Peridot is the gem variety of olivine, a magnesium–iron silicate that forms deep within Earth’s mantle. Its distinctive fresh, grassy to lime-green color is unlike any other gemstone, often glowing warmly even in subdued light. Crystals are orthorhombic and typically occur as short prisms or blocky habits; many are recovered as loose crystals from volcanic cinders or mantle xenoliths (peridotite/dunite nodules). The finest specimens combine vivid, saturated green color with sharp terminations and high transparency—attributes more commonly seen in faceted gems than in natural crystals. Although much peridot is cut, the best matrix or crystal clusters from Pakistan and Myanmar, and the classic xenolith pieces from Arizona and New Mexico, are highly prized by collectors for their combination of form, color, and geological story.
Peridot has captivated people for millennia—ancient sources like Egypt’s Zabargad (St. John’s Island) were mined as early as the first millennium BCE. In modern times, the discovery of superb crystals in Pakistan’s Kaghan Valley and continued production from Myanmar revitalized collector interest by proving that peridot can occur as striking, display-worthy crystals, not just gem rough. Arizona’s San Carlos area and New Mexico’s Kilbourne Hole yielded iconic mantle xenoliths studded with peridot grains—beloved by geology-focused collectors. Peridot occupies a rare niche: it is both widely accessible (affordable small crystals and nodules abound) and elite (top-color, lustrous, sharply terminated crystals on matrix are scarce and command strong prices). Its bright, cheerful green and mantle-origin story ensure enduring popularity across both gem and mineral communities.
Below are key peridot sources known for distinctive aesthetics or historical significance. Each locality’s specimens show different sides of peridot’s appeal—from dramatic, gemmy crystals to geologically fascinating mantle nodules.
Sapat Gali (Kaghan Valley) has produced the world’s most celebrated peridot crystals. Typically stout to blocky prisms with bright glassy luster, they range from yellow-green to rich, saturated lime and can be remarkably transparent. Many are dramatic singles; rarer clusters on serpentinized ultramafic matrix are showpieces. Edges and terminations can be razor sharp, rivaling classic Mogok crystals. Production has fluctuated, and truly fine, undamaged pieces are highly competitive, making Sapat Gali a benchmark for museum-caliber peridot.
Color: The most important factor. Best-in-class peridot shows a saturated, fresh lime to slightly yellowish-green without brown or olive murkiness. Very slight yellow is common; a lively, “electric” green is most desirable. Chromium-rich peridot may show a purer green; excessive iron can push tones brownish. Evaluate color in neutral lighting—top pieces glow in ambient light and do not require strong backlighting.
Clarity and Luster: Collectors value transparent, “glassy” crystals with bright luster and minimal internal fractures. Typical inclusions include tiny “lily-pad” disc-like patterns surrounding crystals or gas bubbles; minor inclusions are acceptable if they don’t cloud the piece. Surface etching is common on basalt-hosted crystals; light, even etching can be attractive, but heavy pitting or matte faces reduce appeal.
Crystal Form: Peridot is orthorhombic; desirable habits are chunky to short prismatic crystals with well-developed faces and crisp terminations. Pakistan and Myanmar crystals often show textbook geometry; Arizona and Xinjiang material more often occurs as singles rather than clusters. Attractive clusters on matrix are rare and command premiums.
Matrix and Associations: True matrix specimens—peridot crystals on serpentinized ultramafic rock or in vesicular basalt—are considerably rarer than loose crystals and can elevate a specimen’s desirability. Xenolith slices from Arizona or New Mexico attract collectors for the geologic story, especially when the olivine grains are large, translucent, and well-distributed.
Size and Condition: Because peridot is brittle and has conchoidal fracture (no true cleavage), sharp terminations are easily chipped. Inspect tips and edges carefully—tiny nicks show as white specks. Given the relative scarcity of pristine larger crystals, a smaller perfect crystal can be more desirable than a larger one with obvious damage.
Aesthetics: Look for balanced composition, strong color visible without backlighting, and contrast (e.g., bright green peridot on dark matrix). In multi-crystal pieces, varied heights and orientations add dynamism. A great peridot “pops” even at a distance.
Repairs: Peridot crystals are often extracted as loose singles. Reattachments (onto original or foreign matrix) and repairs to broken crystals occur. Under magnification, look for straight glue lines, misaligned surface striations, or glossy seams at junctions; some epoxies fluoresce under longwave UV. Assembled specimens (peridot glued to unrelated matrix) do occur—compare mineral associations with known locality paragenesis.
Polishing: Occasionally, lightly polished terminations are used to disguise chips. Natural faces usually have minute growth features; a perfectly mirror-flat surface may indicate polishing. This should be disclosed.
Treatments and Fakes: Peridot is rarely treated in specimen form; heat or irradiation is uncommon and risky. Fracture filling or coatings are possible but not widespread—watch for localized “plastic” shine within cracks. Glass imitations are a risk for cut stones more than specimens; in crystals, check for natural growth features, inclusions, and correct orthorhombic morphology.
Peridot (olivine) has Mohs hardness ~6.5–7 with brittle toughness and conchoidal fracture. It requires gentle handling despite respectable hardness.
Handling: Support specimens with both hands, avoiding pressure on thin edges or tips. Do not stress crystals in clusters. For xenolith slices, protect exposed olivine grains from knocks.
Light and Temperature: Natural color is generally stable, but avoid prolonged direct sunlight and high heat. Peridot is sensitive to thermal shock—do not place near hot lights or in sunlit windows that overheat. Avoid sudden temperature changes.
Chemicals and Cleaning: Peridot can be attacked by acids and strong chemicals. Clean with lukewarm water, a drop of mild dish soap, and a soft brush. Rinse thoroughly, air-dry on a towel. Avoid acids, bleach, harsh oxidizers, ultrasonic or steam cleaners. If removing iron stains from matrix, use mild reducers cautiously and test first; protect the crystal faces and avoid prolonged exposure.
Storage: Provide padded, individual compartments. Keep away from harder minerals that could abrade faces, and also prevent peridot from scratching softer neighbors. Secure display pieces with museum putty or custom stands, especially in vibration-prone settings.
Maintenance: Periodically inspect for loosened repairs or mounting putty. Dust gently with a soft brush to maintain luster. With proper care, peridot’s bright green and glassy surfaces remain vivid for decades.
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