Blauer Stein

The Blue Stone is a rock formation near the village of Randen at around 836 meters above sea level. The rock is now a protected monument of nature and together with its environment, a popular recreation area for the city Blumberg. He has the color of anthracite, which is strongly reminiscent of the blue name. But is weathering the outermost layer of the blue stone gray / brown discoloration (see picture below).

Petrology

The Blue Stone consists of a basalt -like rock, but which corresponds to the chemical composition of a Melilithits. The special feature of this rock is that it does not contain feldspars but only melilite ( a foid ). The rock is so quarzuntersättigt, has become so associated with too small a silicon dioxide content of the basalts.

The olivine nephelinites from blue stone are considered the westernmost occurrence of hegau volcanics.

Included in the rock can be found numerous fragments of the upper mantle ( peridotite xenoliths - ). These were swept in the rapid rise of magma from the melt in the Earth's interior and transported to Eruptionsort.

Formation

The Blue Stone is created in the time of hegau volcanism and is a typical example of the relief inversion. Originally there was a trough at its present location into which flowed the lava. During solidification, by the slow process of cooling the still visible up to twelve meters high, hexagonal shaped basalt columns formed. The basalt columns which were after the emergence in the earth, were visible as the surrounding softer rock eroded away was.

Mythology

The Blue stone was probably used, for example, by the Celts and Alemanni, used as a place of worship. In the basalt columns often faces of interpretations, especially in very dense fog. Today is a landmark of Blumberg region are the pillars.