Bischofite

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Bischofite
Bischofite - Antofagasta.JPG
Bischofite from Antofagasta, Chile
General
Category Halide mineral
Formula
(repeating unit)
MgCl2·6H2O
Strunz classification 03.BB.15
Dana classification 09.02.09.01
Identification
Color Colorless to white
Crystal habit Fibrous to massive
Crystal system Monoclinic - prismatic (2/m)
Twinning polysynthetic
Cleavage None
Fracture Conchoidal to uneven
Mohs scale hardness 1.5–2
Luster Vitreous – greasy
Streak White
Diaphaneity Translucent to transparent
Specific gravity 1.56
Optical properties Biaxial (+)
Refractive index nα = 1.495
nβ = 1.507
nγ = 1.528
Solubility Deliquescent
References [1][2][3]

Bischofite (bishofit) is a hydrous magnesium chloride mineral with formula MgCl2·6H2O. It belongs to halides and is a sea salt concentrate dated from the Permian Period (nearly 200 million years ago). Bischofite is ecologically pure natural magnesium poly-mineral with a unique composition. It contains many macro- and micro-elements vital for human health, in much higher concentrations than can be found in sea or ocean salt. The main bishofit compound is magnesium chloride (up to 350 g/L), moreover, it contains about 70 other elements as impurities, including potassium, sodium, bromine, boron, calcium, silicon, molybdenum, silver, zinc, iron and copper.

History[edit]

Bishofite is named in honor of German geologist Gustav Bischof (1792–1870). Its discovery (1877) is attributed to Carl-Christian Ochsenius.[4]

It is an evaporite formed in an ancient seabed, which was deposited more than 200 million years ago, in the Permian Period.[5]

In 1930–1950, vast bishofite deposits were discovered near the Volga River in Russia. It is easily evaporated and is mined by dissolving an underground dry mineral stratum with artesian water. The resulting brine is pumped out.[5]

Deposits[edit]

Bishofite deposits differ by their composition: some of them are salt basins where bishofite is mixed with other minerals such as carnallite, halite, kieserite and anhydride. These are the so-called bishofite containing rocks which have pink-brown-yellow and orange-red colors.[2] They contain 36–58% of bishofite. Carnallite deposits are known in Staßfurt, Germany – where bishofit was firstly discovered, and carnallite is one of the most important minerals in potassium salt deposits (Solykam deposit, Ural, Russia). Sub-surface bishofite layers were also discovered in Kazakhstan, Turkmenistan, China and the US.[3]

There are bishofite-rich deposits with concentrations of 93–96%. One of those rare deposits is in Volgograd region of Russia. Another one was found in 1990s in Poltava region in Ukraine. This is one of the deepest (2,5 km) and thus oldest bishofite deposits.[5]

Applications[edit]

Bishofite has many applications ranging from construction materials (tile, stone) to agriculture (preplant seeds, plant processing during vegetation period), oil extraction (for grouting and solidifying mortars), medical and chemical industry (production of magnesium metal).

Bishofite is used in form of compresses to treat joint diseases such as arthritis, rheumatic fever[6] osteoarthritis, rheumatoid arthritis, radiculitis, calcaneal spur and traumas, especially in rehabilitation centers of Ukraine, Russia, Belarus, and Lithuania. Bishofit is also applied in gel form.[5]

Bishofit is used in production of the industrial Sorel cement[7] and synthetic carnallite. Bishofit solution is applied to deice roads,[7] similar to sodium chloride, but less corrosive. It is also used in agriculture, veterinary medicine and cattle breeding to increase the crop yield and treat animals.

References[edit]

  1. ^ Webmineral data
  2. ^ a b Handbook of Mineralogy
  3. ^ a b Bischofite on Mindat
  4. ^ Ochsenius, C. (1877): Die Bildung der Steinsalzlager und ihrer Mutterlaugensalze unter specieller Berücksichtigung der Flöze von Douglashall in der Egeln´schen Mulde. Verlag Pfeffer (Halle), 172 p.
  5. ^ a b c d A. A. Spasov (2003). Local bishofite therapy. Volgograd State University. ISBN 5-88462-065-9. 
  6. ^ Hans-Rudolf Wenk, Andreĭ Glebovich Bulakh (2004). Minerals: their constitution and origin. Cambridge University Press. p. 562. ISBN 0-521-52958-1. 
  7. ^ a b Mark A. Shand (2006). The chemistry and technology of magnesia. John Wiley and Sons. p. 216. ISBN 0-471-65603-8. 

External links[edit]

Media related to Bischofite at Wikimedia Commons