metamorphic

Quartzite river stone

Quartzite (SiO2 silicon dioxide)

AI-generated identification · may be incorrect

Mohs hardness of 7, color ranges from grey to tan with dark banding, earthy to vitreous luster, granular micro-crystalline structure, smooth water-worn texture.

Identified July 10, 2026More metamorphic →

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Physical properties

Mohs hardness of 7, color ranges from grey to tan with dark banding, earthy to vitreous luster, granular micro-crystalline structure, smooth water-worn texture.

Formation & geological history

Formed when quartz-rich sandstone is subjected to heat and pressure (metamorphism). Usually found in riverbeds or coastal areas where erosion has rounded the specimen over long periods.

Uses & applications

Commonly used in landscaping, road construction as aggregate, and as decorative river rocks. High-purity quartzite is used to produce glass and metallic silicon.

Geological facts

Quartzite is extremely durable and weather-resistant; it is often harder than the steel blade of a knife. The banding seen in this specimen likely reflects the original sedimentary layers of the parent sandstone.

Field identification & locations

Identify in the field by its inability to be scratched by a steel nail and its grainy, sugary look on a fresh break. Common in glacial till and river basins across North America.