sedimentary

Chert (Yellow Jasper variant)

Microcrystalline Quartz (SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5-7 on Mohs scale; Color: Yellow-brown, tan, ochre; Luster: Waxy to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.65.

Hardness: 6
Color: Yellow-brown, tan, ochre
Luster: Waxy to dull

Identified July 1, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7 on Mohs scale; Color: Yellow-brown, tan, ochre; Luster: Waxy to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.65.

Formation & geological history

Formed through the accumulation of silica-rich fluids in sedimentary environments or by the replacement of carbonate rocks (limestone). Often found in nodules or bedded deposits within prehistoric marine sediments.

Uses & applications

Used historically for stone tools due to its sharp edges; modern uses include lapidary work (jewelry, cabochons), landscaping, and as a component in road construction.

Geological facts

Cultures worldwide used chert/flint for heat-treating to create extremely sharp arrowheads and blades. It can spark when struck against steel, which was essential for early fire-starting.

Field identification & locations

Identify by its waxy appearance, smooth conchoidal (shell-like) fracture, and its ability to scratch glass. Commonly found in riverbeds, gravel pits, and sedimentary outcrops.