igneous
Possible iron-rich basalt or industrial slag
Basalt, likely Fe–Mg silicate rock; exact identification is uncertain from the blurred image
AI-generated identification · may be incorrectDark gray to black, fine-grained, dull to weakly glassy luster, and irregular conchoidal-to-rough fracture; typical basalt hardness is about 6 Mohs and specific gravity 2.8–3.1. Metallic-looking patches or bubbles could instead indicate iron-bearing slag.
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Physical properties
Dark gray to black, fine-grained, dull to weakly glassy luster, and irregular conchoidal-to-rough fracture; typical basalt hardness is about 6 Mohs and specific gravity 2.8–3.1. Metallic-looking patches or bubbles could instead indicate iron-bearing slag.
Formation & geological history
Basalt forms when mafic lava rapidly cools at or near Earth’s surface, commonly in volcanic fields and oceanic crust; ages range from recent to billions of years. Slag is human-produced furnace waste and is not a natural rock.
Uses & applications
Basalt is used as crushed aggregate, road base, railroad ballast, concrete stone, and occasionally decorative stone. Slag may have limited collecting interest but is generally not used as gemstone material.
Geological facts
The specimen’s smooth dark surface and apparent metallic sheen are compatible with basalt, but the shape and possible glassy areas also fit weathered slag or a meteorite fragment. A magnet test and close inspection for vesicles are useful.
Field identification & locations
Basalt commonly occurs in volcanic regions and is usually heavy, opaque, and nonmetallic; slag often has obvious bubbles, flow textures, or shiny glass. Estimated value: $1–$10 as a common rock; roughly $5–$30 if confirmed as an unusual specimen.
