igneous
Iron-rich volcanic rock fragment (likely basalt or weathered scoria)
Basaltic rock; primarily plagioclase feldspar, pyroxene, and iron oxides
AI-generated identification · may be incorrectDark purplish-brown, fine-grained, dull to slightly submetallic surface with possible vesicles or weathering rind; typical hardness about 5–6 Mohs. Exact identification is uncertain from the photograph alone, and it may include iron-oxide staining or alteration.
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Physical properties
Dark purplish-brown, fine-grained, dull to slightly submetallic surface with possible vesicles or weathering rind; typical hardness about 5–6 Mohs. Exact identification is uncertain from the photograph alone, and it may include iron-oxide staining or alteration.
Formation & geological history
Formed when mafic lava cooled rapidly at or near Earth’s surface, generally during the Cenozoic or older volcanic episodes; weathering produced the brown-purple exterior.
Uses & applications
Usually used as aggregate, road stone, or landscaping material rather than jewelry; this small fragment has little commercial value unless tied to a notable locality.
Geological facts
Basalt is the most abundant volcanic rock on oceanic crust and commonly forms lava flows, volcanic islands, and ocean-floor seafloor.
Field identification & locations
Look for a dense, fine-grained texture, dark color, and lack of visible large crystals; a streak, magnetism test, and fresh broken surface would help distinguish basalt from slag, shale, or iron-rich mineral specimens. Common worldwide, especially volcanic regions.
