Quartzite

Quartzite is a metamorphosed rock that may resemble marble by its colour and texture. All individual grains are usually the same size and lack any preferred orientation. The colour may vary from white to light grey, but yellowish or red varieties are also common. Quartzites originate from regional (increased pressure and increased temperature) metamorphism of sedimentary sandstones and/or conglomerates. To be classified as a quartzite, the rocks' content of quartz should exceed 70 %, the exposed sample has 90 % quartz. Quartzites are very hard and resistant to erosion, but often they are very fragile.

The grey colour of quartzite from Vysoký kámen Rock near Kraslice is caused by Fe and Ti minerals, namely hematite and ilmenite, finely and homogeneously dispersed throughout the rock. The veins in orthogonal network and lenses of pure white quartz are the result of silica-rich fluids released during metamorphosis which then precipitated in the cracks.

Quartzites occur as small islets in phylites, schists, and gneisses in several parts of Krušné hory Mts., i.e. around Klínovec. They can also be found in other metamorphic terrains including Smrčiny Mts., Český les, and Slavkovský les Highlands.

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