sedimentary
Chert (Common Jasper)
Microcrystalline Quartz (SiO2)
Hardness: 6.5-7 (Mohs scale), Color: Brown, yellowish-tan, and white, Luster: Waxy to dull, Crystal Structure: Trigonal (microcrystalline), Cleavage: None (conchoidal fracture)
- Hardness
- 6
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Physical properties
Hardness: 6.5-7 (Mohs scale), Color: Brown, yellowish-tan, and white, Luster: Waxy to dull, Crystal Structure: Trigonal (microcrystalline), Cleavage: None (conchoidal fracture)
Formation & geological history
Formed via the accumulation of silica-rich organic remains or chemical precipitation in marine environments; this specimen shows significant water-worn rounding from river or beach transport.
Uses & applications
Used historically for stone tools due to sharp edges; currently used for decorative purposes, landscaping, and lapidary tumbling.
Geological facts
Chert and jasper are among the most common materials used by prehistoric humans for arrowheads because they break with a predictable conchoidal fracture.
Field identification & locations
Identify by its hardness (it will scratch glass), waxy feel, and smooth surfaces from water erosion. Commonly found in riverbeds and glacial tills.
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