sedimentary
Jasper / Chert (River Pebble)
Silicon Dioxide (SiO2) - Microcrystalline Quartz
Hardness: 6.5–7 (Mohs scale), Color: Tan/yellowish with reddish-brown jasper inclusions, Luster: Dull to waxy, Crystal structure: Trigonal/Microcrystalline, Cleavage: None/Conchoidal fracture.
- Hardness
- 6
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Physical properties
Hardness: 6.5–7 (Mohs scale), Color: Tan/yellowish with reddish-brown jasper inclusions, Luster: Dull to waxy, Crystal structure: Trigonal/Microcrystalline, Cleavage: None/Conchoidal fracture.
Formation & geological history
Formed through the accumulation of silica-rich microfossils or chemical precipitation from fluids in oceanic environments or volcanic ash. This specific specimen is a water-worn river pebble, likely transported and rounded by stream or glacial action.
Uses & applications
Used primarily as lapidary material, decorative stones, river rock for landscaping, and historically for stone tools due to its conchoidal fracture.
Geological facts
Jasper-rich pebbles are often found in riverbeds and are nicknamed 'healing stones' in some cultures. The reddish spots are usually caused by iron oxide impurities within the silica matrix.
Field identification & locations
Identify in the field by its hardness (cannot be scratched by steel) and smooth, rounded water-worn texture. Often found in gravel bars and riverbanks across the globe.
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