Slate

Slate is a collective term for different metamorphic rocks and tectonically deformed sedimentary rocks. Their common feature is the excellent cleavage along parallel surfaces.

In the scientific literature, the word slate ( OHG scivaro, MHG Schiver (s), Stone Splitter ',' splinter '; Middle Low German Schiver, slate ', ' shingle ' ) is no longer used without further additives as a rock name.

• 2.1 mining techniques
• 2.2 slate from Germany
• 2.3 Other mining countries

• 3.1 Germany
• 3.2 foreign

Types of slate

Slate from the group of undeformed sedimentary rocks

Tectonically unclaimed, very fine-grained sedimentary rocks ( shale English ) with high proportions of clay minerals were well into the 20th century, the term " slate " when they split into thin sheets. The correct name is now mudstone, only for the rich in organic matter of oil shale, the old name is still used. There are also stratigraphic names that contain the term shale and refer to a regional distribution of rock dumping a certain age. They include the fish in the Aptian shale in northwestern Germany and the Posidonia shale from the Toarcian of the Swabian Alb.

Slate

Argillite (English slate ) are rocks from the transition region of diagenesis to metamorphism. It is tight clastic rocks with black, blackish gray, bluish gray, also greenish, yellowish, red and violet color, which have a closely spaced foliation in the millimeter range.

They are formed from mudstone under directed pressure and elevated temperatures and can both Sedimentiten as well as the metamorphic rocks are attributed. Here, the rock still shows but none of the typical, educated in the metamorphic minerals. In the orogeny the Tonsteinschichten be folded by lateral pressure. During this tectonic processes initially occurs to the system of solution surfaces perpendicular to the prevailing pressure. New clay minerals crystallize on the surface, thus the original mudstone receives its slate-like structure.

The density varies by 2.8 g / cm ³. The composition can only be determined by the X-ray diffraction, since the diameter of the individual mineral grains is well below 20 microns. The rock consists of larger or smaller amounts of clastic material containing quartz and feldspar grains also, and detrital mica and Chloritblättchen addition to the actual clay minerals. In addition, can contain as dark acicular Rutilkriställchen or small pyrite cubes a slate in the smallest quantities of heavy minerals. In the fine-grained rocks are often found fossils, however, were often distorted or destroyed by the deformation. This does not affect microfossils that can be used for dating the rocks.

Belonging to the group of sedimentary or metamorphic rocks is also determined by X-ray diffraction. Here, the temperature-sensitive over geological time behavior of the clay mineral illite is specifically used, the 10Å - reflex is more pronounced with increasing metamorphism.

Crystalline schist

Geologically, it is in these shales (English schist ) to metamorphic rocks (eg mica schist, shale fruit, Glaukophanschiefer ) where new layer silicates such as muscovite, biotite and chlorite have formed under high pressure and high temperatures from the clay minerals, all of which are aligned parallel and thereby cause the good cleavage of the rock. The formation of the typical structure of crystalline schist called Kristalloblastese.

Certain minerals such as glaucophane or the minerals of garnet and amphibole, allow conclusions on the pressure-temperature conditions of metamorphism. The aligned perpendicular to the printing direction of metamorphosis foliation plane has nothing to do with the original sedimentary layering; Foliation and bedding plane can be at any angle to each other.

Roofing and cladding slate stone as

In construction, dark slate to cover gables, roofs and facades is used for jewelry and protection from the elements. Particularly common slate is encountered with half-timbered houses. Was on the Moselle River, in the Hunsrück and the Eifel and is now once again the house building with hewn, compact rubble slate usual.

From the Middle Ages to the mid-20th century slates and stylus were prepared as writing utensils of slate. Until the introduction of large-scale industrial process for making paper and the associated price decline of writing paper slates and stylus were a common writing material for everyday use, which was indispensable in trade, in private households, but particularly in the increasing since the 17th century elementary education sector. From the late 19th century until the cessation of industrial pen slate production in the 1960s, the Thuringian town of Steinach had a world monopoly.

Mining techniques

Today's reduction is determined by the use of modern equipment and machinery. The mechanized sawing recovery not only facilitates the work of the miners, but also contributes to a careful use of the valuable rock.

The mineable shale is cut with a diamond saw along the geological conditions in exact grid. The slate block by block is then carefully removed from the mountain. Wheel loaders provide for loading underground. Loren on the slate is then passed to the mine car to the production well. Once there, he comes with Loren over days in the production halls. Here is the slate blocks are sawn, cleaved and trimmed the end.

In the above-ground production is initially acquiring a diamond saw, the first processing of the slate blocks. It ensures that the different-sized blocks can be largely " waste- free" used for the manufacture of covering stones.

For all the mechanization of modern production hall are the shaping machining operations, the columns and trimming, still running in skilled manual work. Bit by bit, while the blocks divided into plates, which have a thickness of about 5 mm.

Slate from Germany

In the interest of an orderly, roofers, architects, dealers and builders alike transparent competition shale extraction sites were combined with reasonably comparable properties from a region under a name.

So was the denomination of origin at the same time to a property and quality specified as in the famous vineyards. The final determination of the terms and the assignment of the pits was carried out after long negotiations between the Reich and the German roofing trade shale industry in the early 1920s. The result was published in " The German Roofing Trade " from August 7, 1932 in the official section of the magazine. The definitions in 1953 and 1967 confirmed again and be of the slate factories used to this day: Moselschiefer, Thuringian Slate, Slate Hunsrück Slate and Sauerland.

Accordingly, only the slate from the districts Mayen, Polch, waste stream, Trier and the surrounding area may call Moselschiefer. Today only the mines Katzenberg and Margareta Mayen use the title Moselschiefer. The name comes from the historic path of this slate of the Mosel to the Lower Rhine, in the Benelux countries. The name Hunsrück Slate For the districts Altlay, Bundenbach, Kirn, Gemünden and Herrnstein and their surroundings. The extraction sites in Fredeburg, Brilon, Nuttlar etc. fall under the heading of slate from Westphalia and Waldeck, but are also easy Sauerland slate called, although, as in other regions., May be substantial differences in properties within this designation

In production there are still

• In Mayen / Eifel, the two mines Katzenberg (over 300 m deep with a production well ) and Margaret ( with a 485 m long conveyor ramp that allows a removal by truck from underground),
• In the Sauerland in the area around Bad Fredeburg a group mine pits with the beer cellar, Gomer, Magog, with a 150 -year tradition
• In the Hunsrück slate mine Altlay, with an underground mining at a depth of about 120 meters under centuries-old quarrying
• In Bavaria (municipality Geroldsgrün ) (after a 500 meter long adit ) of Lothar healer slate,
• In Saxony in Theuma at Plauen in Vogtland Theumaer fruit shale is mined and processed.

By 2008, was also mined in Thuringia slate, it was there a mine in Unterloquitz and an open pit mine at forging Bach in operation.

The Moselschiefer mining to Mayen is traditionally the most powerful German site with over half of German production.

The largest known shale roof is located in the area around Bad Fredeburg.

In Kaub on the Middle Rhine was won over centuries until 1972 slates of the highest quality. Today the workings of the mine Wilhelm Erbstollen testify to the former importance of the slate mining for the entire region.

Other mining countries

Slate is available in many countries around the world: outside of Europe in North America, South America, South Africa, Japan, China, Siberia and India. In Europe, shale deposits are found in Slovenia, Croatia, Greece, Italy, Czech Republic, Poland, Hungary, Norway, Sweden, Switzerland, Portugal, Spain, France, Belgium, Luxembourg, the United Kingdom and Ireland.

Quantitatively, significant productions can be found - the following order - in Spain, France, Great Britain, Germany and Portugal. The largest consumer country but by far France. This traditional " Shale Country " has a formerly important national production ( Ardoisières d' Angers), but is also the largest purchaser Spanish slate. But traditional " slate " countries in terms of use are also Germany, Benelux and the UK.

Museums

Germany

Slate museums, there are, among others:

• Eifel: German slate mine. It is located in 16 meters depth below the Genoveva Castle in the town of Mayen

• Sauerland: Slate Mining and Heritage Museum Holthausen
• Thuringian Slate Mountains: Thuringian- Franconian Slate Street: On this 100 km long threads road are Slate Museum Ludwig city
• German Slate Museum, Steinach
• Slate Park Lehesten, Lehesten
• Slate Factory Lothar salvation Geroldsgrün
• Mine Morassina, wrought box

Foreign countries

• Welsh Slate Museum ( the slate industry in Wales)

• Musée de l' Ardoise in 49800 Trélazé ( département of Maine -et -Loire, Pays de la Loire)

• Musée de l' Ardoise in Haut- Martelange L- 8823, Luxembourg

• Belgium: 6880 Bertrix

Gallery

Boppard on the Rhine: older house ( natural slate )

Slate Covered Houses in Goslar

Retaining walls of slate in the Botanical Garden Hamburg

A number of shale

Church and houses in Wurzbach covered with slate and encased.

Brilon partial view of a slate roof