Quartz

Oxide	Analysis	Formula
SiO2	100.00%	1.00
Oxide Weight		60.10
Formula Weight		60.10

Notes

Quartz is the mineral form of silica powder used in ceramic glazes and clay bodies. It is the mineral that silica "wants to be" when cooled from molten to solid (it can be other things depending on the speed of cooling). Unlike silica glass, the quartz phase of silica is subject to inversion and accompanying volume and form change when fired through 573C. Room temperature quartz is called alpha quartz, beta quartz exists only above 573C.

Quartz sand is often used in bodies as grog for texture and to increase thermal expansion. Powdered quartz is used in glazes and bodies also. Quartz of very fine particle size (-400 mesh) will typically enter the feldspathic melt or convert to cristobalite during firing if fluxes are lacking, coarse powdered grades help to 'squeeze' glazes into fit. Intermediate sizes (200-300 mesh) seem to be best however, since their greater surface area exerts more compressive squeeze per unit.

Crystalline silica is used in agriculture, paving, brick and tile, concrete, cleansers, foundry casting, ceramics and pottery, paint, glass, soaps, fiber glass, electronics, plaster, sandblasting, industrial effluent filtration, drinking water filtration, hazardous waste control.

Related Information

Here is why quartz is good in clay bodies

The piece on the left is 65% ball clay and 35% nepheline syenite. The one on the right is 65% kaolin and 35% nepheline syenite. Both fire vitreous at cone 6. But the glaze is crazing on the kaolin and not on the ball clay. This is because the ball clay contains significant quartz, that raises the thermal expansion and that puts the squeeze on the glaze and prevents the crazing.

Quartz Rock Rose

Rutilated quartz

Links

URLs	http://en.wikipedia.org/wiki/Quartz_inversion Wikipedia quartz inversion
Minerals	Quartz
Glossary	Co-efficient of Thermal Expansion Ceramics are brittle and many types will crack if subjected to sudden heating or cooling. Some do not. Why? Differences in their co-efficients of thermal expansion.
Temperatures	Quartz inversion (alpha-beta) (540C-600C)
Typecodes	Silica/Quartz Quartz is very abundant and there are many grades and name brands.
Typecodes	Generic Material Generic materials are those with no brand name. Normally they are theoretical, the chemistry portrays what a specimen would be if it had no contamination. Generic materials are helpful in educational situations where students need to study material theory (later they graduate to dealing with real world materials). They are also helpful where the chemistry of an actual material is not known. Often the accuracy of calculations is sufficient using generic materials.
Typecodes	Silica/Quartz Quartz is very abundant and there are many grades and name brands.
Hazards	Cristobalite Toxicity
Hazards	Quartz Toxicity
Hazards	Quartz Toxicity on Clayart
Hazards	Dealing With Dust in Ceramics
Materials	Amorphous Silica
Materials	Silica
Materials	Flint
Materials	VR4/MQ4 Quartz
Materials	P30 Quartz
Materials	VR16 Quartz
Materials	Glass Sand
Materials	Crystalline Silica

Data

Frit Softening Point	1710C M
Density (Specific Gravity)	2.65

By Tony Hansen