Epsomite
A variety of Epsomite Group
What is Epsomite?
Epsomite is a hydrous magnesium sulfate mineral with formula MgSO4·7H2O. 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.
Market Value Factors
Pricing varies for every rock and mineral, so use these universal factors to gauge Epsomite before comparing listings or appraisals.
Size & Weight
Larger, intact specimens usually command higher prices.
Rarity & Demand
Scarce material or popular varieties sell at a premium.
Condition & Finish
Chips, repairs, and heavy wear lower value; clean prep helps.
Treatment & Provenance
Untreated specimens with documented locality are prized.
Epsomite Localities Map
See where Epsomite is found with a localities map, collecting zones, and geology context. Generate a sample map preview below.
Key Characteristics
Formation of Epsomite
Epsomite forms as encrustations or efflorescences on limestone cavern walls and mine timbers and walls, rarely as volcanic fumarole deposits, and as rare beds in evaporite layers such as those found in certain bodies of salt water. It was first systematically described in 1806 for an occurrence near Epsom, Surrey, England, after which it was named. It occurs in association with melanterite, gypsum, halotrichite, pickeringite, alunogen, rozenite and mirabilite.
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Quick Facts
Physical Properties
- Color
- White, grey, colourless, or pink, greenish; colourless in transmitted light.
- Hardness (Mohs)
- 2 - 2.5
- Density
- 1.678 g/cm³
- Streak
- White
Chemical Properties
- Chemical Formula
- MgSO4 · 7H2O
- Elements
- H, Mg, O, S
Also Known As
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Epsomite FAQs
How do I identify Epsomite?
Epsomite can be identified by its hardness of 2 - 2.5 on the Mohs scale, White color. Look for these key characteristics when examining specimens.
What color is Epsomite?
Epsomite typically appears in White, grey, colourless, or pink, greenish; colourless in transmitted light.. Color can vary depending on impurities and formation conditions.
How hard is Epsomite?
Epsomite has a hardness of 2 - 2.5 on the Mohs scale. This makes it a soft mineral that can be scratched easily.
What is the formation of epsomite of Epsomite?
Epsomite forms as encrustations or efflorescences on limestone cavern walls and mine timbers and walls, rarely as volcanic fumarole deposits, and as rare beds in evaporite layers such as those found in certain bodies of salt water. It was first systematically described in 1806 for an occurrence near Epsom, Surrey, England, after which it was named. It occurs in association with melanterite, gypsum, halotrichite, pickeringite, alunogen, rozenite and mirabilite.