Quartzite

Physical Properties

Hardness: 7 on Mohs scale; Color: White to yellowish-gray; Luster: Vitreous to dull; Crystal structure: Trigonal (granular texture); Cleavage: None; Specific gravity: 2.6–2.7

Formation & Geological History

Formed through the regional or contact metamorphism of quartz-rich sandstone. Under intense heat and pressure, the individual quartz grains recrystallize into a dense interlocking mosaic.

Uses & Applications

Used as a decorative stone in architecture, as crushed stone for road construction, in the manufacture of glass and ceramics, and as a durable material for countertops.

Geological Facts

Quartzite is so tough that it often outlasts the surrounding rocks during erosion, frequently forming the caps of ridges and mountains. It is significantly harder and more durable than the sandstone from which it originated.

Field Identification & Locations

Identify in the field by its hardness (it will scratch glass) and its sugary, granular texture. Unlike marble, it will not fizz with acid. Common in orogenic belts and precambrian shields.

Identified on: 5/11/2026

Mode: Standard