igneous
Basalt with an orange mineral vein
Fine-grained basalt, likely containing iron-stained calcite or zeolite; exact identification requires testing
AI-generated identification · may be incorrectDark gray-black, fine-grained, massive and weakly lustrous; likely Mohs 5–6, with a contrasting orange, crystalline vein. Basalt commonly contains plagioclase and pyroxene, while the vein may show cleavage or fizz weakly in acid if calcite.
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Physical properties
Dark gray-black, fine-grained, massive and weakly lustrous; likely Mohs 5–6, with a contrasting orange, crystalline vein. Basalt commonly contains plagioclase and pyroxene, while the vein may show cleavage or fizz weakly in acid if calcite.
Formation & geological history
Basalt forms when low-viscosity mafic lava cools rapidly at or near Earth’s surface, commonly in volcanic fields and oceanic crust. The orange vein likely formed later from hydrothermal or groundwater mineral deposition; its age depends on the host lava.
Uses & applications
Common basalt is used for aggregate, roadstone, riprap, and construction. Attractive specimens with contrasting veins are mainly collected or used decoratively rather than as gemstones.
Geological facts
The orange coloration may result from iron oxides, including limonite or hematite, coating a secondary mineral. Vesicles or fractures in basalt often become filled by calcite, zeolites, agate, or other minerals.
Field identification & locations
Identify basalt by its dark, dense, fine texture and lack of visible large crystals; a streak, hardness, acid, and specific-gravity test can help identify the vein. Basalt is widespread in Hawaii, Iceland, India’s Deccan Traps, oceanic islands, and volcanic regions worldwide.
