sedimentary
Chert (Jasper)
Silicon Dioxide (SiO2)
Hardness: 6.5–7 (Mohs), Color: Tan to dark brown, Luster: Waxy to dull, Crystal structure: Trigonal (microcrystalline/cryptocrystalline), Cleavage: None (conchoidal fracture), Specific gravity: 2.6–2.65
- Hardness
- 6
Identified More sedimentary →
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Physical properties
Hardness: 6.5–7 (Mohs), Color: Tan to dark brown, Luster: Waxy to dull, Crystal structure: Trigonal (microcrystalline/cryptocrystalline), Cleavage: None (conchoidal fracture), Specific gravity: 2.6–2.65
Formation & geological history
Formed through the accumulation of silica-rich organic remains or through chemical precipitation in marine or freshwater environments. This specimen shows characteristic conchoidal fractures and a waxy surface resulting from water erosion.
Uses & applications
Historically used for stone tools due to sharp fracture edges. Today used in jewelry, as landscape stone, and for specimen collecting.
Geological facts
This specimen exhibits a unique pitted or 'frosted' surface texture common in river-worn or desert-exposed chert. It is a microcrystalline variety of quartz.
Field identification & locations
Identify by its hardness (scratches glass), waxy luster, and smooth, curved (conchoidal) fracture surfaces. Common in river beds and sedimentary outcrops worldwide.
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