Quartzite

Physical Properties

Hardness: 7 (Mohs scale), Color: White to light grey (with pinkish/iron staining), Luster: Vitreous to dull, Crystal structure: Trigonal (granular texture), Cleavage: None (conchoidal fracture), Specific Gravity: 2.6 - 2.65

Formation & Geological History

Formed through the regional metamorphism of quartz-rich sandstone. High heat and pressure cause the quartz grains to recrystallize and fuse together, losing their original sedimentary structure. It can be found in various geological ages, often forming prominent ridges.

Uses & Applications

Used as a decorative stone in architecture, as crushed stone for road construction, as ballast for railways, and as a source for silica in glass and ceramic industries.

Geological Facts

Quartzite is so tough that it often outlasts the surrounding rocks on mountainsides. Unlike sandstone, which breaks around the grains, quartzite is so well-fused that it breaks straight through the quartz grains.

Field Identification & Locations

Identify in the field by its inability to be scratched by a steel knife (unlike marble) and its lack of reaction to acid. It is commonly found in fold mountain belts globally.

Identified on: 4/22/2026

Mode: Standard