sedimentary
Quartz Pebble (Chert / Chalcedony Pebble)
Silicon Dioxide (SiO2)
AI-generated identification · may be incorrectHardness 6.5-7 on Mohs scale; tan, beige, to pale brownish color; dull to waxy/earthy luster; microcrystalline/cryptocrystalline texture with no cleavage.
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Physical properties
Hardness 6.5-7 on Mohs scale; tan, beige, to pale brownish color; dull to waxy/earthy luster; microcrystalline/cryptocrystalline texture with no cleavage.
Formation & geological history
Formed through the precipitation of microcrystalline silica from water solutions, subsequently weathered and smoothed by mechanical fluvial or coastal erosion.
Uses & applications
Commonly used as gravel aggregate, landscaping stone, and historically by early humans for stone tools due to its conchoidal fracture.
Geological facts
Pebbles composed of chert or quartz are among the most durable rocks on Earth, often surviving multiple sedimentary erosion-deposition cycles.
Field identification & locations
Identify by testing for high hardness (scratches glass/steel) and rounded water-worn edges; found worldwide in riverbeds, beaches, and gravel beds.
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Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)
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