period: difficult to define

excavation site: Czernica mine pit, Strzegom (Lower Silesia)

Quartz is a silicon dioxide, the most abundant mineral in the Earth’s continental crust (comprises 12.5% of its weight). Regular beach sand is mostly composed of quartz grains. In Strzegom pegmatites, intrusive rocks of granitoid massif, it creates large crystals of up to 60 cm length.

It is difficult to determine its age. The granites in which the pegmatites were created date back to the end of the Carboniferous and the beginning of the Permian, while quartz formed in them in later geological periods. In the smoky version it is slightly coloured because its inner structure was a subject to natural radiation.

The piece comes from the collection of Geological Museum of the National Geological Institute – National Research Institute.