Phylite

Phylite is a remarkable rock known for its satin-silver and sometimes up to goldish shine. Such a shiny appearance is due to a high content of mica - sericite, which is a fine-grained variety of muscovite. Another flaky mineral – chlorite, adds the greenish shade to this rock. Quartz and biotite are other important minerals building this rock. Another characteristic feature of phylite is its fine-grained, finely schistose texture. This texture is responsible for the rocks platy splitting, making phylites useful as pavements, sidings, and roofing shingles.

Phylites are formed by regional metamorphosis from aleuro-pelitic sedimentary rocks – claystones and shists. The transformation to a phylite occurs during low temperature and low pressures. An increase in temperature and pressure would lead to the formation of mica-schists and eventually gneisses instead of phylites.

Phylites are widespread around Hranice near Aš, Cheb and Kraslice. Well-known Holubí skály (Pigeons rocks) at Český mlýn hermitage not far from Potůčky is a spectacular example of phylites. Phylites also form the ancient basement rocks of the southeastern part of Karlovy Vary Region, around Žlutice and Chyše.

Sample donated by Lesy České republiky, s.e. – Regional directorate Western Bohemia.