Peridot in Basalt

Physical Properties

Hardness: 6.5-7 (Mohs); Color: Olive-green to lime-green crystals; Luster: Vitreous (glassy); Crystal Structure: Orthorhombic; Cleavage: Poor; Specific Gravity: 3.2-3.4

Formation & Geological History

Formed deep within the Earth's mantle and brought to the surface by volcanic eruptions. The host basalt is an extrusive igneous rock formed from rapid cooling of lava.

Uses & Applications

Used as a gemstone (peridot) in jewelry and as an industrial abrasive (olivine). High-quality peridot is a birthstone for August.

Geological Facts

Peridot is one of the few gemstones that occurs in only one color. It has even been found in pallasite meteorites, meaning it exists in outer space.

Field Identification & Locations

Identified by the distinct green glassy crystals embedded in dark, fine-grained volcanic rock. Commonly found in volcanic fields like those in Arizona, Hawaii, and Canary Islands.

Identified on: 5/19/2026

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