sedimentary

Chert (Flint) Pebble

Microcrystalline Quartz (SiO2)

AI-generated identification · may be incorrect

Hardness: 7 Mohs scale; Color: Cream, tan, and light brown; Luster: Waxy to dull; Crystal structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.65

Hardness: 7 Mohs scale
Color: Cream, tan, and light brown
Luster: Waxy to dull

Identified May 27, 2026More sedimentary →

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Physical properties

Hardness: 7 Mohs scale; Color: Cream, tan, and light brown; Luster: Waxy to dull; Crystal structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.65

Formation & geological history

Formed through the chemical precipitation of silica or the replacement of carbonate minerals by silica in marine environments. This specimen appears water-worn, likely from a stream or coastal area.

Uses & applications

Used historically for stone tools and fire-starting. Currently used in road construction, landscaping, and occasionally as an abrasive or in decorative gravel.

Geological facts

Chert is so durable that it often survives long after the surrounding rock has weathered away. Early humans prize it because it breaks with a sharp edge, allowing for the creation of arrowheads.

Field identification & locations

Identify by its hardness (will scratch glass), waxy luster, and conchoidal (shell-like) fracture pattern. Commonly found in riverbeds and limestone deposits.