field identification & locations
Identify by its distinctive olive-green color and granular texture. It is commonly found in basaltic lava flows and ultramafic rock complexes. Collectors should look for 'xenoliths' or green nodules within darker volcanic rocks.
