igneous
Likely iron-rich river cobble (weathered basalt or ironstone)
Indeterminate; possibly weathered basalt, with hematite/goethite staining
AI-generated identification · may be incorrectDark reddish-brown, rounded and water-worn, dull to weakly earthy luster, apparently fine-grained with no visible crystals or cleavage. Estimated hardness about 5–6 if basaltic, or variable if ironstone; specific gravity likely moderate to high.
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Physical properties
Dark reddish-brown, rounded and water-worn, dull to weakly earthy luster, apparently fine-grained with no visible crystals or cleavage. Estimated hardness about 5–6 if basaltic, or variable if ironstone; specific gravity likely moderate to high.
Formation & geological history
Probably transported and rounded by a river or stream, with iron oxidation producing the reddish-brown surface. The Belgrade-area setting commonly contains transported sedimentary and igneous clasts, but the photograph does not establish a precise age or lithology.
Uses & applications
Usually a curiosity, landscaping stone, or teaching specimen; not typically valuable for jewelry or construction unless confirmed as a distinctive ore or decorative stone.
Geological facts
The smooth shape indicates abrasion during transport, while the dark red-brown color may reflect hematite or goethite coatings rather than the rock’s original composition.
Field identification & locations
A fresh broken surface, streak test, and magnet test would help: basalt is typically gray-black inside, hematite leaves a red-brown streak, and magnetite-bearing material may attract a magnet. Identification is uncertain without a cut face or tests.
