metamorphic

River Stone (likely Quartzite or Sandstone)

Metamorphosed Quartz-rich Rock (SiO2)

AI-generated identification · may be incorrect

Hardness: 7 (Mohs scale), Color: Tan/Grey, Luster: Dull to earthy, Texture: Fine-grained and smooth due to water erosion, Structure: Granular

Identified July 20, 2026More metamorphic →

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Physical properties

Hardness: 7 (Mohs scale), Color: Tan/Grey, Luster: Dull to earthy, Texture: Fine-grained and smooth due to water erosion, Structure: Granular

Formation & geological history

Formed through the metamorphism of quartz sandstone under high heat and pressure, then weathered and rounded by high-energy river or glacial transport over thousands of years.

Uses & applications

Commonly used in landscaping, as a building material in masonry, in home decor, and sometimes as a substrate for aquariums.

Geological facts

River stones get their characteristic smooth, oval shape from a process called saltation, where they are bounced and rolled along a riverbed, grinding down sharp edges over time.

Field identification & locations

Identify in the field by its smooth, rounded surface and resistance to scratching steel. Commonly found in riverbeds, glacial deposits, and along coastlines.