Porphyry is the name for a variety of granites and igneous rocks with coarse crystals (phenocrysts) in a fine grained matrix.

Porphyry shop

The name porphyry only refers to a rocks fabric. It says nothing about its chemical or mineralogical composition. Thus in modern geology the term is regarded as grandfathered and not in use any longer.

Origin of name: from Greek πορφύρα porphýra, purple
Firstly mined in the Old Kingdom of Ecypt, the puirple coloured so-called imperial porphyry was later highly prized by the Romans. Purple being the royal colour, its use was restricted to the emperor, who also owned the mines.

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Greek porphyry with large edenite phenocryts in a ferriscklerite matrix

Porphyry shop