Peridot

Hardness: 6.5-7 on the Mohs scale. Color: Always green, ranging from yellow-green to olive-green to brownish-green. Luster: Vitreous (glassy) to greasy. Crystal Structure: Orthorhombic. Cleavage: Indistinct in one direction. Specific Gravity: 3.27-3.37. It is one of the few gemstones that occurs in only one color.

Peridot is primarily found in igneous rocks, especially basalt and peridotite, which are deep-seated rocks from the Earth's mantle that are brought to the surface by volcanic activity. It can also be found in meteorites. The formation process involves the crystallization of olivine from magnesium-rich, silica-poor magma. Most peridot occurrences are Phanerozoic in geological age, though the mineral itself can be found in much older rocks.

Peridot is a popular gemstone used in jewelry such as rings, necklaces, bracelets (as seen in the image), and earrings. It is one of the few gemstones that are only found in one color. Smaller, lower-quality peridot can be used as an abrasive or as a refractory material in industrial applications due to its high melting point and resistance to chemical corrosion.

Peridot is the gem variety of the mineral olivine. It is often referred to as 'the evening emerald' for its sparkling green color that looks brilliant even in dim light. Ancient Egyptians called it 'gem of the sun.' Some ancient cultures believed peridot could ward off evil spirits. Peridot has also been found in pallasite meteorites, linking it to extraterrestrial origins.

In the field, peridot can be identified by its distinctive olive-green color and conchoidal fracture. It is often found as rounded grains or as xenocrysts in basaltic lavas. Major sources include the San Carlos Apache Reservation in Arizona, USA (responsible for 80-95% of the world's commercial peridot), China, Myanmar (Burma), Pakistan, and Vietnam. For collectors, good quality peridot should have a vibrant pure green color without brownish tints. The presence of inclusions can reduce its value, though some types of inclusions (like 'lily pad' inclusions) can be diagnostic.