Quartzite is a metamorphic rock formed when quartz sandstone is transformed under high pressure and temperature. The original sand grains fuse into a dense mass consisting almost entirely of quartz. That makes quartzite considerably harder and denser than the sandstone it came from.
Properties
- Hardness — around 7 on the Mohs scale, the same as pure quartz, so very scratch resistant
- Low water absorption — denser than sandstone, so it takes up less dirt and is frost resistant
- Acid resistant — quartz is chemically stable, so quartzite is unaffected by acidic cleaners and acid rain. That clearly distinguishes it from marble and limestone
- Cleavable — many quartzites split along planes, producing natural slabs with a lively surface
Note the trade description: “quartzite” is also used commercially for stones that are geologically sandstone, and there are quartz composites that imitate quartzite but are bound with resin. If in doubt, ask for a technical data sheet giving water absorption and flexural strength.
Where it is used
| Use | Point to watch |
|---|---|
| Internal floor tiling | Very hard wearing; a hard surface, so allow for acoustic treatment |
| Paving and patio slabs | Frost resistant; choose a riven surface for adequate slip resistance |
| Cladding | Often used as stone strip or as a slab on a support system |
| Pool surrounds and wet rooms | A good choice thanks to low absorption; check the slip resistance rating |
| Worktops | Scratch and acid resistant, but harder to work than granite |
Practical tips:
- Working it costs tooling — cutting and drilling calls for diamond tooling; work wet, partly because of the silica dust
- Sealing — a colourless impregnating sealer keeps oil and wine stains out of paler varieties
- Adhesive — use a white tile adhesive under pale quartzite, or the dark adhesive will show through
Related terms
- Quartz
- Sandstone
- Natural stone
- Metamorphic rock
- Frost resistance
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