sedimentary
Chert (Jasper-like Silicate)
Microcrystalline Quartz (SiO2)
Hardness: 7 Mohs; Color: Brownish-green with white quartz veining; Luster: Waxy to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.65.
- Hardness
- 7 Mohs
- Color
- Brownish-green with white quartz veining
- Luster
- Waxy to dull
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Physical properties
Hardness: 7 Mohs; Color: Brownish-green with white quartz veining; Luster: Waxy to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.65.
Formation & geological history
Formed from the accumulation of silica-rich organic remains or chemical precipitation in marine environments; the veins formed later when silica-rich fluids filled fractures.
Uses & applications
Historically used for stone tools due to sharp edges; currently used for decorative stones, tumbling, and as abrasive media.
Geological facts
Chert is so hard it can scratch steel. This specific specimen shows 'secondary mineralization' where white quartz filled cracks in the original host rock.
Field identification & locations
Identify by waxy texture and conchoidal (shell-like) fracture. Commonly found in riverbeds, glacial tills, and sedimentary basins worldwide.
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