sedimentary
River Stone / Cobble
Polymictic lithic conglomerate or sandstone cobble
AI-generated identification · may be incorrectHardness varies from 6 to 7 depending on mineral content; color ranges from dark grey to brown; luster is dull; amorphous rounded shape due to water transport.
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Physical properties
Hardness varies from 6 to 7 depending on mineral content; color ranges from dark grey to brown; luster is dull; amorphous rounded shape due to water transport.
Formation & geological history
Formed through the mechanical weathering, erosion, and prolonged fluvial transport of parent bedrock in river environments over thousands to millions of years.
Uses & applications
Used extensively in landscaping, decorative garden pathways, construction aggregate, and occasionally in masonry.
Geological facts
Water-worn stones like this are smoothed by continuous abrasion against other sediments along riverbeds, a process called attrition.
Field identification & locations
Found abundantly in and along active or ancient riverbeds worldwide; identified by its smooth, rounded morphology and durable mineral composition.
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