Mixed (predominantly sedimentary and igneous)
River Rock (Glacial Cobbles)
Fluvial Alluvium (Mixed lithology including Quartzite, Basalt, and Granite)
Hardness: 5-7 on Mohs scale; Color: Multi-colored (grey, tan, white, brown); Luster: Dull to earthy; Texture: Smooth, rounded, and water-worn; Structure: Granular or massive.
- Hardness
- 5-7 on Mohs scale
- Color
- Multi-colored (grey, tan, white, brown)
- Luster
- Dull to earthy
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Physical properties
Hardness: 5-7 on Mohs scale; Color: Multi-colored (grey, tan, white, brown); Luster: Dull to earthy; Texture: Smooth, rounded, and water-worn; Structure: Granular or massive.
Formation & geological history
Formed through the weathering and erosion of pre-existing bedrock, transported by high-energy water environments like rivers or glaciers during the Pleistocene epoch. Continuous tumbling in water polishes the sharp edges into smooth ovals.
Uses & applications
Used extensively in landscaping, decorative ground cover, construction aggregate, drainage systems, and as architectural accents in gardens and ponds.
Geological facts
River rocks are geological 'time capsules' because a single handful can contain stones formed millions of years apart and from vastly different geographic regions, brought together by glacial movement or long-distance river transport.
Field identification & locations
Identify by their characteristic rounded, smooth surface and lack of sharp edges. Look for them in dry creek beds, riverbanks, and glacial moraines. For collectors, look for unique patterns or inclusions like quartz veining.
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