igneous
Peridotite
Peridotite (composed largely of Olivine (Mg,Fe)2SiO4)
Hardness: 6.5 to 7. Color: Olive-green to yellowish-green. Luster: Vitreous to greasy. Crystal structure: Orthorhombic. Specific Gravity: 3.2 to 4.4. Texture: Phaneritic (coarse-grained).
- Hardness
- 6
- Color
- Olive-green to yellowish-green
- Luster
- Vitreous to greasy
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Physical properties
Hardness: 6.5 to 7. Color: Olive-green to yellowish-green. Luster: Vitreous to greasy. Crystal structure: Orthorhombic. Specific Gravity: 3.2 to 4.4. Texture: Phaneritic (coarse-grained).
Formation & geological history
Forms deep within the Earth's mantle through the slow cooling and crystallization of magma under high pressure. It is typically transported to the surface by tectonic processes or volcanic pipes.
Uses & applications
Primary source of the gemstone peridot; also used in industry as an flux and for sequestration of carbon dioxide due to its high reactivity with CO2.
Geological facts
Peridotite is the dominant rock of the Earth's upper mantle. It is rarely found on the Earth's surface except in specific geological settings like ophiolites or xenoliths in basalt.
Field identification & locations
Identify by its characteristic olive-green color and coarse-grained, sugary texture. Often found in areas of tectonic activity or within volcanic rocks. Tips for collectors include looking for nodules in basalt flows.
