igneous
Possible weathered basalt or iron-rich volcanic stone
Fine-grained mafic rock, possibly basalt; exact identification requires testing
AI-generated identification · may be incorrectSmall rounded gray-brown specimen with dull to weakly earthy luster and probable fine texture; basalt typically has Mohs hardness 5–6, no cleavage, and specific gravity about 2.8–3.1.
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Physical properties
Small rounded gray-brown specimen with dull to weakly earthy luster and probable fine texture; basalt typically has Mohs hardness 5–6, no cleavage, and specific gravity about 2.8–3.1.
Formation & geological history
Likely formed when mafic lava cooled rapidly at or near Earth’s surface, then became rounded and weathered; basalt commonly ranges from Precambrian to recent age.
Uses & applications
Common basalt is used as crushed aggregate, road material, building stone, and occasionally as a lapidary material; this small specimen has mainly educational or collectible value.
Geological facts
The brown surface may reflect oxidation of iron-bearing minerals, while the dark interior suggests a mafic composition.
Field identification & locations
Look for a dense, fine-grained, dark interior, weak magnetism, and possible tiny feldspar crystals; a streak, hardness, magnet, and fresh broken surface would distinguish basalt from slag, chert, or ironstone. Common worldwide in volcanic regions.
