metamorphic
Quartzite River Rock
Quartzite (primarily SiO2)
Hardness: 7 (Mohs scale), Color: tan-gray, Luster: dull to waxy when weathered, Crystal structure: Granular, Cleavage: none (conchoidal fracture), Specific Gravity: 2.6-2.7
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Physical properties
Hardness: 7 (Mohs scale), Color: tan-gray, Luster: dull to waxy when weathered, Crystal structure: Granular, Cleavage: none (conchoidal fracture), Specific Gravity: 2.6-2.7
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone under heat and pressure, subsequently weathered and rounded by fluvial (river) action.
Uses & applications
Used in construction as crushed stone, railway ballast, and frequently as decorative landscaping mulch or drainage stones.
Geological facts
Quartzite is so durable that it often survives multiple cycles of erosion and deposition. It is much harder than the sandstone it originates from.
Field identification & locations
Identify in the field by its inability to be scratched by a steel knife and its rounded, water-worn shape. Commonly found in riverbeds, glacial deposits, and coastal areas.
