igneous
Peridotite (Dunite)
Peridotite (comprising mainly Olivine)
Hardness: 6.5-7 Mohs; Color: Pale yellowish-green to deep olive; Luster: Vitreous to greasy; Crystal structure: Orthorhombic; Specific Gravity: 3.2-4.4
- Hardness
- 6
- Color
- Pale yellowish-green to deep olive
- Luster
- Vitreous to greasy
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Physical properties
Hardness: 6.5-7 Mohs; Color: Pale yellowish-green to deep olive; Luster: Vitreous to greasy; Crystal structure: Orthorhombic; Specific Gravity: 3.2-4.4
Formation & geological history
An ultramafic intrusive igneous rock formed in the Earth's mantle or through magmatic differentiation in early stages of planetary cooling. Often brought to the surface via tectonic uplift or volcanic eruptions.
Uses & applications
Primary source of chromium (as chromite) and magnesium; used as a decorative stone, in refractory linings, and certain gem-quality peridot varieties are used in jewelry.
Geological facts
Peridotite is the dominant rock of the upper part of Earth's mantle. When it consists almost entirely of olivine, it is specifically called Dunite. It is also found in many stony-iron meteorites.
Field identification & locations
Identify by its distinct olive-green color and sugary texture. Found in ophiolites (sections of ocean crust/mantle) or volcanic xenoliths. Collectors look for high olivine content and lack of alteration to serpentine.
