Peridot is the gemstone variety of olivine commonly used in jewelry.
Olivine is a magnesium-iron silicate mineral group found mainly in mafic and ultramafic igneous rocks. Gem-quality olivine is called peridot, and its color is typically yellowish green to olive green. Unlike many colored gems, peridot’s color comes mainly from iron within its crystal structure rather than from trace impurities alone.
Peridot can form in Earth’s mantle and reach the surface in volcanic rocks. It is also found in some meteorites, including pallasites, where green olivine crystals occur alongside metallic iron-nickel. A small amount of peridot has even been identified in extraterrestrial material from the Moon and Mars.
The name is often confused with emerald because both are green, but they are different minerals. Emerald is a variety of beryl, whereas peridot belongs to the olivine group. Peridot is also the birthstone associated with August in many modern birthstone lists.