sedimentary
Chert (Jasper)
Microcrystalline Quartz (SiO2)
AI-generated identification · may be incorrectHardness: 6.5-7 Mohs; Color: Brownish, tan, and reddish-brown bands; Luster: Waxy to dull; Crystal Structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.7
- Hardness
- 6
- Color
- Brownish, tan, and reddish-brown bands
- Luster
- Waxy to dull
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Physical properties
Hardness: 6.5-7 Mohs; Color: Brownish, tan, and reddish-brown bands; Luster: Waxy to dull; Crystal Structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.7
Formation & geological history
Formed via the accumulation of silica-rich organic remains or chemical precipitation from groundwater within sedimentary rock layers like limestone. Usually dates from the Paleozoic or Mesozoic eras.
Uses & applications
Historically used for stone tools (arrowheads); currently used for lapidary work, jewelry (cabochons), and landscaping gravel.
Geological facts
Jasper is an opaque variety of chert. Known as 'nature's flint,' it was essential for prehistoric humans to create sharp-edged tools due to its conchoidal fracture pattern.
Field identification & locations
Identify by its smooth, waxy texture and circular (conchoidal) chips on edges. It cannot be scratched by a steel knife. Found frequently in riverbeds or gravel pits.
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