sedimentary
Jasper / Chert (River Rock)
Microcrystalline Quartz (SiO2)
AI-generated identification · may be incorrectHardness of 6.5-7 on Mohs scale. Opaque, brownish to yellowish color with a dull to waxy luster. Smooth, water-worn surface.
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Physical properties
Hardness of 6.5-7 on Mohs scale. Opaque, brownish to yellowish color with a dull to waxy luster. Smooth, water-worn surface.
Formation & geological history
Formed from silica-rich fluids in sedimentary environments. Its rounded shape indicates it was transported and tumbled by water, likely in a river or stream bed.
Uses & applications
Commonly used for landscaping, tumbled stones, or as a generic lapidary material. Often collected casually.
Geological facts
Rocks like this are often called 'river rocks' or 'stream pebbles' due to their water-worn shapes. The brown/yellow colors are usually due to iron oxide impurities (limonite or goethite).
Field identification & locations
Easily found in riverbeds, glacial till, and gravel deposits worldwide. Can be identified by its hardness (scratches glass) and smooth, rounded exterior.
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