igneous
Porphyritic Basalt
Extrusive Igneous Rock
AI-generated identification · may be incorrectHardness of 6 on the Mohs scale, dark gray to purplish color with dull luster, aphanitic groundmass with visible phenocrysts, and specific gravity around 2.9.
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Physical properties
Hardness of 6 on the Mohs scale, dark gray to purplish color with dull luster, aphanitic groundmass with visible phenocrysts, and specific gravity around 2.9.
Formation & geological history
Formed from rapid cooling of mafic lava on the Earth's surface, often originating in volcanic environments from various geological eras.
Uses & applications
Used extensively in construction as crushed aggregate, railroad ballast, and dimension stone.
Geological facts
Basalt is the most common rock type in the Earth's crust underlying the ocean basins and forming much of the volcanic islands.
Field identification & locations
Identify in the field by its fine-grained dark matrix containing larger distinct crystals like plagioclase, commonly found near volcanic regions.
