igneous
Peridotite / Olivine Xenolith
Ultramafic igneous rock primarily composed of olivine and pyroxene
Hardness of 6.5-7 on the Mohs scale, vibrant green to olive-green color with white or grayish matrix, vitreous to dull luster, granular crystal structure, specific gravity around 3.2-3.4.
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Physical properties
Hardness of 6.5-7 on the Mohs scale, vibrant green to olive-green color with white or grayish matrix, vitreous to dull luster, granular crystal structure, specific gravity around 3.2-3.4.
Formation & geological history
Formed deep within the Earth's upper mantle under extreme heat and pressure, brought to the surface rapidly via volcanic activity (kimberlite or basaltic magmas) as xenoliths.
Uses & applications
Used primarily in scientific research to understand Earth's mantle composition, and source rock for gem-quality peridot.
Geological facts
These rocks offer direct physical samples of the Earth's mantle, originating dozens of miles beneath the crust before being violently ejected by volcanoes.
Field identification & locations
Easily identified by its characteristic bright olive-green crystalline patches enclosed within a weathered basaltic or lighter crust. Found worldwide in volcanic regions, notably Arizona, Hawaii, and kimberlite pipes.
