sedimentary
Chert (Jasper/Quartzite Pebble)
Silicon Dioxide (SiO2)
Hardness: 7 (Mohs scale); Color: Tan, brown, ochre; Luster: Waxy to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65.
- Hardness
- 7 (Mohs scale)
- Color
- Tan, brown, ochre
- Luster
- Waxy to dull
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Physical properties
Hardness: 7 (Mohs scale); Color: Tan, brown, ochre; Luster: Waxy to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65.
Formation & geological history
Formed through the accumulation of silica-rich organic remains or chemical precipitation in sedimentary environments. This specimen shows significant rounding and smoothing due to fluvial (river) or glacial transport over geologic time.
Uses & applications
Historically used for stone tools and arrowheads; currently used in decorative landscaping, as road aggregate, or as a pocket stone for collectors.
Geological facts
Chert is so durable that it often survives as rounded pebbles long after the surrounding softer rock has eroded away. Brightly colored varieties are often called jasper.
Field identification & locations
Identify by its hardness (it will scratch glass) and its smooth, rounded 'river stone' texture. Commonly found in riverbeds, glacial tills, and beaches.
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