igneous rock of dark-crimson ground thickly dotted with small crystals
of felspar. Though there are other colours of precisely the same stone,
as far as its chemical composition goes, yet the ancient Porphyrites, "
purple stone," designated exclusively the first-named kind. It took
also the epithet Leptopsephos from its speckled texture. Egypt alone
produced it in Pliny's age, and in masses of sufficient dimensions for
the largestworks. But under the Lower Empire the Romans obtained an
inexhaustible supply of the finest material from nearer home ; Valéry
observed on the coast of Sardinia vast quarries of Porphyry with shafts
of columns lying about, merely roughed out as they were left by the
workmen. The earliest works in it seen at Rome were statues of Claudius
brought from Egypt by his deputy Vitrasius Pollio, a novelty, which
Pliny remarks, was not received with approbation, at least no one had
up to that time followed his example.
Under the Lower Empire, however, it was largely employed in the most sumptuous edifices then erected, in the form of columns of labra for
the baths, and of sarcophagi. Some of these columns, in a single piece
42 ft. long, are still to be seen fulfilling their original destination
(having mostly been destroyed for the sake of the material), in the
portico to Constantine's Baptistery at Rome, and in the mosque of Sta.
Sophia. It was a fashionable material for the lower parts of the later
imperial busts, having the head alone in white marble or bronze, its
colour aptly reproducing the sovereign purple (a dark crimson dye).
Those ages have left to us certain works in Porphyry, the execution of
which remains a mystery : perhaps the most wonderful things the Roman
sculptor ever produced, considering the elabor-