Dolostone

Dolomite, scientifically dolomite, a carbonate rock that at least 90 percent of the mineral dolomite (chemical formula CaMg ( CO3) 2 (CaCO3 · MgCO3 ) ) exists. At lower levels there is a dolomite dolomitic limestone. Dolomite is ideally white, often off-white, light gray, yellowish-gray or green -gray.

Characteristics, diagnosis

Dolomite stones are compared with the chemically related limestone slightly harder and much more brittle. Since the minerals ( such as calcite ) is highly birefringent, the rocks are light in color and not translucent, so opaque, similar also limestones. A first indication of dolomite results from a splintery rock surface, at least if this was not processed. This lack of smooth washed surfaces is a contrast to the limestone. Diagnosed by the site geologists they are by their very slow process of reaction with acid. A drop of hydrochloric acid ( Recommendation 5 - to 10 - percent ) developed slowly small gas bubbles of carbonic acid; in the cold, the reaction lasts for hours; In contrast to the lime, the vigorous hissing ( bubbles of carbon dioxide ) dissolves in a few seconds. Due to the slow reaction rate of dolomite karst forms a much lesser extent and of a different nature than limestone.

In order to make visible in a dolomite lime / dolomite mixing rock, the rock is with reagents magnesium change their color, colored. An example of this is a proof of quinalizarin.

In the literature it is often called " sugar like " appearance of a spoken. This refers to the construction of fine crystals that are far finer than the now common trade sugar, but coarser than are limestone crystals. In sunlight, the joint surfaces glisten visible. This fine crystallinity is due to recrystallization during or shortly after sedimentation. Sets the dolomitization diagenesis one, remain structural characteristics and contain fossils. A late diagenetic dolomitization blurs any structural characteristics and fossils of the parent material. Therefore, no statement can be made about the fossil content. This often complicates the stratigraphic assignment of dolomitic rock formations.

Formation

Or more simply:

Whereby MgCO3 equal connects to the existing lime mud to dolomite. CH4 is here as representative of the organic substance. The magnesium comes from thickened sea water; by the salt content in the soil, the ground water is hard and shares no longer with the surface. An oxygen exchange take place only by diffusion, and the organic substance decomposes under rot.

Quite often Riffgesteine ​​are dolomitized. This may partly be due to the porosity of the reef, which offers even greater immersion, circulation of the solutions; partially (at least for coral reefs ) Also, remember that the coral is composed of the mineral aragonite unstable, so the conversion is easier.

Occurrence

Dolomite is used as rock world and occurs naturally often associated with limestone on. In Europe, Dolomite (eg the Dolomites ) located in the geologically young mountains alpidischen very often. In Germany dolomite and dolomitic limestones, especially in western and southern Germany are found, so in the Eifel, in the Westphalian town Bergland, in the Swabian and Franconian Alb. Also on the western and southern edge of the Harz, in the Thuringian Slate Mountains and parts of the Vorspessart occurs dolomite. Very powerful dolomite reserves are found in the Swiss Alps and the Bavarian foothills.

The Formerly known as " Anröchter dolomite " Sauerland natural stone is not dolomite. The only dolomite quarry on the Mosel is located in Palzem / Thorn Castle. At the Sauer Mesenich be mentioned.

The only mineable deposits in eastern Germany is the Ostrava dolomite in Saxony.

Types of natural stone

• Kleinziegenfelder dolomite ( Upper Franconia; Unterdietfurt )
• Guard Zeller dolomite (Upper Bavaria)
• Salt inhibiting villages dolomite (Weser -Leine Bergland )
• Harzer dolomite Nüxei ( resin / Suedharz )
• Meskalith, near Trier ( Rhineland -Palatinate )

Other occurrences: Massenkalk ( Bergisch Land, Sauerland); Hösbach - Rottenberg ( Lower Franconia ) Zechsteindolomit.

Foreign varieties:

• Libiaz (Poland).
• Saaremaa / Estonia
• Norway

Use

Dolomite is used for all kinds of flooring ( cut or break rough ), construction of stone walls and dry stone walls, as curbs, as palisades, as blocks of stone as a design stone for the construction of retaining walls and paving stone as used. Shred it serves primarily as an additive in the manufacture of steel in blast furnaces. He is also a main ingredient of mineral wool and technical glasses, use in soil stabilization as well as agricultural lime for agriculture. Powdered dolomite was once called " Vienna Lime " and sold as abrasives; its hardness is just right to scrape calcium deposits, but leave untouched glass and porcelain. In so-called crushing of dolomite is also processed into aggregates for road construction and concrete production. As coarse gravel he also serves for filling gabions ( baskets gravel ).

Granulated dolomite is used as the silica- free (SiO2 - free ) filter material for water treatment. For various other areas of application in water treatment dolomite is burned. These forms at about 900 ° C of dolomite ( CaMg ( CO3) 2 ) calcined dolomite ( CaO · MgO CaMgO2 = ). At lower firing temperature half-burnt dolomite formed ( CaCO3 · MgO) also called Magno, which is used in drinking water treatment for de-acidification ( binding of excess CO2). It reacts preferentially the MgO component. More at Magno ( chemical).

Dolomite is named after the French geologist Déodat de Dolomieu ( 1750-1801 ). Dolomieu made ​​a trip in the time as " bleaching mountains " or " monti pallidi " designated part of the Southern Alps, in the field of language barriers German / Ladin / Italian. After his preliminary information, these mountains would consist of " lime "; He found, first, that the rock is extremely slow dissolve in acid. He walked to the problem and found that the rock - like a lime carbonate - to chemically equivalent proportions of " lime " (CaO) and " Magnesiaerde " ( MgO) was composed.

Dolomieu wanted the new rock, called in honor of his teacher, the Mont Blanc De Saussure as Besteigers Saussurite, but soon afterwards he died himself, and the scientific community named the mineral and the rock after him. Therefore, the " Pale Mountains " of the Southern Alps wear Dolomieus modified name today.