Agrellite
Agrellite is a rare mineral that is silicate is commonly found with Eudialyte and Aegirine (see picture above). Its crystals are located as platy, blocky aggregates and so are not suitable for faceting but when along with Eudialyte, can make cabochons that are beautiful.
Agrellite is only available at a locations that are few the Sheffield Lake complex, Kipawa River, Villedieu Township, Quebec, Canada; the Wausau complex, Marathon County, Wisconsin, USA; the Dara-i-Pioz massif, Alai Range, Tien Shan, Tajikistan; the Murun massif, southwest of Olekminsk, Yakutia, Russia.
| Chemical Formula: | NaCa2(Si4O10)F |
| Sodium Calcium Silicate Fluoride | |
| Molecular Weight: | 394.48 gm |
| Composition: | Sodium | 5.83 % | Na | 7.86 % | Na2O |
| Calcium | 20.32 % | Ca | 28.43 % | CaO | |
| Silicon | 28.48 % | Si | 60.93 % | SiO2 | |
| Oxygen | 40.56 % | O | |||
| Fluorine | 4.82 % | F | 4.82 % | F | |
| — | — % | F | -2.03 % | -O=F2 | |
| 100.00 % | 100.00 % | = TOTAL OXIDE |
| Crystallography: | Triclinic – Pinacoidal |
| Crystal Habit: | Crystals elongated [001], to 10 cm; platy aggregates |
| Twinning: | None |
| Cleavage: | [110] Perfect, [110] Perfect, [010] Poor |
| Fracture: | Irregular/Uneven, Conchoidal |
| Tenacity: | Brittle |
| Moh’s Hardness: | 5.5 |
| Density: | 2.902 (g/cm3) |
| Luminescence: | Fluoresces bright pink under LW UV and duller pink under SW UV. |
| Radioactivity: | Not Radioactive |
| Color: | White, Gray-White, Greenish-White |
| Transparency: | Transparent to Translucent |
| Luster: | Vitreous, Pearly on cleavages |
| Refractive Index: | 1.567 – 1.581 Biaxial ( – ) |
| Birefringence: | 0.0140 |
| Dispersion: |
Strong; r > v |
