Astrophyllite
Astrophyllite is really a titanium that is rare that kinds in breathtaking radiating or star-like sheets with adjustable luster that may be almost metallic in one specimen and pearly or greasy in another. Its colors vary from coppery brown to bronze to reddish brown and might have bright flashes of yellowish, gold, red and orange. Astrophyllite is typically opaque and therefore available only as cabochons. It assumes a good shine and makes a gem that is beautiful.
The main resources of Astropyllite are Mont Saint-Hilaire, Québec, Canada; Narsaq, Kitaa (West Greenland) Province, Greenland; Langesundsfjorden, Larvik, Vestfold, Norway (Type Locality); San Miguel, Azores District (Azores isles), Portugal; Kola Peninsula, Murmanskaja Oblast’, Northern Region, Russia; St. Peters Dome, El Paso County, Colorado, United States Of America.
| Chemical Formula: | (K,Na)3(Fe2+,Mn)7Ti2Si8O24(O,OH)7 |
| Potassium Sodium Iron Manganese Titanium Silicate Hydroxide | |
| Molecular Weight: | 1,289.00 gm |
| Composition: | Potassium | 6.07 % | K | 7.31 % | K2O |
| Sodium | 1.78 % | Na | 2.40 % | Na2O | |
| Magnesium | 1.41 % | Mg | 2.35 % | MgO | |
| Titanium | 7.43 % | Ti | 12.39 % | TiO2 | |
| Manganese | 4.26 % | Mn | 5.50 % | MnO | |
| Iron | 22.75 % | Fe | 29.26 % | FeO | |
| Silicon | 17.43 % | Si | 37.29 % | SiO2 | |
| Hydrogen | 0.27 % | H | 2.45 % | H2O | |
| Oxygen | 37.86 % | O | |||
| Fluorine | 0.74 % | F | 0.74 % | F | |
| – | – % | F | -0.31 % | -O=F2 | |
| 100.00 % | 99.38 % | = TOTAL OXIDE |
| Crystallography: | Triclinic – Pedial |
| Crystal Habit: | Crystals tabular, bladed or acicular, some faces commonly striated, to 10 cm; groups may be stellate. |
| Twinning: | None |
| Cleavage: | Perfect on {001}, Poor on {100} |
| Fracture: | Irregular/Uneven |
| Tenacity: | Brittle |
| Moh’s Hardness: | 3.0 |
| Density: | 3.20 – 3.40 (g/cm3) |
| Luminescence: | None |
| Radioactivity: | Barely Detectable; GRapi = 85.21 (Gamma Ray American Petroleum Institute Units) |
| Color: | Bronze-Yellow to Gold-Yellow, Brown to Reddish Brown |
| Transparency: | Opaque to Translucent in thin leaves |
| Luster: | Sub-Metallic, Pearly, Greasy |
| Refractive Index: | 1.678 – 1.758 Biaxial ( + ) |
| Birefringence: | 0.050 |
| Dispersion: | Strong; r > v |
| Pleochroism: | Strong; X = deep orange-red; Y = orangeyellow; Z = lemon-yellow |
