mineral
Chalcedony (Carnelian/Jasper Pebble)
Cryptocrystalline Quartz (SiO2)
Hardness: 6.5-7 (Mohs scale), Color: Brownish-orange to tan, Luster: Waxy to sub-vitreous, Crystal structure: Trigonal (microcrystalline), Cleavage: None (conchoidal fracture), Specific Gravity: 2.58-2.64
- Hardness
- 6
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Physical properties
Hardness: 6.5-7 (Mohs scale), Color: Brownish-orange to tan, Luster: Waxy to sub-vitreous, Crystal structure: Trigonal (microcrystalline), Cleavage: None (conchoidal fracture), Specific Gravity: 2.58-2.64
Formation & geological history
Forms through the deposition of silica from groundwater in cavities of volcanic rocks or sedimentary formations. This specimen shows significant rounding and frosting from fluvial (river) or beach erosion over thousands of years.
Uses & applications
Used primarily in jewelry as cabochons, lapidary art, and as tumbled gemstones for collectors.
Geological facts
Chalcedony is one of the most common minerals on Earth, but water-worn pebbles like this one often hide beautiful banding or translucency that only becomes visible when wet or polished.
Field identification & locations
Identify by its waxy surface, lack of visible grain, and hardness (it will scratch glass). Commonly found in riverbeds, gravel pits, and along coastlines near volcanic outcrops.
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