Quartz, a mineral formed from igneous rock, is the most abundant mineral found on the crust of the earth. It makes up 12% of the earth's crust.
It is a major component of sand and granite.
Man-sized quartz crystals are known to exist.
Quartz appears in both macrocrystalline and microcrystalline forms.
Rock crystal is a macrocrystalline form.
Quartz's piezoelectric properties are used for controlling frequencies in watches, quartz movement clocks and radio transmitters.
It is a raw material for glass and ceramics industries.
Quartz has a trigonal crystal structure.

Science - Minerals - Rock Crystal