But four or five years ago, the sources from which the Romans obtained some of their most precious varieties of this material have been rediscovered in the range of mountains called Djebel Orousse, north-east of Oran in Algeria.  All over an extensive rocky plateau in this place numerous shallow depressions plainly indicate the existence of very ancient quarries.  A large company has been formed to work and export the marble, which may now be had in illimitable quantity.  The largest specimens of giallo antico existing in Rome are the eight fluted Corinthian pillars, thirty feet high and eleven feet in circumference, with capitals and bases of white marble, which stand in pairs within the niches of the Pantheon.  In consequence of the fires of former generations, the marble has here and there a tinge of red on the surface.  In the Church of St. John Lateran there is a splendid pair of fluted columns of giallo antico, which support the entablature over a portal at the northern extremity of the transept.  They are thirty feet in height and nine feet in circumference, and were found in Trajan’s Forum.  In the Arch of Constantine are several magnificent giallo antico columns and pilasters, which are supposed to have belonged to the triumphal arch of Trajan.  They are so damaged in appearance, and so discoloured by the weather, that it is not easy, without close inspection, to tell the material of which they are composed.  For pavements and the sheathing of interior walls giallo antico was used more frequently than almost any other kind of marble; hence it is mostly found in fragments of thin slabs, with the old polish still glistening upon them.

It is difficult to describe, so as to identify it, the species of marble known as Africano.  It has a great variety of tints, ranging from the clearest white to the deepest black, through yellow and purple.  Its texture is very compact and hard, frequently containing veins of quartz, which render it difficult to work.  Its ancient name is Marmor Chium, for it was brought to Rome from a quarry on Mount Elias, the highest summit in the island of Chios—­the modern Scio—­which contested the honour of being the birthplace of Homer.  It received its modern name of Africano, not from any connection with Africa, but from its dark colour.  It enters pretty frequently into the decoration of the Roman churches, though it is rare to see it in large masses.  It seems to have been much in fashion for pavements, of which many fragments may be seen among the ruins of Trajan’s Forum.  The side wall of the second chapel in the Church of Santa Maria della Pace in the Piazza Navona is sheathed with large slabs of remarkably fine Africano, “with edges bevelled like a rusticated basement.”  In the Belvedere Cortile in the Vatican is a portion of an ancient column of this marble, which is the most beautiful specimen in Rome; and the principal portal of the portico of St. Peter’s is flanked by a pair of fluted Roman Ionic columns of Africano, which are the largest in the city.