sedimentary

Iron-stained chert or siliceous pebble

Microcrystalline quartz (SiO₂), likely ferruginous chert

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; brown to reddish-brown, dull to subtly waxy luster, very fine-grained and dense. It appears massive with irregular fracture rather than visible cleavage; the smoother face may be naturally worn or lightly polished.

Identified August 10, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed when silica-rich groundwater replaced or cemented sediment, with iron oxides producing the brown coloration. Chert commonly ranges from Paleozoic to Cenozoic in age; the Budapest-area regional setting makes transported siliceous gravel plausible.

Uses & applications

Used historically for stone tools and occasionally as aggregate or decorative material. Ordinary pieces have little commercial value, though attractive patterned or flaked specimens may interest collectors.

Geological facts

Chert can produce sharp conchoidal edges when freshly fractured and may resemble jasper when strongly colored by iron. The specimen’s rounded shape suggests stream, gravel-pit, or glacial/river transport.

Field identification & locations

Likely identifiable by its dense feel, lack of visible grains, waxy surface, and inability to scratch with a steel knife; it should scratch ordinary glass. Exact identification would benefit from a fresh break, streak test, and hardness testing.