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Epsomite Efflorescent Powder
SULFATES; HYDROUS SULFATES · ORTHORHOMBIC

Epsomite

MgSO4 · 7H2O

Hardness
2–2.5
Streak
White
Spec. Gravity
1.7
System
Orthorhombic

About

Epsomite most commonly forms as efflorescence on cave walls from deposition of material from saline springs. It generally is formed in arid regions and in dry caves which protect it from rain and moisture, for otherwise it dissolves. Epsomite may also form efflorescence in tunnels of sulfide mines from the deposition of sulfur and magnesium-rich water during mining operations. Itis not commonly seen in collections, for it lacks appeal, is very fragile, and must be kept in dry areas to prevent it from disintegrating.

Epsomite forms a solid solution series with the following similar sulfates: Morenosite, a hydrous nickel sulfate (NiSO4 · 7H2O), and Goslarite, a hydrous zinc sulfate (NiSO4 · 7H2O).
Epsomite was named in 1806 after its typle locality near Epsom, Surrey, England.

Crystal Forms & Aggregates

Other ID Marks

1) Has a bitter, salt-like taste.
2) Soluble in water.

Striking Features

Taste, solubility, and mode of occurrence.

Environment

Uses

Epsomite is an important industrial mineral. It is chiefly used for the production of epsom salts. It is also used in the preparation of pharmaceutical products, for the production of paper and sugar, and as dying material.

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., Epsomite occurs in the saline lake beds on Kruger Mountain, near Oroville, Okanogan Co, Washington, and in the Carlsbad Caverns of New Mexico. Other occurrences are the Kalkar quarry, Santa Cruz Co., California; The Geysers, Sonoma Co., California; the White Caps mine in Manhattan, Nye Co., Nevada; Majuba Hill mine, Pershing Co., Nevada; and Bisbee, Cochise Co., Arizona.

Distinguishing Similar Minerals

Epsomite can be distinguished from other minerals by its habit, taste, and mode of occurrence, although it may be confused with Melanterite, which has a greener color and a different taste.

Photos

Crystal forms

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Modified Prismatic
Prismatic