igneous
Peridotite (Dunite/Lherzolite)
Ultramafic Peridotite
Hardness: 6.5-7 (Mohs); Color: Olive-green to dark grey-green; Luster: Vitreous to dull; Crystal structure: Orthorhombic (Olivine dominant); Specific Gravity: 3.2-3.4
- Hardness
- 6
- Color
- Olive-green to dark grey-green
- Luster
- Vitreous to dull
Identified More igneous →
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Physical properties
Hardness: 6.5-7 (Mohs); Color: Olive-green to dark grey-green; Luster: Vitreous to dull; Crystal structure: Orthorhombic (Olivine dominant); Specific Gravity: 3.2-3.4
Formation & geological history
Formed in the Earth's upper mantle through fractional crystallization of magma. These specimens are often brought to the surface as xenoliths in basaltic flows or through tectonic obduction (ophiolites).
Uses & applications
Primarily used as a major source for magnesium and chromium ores. Some variants are processed for refractory materials due to high melting points. Gem-quality olivine (Peridot) is used in jewelry.
Geological facts
Peridotite is the dominant rock of the Earth's upper mantle. It is rarely seen on the surface because it is chemically unstable in the presence of water and quickly alters to serpentinite.
Field identification & locations
Identify by its distinctive olive-green color and heavy weight. Look for granular texture. Commonly found in ophiolite complexes like the Oman Ophiolite or the Klamath Mountains.
