igneous
Porphyritic Basalt
Mafic extrusive igneous rock
AI-generated identification · may be incorrectHardness of 6 on the Mohs scale, reddish-brown to dark gray color with lighter phenocrysts, dull to sub-to-vitreous luster, fine-grained aphanitic groundmass with distinct crystals.
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Physical properties
Hardness of 6 on the Mohs scale, reddish-brown to dark gray color with lighter phenocrysts, dull to sub-to-vitreous luster, fine-grained aphanitic groundmass with distinct crystals.
Formation & geological history
Formed by the rapid cooling of lava at or near the Earth's surface, often originating from volcanic activity in ancient or recent geological periods.
Uses & applications
Used in construction, road aggregate, and occasionally as a decorative landscaping stone.
Geological facts
Porphyritic texture indicates a two-stage cooling process where larger crystals grew beneath the surface before the lava erupted.
Field identification & locations
Identified in the field by contrasting larger crystals embedded in a dense, dark, fine-grained matrix; commonly found in volcanic regions worldwide.
