sedimentary

Chert (specifically Flint or Jasper variant)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5-7 Mohs; Color: Brown, tan, or reddish-brown; Luster: Waxy to dull; Crystal structure: Trigonal (microscopic); Cleavage: None (conchoidal fracture); Specific gravity: 2.65.

Hardness: 6
Color: Brown, tan, or reddish-brown
Luster: Waxy to dull

Identified March 31, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7 Mohs; Color: Brown, tan, or reddish-brown; Luster: Waxy to dull; Crystal structure: Trigonal (microscopic); Cleavage: None (conchoidal fracture); Specific gravity: 2.65.

Formation & geological history

Formed through the accumulation of silica-rich organic remains (like diatoms or radiolaria) or through chemical precipitation in sedimentary environments. Can be found in limestone or chalk beds.

Uses & applications

Historically used for stone tools (arrowheads, scrapers) due to its sharp edges; used today in road construction, as a high-silica industrial material, and occasionally in jewelry as Jasper.

Geological facts

Chert was one of the most important minerals for early humans because its conchoidal fracture allows it to be shaped into incredibly sharp tools. This specific piece appears to show 'knapping' or intentional flaking, suggesting it might be an archaeological lithic flake.

Field identification & locations

Identify in the field by its waxy texture and shell-like (conchoidal) fractures. It is much harder than steel and cannot be scratched by a knife. Common in riverbeds and limestone outcrops.