metamorphic
River Stone (likely Quartzite or Sandstone)
Metamorphosed Quartz-rich Rock (SiO2)
Hardness: 7 (Mohs scale), Color: Tan/Grey, Luster: Dull to earthy, Texture: Fine-grained and smooth due to water erosion, Structure: Granular
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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.
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