Amblygonite
Amblygonite is really a beautiful gem straw yellow that is usually pale. Darker, more”lemon that is saturated yellowish gems are rarer and more highly prized. An extremely rare lilic amblygonite that is colored from Karibib, Namibia. Amblygonite is very closely related to Montebrasite and varies just by optiacal property. Amblygonite is optically (-) and Montebrasite is optically (+). It may be that if many Amblygonite gems where retested, they might actually be Montebrasites. In general, it is thought that many gems being yellow the market are Amblygonite, & most colorless gems are Montebrasite, but this does not always hold true.
The localities that are few analyzed material include: from Chursdorf and Arnsdorf, near Penig, Saxony, Germany. On Utö Island, near Stockholm, Sweden. In america, at Hebron, Oxford County, Maine; large crystals in San Domingo Wash, northeast of Wickenburg, Maricopa County, Arizona. Through the Tanco pegmatite, Bernic Lake, Manitoba, Canada. At Coolgardie, Western Australia. From near Karibib, Namibia. In the Muiâne pegmatite, Alto Ligonha district, Mozambique.
| Chemical Formula: | LiAl(PO4)(F,OH) |
| Lithium Aluminum Phosphate Fluoride Hydroxide | |
| Molecular Weight: | 151.41 gm |
| Composition: | Sodium | 3.80 % | Na | 5.12 % | Na2O |
| Lithium | 3.44 % | Li | 7.40 % | Li2O | |
| Aluminum | 17.82 % | Al | 33.67 % | Al2O3 | |
| Phosphorus | 20.46 % | P | 46.88 % | P2O5 | |
| Hydrogen | 0.17 % | H | 1.49 % | H2O | |
| Oxygen | 44.91 % | O | |||
| Fluorine | 9.41 % | F | 9.41 % | F | |
| — % | F | —3.96 % | —O=F2 | ||
| 100.00 % | 100.00 % | = TOTAL OXIDE |
| Crystallography: | Triclinic – Pinacoidal |
| Crystal Habit: | Crude crystals, typically equant with complex form development, to 1.5 m; massive. |
| Twinning: | On several laws, with microscopic polysynthetic twinning common. |
| Cleavage: | [100] Perfect, [110] Good, [011] Distinct |
| Fracture: | Irregular/Uneven, Sub-Conchoidal |
| Tenacity: | Brittle |
| Moh’s Hardness: | 5.5 – 6.0 |
| Density: | 3.04- 3.11 (g/cm3) |
| Luminescence: | None |
| Radioactivity: | Not Radioactive |
| Color: | Milk-white, yellowish, beige, salmon-pink, greenish, bluish, grey |
| Transparency: | Transparent, Translucent |
| Luster: | Vitreous to Greasy, Pearly on good cleavages |
| Refractive Index: | 1.578 – 1.613 Biaxial ( – ) |
| Birefringence: | 0.020 – 0.030 |
| Dispersion: | r > v |
| Pleochroism: |
None |
