sedimentary

Polished brown flint/chert (likely)

Microcrystalline quartz, SiO₂ (chalcedonic flint/chert)

AI-generated identification · may be incorrect

Dark brown to reddish-brown, waxy-to-glassy luster with a pale blue reflected highlight, fine-grained and lacking visible crystals; hardness about 6.5–7 Mohs, no obvious cleavage, conchoidal fracture, density roughly 2.6 g/cm³. The surface appears naturally weathered or lightly polished.

Identified August 10, 2026More sedimentary →

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Physical properties

Formation & geological history

Silica-rich sediment or biogenic silica recrystallized into dense chert, commonly within limestone or chalk; formation ages vary widely. Around 47.6°N, 19.3°E (Hungary), flint/chert is geologically plausible in regional sedimentary gravel and limestone-derived deposits.

Uses & applications

Used historically for tools, arrowheads, and fire-starting; today mainly collected, tumbled, or used decoratively. Ordinary pieces have little commercial value.

Geological facts

The turquoise-blue patch is likely reflected light or a thin surface coating rather than an intrinsic blue mineral; true identification would benefit from a fresh fracture and streak test.

Field identification & locations

Look for conchoidal, shell-like fracture, very fine texture, and inability to scratch it with a steel knife (quartz scratches glass). Common in sedimentary terrains and gravels; avoid destructive testing on valuable pieces.