Peridot

Hardness: 6.5-7 on the Mohs scale. Color: Typically yellowish-green to olive green; can also be brownish-green. Luster: Vitreous (glassy) to oily. Crystal Structure: Orthorhombic. Cleavage: Poor in one direction. Specific Gravity: 3.2-4.4. Often found as small, rounded grains or irregular masses.

Peridot is the gem-quality variety of the mineral olivine. It forms in mafic and ultramafic igneous rocks at high temperatures and pressures deep within the Earth's mantle and is brought to the surface by volcanic activity. It can also be found in certain types of meteorites. Geological Age: Formed during various geological periods, depending on the volcanic activity that brought it to the surface, ranging from millions to billions of years old.

Industry: Olivine (the mineral group peridot belongs to) is used in various industrial applications, including refractory materials, metallurgy (as a flux), and as a sand substitute in foundries. Jewelry: Peridot is a popular gemstone, used in rings, necklaces, earrings, and bracelets. Its bright green color makes it attractive for various jewelry designs.

Peridot is often referred to as the 'gem of the sun' by ancient Egyptians, who mined it on St. John's Island (Zabargad) in the Red Sea. Small peridot crystals have been found in pallasite meteorites, indicating its extraterrestrial origin. It is one of the few gemstones that only comes in one color (green), though the intensity and hue can vary. The intensity of green depends on the amount of iron present in the crystal structure.

Field Identification: Peridot's distinctive olive-green color is its most identifying characteristic. It can be distinguished from other green gems by its strong double refraction, which causes a 'sleepy' or 'velvety' appearance when viewed through a loupe. It is also one of the few gemstones that is idiochromatic, meaning its color comes from components of its basic chemical composition rather than from trace impurities. Common Locations: Major sources include the San Carlos Apache Reservation in Arizona, USA (which produces a significant portion of the world's commercial peridot), China, Myanmar (Burma), Pakistan, Vietnam, and Norway. Tips for Collectors: Look for stones with a vibrant, intense green color and good clarity. Be aware that smaller stones are more common, and larger, high-quality peridots are rare and command higher prices.