| Tschermigite | |
|---|---|
Tschermigite from Tschermig, Bohemia. |
|
| General | |
| Category | Sulfate minerals |
| Chemical formula | NH4AlSO4·12H2O |
| Strunz classification | 07.CC.20 |
| Crystal symmetry | m3 (2/m 3) - Diploidal |
| Unit cell | a = 12.24Å |
| Identification | |
| Color | Colorless, white; colorless in transmitted light |
| Crystal system | Isometric |
| Fracture | Conchoidal |
| Mohs scale hardness | 1½ - 2 |
| Luster | Vitreous, silky |
| Diaphaneity | Transparent |
| Specific gravity | 1.645 |
| Optical properties | Isotropic |
Tschermigite is a mineral form of ammonium alum, formula NH4AlSO4·12H2O. It is found in burning coal seams, bituminous shale and fumaroles. Because of its extreme water solubility it is unlikely to persist except in the dryest of conditions. Discovered in 1852 at Cermiky, also known as Schermig in Bohemia. It is colorless and named for where it was discovered.