In short. In a ceramic body, quartz is the non-plastic filler that sets thermal expansion and limits deformation in firing. Vitreous china sanitaryware carries 17 to 31% quartz. Buyers check Fe2O3 and TiO2 because they colour the fired body, and fineness because coarse quartz raises the risk of cracks on cooling. India’s IS 11464:2021 caps Fe2O3 at 0.25% for white bodies.
What does quartz do in ceramics?
In a body, quartz is the non-plastic filler. It reduces plasticity, raises the vitrification temperature and sets the thermal expansion of the fired piece. Residual quartz and mullite form the framework that keeps the body from deforming in the kiln.
In a glaze, silica dissolves into the melt. More silica lowers glaze expansion, which helps prevent crazing.
Published compositions put vitreous china sanitaryware at 17 to 31% quartz, and ceramic tiles at 8 to 30%, with an average of 23%.
What do ceramic buyers check?
| Parameter | Grade 1: white bodies, transparent glazes | Grade 2: opaque-glazed bodies |
|---|---|---|
| SiO2 | 98% or more | 96% or more |
| Fe2O3 | 0.25% or less | 1.0% or less |
| Al2O3 | 1.0% or less | 2.0% or less |
| TiO2 | 0.1% or less | 1.0% or less |
| CaO | 0.5% or less | 1.0% or less |
| Loss on ignition | 0.5% or less | 1.0% or less |
The same standard sets moisture at 2% or less and relative density at 2.5 to 2.7. It asks for a white fired colour with no coloured specks at 1200 °C in an oxidising atmosphere, and a grain size agreed with the buyer, normally finer than 75 µm.
Glaze makers often use finer silica. A 325 mesh (45 µm) grade dissolves more readily in a glaze than a 200 mesh grade, while bodies often use the coarser grade for its effect on expansion.
Which standards and test methods apply?
- IS 11464:2021, Quartz for Ceramic Industry (India).
- ASTM C371, Wire-Cloth Sieve Analysis of Nonplastic Ceramic Powders.
We found no ISO or EN product standard for ceramic quartz, so the buyer’s own specification sets the limits.
Where does crushed vein quartz fit?
- Quartz changes volume sharply near 573 °C. Large undissolved particles raise the risk of dunting, cracks that form as the ware cools. Top size matters as much as the median.
- Steel balls and mill liners wear, and the iron shows as specks in a white body. Pebble mills with flint media have long been used to avoid it, and magnetic separation is a common way to remove iron.
- Run a fired-colour test on the sample at your own kiln temperature. It shows specks a chemical table can miss.
What should a ceramic quartz request include?
- The end use: white body, opaque-glazed body or glaze.
- Limits for Fe2O3, TiO2, Al2O3, CaO and loss on ignition, with the analysis method.
- The particle-size distribution: top size, the share over 45 or 75 µm, and D50 if you test by laser diffraction.
- Fired colour and speck limits, and the firing temperature.
- Moisture, packing, monthly volume and destination port.
What we supply
We supply quartz powder milled from Sri Lankan vein quartz to the mesh or micron grade you set. Each batch ships with a Certificate of Analysis reporting SiO2, Fe2O3, Al2O3, TiO2, CaO, Na2O, K2O, moisture and particle-size distribution. Send your specification and we tell you what we can hold from shipment to shipment.
Sources
- Cerâmica (2017), vitreous china sanitaryware bodies
- ceramica.info (2025), quartz content of Italian ceramic surfaces
- Bureau of Indian Standards, IS 11464:2021, Quartz for Ceramic Industry
- Digitalfire Reference Library: Silica
- Digitalfire Reference Library: Quartz inversion
- ASTM C371, Wire-Cloth Sieve Analysis of Nonplastic Ceramic Powders
- US Bureau of Mines IC 7139, Grinding pebbles and tube-mill liners (1940)
- Xie et al. (2023), review of quartz purification routes, Minerals and Mineral Materials
Industry context. Figures on this page describe common industry practice and published standards, from the sources listed. They are not a specification for our material. Our values are on each batch COA. Published October 2026.