Bluestone

Blaustein is a trade name for different rocks. Among the most famous blue stones include:

• Right Blaustein - a slate from the Unterordovicium with an age from 488.3 to 478.6 million years ago and
• Aachener Blaustein - a limestone from the Middle to Upper Devonian with an age from 392 to 374.5 million years ago and the Lower Carboniferous with an age from 359.2 to 328.3 million years ago.

Demarcation

Since the quarries near Aachen are exhausted, no more high-quality material can be produced there. As a substitute Belgian granite is usually used, which is often referred to as " Petit Granit ", whose characteristic feature is the massive occurrence of Seelilienstilgliedern ( crinoids ). The stone is also mined today in Belgium, at Soignies ( Hainaut) and Tournai ( Ourthe valley ). Belgian granite is also a limestone and no igneous rock as is the granite.

The English word "blue stone" refers to a dolerite rock, from which there are also some stone blocks of Stonehenge.

Right Blaustein

Right Blaustein came from the right place at St. Vith in eastern Belgium. The bluish slate was won there first in opencast and underground mining from 1880. Before the First World War, the mine was exhausted and was closed. Since 18 May 2007, it has reopened as a visitor mine.

Aachener Blaustein

Aachener Blaustein is the trade name for a dark gray to black limestone from different geological systems, which had been dug on the northern edge of the Fens high in the southeast of Aachen. Presumably the name comes from the Flemish masons who came to the city fire in the 17th century to Aachen and here the name Blaw Stejn introduced. Already Hermann von Weinberg (1518-1597), councilor in Cologne, describes in his memoirs, the book Weinberg, grave stones of bluestone.

The rocks of the Lower Walhorn - Massenkalk from the Givetian, the Upper Walhorn - Massenkalk from the Frasnian and Frasnian - Knollenkalk are among the most used Blaustein varieties of the Devonian. The Lower, Middle and Upper Carboniferous were processed as bluestone from the Lower Carboniferous. A characteristic feature of the Aachen blue stones is the occurrence of numerous fossils such as bryozoans ( Bryozoa ), goniatites, Hydrozoa, corals and stromatoporoids. The stone has freshly cut and polished an almost black, blue-gray to blue-green color. This will change to white gray when it is exposed to long period of weathering.

Blaustein was used as a stone for window surrounds, door sills, stairs, flooring, grave times and church interiors as altars and baptismal font. Many baroque buildings of Aachen and the surrounding area as well as the base of the Gothic choir hall of Aachen cathedral is built of blue stone. The medival channel for Pau was made ​​of this material.