Notes on ‘Introduction’ to Architecture
Porphyry and Porphyry Quarries
[See § 2, Of Porphyry, ante, p. 26.]
Porphyry, which is mineralogically described as consisting of crystals of plagioclase felspar in a purple felspathic paste, is a very hard stone of beautiful colour susceptible of a high polish. ‘No material,’ it has been said, ‘can approach it, either in colour, fineness of grain, hardness or toughness. When used alone its colour is always grand; and in combination with any other coloured material, although displaying its nature conspicuously, it is always harmonious’ (Transactions, Royal Institute of British Architects, 1887, p. 48). Though obtained, as Vasari knew, from Egypt, it was not known to the dynastic Egyptians, but was exploited with avidity by the Romans of the later imperial period. The earliest mention of it seems to be in Pliny, Hist. Nat., XXXVI, 11, under the name ‘porphyrites’ and statues in the material were according to this author sent for the first time to Rome from Egypt in the reign of Claudius. The new material was however not approved of, and for some time was by no means in fashion. It was not indeed till the age of the Antonines that as Helbig remarks ‘the preference for costly and rare varieties of stone, without reference to their adaptability for sculpture, began to spread.’ After this epoch, the taste for porphyry and other such strongly marked or else intractable materials grew till it became a passion, and the Byzantine emperors carried on the tradition of its use inherited by them from the later days of paganism. The material was quarried in the mountains known as Djebel Duchan near the coast of the Red Sea, almost opposite the southern point of the peninsula of Sinai, and the Romans carried the blocks a distance of nearly 100 miles to Koptos on the Nile whence they were transported down stream to Alexandria, where Mr Brindley thinks there would be reserve dépôts where lapidaries and artists resided, a source of supply for the large quantities used by Constantine. The same authority estimates that there must be about 300 monolith porphyry pillars still extant in Europe, the finest being the eight great columns under the side apses in S. Sophia, Constantinople. The most important of all porphyry monuments is the column, 100 feet high, which Constantine erected at Constantinople where it still stands though somewhat mutilated and damaged by fire. It consisted in nine cylindrical drums each 11 feet long and 11 feet in diameter.
The quarries, as Vasari later on remarks, were in his time not known, and seem never to have been worked since the time of the Romans. The site of them was visited by Sir Gardner Wilkinson in 1823, and they were rediscovered by Mr Brindley in 1887. If they are again to be worked, the material will now be transferred to the Red Sea coast, distant only about 20 miles. Mr Brindley’s account of his expedition, with notes on the material, is contained in the Transactions of the Royal Institute of British Architects for 1888.