Epsomite, Epsom salt, or magnesium sulfate heptahydrate, is a hydrous magnesium sulfate mineral with formula .
Physical properties
Epsomite crystallizes in the orthorhombic system. The normal form is as massive encrustations, while acicular or fibrous crystals are rarely found. It is colorless to white with tints of yellow, green and pink. It is a soft mineral with variable Mohs hardness around 2.0~2.5, and it has a low specific gravity
It is readily soluble in water, and absorbs water from the air. It converts to hexahydrate with the loss of one water molecule and a switch to monoclinic structure.
It was later systematically described in 1806. It occurs in association with melanterite, gypsum, halotrichite, pickeringite, alunogen, rozenite, and mirabilite.
Uses
Epsom salt is commonly sold as the main ingredient in bath salt, with additives such as glycerin (used as a humectant) and fragrances. The purpose of bath salts is mostly to make the bathing experience more enjoyable and serve as a vehicle for cosmetics, though they are said to improve cleaning and aid in exfoliation.
Research on topical magnesium (for example Epsom salt baths) is very limited. The trade organization 'Epsom Salt Council' recommends bathing 2 or 3 times/week, using Epsom salts each time.
Gallery
thumb|left|350px|The crystal structure of epsomite.
thumb|left|Scanning electron micrograph of epsomite fibers magnified 300 times, from a sample found on a wall of a former limestone quarry cavern in Ohio.
See also
- Magnesium sulfate