Key properties
| Chemical formula | KAlSi3O8 |
| Crystal system | Triclinic |
| Mohs hardness | 6-6.5 |
| Toughness | Poor (cleavage-prone) |
| Refractive index | 1.522-1.530 |
| Birefringence | 0.0080 |
| Optic character | Biaxial negative (-) |
| Specific gravity | 2.54-2.58 |
| Cleavage | Perfect and easy in two directions at nearly 90 degrees |
| Fracture | Uneven to splintery |
| Habit | Prismatic to blocky crystals (among the largest known crystals); also massive; characteristically shows tartan (gridiron) albite-pericline twinning |
| Lustre | Vitreous to pearly; polish: Vitreous to greasy |
| UV fluorescence | Usually inert to weak yellowish green in long-wave UV; inert in short-wave. |
| Pleochroism | None |
| Cause of colour | Gem amazonite's green to bluish green is produced by natural-radiation-activated colour centres involving lead (Pb) and water/OH groups in the structure. |
| Typical inclusions | Grid-like white veining from exsolved albite (perthite), quartz and mica flecks; the tartan twinning is often visible under magnification |
| Stability | Stable to light; heat can crack, cleave or lighten colour; attacked by hydrofluoric acid, and impurities may react with other acids |
| Heat sensitivity | May crack, cleave or lose colour with heat |
| Care and cleaning | Warm soapy water only; never ultrasonic or steam |
| Availability | Limited; cut material appears regularly in the trade but in modest volume |
| Recognition | Mottled green to greenish blue feldspar with grid-like white streaks, spot RI about 1.53, aggregate (AGG) polariscope reaction in fine-grained material, and two perfect cleavages. |
Varieties
Amazonite
| Colour | light green to greenish blue, often white-streaked |
| Transparency | opaque |
| Clarity type | Opaque ornamental material |
| Phenomena | Rare aventurescence from reflective inclusions |
| Appearance | Turquoise- to jade-like greenish blue, mottled and criss-crossed with white grid streaks; takes a soft vitreous to slightly greasy polish. |
| Trade names | amazonite • amazon stone |
| Misnomers | Colorado jade • Pikes Peak jade (both improper jade designations) |
| Typical sizes | 1 to 20 ct commonly; rough is plentiful so large cabochons and carvings are easy to cut |
| Cutting styles | Cabochons, beads, carvings; rarely faceted |
| Key separations | vs turquoise: turquoise RI about 1.61-1.62 and absorbs water (wetted surface darkens); amazonite reads about 1.53 and shows cleavage; vs green jadeite: jadeite RI 1.66 and SG 3.3; vs dyed howlite/magnesite: dye pools in surface cracks, SG and texture differ; vs green chalcedony: chalcedony is waxy with no cleavage |
| Sources (localities) | Brazil (main) • Madagascar • Russia (Ilmen Mountains, classic) • USA (Colorado, Pikes Peak) • Norway |
| Availability | Limited but regular supply; very large carvings obtainable |
| Market notes | Inexpensive ornamental gem popular in ethnic-style and carved jewellery; colour evenness and polish quality drive price |
| Care notes | Warm soapy water; no ultrasonic or steam; keep away from acids and heat |
| In short | Amazonite is the green to greenish blue microcline used for beads, cabochons and carvings, easily recognised by its white grid veining. Lead-related colour centres create the colour. It is a low-cost ornamental stone that needs gentle handling. |
| Size (ct) | USD per carat | Tier | As of |
|---|---|---|---|
| 1.00–10.00 | $1.00 – $8.00 | commercial | 2026-10-26 |
| 10.00–100.00 | $1.00 – $6.00 | commercial (carving rough and large cabs) | 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
· 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 #60 · gem #98
Related materials: Orthoclase Feldspar
Identification wizard · All 83 materials · Singapore gem labs