igneous
Likely iron-rich volcanic rock (basalt/pyroclastic fragment)
Basaltic rock, potentially weathered andesite; exact identification requires testing
AI-generated identification · may be incorrectDark gray to black, fine-grained, dull to slightly submetallic, with rusty-brown iron-oxide staining and irregular fracture. Likely hardness about 5–6, no obvious cleavage, and moderate-to-high specific gravity; visible texture is insufficient for certainty.
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Physical properties
Dark gray to black, fine-grained, dull to slightly submetallic, with rusty-brown iron-oxide staining and irregular fracture. Likely hardness about 5–6, no obvious cleavage, and moderate-to-high specific gravity; visible texture is insufficient for certainty.
Formation & geological history
Probably formed when iron- and magnesium-rich lava cooled rapidly at or near Earth’s surface, then weathered and oxidized. Basaltic rocks range from ancient Precambrian examples to recent volcanic deposits.
Uses & applications
Common basalt is used as crushed aggregate, road stone, concrete material, and occasionally building stone; this small fragment has little commercial value unless from a notable locality.
Geological facts
The rusty areas commonly represent limonite or hematite produced by alteration of iron-bearing minerals. A strong magnet response would support magnetite-bearing basalt, but does not by itself prove a meteorite.
Field identification & locations
Common in volcanic regions worldwide, including Hawaii, Iceland, India, and oceanic crust. Check for vesicles, a fine crystalline texture, streak (usually none), magnetism, and a nonmetallic interior; fusion crust or unusual density would warrant meteorite testing.
