Rock crystal
is a colorless, transparent variety of quartz. They are characterized by impeccable cleanliness, strong gloss, and high resistance to acids and alkalis. It is only dissolved in hydrofluoric acid. Rock crystals weighing many tons are known, but stones worth polishing are rare. Famous are the small, water-transparent crystals from the Carrara marbles (Italy) and the so-called diamonds from Herkimer (Herkimer County, New York) - their diameter does not exceed 1 cm.
Silicon
is a chemical element from the group of semi-metals in the periodic table. In the form of single crystals, it is widely used in the electronics industry.
Citrine
is a variety of quartz. It is transparent yellow to orange-brown, and the name comes from the old French word “citrin”, which means yellow. Natural citrine can be found in the same environment as smoked quartz, however it could be synthetically-grown from seeds of natural rock crystal.
