sedimentary
Chert / Jasper
Silicon Dioxide (SiO₂)
Hardness: 6.5–7 (Mohs scale); Color: Olive green to brownish-yellow; Luster: Dull to waxy; Structure: Microcrystalline/Cryptocrystalline quartz; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6–2.7
- Hardness
- 6
- Color
- Olive green to brownish-yellow
- Luster
- Dull to waxy
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Physical properties
Hardness: 6.5–7 (Mohs scale); Color: Olive green to brownish-yellow; Luster: Dull to waxy; Structure: Microcrystalline/Cryptocrystalline quartz; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6–2.7
Formation & geological history
Formed from the accumulation of silica-rich organic remains (like diatoms or radiolaria) or chemical precipitation from hydrothermal fluids in sedimentary basins. Hardened over millions of years through lithification.
Uses & applications
Historically used for stone tools (arrowheads). Modernly used for landscaping, jewelry (when polished), and as an abrasive in industrial applications.
Geological facts
This specimen shows the characteristic 'conchoidal' fracture pattern, which creates sharp, curved edges similar to broken glass. This property made it the primary material for prehistoric survival tools.
Field identification & locations
Identify in the field by its hardness (it should scratch glass), smooth texture, and curved breakage lines. Commonly found in riverbeds or as nodules within limestone layers.
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