<Tr> <Th> Other characteristics </Th> <Td> lattice: hexagonal, Piezoelectric, may be triboluminescent, chiral (hence optically active if not racemic) </Td> </Tr> <Tr> <Th> References </Th> <Td> </Td> </Tr> <P> Quartz is a mineral composed of silicon and oxygen atoms in a continuous framework of SiO silicon--oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical formula of SiO . Quartz is the second most abundant mineral in Earth's continental crust, behind feldspar . </P> <P> Quartz crystals are chiral, and exist in two forms, the normal α - quartz and the high - temperature β - quartz . The transformation from α - quartz to beta - quartz takes place abruptly at 573 ° C (846 K). Since the transformation is accompanied by a significant change in volume, it can easily induce fracturing of ceramics or rocks passing through this temperature limit . </P>

Where can quartz be found in the world