Baryte

• Barite
• Barium sulfate

Barite, also known by its synonym, barite and its chemical name barium sulfate, a commonly occurring mineral from the mineral class of " sulfates and relatives " (see Classification ). It crystallizes in the orthorhombic crystal system with the chemical composition of Ba [ SO4 ], wherein barium may also be enhanced by replacing strontium ( Diadochie ).

Barite developed mostly tabular to prismatic crystals, but also massive mineral aggregates, which are in pure form colorless or white in color, but can also take many other colors by foreign admixtures.

• 6.1 Germany 6.1.1 active
• 6.1.2 Down

Special Features

Some barytes show with long-wave UV light a yellow, orange or pink fluorescence. In short wavelength UV light can be observed occasionally phosphorescence.

Barite is chemically very resistant and dissolves slowly in hot concentrated sulfuric acid. However, on heating the mineral tends to crack and produces a yellow-green flame coloration.

Etymology and history

Barite was named after the Greek word βαρύς [ Barys ] named for difficult due to its relatively high for a mineral density of 4.5 g/cm3. The miner's name barite indicates that property.

It is first mentioned the name of barite D.L.G. Karsten in written by him, first edition of the Mineralogical Tables (Berlin, 1800).

Classification

In the now outdated but still in use 8th edition of the mineral classification by Strunz the barite for mineral class of " sulfates, selenates, tellurates, chromates, molybdates, tungstates ," and there belonged to the department of " water clear Sulfate without foreign anions ", where he served as the namesake of the " Barytgruppe " together with anglesite, Celestine and Hashemit formed a distinct group.

The 9th edition used since 2001 and valid by the International Mineralogical Association (IMA ) of the Strunz'schen Mineral classification assigns the barite also in the class of " sulfates ( selenates, tellurates, chromates, molybdates and tungstates ) " and then in the Department of " Sulfate ( selenates, etc. ) without additional anions, without H2O" one. This division, however, is further divided according to the size of the cations involved, so that the mineral is "With only large cations " to find according to its composition in the subdivision, where there is also the " Barytgruppe " with the system no. Forms 7.AD.35 and the other members Anglesit, Celestine and Olsacherit.

The mostly commonly used in English-speaking classification of minerals according to Dana assigns the barite in the class of " sulfates, chromates and molybdates " and there in the department of " sulfates " one. Again, barite namesake of the " Barytgruppe " with the system no. 03/28/01 and the other members celestite and anglesite within the subdivision " water outdoors acids and sulfates (A2 ) XO4 " to find.

Varieties and modifications

Radiobaryt contains small amounts of radium in tenths of a percent, which replace the barium in the structure partially. Depending on the radium content, it may be the strongest natural radioactive mineral, in a single sample 31.8 MBq / g were detected. Barytes with more than 70 Bq / g, are generally as already mentioned Radiobaryte.

Wüstenhaftem in air caused as a special form of growth, in which sand particles are trapped between the tabular crystals, called Barytrosen. These are similar to sand roses and are formed under similar conditions.

As Hokutolith a lead-containing and sometimes radium -containing barite variety is called.

Education

Barite formed from hydrothermal solutions or sedimentary, partly with the involvement of biological processes. He is mainly associated with calcite, dolomite, fluorite, galena, gypsum, rhodochrosite, sphalerite and stibnite, but can also be found with many other minerals together.

Sedimentary exhalative deposits

The most important types of deposits are SEDEX deposits. Because barium sulfate is only very slightly soluble, is a precipitation of the mineral often made ​​in places in which to mix barium and sulfate -rich solutions. So the submarine SEDEX deposits form in the mixture ascending bariumreicher hydrothermal solutions with sulfate-containing seawater. This type of deposit may contain several million to several billion tons of barite, which are often, but not always, associated with Pb -Zn -Ag - rich massive sulphides. Examples are the deposits in the Brooks Range in Alaska with about two billion tons of barite, Nevada Barytgürtel in the U.S. or the deposits Meggen and Rammelsberg in Germany (both decommissioned).

Vein deposits

Vein deposits form on columns in different rocks. The gears can be several meters thick and contain several million tons of barite. Often come in the aisles next to barite and fluorite, quartz, calcite, and various sulfides.

Locations

Germany

Active

In Germany barite is currently being mined in the Clara mine in Oberwolfach in the Black Forest.

The deposit Mitre at Ilmenau in the Thuringian Forest was built in 2005-2008 and is currently due to lack of sales still.

In precipitation at Bear Stone in the Ore Mountains was started in 2013 with the mining of fluorite and barite.

Decommissioned

Until June 2007, was still mined in Bad Lauterberg on the pit hills and clouds in Schwerspatbergwerk Dreislar in Sauerland barite. Until 1991, the deposit was mined Brunndöbra in the Saxon Vogtland. Less significant areas were in Richelsdorfer Mountains in Sontra, in the Spessart in Lohr am Main (eg legal Bach, Partenstein and Frammersbach ) and in Saarland Nohfelden- iron. Between the villages of Aue and grove village ( Schmalkalden ), there were 1887 to 1978 a Schwerspatmühle that " Auehütte ". The station still bears that name. It was established in 1887 in the building of the mill a previous iron smelting by the family Utendoerffer. As in the GDR VEB she graduated in 1978. Hartenrod In today Bad Endbach in Marburg- Biedenkopf (Hesse), a high-quality barytes were in the pits "Bismarck" from 1884 and " Koppe " from 1919 to 1957 broken down and in the connected Spatmühle processed. In the Odenwald barite was mined 1800-1939 at three key locations: in Schriesheim on the mountain road along the fractures of Schriesheim formation, in small Umstadt ( now part of Greater Umstadt ) ( 1839 to 1931 approximately 650,000 tons barythaltiges rock) and in the central area of the Odenwald to Reichelsheim between the upper and upper - Kainsbach Easter.

Other Locations in Germany include Freiberg, Ruschberg ( Grube Clara Hall ), neck bridge, Poehla, the resin, the Lahn- Dill area, the Christophstal in Freudenstadt ( Christoph mine tunnel ) and the Thuringian Forest.

Internationally important deposits

Alston Moor, Cumbria, Frizington, Mowbray and Isle of Arran (whose deposits have been known since 1770) in the UK, Iglesias in Sardinia, Baia Sprie and Cavnic in Romania, Banská Štiavnica in Slovakia, Dědová hora and Pribram in the Czech Republic, and Elk Creek / South Dakota in the United States.

More Locations

Overall, barite so far (as of 2011) are detected at around 8600 localities, including in rock samples of the Mid-Atlantic Ridge and the Central Indian Ridge and at several places of the Pacific Ocean. Outside the earth barite was still on the moon, more precisely in the rock samples in the vicinity of the landing sites of Luna 16 ( Mare Fecunditatis ), 20 and 24 ( Mare Crisium ).

Crystal structure

Barite crystallizes in the orthorhombic space group Pnma ( Raumgruppen-Nr. 62) with the lattice parameters a = 8.88 Å; b = 5.46 Å and c = 7.16 Å and four formula units per unit cell.

The anion [ SO4 ] 2 - forms a slightly distorted tetrahedron with sulfur at the center and oxygen at the four corners. Within the Anionenkomplexes prevails atomic bond between the Barium2 ion and the surrounding oxygen ions, respectively 12, however, ionic bonding.

Use

The principal use for barite is in deep drilling as an additive for drilling fluids. The reason for this is the high density of the barium, with which a high hydrostatic pressure is generated in the liquid, which stabilizes the borehole and allows to transport the crushed by the drill bit to the rock surface.

Furthermore, barite for the production of white pigments such as Lithopone and photographic papers used and is itself also in the Colour Index under CI Pigment White 22, and C. I. 77120 listed. It is as much a part of heavy concrete as contrast agents in radiological studies of the stomach. Barite is also reduced as a raw material for the production of barium.

In the automotive industry, barite plastics and insulation mats is added to reduce the sound transmission.

As a gemstone barite is rarely used because it is too soft ( Mohs hardness 3 to 3.5 ) and sensitive ( perfect cleavage ). It is preferably ground by collectors in the form of a faceted octagon.

As aggregate Barite is used to reduce the permeability of concrete beams ( barite concrete ). Field of application are, for example, walls in X-ray rooms in hospitals or treatment rooms in the radiotherapy.