| Bischofite | |
|---|---|
| General | |
| Category | Halide mineral |
| Chemical formula | MgCl2·6(H2O) |
| 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 MgCl2·6(H2O). 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 which is unique by its composition, and which by content of important for human health and vital activity macro- and micro-elements much more exceeds the natural analogies like sea and ocean salts. 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.
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Bishofite was discovered in the Staßfurt salt deposits in Germany by German geologist Gustav Bischof in the second half of 19th century. It is named “bishofite” in honor of its discoverer.[3]
It is an evaporite formed in an ancient seabed which were deposited more than 200 million years ago, in the Permian Period.[4]
In 1930–1950, vast bishofit deposits were discovered near the Volga River in Russia. It is easily evaporated and is mined by dissolving underground dry mineral stratum with artesian water. The resulting brine is pumped out.[4]
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 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.[4]
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[5] 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.[4]
Bishofit is used in production of the industrial Sorel cement[6] and synthetic carnallite. Bishofit solution is applied to deice roads,[6] 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.