igneous
Weathered brown stone, likely basalt or iron-stained volcanic rock
Indeterminate; possibly vesicular basalt (mafic silicate rock)
AI-generated identification · may be incorrectDark brown to black, dull-to-earthy luster, fine-grained and irregularly rounded, with possible weathering pits; typical basalt hardness is about 6 Mohs and specific gravity 2.8–3.1. The image is insufficient to confirm mineral composition or cleavage.
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Physical properties
Dark brown to black, dull-to-earthy luster, fine-grained and irregularly rounded, with possible weathering pits; typical basalt hardness is about 6 Mohs and specific gravity 2.8–3.1. The image is insufficient to confirm mineral composition or cleavage.
Formation & geological history
If basalt, it formed when iron- and magnesium-rich lava cooled rapidly at or near Earth’s surface, commonly during Cenozoic or older volcanic activity. The rounded shape likely results from stream, beach, or surface weathering.
Uses & applications
Common basalt is used as aggregate, roadstone, riprap, and building stone; this small specimen has little commercial or jewelry value.
Geological facts
Brown coloration commonly reflects oxidation of iron-bearing minerals to limonite or hematite. No diagnostic crystal faces, fossils, or metallic meteorite features are visible.
Field identification & locations
Look for a dense, fine-grained texture, black streak, lack of fizz in dilute acid, and possible tiny vesicles; a fresh broken surface and hardness test would help distinguish basalt from ordinary weathered rock. Common worldwide in volcanic regions and river gravels.
