Rock crystal is a water-transparent, colourless variety of quartz. The formation of rock crystal is mainly associated with medium- and low-temperature hydrothermal processes during the formation of cavities (crystal vaults) in quartz, quartz-feldspar, quartz-carbonate veins and in granite pegmatites. In such cavities, its crystals sometimes reach a large size (to 1.5 m in length).
Hydrothermal deposits of the Southern and Subpolar Urals, the Caucasus, Yakutia, Pamir, Kazakhstan, pegmatites of Volyn (Ukraine), etc. are famous for the best quartz crystals and druses.
Defect-free rock crystals have piezoelectric properties and are used in radio engineering (radio wave stabilizers, resonators, tube generators). Piezoelectric quartz is also used for echo sounders – devices detecting underwater rocks, measuring the sea depth and for underwater communications.
In the optical mechanics, rock crystals are used for various optical devices (prisms for spectrographs, lenses and quartz wedges for microscopes, preparations for polarimeters, saccharimeters, etc.).
Rock crystal is used in jewellery, as well as for melting special quartz glasses, which are widely used in various industries.