igneous
Peridotite (Olivine/Peridot)
Peridotite: (Mg,Fe)2SiO4 (Olivine-rich ultramafic rock)
Hardness: 6.5–7; Color: Olive-green, yellowish-green; Luster: Vitreous to dull; Structure: Granular/Crystalline; Specific Gravity: 3.2–3.4; Cleavage: Poor/Conchoidal fracture.
- Hardness
- 6
- Color
- Olive-green, yellowish-green
- Luster
- Vitreous to dull
Identified More igneous →
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Physical properties
Hardness: 6.5–7; Color: Olive-green, yellowish-green; Luster: Vitreous to dull; Structure: Granular/Crystalline; Specific Gravity: 3.2–3.4; Cleavage: Poor/Conchoidal fracture.
Formation & geological history
Formed in the Earth's mantle through slow cooling of ultramafic magma. It is a major constituent of the upper mantle and is often brought to the surface by volcanic activity as xenoliths.
Uses & applications
Primary source of the gemstone peridot; also used as a decorative stone and for carbon sequestration research. Historically used as a source of magnesium and chromium.
Geological facts
Peridotite is the main rock type of the Earth's upper mantle. Gem-quality olivine within it is known as Peridot, which is the birthstone for August.
Field identification & locations
Identify by its distinctive olive-green color and granular texture. Commonly found in volcanic areas (Hawaii, Arizona) and ophiolite complexes. Look for small, glassy green crystals embedded in darker basaltic matrix.
