Quartzite

Physical Properties

Hardness: 7 (Mohs scale), Color: Dirty white to light grey with graininess, Luster: Vitreous to dull, Crystal structure: Trigonal (microcrystalline), Cleavage: None (conchoidal fracture), Specific gravity: 2.6-2.7

Formation & Geological History

Formed through the intense heating and pressure (metamorphism) of quartz-rich sandstone. Most commonly found in orogenic (mountain-building) belts where tectonic plates collide.

Uses & Applications

Used in construction as crushed stone or road ballast, as a raw material for glass and ceramics (if high purity), and sometimes as dimension stone for buildings.

Geological Facts

Quartzite is so hard and chemically resistant that it often forms the resistant ridges and peaks of mountain ranges. It is harder than the steel of a knife blade.

Field Identification & Locations

Identify in the field by its sugary texture on broken surfaces and its ability to scratch glass easily. It will not react with acid, unlike similar-looking marble.

Identified on: 4/22/2026

Mode: Standard