| Boxbgcolor: |
|
| Formula: | BaAl2(CO3)2(OH)4 · H2O |
| Imasymbol: | Dsr[1] |
| Strunz: | 5.DB.10 |
| System: | Orthorhombic |
| Dana: | 16b.2.1.2 |
| Class: | Dipyramidal H-M symbol: mmm (2/m 2/m 2/m) |
| Unit Cell: | 878.36 |
| Color: | White |
| Mohs: | 2.5 - 3 |
| Luster: | Vitreous, silky |
| Opticalprop: | Biaxial (-) |
| Refractive: | nα = 1.518 nβ = 1.590 nγ = 1.601 |
| Birefringence: | 0.083 |
| 2V: | 30° - 40° |
| Dispersion: | Relatively strong |
| Fluorescence: | None |
| Streak: | White |
| Gravity: | 2.96 |
| Density: | 2.96 |
| Diaphaneity: | Transparent |
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]
It is a member of the carbonates family,[4] mostly consisting of oxygen (44.29%), barium (34.56%) and aluminum (13.58%), but otherwise contains carbon (6.05%) and hydrogen (1.52%).[5] It is associated with weloganite, dawsonite, quartz, and plagioclase.[6] It grows into tapering acicular crystals, elongated along [001] and bladed on . It is typically in divergent spherical and hemispherical aggregates. It occurs in cavities in alkalic sill in limestone.[7] Size is up to 5 mm. It is soluble in dilute hydrogen chloride, and dissolves readily with a effervescence.[8] It is the barium analogue of dundasite.[9] Dresserite does not show any kind of luminescence whatsoever. The measured density of the mineral, due to its fibrous nature, is too low. The differential thermal analysis (DTA) curve of the mineral is similar to dundasite's in appearance. The principal endothermic peak is at 384°C. When heated up to this degree, dresserite loses all of its water and carbon dioxide.[10]