sedimentary

Chert (White Chert)

Silicon Dioxide (SiO2)

AI-generated identification · may be incorrect

Hardness: 7 (Mohs scale), Color: White to grey, Luster: Waxy to dull, Crystal Structure: Cryptocrystalline (Microcrystalline Quartz), Cleavage: None (Conchoidal fracture), Specific Gravity: 2.6

Identified April 10, 2026More sedimentary →

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Physical properties

Hardness: 7 (Mohs scale), Color: White to grey, Luster: Waxy to dull, Crystal Structure: Cryptocrystalline (Microcrystalline Quartz), Cleavage: None (Conchoidal fracture), Specific Gravity: 2.6

Formation & geological history

Formed through the accumulation of silica-rich organic remains (like diatoms or radiolarians) or by chemical precipitation from silica-rich fluids in limestone or chalk beds. Usually found in Paleozoic to Mesozoic sedimentary layers.

Uses & applications

Historically used for stone tools (arrowheads). Modern uses include abrasive tools, road surfacing, jewelry (when vibrantly colored), and as a silica source in glassmaking.

Geological facts

Chert was one of the most important minerals for early humans because its conchoidal fracture creates razor-sharp edges. Flint is the dark variety of chert.

Field identification & locations

Identify in the field by its hardness (it will scratch glass), its shell-like (conchoidal) fracture pattern, and its smooth, waxy texture. Commonly found in stream beds and limestone outcrops.