Quartzite

Physical Properties

Hardness: 7 (Mohs scale), Color: Pinkish-red to brownish, Luster: Vitreous to dull, Crystal structure: Granular/Massive, Cleavage: None, Specific gravity: 2.6 - 2.7

Formation & Geological History

Formed through the metamorphism of quartz-rich sandstone under extreme heat and pressure, typically in convergent plate boundaries during mountain-building events like the Proterozoic eon.

Uses & Applications

Used in construction as road ballast, roofing granules, and decorative stone in landscaping or interior design due to its durability and color.

Geological Facts

Quartzite is so tough that it often outlasts the mountain ranges in which it forms, eventually appearing as rounded river stones or glacial till like the specimen shown.

Field Identification & Locations

Identify by its ability to scratch glass and its sugary, granular texture. Commonly found in areas with ancient bedrock or glacial deposits, such as the Upper Midwest of the US.

Identified on: 5/15/2026

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