What is slate


Author: Torsten Purle (steine-und-minerale.de) | Last update: April 15, 2021

Slate - properties, formation and use

english: slate | French: ardoise

Slate - A plate-like rock

The name slate comes from the Middle High German Schiver and was mainly used by miners of the Middle Ages to describe the character of some stones that were processed or used in Splinters or plates disintegrate, or as the linguist Justus Georg Schottel (1612 to 1676) wrote in 1663 that the word slate from "slate: split" descends.

Properties of slate

definition: Slates are not independent rocks, but a type of structure of metamorphic rocks.

A closer look at slate reveals that it is slate consists of many plates and leaf-like structures lying on top of one anotherwhose mineral arrangement indicates either lineation (linear structure) or foliation (sequence of cleavage surfaces) - an observation made by Johan Gottschalk Wallerius (1709 to 1785, chemist and mineralogist) as early as 1763: "All slate breaks and clumps into layers, panes and tablets; the thinner the more noble ".

The mineral composition of slate is in the form of the Main issues (Minerals, the majority of which are) determined by clay minerals (sheet silicates), quartz and feldspars.

Subordinate as so-called. Side effects With a share of up to five percent in the composition and often eponymous for various slates, the minerals of the

in appearance.

This is characteristic of the fine to medium-grained rock parallel adjustment of the building-up batch parts. The minerals lying next to each other mean that, in contrast to precisely divisible, plate-like sedimentary rocks, the rock does not break flat, but has fracture points. Nevertheless, the cleavage areas can be easily divided from one another.

The The color of slate varies with its composition and the minerals it contains from gray (e.g. amphibolic slate) to black (clay slate) through green (green slate), blue to silver and whitish (white slate).

Formation and distribution of slate

The formation of slate takes place over several million years.
Are a prerequisite for slate formation initially loosely deposited mineralsresulting from the weathering of rocks with corresponding mineral contents.
These will superimposed by further sediments and solidified diagenetically to form claystone.

To achieve the development to slate are the following step increased temperature and pressure conditions required. As a result of the metamorphosis, the mixture parts are melted, partially converted and then recrystallized - adapted to the prevailing thermodynamic conditions.
If the rocks are exposed to unilateral pressure, the crystals are adjusted next to each other, plate-like or slate-like.

Slate is very common around the world; Sometimes names of mountains refer to possible slate deposits, e.g. Thuringian or Rhenish slate mountains, Moselle slate, to schisty sites. Slate can also be found in countries with a share of the Alps, in the Balkans, in Zambia, Namibia, Mozambique, USA and in the Andes / South America.

Importance and use of slate

Slate is used in a variety of ways, be it as roof covering or facade cladding (very often seen in towns and villages in the Thuringian Slate Mountains), writing pad (slate), tiles or building material, so that as early as 1777 Carl von Linné (1707 to 1778, doctor and naturalist) Schist or Schistus differentiated according to its use in "probing stone, whetstone, grindstone, table stone, writing slate and roofing slate".

In order to illustrate the economic importance of slate, the Professional Association of German Geoscientists (BDG) has awarded Rock of the Year 2019.

See also:
⇒ Differentiate between clay slate and mica slate
⇒ The garnet mica slate from the Ötztal
⇒ Ore - metal containing minerals and rocks

⇒ Schottel, J. G. (1663): Schiefer. IN: Detailed work Von der Teutschen HaubtSsprache. The third book / it deals with word assembly / that is: of artful assembly and good use of the German words / including various comments and explanations / also other things related to the linguistic being
⇒ Wallerius, J. G. (1763): Schiefer. IN: Mineralogy, or mineral kingdom
⇒ Linnaeus, C. v. (1777): Schiefer, Schistus. IN: The knight Carl von Linné's Royal Swedish personal physician complete natural system of the mineral kingdom. Volume 17
⇒ Pellant, C. (1994): Stones and Minerals. Ravensburger nature guide. Ravensburger Buchverlag Otto Maier GmbH
⇒ Schumann, W. (1991): Minerals rocks - characteristics, occurrence and use. FSVO nature guide. BLV Verlagsgesellschaft mbH Munich
⇒ Maresch, W., Medenbach, O .; Trochim, H.-D. (1987): The colored natural guide rocks. Mosaik Verlag GmbH Munich
⇒ Murawski, H. (1992): Geological Dictionary. Ferdinand Enke Verlag Stuttgart
⇒ Okrusch, M. and S. Matthes (2009): Mineralogy: An introduction to special mineralogy, petrology and deposit science. Springer Verlag Berlin Heidelberg