MARBLE. - For sculpture, the marbles most generally used are the white ones, called for that very reason statuary marbles, among which the most prized are those of fine grain that allow cleaner and more delicate work. Famous in antiquity were the Greek marbles, above all the Parian; today the very rich quarries of Carrara, already known in the 2nd century B.C. and exploited from the 12th century onward, supply material to the whole world.
Only the Egyptians commonly used for sculpture the colored marbles with which they were rich: porphyry, granite, basalt, all of great hardness and hostile to the chisel, and which therefore required extreme technical skill. Among the Greeks and Romans their use was introduced only in late antiquity, almost always for decorative sculptures that sought an effect of sumptuousness rather than of pure beauty (vases, craters, feet of ta-
Its use continued in early Christian times: monumental porphyry sculptures of the 4th century are the two sarcophagi of St. Helena and St. Constance, now in the Vatican Museums. For the same purpose of rarity and technical preciousness, polychrome marbles came back into use by the sculptors of the late 16th century, and Vasari cites as works of extreme virtuosity three porphyry ovals by Tadda, a sculptor from Fiesole, one with the head of Christ, the others with the portraits of Duke Cosimo and Duchess Leonora. Likewise, for a display of technical skill, about a century later, Algardi sculpted in touchstone (that is, in the very hard ancient black) the soft sleeping putto of the Borghese Gallery, which is a tour de force even among the virtuosities of the sumptuous 17th century; at that time polychrome marbles were in fashion not only in decorative sculptures but also in the accessories of sepulchral monuments (Rome, monument of Gregory XV by Legros, in S. Ignazio; of Alexander VII by Bernini, in S. Peter's, etc.), and they continued to be used with conspicuous excesses until the neoclassical age returned to the exclusive use of white marble.
In architecture, marble served in ancient Greece as a building material, that is, for the very skeleton of the building; among the Romans it was used for facing with ever greater splendor of polychromy and technique. Polychrome marbles were also used for structural elements - columns, capitals, entablatures: granite (from which colossal columns were obtained, such as those of the Pantheon and of the Baths of Diocletian, later S. Maria degli Angeli), cipollino, serpentine, porphyry, etc. In early Christian churches these elements are often spolia (that is, coming from pagan buildings), and therefore one frequently finds columns of different material and dimensions aligned together; but in the churches of the Exarchate - at Ravenna, at Grado, at Parenzo - the greater wealth and structural possibilities allowed the use of marbles from Greek quarries specially worked. For the decorative parts, Christian art continued and perfected the techniques already in use in the classical era: lithostrata for floors, and with a few additions of glass tesserae also for vaults (S. Costanza in Rome); opus sectile for the facing of walls. And the delicate pierced technique achieved clarity of style, with flat ornaments on deeply hollowed backgrounds, with a vivid chiaroscuro effect, for capitals and chancel screens.
Throughout the Middle Ages architecture sought in marble a sober polychromy, associating with white mostly a single color, sometimes two. The diversity of coloristic effects in the various regions is determined by the availability of local materials: thus the green of Prato and the portoro help to characterize respectively Tuscan and Ligurian architecture, in which bands alternate, in the facades and interiors of churches, white and dark green (churches of Pistoia) or white and black (cathedral of Genoa; St. Peter's in Portovenere, etc.). In Rome the use of colored marbles on the exteriors of churches was abandoned in the late Renaissance, which introduced a far greater variety of polychromy in the interior, after Raphael was the first to employ precious colored marbles in the Chigi Chapel in S. Maria del Popolo in Rome. In the same city the later examples are countless, with ever-increasing splendor in Baroque architecture. There the columns were of precious marbles (revetments of Sicilian jasper in S. Marco and in S. Maria in Via Lata; fior di persico in S. Antonio dei Portoghesi; Verona yellow in the Cybo Chapel in S. Maria del Popolo, etc.) and rare marbles were combined with bronze and hardstones in altars (examples of exceptional richness are the altars of S. Ignazio at the Gesù and of the Pauline Chapel in S. Maria Maggiore), in ciboria, in pulpits. With no less sumptuousness, but with greater softness of chromatic harmonies, marble is used in the interiors of churches and chapels, especially in southern Italy and in Sicily during the 18th century; but in the Rococo the use of stucco increasingly takes over. The 19th century returns, in architecture too, to the almost exclusive use of white marble, and when, rarely, it has recourse to colored marbles, it maintains a great coldness of polychromy. Today polychrome marble in architecture is used in a more or less happy imitation of Baroque models (v. also the entries: ALTARE; CIBORIO; RIVESTIMENTO).
