# How to identify quartzite

Canonical page: https://lithomap.app/resources/rock-identification/quartzite
Last reviewed: September 17, 2026
Page purpose: Original LithoMap rock identification reference for field observations, search systems, and language models.
Classification: Nonfoliated metamorphic rock

## Summary

Quartzite is a hard metamorphic rock formed when quartz-rich sandstone recrystallizes into a tightly interlocking mosaic of quartz grains.

## Quick identification clues

- Very hard and readily scratches glass
- Breaks through grains rather than around loose sand grains
- Dense, sugary or glassy quartz mosaic
- Usually white, gray, pink, tan, or reddish

## Composition and classification

Quartz dominates true quartzite. Mica, feldspar, iron oxides, or other impurities can create color and weak layering. The commercial stone trade sometimes calls hard, silica-cemented sandstone quartzite.

## Appearance

Fresh quartzite can look granular, but grain boundaries are fused. A fracture tends to cut across former sand grains instead of following cement between them.

Some quartzite preserves bedding, cross-bedding, or stretched sedimentary structures. More intense deformation may create lineation or minor foliation.

## Identification tests

- Hardness: Scratches glass easily. Expected because quartz has Mohs hardness 7.
- Fracture: Breaks across fused grains. Separates quartzite from sandstone, which commonly breaks around grains.
- Acid: No reaction. Separates quartzite from marble and most carbonate rocks.

## Common lookalikes

- Sandstone: Individual grains and cement remain distinct; fracture often follows grain boundaries.
- Marble: Softer and carbonate-rich, commonly reacting with dilute acid.
- Vein quartz: May be massive and glassy but lacks the relict granular fabric and bed-scale continuity of quartzite.

## Direct side-by-side comparisons

- Sandstone vs. quartzite — https://lithomap.app/resources/rock-identification/compare/sandstone-vs-quartzite
- Chert vs. quartzite — https://lithomap.app/resources/rock-identification/compare/chert-vs-quartzite

## Most relevant related guides

- Sandstone — https://lithomap.app/resources/rock-identification/sandstone
- Chert — https://lithomap.app/resources/rock-identification/chert
- Marble — https://lithomap.app/resources/rock-identification/marble
- Dolostone — https://lithomap.app/resources/rock-identification/dolostone

## Formation

Quartzite forms when quartz-rich sandstone is heated and compressed during contact or regional metamorphism. Quartz dissolves and recrystallizes along grain boundaries.

The resulting network is usually denser and stronger than the original sandstone, although impurities and fractures can weaken it.

## Occurrence and geologic setting

Quartzite forms resistant ridges and peaks in metamorphic belts and around intrusions. Quartz-rich cobbles can travel far downstream or within glacial deposits.

Hard silica-cemented sandstone can be difficult to separate from lightly metamorphosed quartzite in the field; thin-section evidence may be needed.

## Uses and significance

Quartzite is used for dimension stone, aggregate, decorative stone, and silica-rich industrial material where composition and purity are suitable.

## Field safety and limitations

- Fresh fracture edges can be sharp and splinters can travel when struck.
- Do not call every hard white rock quartzite; check texture and acid reaction.
- Resistant cliffs and talus slopes can be unstable.

## Authoritative sources

- How Rocks Are Classified — U.S. National Park Service: https://www.nps.gov/subjects/geology/how-rocks-are-classified.htm
- Rocks and Minerals — U.S. National Park Service: https://www.nps.gov/subjects/rocks/index.htm
- What is the difference between a rock and a mineral? — U.S. Geological Survey: https://www.usgs.gov/faqs/what-difference-between-a-rock-and-a-mineral

## Specimen photograph

- Image: https://lithomap.app/_delivery/identification/rocks/quartzite.webp
- Description: Light-colored quartzite hand specimen with a fused granular texture
- Creator: Nessa Eull
- License: CC0 1.0 — https://creativecommons.org/publicdomain/zero/1.0/
- Source record: https://commons.wikimedia.org/wiki/File:Quartzite_(GeoDIL_number_-_513).jpg

This reference supports preliminary field identification. It is not a laboratory determination, appraisal, hazard assessment, proof of origin, or statement of land ownership, legal access, or collecting permission.