Bavenite
| Bavenite | |
|---|---|
Bavenite. Aggregate of lamellar crystals, with pyrite microcrystals on them.Cadalso de los Vidrios (Madrid), Spain. 13 mm | |
| General | |
| Category | Minerals |
| Formula | Ca4Be2Al2Si9O26(OH)2 |
| IMA symbol | Bvn |
| Strunz classification | 9.DF.25 |
| Dana classification | 70.5.3.1 |
| Crystal system | Orthorhombic |
| Crystal class | Pyramidal H-M Symbol: mm2 |
| Space group | Am2a |
| Unit cell | 2,250.52 |
| Identification | |
| Color | White, Green, Pink, Brown |
| Cleavage | Perfect on {001} Fair on {100} |
| Fracture | Uneven |
| Mohs scale hardness | 5.5 |
| Luster | Vitreous - Pearly |
| Streak | White |
| Diaphaneity | Transparent to translucent |
| Density | 2.7 |
| Optical properties | Biaxial (+) |
| Refractive index | nα = 1.578 - 1.586 nβ = 1.579 - 1.586 nγ = 1.583 - 1.593 |
| Birefringence | 0.005 - 0.007 |
| 2V angle | 22° - 60° |
| Dispersion | Moderate r < v |
| Ultraviolet fluorescence | None |
| Solubility | Unsoluble in acids |
Bavenite is a calcium beryllium aluminosilicate, and it is a part of the Bavenite-Bohseite series. Its name originates from its type locality, which is Baveno, Italy. This mineral is approved by the IMA, and got grandfathered, meaning it is still believed to refer to a valid mineral species. It was discovered in 1901 in a pink granite mined in Lago Maggiore. When bavenite was discovered, it was considered as a member of the zeolite series. Later it was removed from the series as unlike zeolites, bavenite loses the water stored in its crystal lattice in a way higher temperature, between 210 and 320 °C. It is a cheap mineral considering its rarity.