Diabase

As diabase (Greek διαβαίνω diabainō, pass ') are referred to various basic rocks.

In the U.S. geologic literature as " diabase " a basaltic, medium -grained subvulkanisches ( hypabyssales ) rock called that the dolerite corresponds roughly to a traditional German understanding.

Wimmenauer (1985 ) uses the term also for a basaltic rock sub-volcanic origin, but the diabase adjacent territory then on the dolerite that the latter has no transformations of the original mineral inventory.

Traditionally, however, is called diabase, a greenish colored by slight metamorphosis ( " vergrüntes " ), originally basaltic, pre- Permian (mostly Paleozoic ) igneous meant, which is found in Europe, especially in the Variscan rock complexes and named because of its coloring and greenstone will. In this sense, we find the name in many older geological writings and maps. Another also defined as a pre- Permian basic rock is the melaphyre. It is provided along with the diabase was traditionally in the group known as " paleobasalts ".

The International Association of Geological Sciences ( IUGS ​​) does not recommend the further use of the term diabase in traditional German understanding and recommends the name as a synonym of diabase dolerite ( " Mikrogabbro " ) to look at. In more recent geological maps, therefore, are traditionally among the rock names as " diabase " declared formations terms like Spilit, Pikrit or metabasalt. However, the term diabase is discussed below in terms of the traditional conception due to the longstanding use of the German language area.

Structure and mineral composition

Diabase have a dense, fine-to medium -grained microstructure. In some varieties of feldspar phenocrysts larger may be constructed which give the rock a porphyritic texture. Characteristic in this case is a mixture of bulky arranged Feldspatleisten ( ophitisches or intersertales structure).

The parent rocks of Diabases were originally from tholeiit - basaltic composition. The typical greenish color goes back to the Anchimetamorphose of the rock, a precursor of metamorphosis. It is caused by the formation of chlorite and hornblende from augite and the conversion of shares of the feldspars in epidote. The calcium of some plagioclase is also partially converted into calcite.

Diabase has an unusually high density, which can be up to 3000 kg / m³, and is particularly resistant to weathering.

Occurrence

Diabase occur as igneous rocks in numerous Paleozoic rock units, especially in the Variscides of Central and Western Europe. They represent the submarine volcanic activity in the Paleozoic ocean basin, including the following, during the Variscan orogeny, pushed together and the European Kontientalblock ( Baltica ) were annexed. In Germany they are widespread in the Devonian and Lower Carboniferous of the slate mountains, either massive, inter alia, in the form of pillow lava, or as Diabasbrekzien and Diabastuffe (such as the slaty -educated, so-called " greenstone "). Frequently associated with the diabase is intrusive in the form of gears and sticks occurring dolerite.

In the Thuringian- Franconian - Vogtländische Slate Mountains are the diabase consistently Devonian age. There they form the typical domed, especially in the Vogtland landscapes. A geotourism attraction is the " Stone Rose" with castle hall, a natural monument whose present form goes back to the typical weathering of Lavakissen.

In the Rhenish Slate Mountains Central and Upper Devonian diabase represent the most significant volcanic phase of Dill and Lahn trough. The diabase of the Middle and Upper Devonian of the Sauerland are called " Hauptgrünsteinzug " means. In the Lower Carboniferous were with the " Deckdiabas " the Rhenish Slate Mountains and also promoted in the resin to a greater extent submarine pillow lava.

Diabase are also common in the Devonian and Carboniferous of southern England. Other European Diabasvorkommen are described from the Silurian of the Prague trough. Other deposits are inter alia in Finland, India and Turkey.

Economic importance and use

Diabase has already been processed in the stone age tools such as axes, hatchets, blades, drills and scrapers. Nowadays it is used in road construction, for grave stones or stone sculptures and rare as polished natural stone flooring and cladding panels.

Economic Importance

In the Lahn and Dill area to date with the greenstone -related diabase and the " Deckdiabas " of the Lower Carboniferous are mined in many quarries. In the area on the east boundary of the former Dill district and especially in subsequent former district Biedenkopf ( Hessian hinterland ) in central Hesse were operated at the beginning of the 20th century large and profitable quarry operations, which gave a total of up to 650 employees work and bread. The materials found there Paläopikrit - diabase, also called the " hinterlands greenstone " is a very poor silicate type of unterkarbonischen magmatism. He is not connected by transitions with the basic diabases and Olivindiabasen of Deckdiabases and is intrusive in Devonian rocks. It is characterized by its black-brown, irregular grained weathering rind ( the color of the fresh rock is black green). A flaming or drawing is caused by accumulation of plagioclase ( Kalkalkalifeldspäten ), which can be up to 54 % in those games. Diabassteinbrüche be further in the resin, mainly operated in the Vogtland region in the Sauerland for gravel production.

Use

Diabase were processed as building stone earlier in the construction industry frequently columns, monuments and grave stones. Stone sculptor working, grind and polish sculptures like diabase, because manufactures a tension between polish and rough surfaces in surface treatment. Diabase can be hand- edit relatively well. If diabase handled with the palms, he takes on the skin fat and there are the so-called flatterer that feel comfortable and shine. As a stone only the Diabassorte Hessian- Neugrün is processed into grave stones today in Germany. Diabase can be used to gravel, paving stones and paving material. Every now and then diabase in the construction industry for facade panels, floor and stair coverings used. Diabase is next to basalt finely ground used as a so-called Urgesteinsmehl to Gartenbodenverbeserung.

Occasionally diabase is also used as an aggregate for concrete high density.

Types of natural stone

A selection of diabase, which were respectively found as natural stones using:

• Hessian- Neugrün Glad Bach Rachel Hausen, Steffensberg - Steinperf, Bad Endbach - Hartenrod, Bad Endbach - Bottenhorn, Bad Endbach - Dernbach and Holzhausen, all in the district of Marburg -Biedenkopf in Hesse
• Diabase Nakkila ( Nakkila in Finland)
• Eurajoki ( Eurajoki in Finland)
• Baringdong Dark and Light Baringdong ( at Ba Rinh Dong in Vietnam)
• Verde India ( at Halebid and Harnahalli in India)
• Pista Green ( Chamrajnagar in India)
• Gemlik ( Bursa Gemlik in Turkey)