Pitchstone

Pechstein as volcanic glass, a rock of volcanic origin with a water content of up to 8 percent by mass. Pechstein is one of the rhyolites such as obsidian and perlite. The term was coined in 1759 by Pechstein Christian Friedrich Schulze. Its formation is not understood up to now, however, the devitrification of obsidian is discussed as one of the possible mechanisms among others.

Properties

The color of Pechstein varies depending on the deposits. It ranges from brown to red and green to deep black. The shiny black as pitch gave the rock its name. Pechstein has a conchoidal fracture, and usually small phenocrysts of quartz, feldspar, pyroxene or hornblende. The rock may have a mottled or fat shiny appearance and show through the phenocrysts a porphyritic texture.

Occurrence

Pechstein deposits in Germany are in the Rotliegendschichten around Zwickau, in the Garsebacher Switzerland, community Klipphausen at Meissen, and in the Black Forest. An important individual information from the Upper Carboniferous, for example, the " ball Pechstein of Spechthausen " in Tharandter forest. Other important Pechstein deposits can be found on the Scottish islands of Arran, Mull, Skye and Eigg (An Sgurr ).

Use

The Pechstein of Arran was made into artifacts since the Mesolithic. In the Neolithic Pechstein or artifacts from Pechstein was also exported to Ireland.