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PORPHYRITES.
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PORPHYRITES: Porphyry.
An 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 largest works. But under the Lower Empire the Romans obtained an
inexhaustible supply of the finest quality 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 Pollio's 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
*
Which was sawn up into thin plaques in Gothic times for making the "
Opus Alexandrinum," the then much admired pavement for churches : in imitation of the ancient " sectile."
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