Rock & Mineral Encyclopedia

Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.

Peridot

The gem-quality green variety of olivine, peridot is colored by iron and is one of the few gems found in only one color.

A dense, coarse-grained ultramafic rock rich in olivine that makes up most of the Earth's upper mantle.

An ultramafic intrusive rock made almost entirely of olivine, representing mantle material.

The most common type of mantle peridotite, made of olivine with both orthopyroxene and clinopyroxene, representing fertile upper-mantle rock.

An ultramafic rock of olivine and clinopyroxene, a peridotite variety common as cumulate layers in mafic intrusions.

A depleted mantle peridotite of olivine and orthopyroxene, the refractory residue left after basaltic melt is extracted from the mantle.

A rare, ancient ultramafic volcanic rock formed from extremely hot magma, famous for its spinifex texture.

A dense, dark ultramafic plutonic rock composed almost entirely of pyroxene minerals, often associated with peridotite and layered intrusions.