igneous
Weathered iron-rich basalt or laterite
Basalt, likely limonitized/goethite-stained; exact identification requires testing
AI-generated identification · may be incorrectDark reddish-brown, fine-grained, dull to earthy luster, with black iron-oxide patches and no visible crystals or cleavage. Typical basalt hardness is about 6 Mohs and specific gravity 2.8–3.1; weathering may reduce surface hardness.
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Physical properties
Dark reddish-brown, fine-grained, dull to earthy luster, with black iron-oxide patches and no visible crystals or cleavage. Typical basalt hardness is about 6 Mohs and specific gravity 2.8–3.1; weathering may reduce surface hardness.
Formation & geological history
Probably an iron-oxidized volcanic rock formed from rapidly cooled basaltic lava, then altered by prolonged tropical or humid-weathering processes. Its precise geological age cannot be determined from the image.
Uses & applications
Common basalt is used as crushed aggregate, road metal, paving stone, and construction material; this weathered piece has mainly educational or modest collector interest.
Geological facts
The rusty coloration commonly comes from hematite, goethite, or limonite replacing iron-bearing minerals. Black areas may represent magnetite or less-weathered basalt.
Field identification & locations
Look for a dense, fine-grained texture, faint attraction to a strong magnet, and a reddish-brown streak or powder from weathered surfaces; a glassy streak or strong metallic luster would suggest a different iron mineral. Basalt and laterite occur worldwide, especially volcanic and tropical regions.
