igneous
Peridotite / Olivine (Dunite)
Peridotite (predominantly Olivine: (Mg, Fe)2SiO4)
Hardness: 6.5-7 on Mohs scale; Color: yellowish-green, olive-green to pale green; Luster: vitreous to dull/earthy when weathered; Crystal Structure: orthorhombic (granulate mass); Cleavage: poor; Specific Gravity: 3.2-3.4.
- Hardness
- 6
- Color
- yellowish-green, olive-green to pale green
- Luster
- vitreous to dull/earthy when weathered
Identified More igneous →
Explore Peridotite / Olivine (Dunite) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 6.5-7 on Mohs scale; Color: yellowish-green, olive-green to pale green; Luster: vitreous to dull/earthy when weathered; Crystal Structure: orthorhombic (granulate mass); Cleavage: poor; Specific Gravity: 3.2-3.4.
Formation & geological history
Formed deep within the Earth's mantle under intense pressure and high temperatures, brought to the surface through tectonic uplift or deep volcanic eruptions (such as kimberlite or basalt flows).
Uses & applications
Olivine and peridotite are mined for use as refractory materials in steelmaking, foundry sand, and occasionally as a CO2 sequestration medium. High-quality gem-grade transparent crystals are used as peridot gemstones.
Geological facts
Peridotite makes up most of the Earth's upper mantle. Olivine is also one of the first minerals to crystallize from a cooling basaltic magma according to Bowen's Reaction Series.
Field identification & locations
Identified by its distinctive pale olive-green or yellowish-green sugary granular texture and high density. Commonly found in ultramafic intrusive complexes, ophiolites, and mantle xenoliths inside basaltic rocks.
