sedimentary
Quartz (Chert/Chalcedony variety)
Silicon Dioxide (SiO2)
Hardness: 7 on Mohs scale; Color: Cream, honey-yellow, and light orange; Luster: Waxy to vitreous; Structure: Microcrystalline (Cryptocrystalline); Cleavage: None (conchoidal fracture).
- Hardness
- 7 on Mohs scale
- Color
- Cream, honey-yellow, and light orange
- Luster
- Waxy to vitreous
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Physical properties
Hardness: 7 on Mohs scale; Color: Cream, honey-yellow, and light orange; Luster: Waxy to vitreous; Structure: Microcrystalline (Cryptocrystalline); Cleavage: None (conchoidal fracture).
Formation & geological history
Formed via the precipitation of silica from groundwater or within sedimentary rock cavities. This specimen appears to be a water-worn river stone, likely millions of years old, originating from a silica-rich sedimentary environment.
Uses & applications
Used for decorative landscaping, lapidary tumbling, and historically for stone tools due to its sharp fracture edges. High-quality pieces are used in jewelry.
Geological facts
This specimen shows characteristic banding or zoning typical of chalcedony. It has been naturally rounded by fluvial (river) or glacial action, softening its original jagged edges.
Field identification & locations
Identify by its inability to be scratched by a steel knife and its waxy surface texture. Commonly found in riverbeds, gravel pits, and coastal beaches globally.
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