Epsomite is most commonly formed by the deposition of material by saline springs as efflorescence on cave walls. It is a mineral of hydrous magnesium sulfate with the MgSO4•7H2O formula. In the orthorhombic system, epsomite crystallizes as rarely discovered acicular or fibrous crystals; the usual type is as massive encrustations. It typically forms as powdery, fibrous, or botryoidal crusts forming on magnesium-rich rocks as efflorescences or deposits around mineral springs.
Deposits of Epsomite are formed by mineral water evaporation, as at Epsom, Surrey, Eng., where it was discovered in 1695. It is also present in coal or metal mines, in limestone caves, and in the oxidized sulfide ore deposits as crusts and efflorescences. It is extremely water-soluble, and will therefore not last long in the climate of Wisconsin under unregulated conditions. It’s colorless to white, with black, green, and pink tints. The hardness of Mohs is 2 to 2.5 and has a low specific gravity of 1.67. It is typically produced in arid regions and in dry caves that shield it from rain and moisture, as it dissolves otherwise.
Epsomite is the same because of the household chemical, Epsom salt, and is quickly soluble in water. It’s going to also form efflorescence in tunnels of sulfide mines from the deposition of sulfur and magnesium-rich water during mining operations. Like Epsom salts, the distilled compound is used in medicine. It absorbs water from the air and, with the loss of one water molecule and a transition to monoclinical form, transforms to hexahydrate.
Epsomite is not widely seen in collections because it lacks appeal, is very delicate, and must be stored in dry areas in order to prevent it from breaking down. It occurs in various locations in the Upper Mississippi Valley zinc-lead district as silky white tufts intermixed with melanterite, copiapite, gypsum, and goslarite. Epsomite occurs on limestone cavern walls and mine timbers and walls as encrustations or efflorescences, occasionally as volcanic fumarole deposits, and as rare beds in evaporite layers such as those found in some saltwater bodies.
White epsomite needles growing down from the roof of Les Ferre’s mine, Catalona, Spain.
Epsomite was named in 1806 after its typle locality near Epsom, Surrey, England. The epsomite group includes primary solid solution series with morenosite (NiSO4•7H2O) and goslarite (ZnSO4•7H2O); Kieserite (MgSO4•H2O) could be a less hydrated sulfate. Epsomite is a significant mineral for the industry. It is used mainly for the processing of Epsom salts. It is also used in the preparation of pharmaceuticals, in the manufacture of paper and sugar, and in the manufacture of dying materials.
Due to the modification of iron sulfides in the dolostone matrix, these minerals form. In Epsom, Surrey, England, which is the place it is named after, Epsomite was discovered as crusts formed by thermal springs. It also occurs in some areas of Africa’s Sahara Desert, Central Australia’s desert, and Chile’s Atacama Desert, where it often forms dense beds. Some specific described localities include the Helena-Roachdale Mine within the center of sec. 7 and therefore the Galena Level Mine within the SW sec. 4, both in T.1N. R.2E. near Shullsburg.