sedimentary

Brown Chert

Microcrystalline Quartz (SiO2)

Hardness: 6.5-7 (Mohs scale); Color: Brown, tan, and cream; Luster: Waxy to dull; Crystal structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.65

Hardness: 6
Color: Brown, tan, and cream
Luster: Waxy to dull

Identified June 5, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7 (Mohs scale); Color: Brown, tan, and cream; Luster: Waxy to dull; Crystal structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.65

Formation & geological history

Formed through the accumulation of silica-rich organic remains or chemical precipitation within sedimentary layers, often associated with limestone or chalk beds. This specimen shows river-worn tumbling.

Uses & applications

Historically used for stone tools and starting fires; currently used as construction aggregate, decorative landscaping stone, and for lapidary tumbling.

Geological facts

Chert is essentially the same material as flint, but the term 'chert' is generally used for lighter-colored or more impure varieties. It is extremely durable and weather-resistant.

Field identification & locations

Identify in the field by its smooth, waxy feel and signature shell-like (conchoidal) fractures. Common in riverbeds and areas with exposed sedimentary strata.