Key properties
| Chemical formula | AlPO4·2H2O |
| Crystal system | Orthorhombic |
| Mohs hardness | 4.5-5 |
| Toughness | Poor |
| Refractive index | 1.560-1.590 |
| Optic character | Biaxial negative; gem material reads as aggregate (single spot about 1.57) (-) |
| Specific gravity | 2.50-2.61 |
| Cleavage | None seen in massive material |
| Fracture | Uneven to splintery; porous material can be granular |
| Habit | Massive nodules, vein fillings and crusts formed near the surface in altered phosphatic rocks |
| Lustre | Dull to waxy; polish: Waxy to vitreous |
| UV fluorescence | Inert to weak green in LW and SW UV |
| Pleochroism | None |
| Cause of colour | Trivalent chromium (Cr3+), often with iron, tinting the hydrated aluminium phosphate green |
| Typical inclusions | Yellow to brown matrix (limonite, crandallite, wardite) networks • light/dark green mottling • spiderweb matrix in the best Nevada material |
| Stability | Stable to light. Heat sensitive — it dehydrates and can crack. Attacked by acids |
| Heat sensitivity | High |
| Care and cleaning | Brief warm soapy water only; never ultrasonic or steam; keep from acids and heat |
| Availability | Limited — a regional American collector and designer stone; sporadic on the general market |
| Recognition | Unfamiliar — almost always explained next to turquoise |
Varieties
Variscite
| Colour | light to medium yellowish green to bluish green, commonly mottled or veined with yellow-brown matrix |
| Transparency | opaque |
| Clarity type | Opaque — matrix pattern and evenness of green set the grade |
| Phenomena | None |
| Appearance | Crisp apple- to mint-green with creamy yellow-brown matrix webs; greener and usually brighter than the average turquoise |
| Trade names | Utahlite • amatrice/amatrix (Nevada trade names) • sabalite (banded, Utah) • trainite (banded with crandallite) |
| Misnomers | Nevada turquoise • California turquoise (variscite historically sold as turquoise) |
| Typical sizes | Nodules yield small to medium cabochons; large clean slabs scarce |
| Cutting styles | Cabochons • carvings • inlay; nodules sometimes cut and polished whole or as slab halves |
| Key separations | vs turquoise: variscite RI 1.56-1.59 (turquoise 1.61-1.65, spot 1.61-1.62), variscite usually greener with yellow-brown matrix; variscite commonly shows a 688 nm chromium line. vs serpentine: waxy feel, much softer. vs jadeite/nephrite: their RIs and SGs are far higher (1.66/3.3) |
| Sources (localities) | United States: Utah (Fairfield/Clay Canyon; Lucin) • Nevada (Candelaria Hills, Esmeralda County; Lander County) • Wyoming • plus Australia (Queensland) • Germany • Poland • Spain • Brazil |
| Availability | Limited — old-locality stock circulates among collectors |
| Market notes | Utah and Nevada names carry weight with American turquoise dealers; 'variquoise' (natural variscite-turquoise intergrowth) is a niche curiosity |
| Care notes | Soft and porous: rings risky, pendants and earrings fine; no acids, no heat, no ultrasonic |
| In short | Utah-Nevada's apple-green turquoise stand-in: softer, greener, with yellow-brown matrix. Spot RI about 1.57 and a 688 nm line make the separation easy and worth demonstrating. |
| Size (ct) | USD per carat | Tier | As of |
|---|---|---|---|
| 2.00–20.00 | $3.00 – $20.00 | commercial cabochons | 2026-10-26 |
| 3.00–20.00 | $30.00 – $100.00 | fine Nevada spiderweb matrix | 2026-10-26 |
Retail market survey, per carat unless noted. Ranges describe what commercial to fine stones trade at; exceptional stones and provenance premiums sit above them.
Sources
GIA gem encyclopedia · mindat.org · Wikipedia
Data compiled and fact-checked against gemmological literature, October 2026 (JDMIS gem reference). Properties are ranges accepted in gemmological practice; individual stones vary.
See also
Gemstone reference entries: gem #91
Related materials: Turquoise
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