Quartz, SiO2, is comprised of two chains, both spirals of SiO4 tetrahedra parallel to the c axis. In the alpha-quartz structure (low temperature form to 573 oC at 1 bar), these chains are kinked and the structure has trigonal symmetry. In the beta-quartz structure (high temperature form, above 574.3 oC), the chains expand (the tetrahedra are not twisted) and the symmetry is hexagonal with a more open structure than the alpha form. The beta form is non-quenchable and not found under ambient conditions. An intermediate phase between 573 – 574.3 oC is known to exist. Quartz is a common associated phase in clay, but generally forms grains larger than clay particles (about 0.2 – 0.4 micrometers) and therefore quartz particles can be removed by size separation.

Quartzine is a rock term to describe a mixture of a fibrous [0001] variety of microcrystalline (length slow) quartz and moganite. Cf., chalcedony