Epsomite

Epsomite
Epsomite formation from a Calatayud, Spain cave
General
CategorySulfate mineral
Formula
(repeating unit)
MgSO4·7H2O
IMA symbolEsm[1]
Strunz classification7.CB.40
Dana classification29.6.11.1
Crystal systemOrthorhombic
Crystal classDisphenoidal (222)
H-M symbol: (2 2 2)
Space groupP2₁2₁2₁
Unit cella = 11.86, b = 11.99
c = 6.858 [Å]; Z = 4
Identification
ColorWhite, grey, colorless, or pink, greenish
Crystal habitAcicular to fibrous encrustations
TwinningRarely observed on {110}
Cleavage{010} perfect {101} distinct
FractureConchoidal
Mohs scale hardness2
LusterVitreous, silky when fibrous
DiaphaneityTransparent to translucent
Specific gravity1.67–1.68
Optical propertiesBiaxial (−)
Refractive indexnα = 1.433 nβ = 1.455 nγ = 1.461
Birefringenceδ = 0.028
2V angleMeasured: 52°
SolubilityIn water
Alters toDehydrates in dry air
References[2][3][4]

Epsomite, Epsom salt, or magnesium sulfate heptahydrate, is a hydrous magnesium sulfate mineral with formula MgSO4·7H2O.

  1. ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. Vol. 85, no. 3. pp. 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
  2. ^ "Epsomite". Web Mineral (webmineral.com).
  3. ^ "Epsomite". Mindat.org.
  4. ^ Epsomite (PDF) (Report). Handbook of Mineralogy – via Dept. Geology, University of Arizona.