igneous
Peridotite
Ultramafic intrusive rock (Peridotite / Dunite)
Mohs hardness 6.5-7 (olivine), color Olive green to dark green, luster vitrous to dull, granular crystal structure, specific gravity approximately 3.2-3.4
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Physical properties
Mohs hardness 6.5-7 (olivine), color Olive green to dark green, luster vitrous to dull, granular crystal structure, specific gravity approximately 3.2-3.4
Formation & geological history
Formed in the Earth's mantle through slow cooling of magma under high pressure. It is the dominant rock of the upper mantle and is often brought to the surface as xenoliths in basalt or through tectonic uplift.
Uses & applications
Primary source of chromium (chromite) and magnesium. Sometimes used as a source for Peridot gemstones. Also used for carbon sequestration research.
Geological facts
Peridotite makes up most of the Earth's upper mantle, meaning the majority of our planet's mass consists of rocks very similar to this specimen.
Field identification & locations
Identified by its distinctive olive-green color (from olivine) and heavy weight relative to its size. Can be found in ophiolites or as nodules in volcanic lava fields.
