| Epsomite | |
|---|---|
Epsomite formation in a New Mexico, cave |
|
| General | |
| Category | Sulfate mineral |
| Chemical formula | MgSO4·7H2O |
| Strunz classification | 07.CB.40 |
| Dana classification | 29.6.11.1 |
| Crystal symmetry | 222 |
| Identification | |
| Color | White, grey, colorless, or pink, greenish |
| Crystal habit | Acicular to fibrous encrustations |
| Crystal system | Orthorhombic |
| Cleavage | {010} perfect {101} distinct |
| Fracture | Conchoidal |
| Mohs scale hardness | 2 |
| Luster | Vitreous |
| Diaphaneity | Transparent to translucent |
| Specific gravity | 1.67 - 1.68 |
| Optical properties | Biaxial (-) |
| Refractive index | nα = 1.433 nβ = 1.455 nγ = 1.461 |
| References | [1][2] |
Epsomite is a hydrous magnesium sulfate mineral with formula MgSO4·7H2O or simply MgSO4. Epsomite forms as encrustations or efflorescences on limestone cavern walls and mine timbers and walls, as a volcanic fumaroles, and as rare beds in evaporate layers. It was first systematically described in 1806 for an occurrence near Epsom, Surrey, England, after which it was named.
Epsomite crystallizes in the orthorhombic system as rarely found acicular or fibrous crystals, the normal form is as massive encrustations. It is colorless to white with tints of yellow, green and pink. The Mohs hardness is 2 to 2.5 and it has a low specific gravity of 1.67.
Epsomite is the same as the household chemical, Epsom salt, and is readily soluble in water. It absorbs water from the air and converts to hexahydrate with the loss of one water molecule and a switch to monoclinic structure.