Peridotite

Physical Properties

Hardness: 6.5–7 Mohs scale; Color: Dark green, olive green, or black; Luster: Vitreous to dull; Crystal structure: Phaneritic (coarse-grained); Specific gravity: 3.2–3.4.

Formation & Geological History

Formed in the Earth's mantle through the slow cooling of magma high in magnesium and iron. It is an intrusive rock that originates from great depths, often brought to the surface via tectonic uplift or volcanic eruptions.

Uses & Applications

Primary source of magnesium and chromium ores. Varieties like Dunite are used in refractory materials. Gem-quality olivine found within it is sold as Peridot.

Geological Facts

Peridotite is the dominant rock type of the Earth's upper mantle. It is highly susceptible to weathering and often undergoes 'serpentinization,' turning into serpentinite when exposed to water.

Field Identification & Locations

Identify in the field by its high density, dark green coloration, and grainy texture. Commonly found in ophiolite complexes, oceanic crust sections pushed onto land, and kimberlite pipes.

Identified on: 4/19/2026

Mode: Standard