Quartzite

Physical Properties

Hardness: 7 on Mohs scale; Color: Yellowish-tan to earthy brown; Luster: Vitreous to dull; Crystal structure: Trigonal/Hexagonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.7

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, creating an extremely durable rock.

Uses & Applications

Used as a decorative stone in landscaping, as crushed stone for road construction, in the manufacturing of glass and ceramics, and occasionally for primitive tools due to its hardness.

Geological Facts

Quartzite is so tough that it often outlasts the surrounding rocks during erosion, frequently forming the peaks of mountains and ridges.

Field Identification & Locations

Identify in the field by its inability to be scratched by a steel knife and its grainy, sandpaper-like texture that doesn't rub off. It is commonly found in mountainous regions or ancient riverbeds as rounded cobbles.

Identified on: 4/13/2026

Mode: Standard