The mineral epsomite

	Chemical Formula	MgSO₄ · 7H₂O
	Composition	Hydrous magnesium sulfate, sometimes with iron replacing some magnesium
	Variable Formula	(Mg,Fe)SO₄ · 7H₂O
	Color	White, colorless, gray
	Streak	White
	Hardness	2 - 2½
	Crystal Forms and Aggregates	(Orthorhombic) Does not form in visible crystals. Occurs massive, earthy, acicular, encrusting, globular, stalactitic, as fibrous groupings, as cotton-like bunches, and as felt-like masses.
	Transparency	Transparent to translucent
	Specific Gravity	1.7
	Luster	Vitreous, silky, dull
	Cleavage	Indiscernible
	Fracture	Conchoidal, earthy
	Tenacity	Brittle
	Other ID Marks	1) Has a bitter, salt-like taste 2) Soluble in water
	Other Names	Epsom, Epsom Salt, Bitter Salt
	In Group	Sulfates ; Hydrous sulfates
	All About	Epsomite most commonly forms as efflorescences on cave walls from deposition of material from saline springs. It exists only in arid regions and in dry caves which protect it from rain and moisture, for otherwise it dissolves. Epsomite may also form efflorescences in tunnels of sulfide mines from the deposition of sulfur and magnesium-rich water which is created through mining operations. Epsomite is not commonly seen in collections, for it lacks appeal, is very fragile, and must be kept in dry areas to prevent it from disintegrating.
	Uses	Epsomite is used in the preparation of pharmaceutical products, as well as in dying material. It is used in the production of paper and sugar. Its most popular use is for the production of Epsom salts.
	Striking Features	Taste, solubility, and mode of occurrence
	Popularity (1-4)	3
	Prevalence (1-3)	2
	Demand (1-3)	2
	Distinguishing Similar Minerals	Epsomite can be distinguished from other minerals by its habit, taste, and occurrence, although it may be confused with Melanterite, which has a greener color and tastes different.
	Commonly Occurs With	Gypsum, Aragonite, Pyrite, Calcite, Mirabilite (Limestone)
	Noteworthy Localities	Epsomite was found as crusts produced by thermal springs in Epsom, Surrey, England, which is the locality it is named after. It occurs in certain areas in the Sahara Desert of Africa, the desert of Central Australia, and the Atacama Desert of Chile, where it sometimes forms thick beds. In the U.S., it occurs in the saline lake beds on Kruger Mountain, near Oroville, Okanogan Co, Washington. It also occurs in the Carlsbad Caverns of New Mexico. Other occurrences are the Alma mine near Leona Heights, Alameda Co., California; Kalkar quarry, Santa Cruz Co., California; The Geysers, Sonoma Co., California; White Caps mine, Nye Co., Nevada; Majuba Hill mine, Pershing Co., Nevada; and Bisbee, Cochise Co., Arizona.
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