igneous
Porphyritic Basalt or Rhyolite Porphyry
Igneous porphyritic rock
AI-generated identification · may be incorrectHardness varies between 6 and 7 on the Mohs scale depending on phenocryst mineralogy. Features large white plagioclase or quartz phenocrysts set in a finer-grained dark or grey aphanitic matrix.
Identified More igneous →
Explore Porphyritic Basalt or Rhyolite Porphyry in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness varies between 6 and 7 on the Mohs scale depending on phenocryst mineralogy. Features large white plagioclase or quartz phenocrysts set in a finer-grained dark or grey aphanitic matrix.
Formation & geological history
Formed through a two-stage cooling process beneath and at the Earth's surface, where slow cooling produced large crystals followed by rapid cooling of the surrounding magma.
Uses & applications
Used primarily as crushed stone for construction, aggregate in concrete, and decorative landscaping material.
Geological facts
Porphyry textures are common in volcanic and subvolcanic intrusive environments worldwide, often associated with major ore deposits.
Field identification & locations
Identified by distinct large crystals embedded in a fine-grained matrix. Found globally in volcanic provinces and ancient mountain belts.
