| Alloriite [Aor] | |
|---|---|
| General | |
| Category | mineral |
| Formula (repeating unit) | Na5K1.5(Al6Si6O24)(SO4)(OH)0.5 * H2O |
| IMA symbol | Aor[1] |
| Strunz classification | 8/J.09-92 |
| Crystal system | Trigonal |
| Crystal class | Ditrigonal Pyramidal-3m |
| Space group | Trigonal |
| Unit cell | a = 12.892(3) Å, c = 21.340(5) Å; |
| Identification | |
| Color | Colorless to pale violet |
| Cleavage | Imperfect parallel to {1010} |
| Mohs scale hardness | 5.0 |
| Luster | Vitreous |
| Streak | White |
| Specific gravity | 2.35 |
| Birefringence | δ = 0.002 |
| Melting point | 1540 °C |
| References | [2][3] |
Alloriite is a silicate mineral that belongs to the cancrinite group, or more specifically the feldspathoid group. It is currently only found in Italy. It was discovered by and named for the Italian mineralogist Roberto Allori, an avid mineral collector who has also done research on piergorite and willhendersonite. The mineral appears as a crystal that is approximately 1.5 by 2 mm in length. The crystal grows as both tabular and prismatic crystals, and commonly occurs with sanidine, biotite, andradite, and apatite. It was approved of being a mineral in 2006 by the International Mineralogical Association. Afghanite is a cancrinite group mineral that is very similar to alloriite in both its chemical composition and its physical properties.