Peridotite
Rock made of olivine, pyroxene
Common
A dense, coarse-grained ultramafic rock of olivine and pyroxene, bright to dark green, named after the peridot gem. It is the main rock of Earth’s upper mantle; its outcrops weather earthy yellow as the olivine breaks down.
Rock
- Kind of rock
- Plutonic igneous rock
- Rock family
- Ultramafic rock (peridotite, serpentinite)
- Texture
- coarse-grained
- Also contains
- Chromite, Plagioclase
- Deposits
- Lateritic deposit, Kimberlite pipe
- How it forms
- Comes from the mantle, as slabs thrust up with ocean floor, as nodules carried up by basalt and kimberlite from 30 to 200 km down, or as crystals settled out of mantle magmas.
- Uses
- Weathers to serpentinite and to the nickel laterites; its layered intrusions hold chromite.
Crystallography
- Habits
- Granular, Massive
Physical properties
- Luster
- Vitreous
- Colors
- dark green, green, yellow
- Transparency
- Opaque
Geology
- Origins
- Igneous
- Geography
- worldwide, USA (Kilbourne Hole, New Mexico; Oahu, Hawaii), Canada (Theo’s Flow, Ontario)
Classification
- Rarity
- Common
- Gem quality
- No
Sources
- Peridotite. Wikipedia.
- M. R. Gillespie, M. T. Styles, BGS Rock Classification Scheme, Volume 1: Classification of igneous rocks (Research Report RR 99-06). British Geological Survey, 1999.
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