igneous
Porphyritic Basalt
Extrusive igneous rock with plagioclase phenocrysts
AI-generated identification · may be incorrectHardness 6 on Mohs scale, dark gray fine-grained matrix with contrasting lighter yellowish or white phenocrysts, dull to sub-vitreous luster.
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Physical properties
Hardness 6 on Mohs scale, dark gray fine-grained matrix with contrasting lighter yellowish or white phenocrysts, dull to sub-vitreous luster.
Formation & geological history
Formed from rapid cooling of mafic lava flows on Earth's surface, allowing larger crystals to form before the groundmass solidified.
Uses & applications
Used in construction, aggregate, road base, and as decorative stone.
Geological facts
Basalt is the most common rock type in the Earth's oceanic crust and is also found abundantly on the Moon and Mars.
Field identification & locations
Identified by its dark, heavy, fine-grained groundmass peppered with distinct lighter crystal spots; common worldwide in volcanic regions.
