porphyry
porphyry.
1. Beautiful and very hard rock quarried in Egypt in Antiquity, deep purplish-red in colour, capable of taking a high polish.
2. Black or green stones of porphyritic structure quarried in Sardinia, Greece, etc.
3. Any unstratified or igneous rock having a homogeneous base containing crystals of one or more minerals, e.g. felspar porphyry, claystone porphyry, porphyritic granite, and porphyritic greenstone. The best-known are porfido rosso (deep red with whitish spots), porfido nero (black with white spots), serpentino nero antico (black with lighter oblong spots), porfido verde (very dark, almost black, with fine green shades), porfido di Vitelli (pea-green with small lighter green spots), and a blue porphyry found by the Romans at Fréjus. The so-called rosso antico was not a porphyry, but was in fact a marble found in Greece or Italy, and was both cheaper and easier to work. The finest rosso antico occurred at Brescia, was deep blood-red or liver in colour, with a fine grain, and could take a high polish.
1. Beautiful and very hard rock quarried in Egypt in Antiquity, deep purplish-red in colour, capable of taking a high polish.
2. Black or green stones of porphyritic structure quarried in Sardinia, Greece, etc.
3. Any unstratified or igneous rock having a homogeneous base containing crystals of one or more minerals, e.g. felspar porphyry, claystone porphyry, porphyritic granite, and porphyritic greenstone. The best-known are porfido rosso (deep red with whitish spots), porfido nero (black with white spots), serpentino nero antico (black with lighter oblong spots), porfido verde (very dark, almost black, with fine green shades), porfido di Vitelli (pea-green with small lighter green spots), and a blue porphyry found by the Romans at Fréjus. The so-called rosso antico was not a porphyry, but was in fact a marble found in Greece or Italy, and was both cheaper and easier to work. The finest rosso antico occurred at Brescia, was deep blood-red or liver in colour, with a fine grain, and could take a high polish.
Bibliography
Butters (1996);
Delbrück (1932);
J. Papworth (1832)
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porphyry