IMA Code

Esm

	Formula	Name	Family	Number min-max	Isotope mole fraction	State	Relevance
	$Mg^{2+}$	Magnesium(II) cation	element	1		constituent cation	main
	$(SO_4)^{2-}$	Sulfate anion	chemical function	1		anionic radical	main
	$H_2O$	Water	molecule	7		hydration	main

Composition comments

:Common impurities: Ni, Fe, Co, Mn, Zn - Effloresces in dry air. Very soluble in water. Deliquescence: 90.1% (20°C), 94% (30°C)

Chemical functions

	Function	Number
	$(SO_4)^{2-}$	1
	$R-OH$	2

Chemical bonds

	Bond	Number
	$-O-H$	2
	$\dddot - \dddot - \dddot - S \dddot - O^{-1/2}$	4

Oxides

Formula	$MgO$	$SO_{3}$	$H_{2}O$
Mass fraction (%)	16.35	32.48	51.16

Strunz

Class

sulfates - chromates - molybdates - tungstates (07)

Division

sulfates (selenates, etc.) without additional anions, with H2O (07.C)

Family

with only medium-sized cations (07.CB)

Code

07.CB.40

Dana

Major class

sulfates, chromates, selenates (VI)

Class

hydrated acid and sulfates (29)

Type

where AXO4.x(H2O) (29.06)

Group

Epsomite group (Heptahydrates, orthorhombic) (29.06.11)

Code

29.06.11.01

Phase type

crystalline

Crystal system

orthorhombic

Crystal class

disphenoidal

Crystal class symbol

222 (D2)

Crystal spacegroup

P2(1)2(1)2(1)

Refringence type

biaxial

Refringence sign

negative

Birefringence

0.028

Refraction index $n_{\alpha}$

1.433

Refraction index $n_{\beta}$

1.455

Refraction index $n_{\gamma}$

1.461

Pure color

colorless

Color

colorless, white, yellowish white, greenish white, pinkish white

Diaphaneity

transparent to translucent

Luster

vitreous

Links

• Wikipedia: Epsomite
• SaltWiki: Epsomite
• Webmineral: Epsomite
• Mindat: Epsomite
• Handbook of Mineralogy (Min. Soc. Am): Epsomite