_Porphyry._--The “porphyry powdered with bright stars” of the poet is used for the columns of the exedras, and for some of the panels on the walls. The Anonymous author states that these columns came from a temple of the Sun, but the Silentiary says “they loaded the boats on the bosom of the Nile,” and there seems no reason to doubt that the columns came direct from the porphyry quarries at Mons Porphyrites in Egypt. This porphyry mountain is at Djebel Dochan, twenty-five miles north-east from Thebes. Lepsius[353] seems to prove that the quarries were worked as long as the Nile canal remained open; and ships still sailed on the canal till the appearance of Islam. Letronne[354] gives details of the method of transit. The porphyry was brought from the quarry to the Red Sea, and then by the Nile canal to the Lower Nile, and hence into the Mediterranean. On this evidence we would say that the porphyry used at Constantinople in Justinian’s reign was quarried for the purpose, and not brought from Roman buildings. _Marmor Molossium._--“The marble that the land of Atrax yields,” is called elsewhere in the poem “Thessalian,” and, from the province in Thessaly where it was found, “Molossian.” Corsi and Garofalo both wrongly describe Molossian as _Fior di Persico_. The marble really is the brecciated serpentine and limestone, now called Verde Antico, the _Lapis Atracius_ of the ancients, of which the eight great columns in the nave and many others are formed. Here again it has been said that these eight large columns were taken from a building at Ephesus, but the Silentiary says, “Never were such columns hewn from sea-washed Molossis,” and we can hardly doubt that they were quarried especially for S. Sophia, together with the rest of the enormous quantity used in the church. The quarries were near Atrax in Thessaly, and the marble is best named as by French writers, Thessalian green. _Lapis Lacedaemonius._--“The fresh green, like emerald, from Sparta,” was probably the porphyry quarried in Mount Taygetus in Laconia. This green porphyry, called by Corsi _serpentino_, is used in the opus sectile of S. Sophia. As a green porphyry is obtainable in Egypt, the former should be distinguished as Spartan. _Proconnesium._--“The hills of Proconnesus,” according to Paulus, “strewed the floor.” The same marble was also used for the columns in the upper aisles, for the eight square columns below, and for the capitals, door frames, window lattices and other structural parts; also for the plating of the lower arcade and other parts of the wall-surfaces, and as frames to the coloured marbles. It is a soft white, or white with gray-banded streaks. The quarries of Marmora are still worked. This marble was greatly prized in Classic times, and Pliny mentions that it was used at the palace of Mausolus, where, it is said, the method of plating brick walls with marble was first applied. It closely resembles gray Carystian but they should not be confounded.