Quartzite

Physical Properties

Hardness: 7 (Mohs scale); Color: Grayish-white with pinkish or purplish tints; Luster: Vitreous to dull; Structure: Granofelsic; Cleavage: None; Specific Gravity: 2.6-2.7

Formation & Geological History

Formed through the regional metamorphism of quartzose sandstone. This occurs when sandstone is subjected to intense heat and pressure, causing quartz grains to recrystallize and fuse together.

Uses & Applications

Used as crushed stone for road construction, railway ballast, and in the manufacturing of glass and ceramics. It is also a popular material for ornamental stone and interior decor.

Geological Facts

Quartzite is so tough that it often outlasts the surrounding rocks in weathering processes, frequently forming hills and ridges. It is often confused with marble but can be distinguished because quartzite will not react to acid and is much harder.

Field Identification & Locations

Identify in the field by its sugary texture and extreme hardness (it will easily scratch glass). Common in mountain ranges and regions with ancient metamorphic crust. Look for fractures that cut through the grains rather than around them.

Identified on: 4/13/2026

Mode: Standard