sedimentary
Chert (Flint) Pebble
Microcrystalline Quartz (SiO2)
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
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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.
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