sedimentary

Chert (specifically Flint or Jasper variant)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5-7 on Mohs scale; Color: tan, brown, and translucent cream; Luster: waxy to vitreous; Crystal structure: Trigonal (microscopic fibers); Cleavage: None (showcases conchoidal fracture); Specific gravity: 2.65.

Hardness: 6
Color: tan, brown, and translucent cream
Luster: waxy to vitreous

Identified June 21, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the accumulation of silica-rich organic remains (like diatoms or radiolarians) or through the chemical precipitation of silica in groundwater. It often replaces carbonate minerals in limestone or chalk beds.

Uses & applications

Historically used for stone tools (knapping arrows and scrapers) and starting fires. Modernly used as a decorative stone, in jewelry (as Jasper or Agate), and as an abrasive in some industrial applications.

Geological facts

Chert was one of the most vital materials for prehistoric humans because of its ability to fracture into extremely sharp, glass-like edges. It is chemically very stable and resistant to weathering.

Field identification & locations

Identify in the field by its waxy texture, extreme hardness (it will scratch glass), and the shell-like (conchoidal) curves on broken surfaces. Often found as nodules in limestone or as seafloor bedded deposits.