Dresserite
From Wikipedia, the free encyclopedia
| Dresserite | |
|---|---|
 | |
| General | |
| Category | Minerals |
| Formula | BaAl2(CO3)2(OH)4 · H2O |
| IMA symbol | Dsr[1] |
| Strunz classification | 5.DB.10 |
| Dana classification | 16b.2.1.2 |
| Crystal system | Orthorhombic |
| Crystal class | Dipyramidal H-M symbol: mmm (2/m 2/m 2/m) |
| Unit cell | 878.36 |
| Identification | |
| Color | White |
| Mohs scale hardness | 2.5 - 3 |
| Luster | Vitreous, silky |
| Streak | White |
| Diaphaneity | Transparent |
| Specific gravity | 2.96 |
| Density | 2.96 |
| Optical properties | Biaxial (-) |
| Refractive index | nα = 1.518 nβ = 1.590 nγ = 1.601 |
| Birefringence | 0.083 |
| 2V angle | 30° - 40° |
| Dispersion | Relatively strong |
| Ultraviolet fluorescence | None |
Dresserite is a mineral of the dresserite group, named in honor of John Alexander Dresser, geologist. It was approved by the IMA in 1968, but only a year after was it published.[2] The rare mineral can only be found in Francon quarry, Canada. The quarry is located in the middle of the city of Montréal, but had been closed in 1981 and will not reopen in the future.[3]