Quartzite

Physical Properties

Hardness: 7 (Mohs scale), Color: tan, yellow, orange (due to iron oxide staining), Luster: Vitreous to dull, Crystal Structure: Hexagonal (microcrystalline), Cleavage: Indistinct/Conchoidal fracture

Formation & Geological History

Formed through the metamorphism of quartz-rich sandstone. High heat and pressure cause quartz grains to recrystallize and fuse together into a dense, hard rock. Typically found in mountain belts and Precambrian shields.

Uses & Applications

Used as crushed stone for road construction, railway ballast, and as a decorative stone in landscaping. High-purity quartzite is used to produce glass and metallurgical-grade silicon.

Geological Facts

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

Field Identification & Locations

Identify by its hardness (scratches glass) and sand-like sugary texture. Unlike sandstone, quartzite fractures through the grains rather than around them. Found globally in metamorphic terrains.

Identified on: 5/5/2026

Mode: Standard