Peridot

Peridot is one of the few gemstones that comes in only one color. While the shade varies from yellow-green to deep olive, the green is always there — it's not caused by trace impurities like most colored gems, but by iron that's fundamental to the mineral's crystal structure. Every peridot crystal is green by nature.

For collectors, peridot is special because of its accessibility. The world's most important peridot source — Peridot Mesa on the San Carlos Apache Reservation in Arizona — produces crystals that weather out of basalt and can be picked up from the surface. It's one of the few gemstones you can find as loose, gem-quality crystals without mining.

Appearance & Identification

Peridot is straightforward to identify in the field once you know what to look for:

• Color: Yellow-green to olive green. The best gem material is a saturated, vivid green without brownish overtones. Lighter, more yellowish material is also common.
• Luster: Vitreous (glassy) to oily. The slightly oily sheen is distinctive — most other green minerals look either purely glassy or waxy, not oily.
• Crystal form: Peridot rarely forms well-defined crystals in collecting contexts. Most material from Arizona occurs as rounded, irregular grains or fragments weathered out of basalt. When crystal faces are present, they show orthorhombic symmetry.
• Hardness: 6.5–7 on the Mohs scale. It will scratch glass and cannot be scratched by a steel knife. This is a key distinction from softer green minerals like apatite (5) or prehnite (6–6.5).
• Transparency: Gem-quality peridot is transparent. Lower-grade material may be translucent. Opaque green material is likely not peridot.
• Double refraction:Peridot has strong double refraction — if you look through a transparent crystal at a line, you'll see two lines. This is visible with a 10x loupe in larger stones and is a definitive identification test.

How Peridot Forms

Olivine (the parent mineral of peridot) crystallizes deep in the Earth's upper mantle, at depths of 20–55 miles. It's one of the first minerals to crystallize from cooling magma and one of the most abundant minerals in the mantle.

Peridot reaches the surface through volcanic activity. When basaltic magma erupts, it carries olivine crystals with it. In Arizona, these olivine-bearing basalt flows are millions of years old. As the basalt weathers and erodes, the more resistant olivine crystals are released and concentrate in soil, erosion channels, and — famously — in ant hills, where ants bring the small crystals to the surface as they excavate their tunnels.

The most extraordinary peridot source is extraterrestrial. Olivine is common throughout the solar system — it has been found on Mars, on the Moon, and in pallasite meteorites, where gem-quality olivine crystals sit embedded in a matrix of iron-nickel metal. Pallasitic peridot is among the rarest collectible material on Earth.

Where Peridot Is Found

Arizona — The World's Peridot Capital

The San Carlos Apache Reservation in east-central Arizona is the most important peridot source on Earth. The Peridot Mesa area produces an estimated 80–95% of the world's commercial peridot. The material is known for its vivid, saturated green color and ranges from small chips to gem-quality stones exceeding 10 carats.

Collecting on the reservation requires a tribal permit from the San Carlos Apache Tribe. The crystals are found loose on the surface and in shallow soil — no mining or heavy equipment is needed. The best crystals are found in:

• Ant hills — Ants bring small crystals to the surface as they excavate. Some collectors specifically seek out ant mounds for the cleanest material.
• Erosion channels — Rainwater concentrates the denser olivine crystals in low spots and drainage channels.
• Weathered basalt surfaces — As the basalt decomposes, loose crystals appear on the soil surface.

For the full Arizona collecting experience, see our Arizona rockhounding guide — which covers Peridot Mesa alongside 10 other documented sites.

US Occurrence Context

Arizona dominates the US peridot story, but it is not the only place olivine shows up. Small olivine-rich grains also occur in Hawaiian basalt-derived sands, limited mantle-derived basalt localities in New Mexico can produce collector interest, and scattered eastern US reports occasionally surface in metamorphic or igneous contexts. For most collectors, though, Arizona remains the only realistic place to plan a dedicated peridot trip around loose recoverable material.

Other Sources

• Hawaii — Olivine-rich basalt weathers into green sand on Papakolea Beach (Mahana Beach) on the Big Island. The grains are too small for gem use but make for a striking geological sight. Collecting is prohibited at this protected site.
• Pakistan / Myanmar — The Suppat region of Pakistan and Mogok in Myanmar produce some of the finest large, deep-green peridot crystals in the world. Pakistani stones are prized for their intense color and can exceed 50 carats.
• China — Significant commercial production from Hebei province. Chinese material tends toward lighter, more yellowish green.
• Norway (Seiland) — Historic source of large peridot crystals, though deposits are largely exhausted.
• Egypt (Zabargad Island)— The ancient source of peridot, mined for over 3,500 years. The Egyptians called it the “gem of the sun.” The island is now a protected area.
• Meteorites — Pallasite meteorites contain olivine crystals in iron-nickel matrix. The Esquel meteorite (Argentina) and Fukang meteorite (China) contain spectacular gem-quality olivine. Slices are available from meteorite dealers at premium prices.

Similar Minerals & Lookalikes

Several green minerals can be confused with peridot in the field. Here's how to tell them apart:

Beginner Tips for Collecting Peridot

• Arizona is the destination. If you want to collect peridot in the field, the San Carlos Reservation is the place. Contact the tribe for permits well before your trip — availability varies.
• Look in ant hills and erosion channels. The crystals concentrate in these spots. Walk slowly and scan the ground — peridot grains catch the light distinctively.
• Wet the crystals. Like most minerals, peridot shows its true color better when wet. A spray bottle helps you evaluate quality in the field.
• Grade by color and clarity. The most valuable material is saturated green without brown or yellow overtones, and transparent without visible inclusions. Hold crystals up to the light to check.
• Handle with care. Peridot is moderately hard (6.5–7) but brittle. It chips and fractures more easily than quartz. Wrap finds individually in tissue or newspaper.
• Timing matters. Arizona desert heat makes October through April the best collecting season. Avoid summer — temperatures at Peridot Mesa regularly exceed 100°F.

Planning a trip? Read our complete Arizona collecting guide for GPS coordinates, BLM regulations, desert safety tips, and 10 other documented sites beyond Peridot Mesa. Or explore other mineral profiles to learn what else you might find in the field.