igneous
Peridotite
Ultramafic igneous rock
Hardness: 6-7 (depending on constituent minerals), Color: Dark green to brownish-green, Luster: Vitreous to dull, Crystal structure: Coarse-grained (phaneritic) texture composed mainly of olivine and pyroxene, Specific Gravity: 3.2 - 3.4
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Physical properties
Hardness: 6-7 (depending on constituent minerals), Color: Dark green to brownish-green, Luster: Vitreous to dull, Crystal structure: Coarse-grained (phaneritic) texture composed mainly of olivine and pyroxene, Specific Gravity: 3.2 - 3.4
Formation & geological history
Formed deep within the Earth's mantle through the cooling and crystallization of ultramafic magma or as solid mantle rock brought to the surface through tectonic processes and volcanic activity.
Uses & applications
Primarily of scientific interest as samples of the Earth's upper mantle; source rock for diamonds and chromium; sometimes carved or polished as ornamental stone.
Geological facts
Peridotite is the dominant rock type of the Earth's upper mantle. When partially melted, it produces basaltic magma. It is also the principal host rock for diamonds, which form under high pressure in the mantle and are brought up by kimberlite pipes.
Field identification & locations
Identify by its dark, dense, greenish appearance with visible olivine grains. Commonly found in ophiolite sequences, convergent plate boundaries, and mantle xenoliths within volcanic rocks.
