sedimentary
Chert / Jasper
Silicon Dioxide (SiO2)
AI-generated identification · may be incorrectHardness: 6.5-7 Mohs; Color: Dark grey to black with orange/brown iron staining and white veins; Luster: Dull to waxy; Crystal Structure: Microcrystalline/Cryptocrystalline; Cleavage: None (conchoidal fracture).
- Hardness
- 6
- Luster
- Dull to waxy
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Physical properties
Hardness: 6.5-7 Mohs; Color: Dark grey to black with orange/brown iron staining and white veins; Luster: Dull to waxy; Crystal Structure: Microcrystalline/Cryptocrystalline; Cleavage: None (conchoidal fracture).
Formation & geological history
Formed as chemical precipitates from silica-rich fluids or from the accumulation of siliceous remains of microscopic organisms (like diatoms or radiolarians) in marine environments.
Uses & applications
Primarily used as a lapidary material for polishing and jewelry. Historically used for making stone tools (arrowheads, scrapers) due to its sharp edges.
Geological facts
This specimen appears to be water-worn, likely found in a riverbed or on a beach. The white veins are typically quartz or calcite filling fractures in the host rock.
Field identification & locations
Identify in the field by its hardness (will scratch glass), conchoidal (shell-like) fracture, and smooth texture. Common in sedimentary basins worldwide.
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