sedimentary

Chert

Microcrystalline Quartz (SiO2)

AI-generated identification · may be incorrect

Hardness: 7 on Mohs scale; Color: typically tan, brown, or gray in this specimen; Luster: waxy to dull; Crystal Structure: Trigonal (microcrystalline); Cleavage: none, exhibits conchoidal fracture.

Hardness: 7 on Mohs scale
Color: typically tan, brown, or gray in this specimen
Luster: waxy to dull

Identified June 14, 2026More sedimentary →

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Physical properties

Hardness: 7 on Mohs scale; Color: typically tan, brown, or gray in this specimen; Luster: waxy to dull; Crystal Structure: Trigonal (microcrystalline); Cleavage: none, exhibits conchoidal fracture.

Formation & geological history

Formed via the accumulation of silica-rich organic remains (like radiolarians or diatoms) or through chemical precipitation in marine environments where silica replaces carbonate material.

Uses & applications

Historically used for making stone tools (arrowheads/scrapers) due to its sharp edges; used today as a decorative aggregate in landscaping and as a component in road construction.

Geological facts

Chert is so hard it can scratch steel and was used by prehistoric humans globally to create fire when struck against iron pyrites or steel, due to its ability to produce sparks.