sedimentary

Chert (Flint/Jasper variety)

Microcrystalline quartz (SiO2)

AI-generated identification · may be incorrect

Hardness: 7 on Mohs scale; Color: Tan, beige, or white with waxy luster; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.7

Hardness: 7 on Mohs scale
Color: Tan, beige, or white with waxy luster

Identified June 30, 2026More sedimentary →

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Physical properties

Hardness: 7 on Mohs scale; Color: Tan, beige, or white with waxy luster; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.7

Formation & geological history

Formed through the precipitation of silica from groundwater or the accumulation of siliceous skeletal remains (diatoms, radiolaria) in deep-sea environments. It often occurs as nodules in limestone or chalk beds.

Uses & applications

Historically used for stone tools and weapons due to its sharp edges; modernly used as a decorative stone, in jewelry (as jasper), or as a source of silica.

Geological facts

Chert has been used by humans for hundreds of thousands of years to create arrowheads and scrapers because it produces extremely sharp, glass-like edges when struck.

Field identification & locations

Look for a smooth, waxy surface and a distinctive 'shell-like' curved fracture pattern (conchoidal). It is commonly found in stream beds or eroded out of sedimentary rock layers.