Very like Pentelic marble, but easily distinguishable, is the Marmor Porinum, the Marmo Grechetto duro of the Italians. It is intermediate in the quality of its grain between Parian and Pentelic marble, being finer than the former and not so fine as the latter. The column in front of the Church of Santa Maria Maggiore, removed by Paul V. in 1614 from the Basilica of Constantine, is composed of this species; as well as the celebrated Torso Belvedere of the Vatican, found near the site of the Theatre of Pompey, to which Michael Angelo traced much of his inspiration, and which, as we learn from a Greek Inscription at the base, was the work of the Rhodian sculptor Apollonios, who carved the group of the "Farnese Bull."
Not unlike this Porine marble was the _Marmor Hymettium_ of the ancients; but it was never a great favourite in Rome on account of its large grain and dingy white colour, slightly tinged with green and marked by long parallel dark gray veins of unequal breadth. The metamorphic action was not sufficiently energetic to destroy the last traces of organic matter and the original stratification of the rock; and the crystallising force was not sufficiently exercised to allow of the entire rearrangement of the whole of the particles so as to expel the included impurities. This marble was not therefore fitted for sculpture; but it could be used for certain architectural purposes and for ornamentation. It used to be quarried extensively on Hymettus, the well-known mountain of Attica, celebrated for the quantity and excellence of its honey. The rock on which the aromatic flowers grew in such profusion for the bees, did not, however, partake of the same delightful quality. In working it a peculiar fetid odour of sulphuretted hydrogen, somewhat like that of a stale onion, was emitted, which gave rise to its modern Italian name--Marmo Cipolla. This repulsive quality, however, disappeared quickly on exposure. The finest specimens of this marble in Rome are the forty-six columns in the Church of St. Paul's, outside the gate, which belonged originally to the Basilica Æmilia in the Forum, founded about forty-five years before Christ, and were transferred to the new building when the venerable old church, in which they had stood for fifteen hundred years, was destroyed by fire. Nothing too can be finer than the two rows of Ionic columns of Hymettian marble which divide the immense nave of Santa Maria Maggiore from the side aisles. There are eighteen on either side, each upwards of eight feet in circumference, and are supposed to have been taken from the Temple of Juno Lucina, whose site is assigned by antiquaries to the immediate vicinity. Similar rows of fluted Doric columns of the same marble, ten on each side, adorn the Church of St. Pietro in Vincoli. They are ancient, and belonged to some temple or basilica of the Forum. There are also five ancient pillars of Hymettian marble in the upper Church of San Clemente, taken from the same prolific source. The wall which surrounds the unique choir or presbytery of this most interesting old church is also composed of great slabs of Hymettian marble, taken from the original subterranean church and hastily put together. Some of the ancient pillars of Hymettian marble belonging to the peristyle of the temple of Ceres and Proserpine, still as widely spaced as they used to be, adorn the Church of Santa Maria in Cosmedin, built on the foundation of that shrine; while twenty-four remarkably fine fluted Corinthian columns of the same material divide the triple nave of Santa Sabina on the Aventine, and are supposed to have belonged to the ancient Temple of Juno Regina, erected by Camillus after the destruction of the Etruscan city of Veii. Hymettian marble was one of the first--if not actually the first--species introduced into Rome. In the year of Rome 662, Lucius Crassus the orator brought to the city six columns of it, each twelve feet in height, with which he adorned his house on the Palatine Hill, receiving, on account of this circumstance, from Marcus Brutus the nickname of the Palatine Venus. At the present day the marble is used for corner-stones in the ordinary houses of Athens.