sedimentary

Flint / Chert

Microcrystalline quartz (SiO2)

Hardness: 7 on the Mohs scale. Color: Generally gray, brownish, or yellowish due to impurities. Luster: Waxy to dull. Crystal structure: Cryptocrystalline/microfibrous quartz (chalcedony). Cleavage: None, exhibits characteristic conchoidal fracture. Specific gravity: 2.60 to 2.65.

Hardness: 7 on the Mohs scale
Color: Generally gray, brownish, or yellowish due to impurities
Luster: Waxy to dull

Identified August 1, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the diagenesis of siliceous oozes, accumulation of skeletal remains of marine organisms like diatoms or radiolarians, or the replacement of limestone/chalk by silica-rich groundwaters over millions of years.

Uses & applications

Historically used for making stone tools, arrowheads, and striking fire due to its sharp conchoidal fracture edges. Today used in decorative items, lapidary, and historically in flintlock firearms.

Geological facts

Flint was one of the most critical materials for early human technological development during the Stone Age because it can be chipped to form extremely sharp edges. The specimen shows a distinct conchoidal fracture notch.

Field identification & locations

Easily identified in the field by its extreme hardness, waxy luster, and distinctive conchoidal fracture (curved, shell-like breakage patterns seen clearly on this specimen). Found globally within chalk and limestone formations, highly plausible in the sedimentary basins of Eastern Europe/Romania.