sedimentary
Red Chert (Jasper)
Silicon Dioxide (SiO2)
AI-generated identification · may be incorrectHardness: 6.5-7 Mohs; Color: Opaque reddish-brown; Luster: Dull to waxy; Structure: Microcrystalline; Cleavage: None (conchoidal fracture).
- Hardness
- 6
- Color
- Opaque reddish-brown
- Luster
- Dull to waxy
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Physical properties
Hardness: 6.5-7 Mohs; Color: Opaque reddish-brown; Luster: Dull to waxy; Structure: Microcrystalline; Cleavage: None (conchoidal fracture).
Formation & geological history
Formed from the accumulation of silica-rich microfossils (like radiolaria) or chemical precipitation in marine environments, often associated with iron impurities that provide the red color.
Uses & applications
Used historically for stone tools and weapons (due to sharp edges upon fracturing); currently used in jewelry (cabochons), landscaping, and as a collector specimen.
Geological facts
Chert is so hard it can scratch steel. Red varieties are often referred to as Jasper, especially when they take a high polish. It was one of the most important minerals for prehistoric humans to create arrowheads.
Field identification & locations
Identify by its 'flint-like' waxy texture, smooth curved (conchoidal) fractures, and its inability to be scratched by a steel knife. Common in riverbeds and sedimentary outcrops.
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