Peridot

Hardness: 6.5-7.0 (Mohs scale), Color: Typically olive green, yellowish-green, or brownish-green. Can also be yellow or brown. Luster: Vitreous to greasy. Crystal Structure: Orthorhombic. Cleavage: Poor, conchoidal fracture. Specific Gravity: 3.2-4.4

Peridot forms in mafic and ultramafic igneous rocks, such as basalt, peridotite, and dunite. It typically crystallizes from magma deep within the Earth's mantle and is brought to the surface through volcanic activity. It can also be found in some meteorites. Geological Age: Varies depending on the volcanic activity, but primary deposits are often associated with relatively young volcanic rocks (millions of years old).

Primarily used as a gemstone in jewelry (rings, necklaces, earrings). Less commonly, industrial-grade olivine (non-gem quality) is used as a refractory material, in sandblasting, and as a raw material for fertilizers.

Peridot is the gem-quality variety of olivine. It is one of the few gemstones that occurs in only one color: green. The intensity of green depends on the amount of iron present. Peridot has been used in jewelry for thousands of years, with ancient Egyptians calling it the 'gem of the sun.' Some ancient peridot may have originated from meteorites.

To identify peridot in the field, look for its distinctive olive-green color and oily or greasy luster. It is often found as small, rounded grains or embedded crystals in basaltic rocks. Common locations include volcanic regions, particularly those with basalt flows. Significant deposits are found in Arizona (San Carlos Apache Reservation), Myanmar, Pakistan, and China. For collectors, look for well-formed crystals and vibrant green colors. It's relatively soft for a gemstone, so care should be taken to prevent scratches.