Andesine
Andesine is really a number of Albite and a known member of this Feldspar Group of minerals that includes Albite, Amazonite, Andesine, Anorthite, Bytownite, Hyalophane, Labradorite, Moonstone, Oligoclase, Orthoclase, Sanidine and Sunstone. Andesine can be an intermediate person in the Plagioclase Feldspars in a solution that is solid between Albite and Anorthite and close to Labradorite. It’s a rock that is common mineral but crystals are unusual.
Sourced elements of gem quality Andesine crystals are from recent finds in Congo, Asia and Tibet. A find that is small 2002 in the Goma part of the Democratic Republic of Congo produced a somewhat small amount of beautiful red, green and yellowish gems. The Asia Andesine just isn’t as intense red as the Congo material, a lot more of an orangish-red. Another find of gem quality crystals occurred in Tibet in 2005. This material, also referred to as Tibet Sunstone, is more of the yellow to base that is greenish-yellow with weak to strong coppery overtones. The Tibet Andesine has very look that is different the intense red of the Congo Andesine, but nevertheless makes very beautiful and unique gems.
| Category: | Plagioclase, Feldspar, Tectosilicate |
| Chemical Formula: | (Na,Ca)[Al(Si,Al)Si2O8] |
| Sodium Calcium Aluminum Silicate | |
| Molecular Weight: | 521.21 gm |
| Composition: | Sodium | 5.14 % | Na | 6.92 % | Na2O |
| Calcium | 5.97 % | Ca | 8.35 % | CaO | |
| Aluminum | 14.06 % | Al | 26.57 % | Al2O3 | |
| Silicon | 27.18 % | Si | 58.16 % | SiO2 | |
| Oxygen | 47.65 % | O | |||
| 100.00 % | 100.00 % | = TOTAL OXIDE |
| Crystallography: | Triclinic – Pinacoidal |
| Crystal Habit: | Crystals rare, to 2 cm; commonly massive, cleavable, or granular. |
| Twinning: | Commonly twinned after Albite, Pericline, and Carlsbad laws. Also twinned after a law similar to the Manebach law. |
| Cleavage: | Perfect on {001}, less Perfect on {010}, {110} observed |
| Fracture: | Irregular/Uneven to Conchoidal |
| Tenacity: | Brittle |
| Moh’s Hardness: | 6.0 – 6.5 |
| Density: | 2.66 – 2.68 (g/cm3) |
| Optical Properties: | Biaxial (+/-) |
| Luminescence: | None |
| Radioactivity: | Not Radioactive |
| Color: | White, Grayish, Green, Yellow, Reddish, Orangish-Red, Red |
| Transparency: | Transparent to Translucent |
| Luster: | Subvitreous to Pearly |
| Refractive Index: | 1.543 – 1.562 Biaxial ( +/- ) |
| Birefringence: | 0.0080 – 0.0090 |
| Dispersion: | Weak, r > v |
| Pleochroism: |
None |
