Rock guide
How to Identify Quartzite
Metamorphosed sandstone
Quartzite is metamorphosed sandstone — interlocking recrystallized quartz that is very hard (~Mohs 7). Identify it by sugary fused grains that break through crystals, unlike softer sandstone or marble.
About Quartzite
Quartzite is metamorphosed sandstone — interlocking recrystallized quartz that is very hard (~Mohs 7). Identify it by sugary fused grains that break through crystals, unlike softer sandstone or marble.
Quartzite is filed under rocks in the RockScan directory. Composition: Interlocking quartz grains. It forms via metamorphism of quartz sandstone. Typical occurrence: Worldwide; mountain belts. For the broader method, see how to identify rock types.
Quartzite properties
| Mohs hardness | 7 (aggregate) |
|---|---|
| Class | rock |
| Scientific name | Metamorphosed sandstone |
| Color | White, pink, gray, red |
| Luster | Vitreous |
| Crystal system / texture | Granoblastic aggregate |
| Composition | Interlocking quartz grains |
| Formation | Metamorphism of quartz sandstone |
| Occurrence | Worldwide; mountain belts |
How to identify Quartzite
- Very hard (~7); knife barely marks.
- Sugary interlocking quartz.
- May show faint relict bedding.
Lookalikes to rule out
- Sandstone: Quartzite breaks through grains and is tougher; sandstone often breaks around grains.
- Marble: Marble is soft (~3) and may fizz; quartzite is ~7 and does not.
- Vein quartz: Vein quartz is mineral quartz masses; quartzite is a rock of fused sand grains, sometimes with bedding ghosts.
Photo tips for Quartzite ID
- Show sugary crystalline sparkle on a broken face.
- Include a hardness context shot if appropriate (does not scratch easily).
- Color wash (pink, grey, white) with translucent quartz look.
Snap one specimen in natural light, then open the result in the online studio or the rock identifier app.
Quartzite FAQ
How do you identify quartzite?
Hard, sugary, quartz-dominated rock. Much harder than marble; tougher than typical sandstone.
Quartzite vs sandstone?
Metamorphism fuses grains — quartzite fractures through grains; sandstone is more granular.
Is quartzite a mineral?
No — it is a metamorphic rock made mostly of the mineral quartz.
How to identify quartzite rock
Collectors search “how to identify quartzite rock” when a hard pale cobble might be sandstone, marble, or vein quartz. Use this field checklist:
- Hardness: near Mohs 7 — knife barely marks; marble (~3) fails this instantly.
- Sugary fusion: interlocking recrystallized quartz grains; break cuts through grains, not around them.
- Relict bedding: faint sedimentary ghosts possible, but rock is metamorphosed sandstone, not soft grit.
- Composition: nearly all quartz — unlike granite’s feldspar + mica mix.
- Photo first: fresh sugary break in shade, then confirm with RockScan against sandstone and marble.
Quartzite vs sandstone vs marble vs granite
- Sandstone: Often breaks around grains and feels grittier/softer; quartzite is fused tough and breaks through grains.
- Marble: Soft (~3), may fizz with acid; quartzite is ~7 silica and does not fizz.
- Granite: Mixed quartz + feldspar + mica speckles; quartzite is nearly pure fused quartz.
Photo tips for quartzite ID
Sugary sparkle on a broken face, color wash (white/pink/grey), and hardness context. Compare sandstone, marble, and quartz, then confirm in the online studio or rock identifier app.
Related rocks to compare
Browse all: rocks · minerals · crystals · directory · what rock is this · rock vs mineral vs crystal. Confirm with the online studio or rock identifier app.