Andesite Porphyry

Hardness 6-7, grey color with white phenocrysts, dull to sub-vitreous luster, porphyritic texture.

Formed by the slow cooling of magma under the earth's surface allowing larger crystals to form, followed by rapid cooling upon eruption, creating the fine-grained matrix.

Used in construction, gravel, and sometimes as dimension stone.

The term 'porphyry' refers to the texture of the rock, not its chemical composition.

Identifiable by its distinct porphyritic texture with visible phenocrysts in a fine-grained groundmass. commonly found in volcanic regions.