sedimentary

Weathered flint/chert nodule

Microcrystalline quartz (SiO₂), likely chert or flint

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; tan, gray, and brown coloration with dull to waxy luster, no visible crystals, and conchoidal fracture. The rounded, irregular shape and weathered surface suggest a naturally eroded nodule.

Identified August 14, 2026More sedimentary →

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Physical properties

Formation & geological history

Chert forms when silica replaces or accumulates within sedimentary rocks, commonly limestone or chalk, during diagenesis. Its exact geological age cannot be determined from the photograph; nodules range from Paleozoic to Cenozoic.

Uses & applications

Used historically for sharp tools, fire-starting, and construction aggregate; attractive pieces may be collected, but this specimen appears modest in gem or commercial value.

Geological facts

Flint is generally a dark, dense variety of chert, while chert includes lighter colors. Freshly broken surfaces are typically glassy and produce very sharp edges.

Field identification & locations

Identify it by its dense lightweight feel, waxy appearance, lack of cleavage, and sharp conchoidal fracture; a steel file should barely scratch it. Common in sedimentary terrains worldwide, especially chalk and limestone regions.