Olivine (Peridotite)

Physical Properties

Hardness: 6.5–7; Color: Olive-green, yellow-green to brownish; Luster: Vitreous (glassy) to earthy; Crystal Structure: Orthorhombic; Specific Gravity: 3.2–4.4.

Formation & Geological History

Formed in the Earth's upper mantle and brought to the surface through volcanic activity. It is a primary constituent of ultramafic igneous rocks like peridotite and basalt. Often found in volcanic deposits or as weathered nodules.

Uses & Applications

Used as a gemstone (Peridot), in sandblasting, as a refractory material in steel manufacturing, and for carbon sequestration research.

Geological Facts

Olivine is one of the most common minerals in the Earth's subsurface by volume, making up a large portion of the mantle. It has also been discovered in meteorites and on the surface of Mars and the Moon.

Field Identification & Locations

Identify by its distinctive olive-green color and granular texture. Often found in volcanic areas or riverbeds downstream from basaltic outcrops. Collectors should look for transparent green crystals for gem quality.

Identified on: 4/30/2026

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