Barrerite
From Wikipedia, the free encyclopedia
CategoryTectosilicate minerals
FormulaNa2(Si7Al2)O18·6H2O
| Barrerite | |
|---|---|
 Barrerite from Kuiu Island, Alaska, USA. | |
| General | |
| Category | Tectosilicate minerals |
| Group | Zeolite group, stilbite subgroup |
| Formula | Na2(Si7Al2)O18·6H2O |
| IMA symbol | Bre[1] |
| Strunz classification | 9.GE.15 |
| Crystal system | Orthorhombic |
| Crystal class | Dipyramidal (mmm) H-M symbol: (2/m 2/m 2/m) |
| Space group | Amma |
| Identification | |
| Color | White, pink |
| Cleavage | Perfect |
| Mohs scale hardness | 3 - 4 |
| Luster | Vitreous-glassy |
| Streak | White |
| Diaphaneity | Transparent to translucent |
| Specific gravity | 2.13 |
| Optical properties | Biaxial (-) |
| Refractive index | nα = 1.479 nβ = 1.485 nγ = 1.489 |
| References | [2][3][4] |
Barrerite is a tectosilicate mineral and a member of the zeolite family. It is one of the rarer zeolites. It was named for Richard Barrer, a New Zealand-born chemist.[4]
Barrerite crystal are white to pinkish, with a vitreous-glassy luster. The crystal system is orthorhombic and is flat and tabular in appearance. It has a Mohs hardness of 3 to 4 and its cleavage is perfect. Barrerite has a white streak and a density of 2.13.
It was first described in 1974 for an occurrence in Sardinia at Sant' Efisio Tower on Cape Pula in Cagliari Province.[4] It has also been reported from Rocky Pass, Kuiu Island, Alaska, and a few other localities.
