sedimentary

Chert (White Variety)

Microcrystalline Silica (SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5-7 on Mohs scale; Color: Cream to white; Luster: Waxy to dull; Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6

Hardness: 6
Color: Cream to white
Luster: Waxy to dull

Identified July 8, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7 on Mohs scale; Color: Cream to white; Luster: Waxy to dull; Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6

Formation & geological history

Formed as nodules or layers in limestone through the accumulation of silica-rich organic remains (like diatoms or radiolaria) or chemical precipitation from groundwater.

Uses & applications

Historically used for stone tools and arrowheads due to sharp edges; currently used for landscaping, road ballast, and concrete aggregate.

Geological facts

Chert is chemically identical to quartz but has a much finer grain structure. High-quality varieties of chert are often called flint. It is one of the most common materials used by early humans for lithic technology.

Field identification & locations

Identify by its waxy luster, extreme hardness (scratches glass), and shell-like (conchoidal) fracture pattern. Commonly found in stream beds or within limestone outcrops.