MOSAIC

in art, decoration of a surface with designs made up of closely set, usually variously coloured, small pieces of material such as stone, mineral, glass, tile, or shell. Unlike inlay, in which the pieces to be applied are set into a surface that has been hollowed out to receive the design, mosaic pieces are applied onto a surface that has been prepared with an adhesive. Mosaic also differs from inlay in the size of its components. Mosaic pieces are anonymous fractions of the design and rarely have the dimensions of pieces for intarsia work (fitted inlay usually of wood), whose function is often the rendering of a whole portion of a figure or pattern. Once disassembled, a mosaic cannot be reassembled on the basis of the form of its individual pieces. Technical insight is the key to both the creation and the appreciation of mosaic, and the technical aspects of the art require special emphasis. There are also significant stylistic, religious, and cultural aspects of mosaic, which has played an important role in Western art and has appeared in other cultures. Although mosaic is an art form that appears in widely separated places and at different times in history, in only one placeByzantiumand at one time4th to 14th centuriesdid it rise to become the leading pictorial art. in art, surface decoration of small coloured componentssuch as stone, mineral, glass, tile, or shellclosely set into an adhesive ground. The mosaic pieces, usually small squares, triangles, or other regular shapes (called tesserae), are applied to the surface, frequently a wall or floor, which has been prepared with mortar or adhesive to receive the design. A brief account of mosaic follows. For full treatment, see Decorative Arts and Furnishings: Mosaics. Mosaic differs from inlay in that the pieces are applied to the surface and not inset into a recess below the surface. Each mosaic piece is small, and it is only when the piece forms part of an overall mosaic design that it takes on decorative significance. Mosaic as an art form has most in common with painting. It represents a design or image in two dimensions. It is also, like painting, a technique appropriate to large-scale surface decoration. Unlike the painter, however, the mosaic artist is limited in the range of colours available to him by the physical limitation of his materials. It is difficult, therefore, to achieve the same variation of light and shadow as is possible in painting, although mosaic has qualities that render it more effective for distance effects. The light-catching qualities of the glass tesserae used in Byzantine mosaic work, for example, as well as the elimination of the middle tones in Byzantine mosaics gave a greater brilliance than painting ever did. Like each decorative medium, mosaic has qualities unique to itself, which lends it particular suitability to certain decorative functions. The earliest known mosaics date from the 8th century BC and are made of pebbles, a technique refined by Greek craftsmen in the 5th century. Pebbles of uniform size, ranging in colour from white to black, were collected and used uncut to form floor and pavement mosaics. Even with this seemingly limited technique, Greek craftsmen were able to create elaborate and complex designs, using pebbles between one and two centimetres in diameter and outlining areas with tiny black pebbles. By the 4th century, pebbles painted red and green were added to give greater variety of effect. Throughout antiquity, mosaic remained primarily a technique used for floors or pavements where durability and resistance to wear were paramount considerations. Stone, especially marble and limestone, was particularly suitable for this purpose. It could be cut into small pieces and the natural colours of stone provided a reasonable basic range of hues for the artist. The use of glass for mosaic originated in the Hellenistic period, and it was to remain the most important mosaic material right through the Byzantine period. Glass could be made in any colour, and thus the range of colour available to the artist was virtually unlimited. Glass was less suitable than stone for floors, though its lightness made it particularly suitable for wall mosaic where durability was not so important. During the Early Christian period, gold and silver glass tesserae were invented, made by applying metallic foil to the glass. This mirror glass enabled even greater intensity of light to be created, and gold in particular was to create one of the most characteristic effects of the great shimmering mosaics of the Byzantine period. In the 6th century AD, Byzantine mosaicists were using a gold background as the norm. They also developed a technique of setting tesserae into the mortar at a sharp angle to reflect the maximum amount of light. The Romans used mosaic widely, particularly for the floors of domestic buildings. Fine examples have survived from Pompeii, Herculaneum, and Ostia. During the Early Christian period, wall mosaics came into favour as church decoration, and these were to remain the major form of decorative art throughout the Byzantine period. The greatest examples of Byzantine mosaic work are at Ravenna at the churches of S. Apollinaire Nuovo and S. Vitale, where the continuous skin of rich mosaic is an integral part of the architecture. Striking later examples were executed at Torcello, near Venice, in the 12th century; at Daphni, near Athens, in the 11th century; and at St. Mark's cathedral, in Venice, from the 11th to the 14th century. The influence of these Byzantine mosaics spread throughout Europe, but mosaic gradually declined in popularity as the quest for realism in the Renaissance led to a reaction against the stylized decorative quality of Byzantine art. It enjoyed a revival in the 19th century, when many public buildings were decorated with mosaics, usually of mass-produced ceramic tile or glass tesserae. Mosaic has also come to be practiced as an independent fine art (as exemplified by abstract compositions that may be hung on walls like paintings). Pre-Columbian American Indians favoured mosaics of semiprecious stones such as garnet and turquoise and mother-of-pearl. These were normally used to encrust small objects such as shields, masks, and cult statues. Mexican artists in the 20th century have been among the greatest proponents of mosaic, primarily of natural stone, which has been widely used to decorate modern architecture in Mexico. in botany, plant disease caused by various strains of several hundred viruses. Symptoms are variable but commonly include irregular leaf mottling (light and dark green or yellow patches or streaks). Leaves are commonly stunted, curled, or puckered; veins may be lighter than normal or banded with dark green or yellow. Plants are often dwarfed, with fruit and flowers fewer than usual, deformed, and stunted. Flowers may be blotched or streaked (flower breaking), a condition appreciated in certain tulips, often termed Rembrandt tulips, for their attractive and colourful streaking. Mosaic symptoms may be masked or latent, especially at temperatures above 27 C (81 F), and are sometimes confused with nutrient deficiency or herbicide injury. The causal viruses are spread by aphids and other insects, mites, fungi, nematodes, and contact; pollen and seeds can carry the infection as well. Mosaic can be avoided by using virus-free seeds and plants, growing resistant varieties, separating new from old plantings, rotating annuals, and observing stringent sanitation and pest-control measures. Additional reading General works A. Blanchet, La Mosaique (1928); E.W. Anthony, A History of Mosaics (1935, reprinted 1968); P. Fischer, Das Mosaik (1969); H.P. L'Orange and P.J. Nordhagen, Mosaikk (1958; Eng trans., 1966), deals with the history of the art from its beginnings to c. AD 900. Greek and Roman mosaic Of the literature on Greek and Roman mosaic, the following works are of particular importance: (pebble mosaic): R.S. Young, Gordion 1956: Preliminary Report, Am. J. Archaeology, 61:319331 (1957); D.M. Robinson, Excavations at Olynthus, vol. 5, 8, and 13 (1933, 1938, 1950). (pebble-tessera mosaic): C.M. Robertson, Greek Mosaics, J. Hellenic Stud., 85:7289 (1965); B.R. Brown, Ptolemaic Paintings and Mosaics and the Alexandrian Style (1957); J. Chandnard, Les Mosaques de la maison des masques (1933). (floor mosaicRoman): Colloque sur la mosaque grco-romaine, Actes (1965); H.E. Blake, articles on Roman mosaics in Mem. Am. Acad. Rome, 8:7160, 13:69214, and 17:81130 (1930, 1936, 1940); K.M. Phillips, Subject and Technique in Hellenistic-Roman Mosaics: A Ganymede Mosaic from Sicily, Art Bull., 42:243262 (1960); R.P. Henks, Catalogue of the Greek, Etruscan and Roman Paintings and Mosaics in the British Museum (1933); D. Levi, Antioch Mosaic Pavements (1947); I. Lavin, The Hunting Mosaics of Antioch and Their Sources, Dumbarton Oaks Papers, no. 17 (1963). H. Stern, Origine et dbuts de la mosaque murale, tudes d'archologie classique, vol. 2 (1959). Early Christian mosaic M. van Berchen and E. Clouzot, Mosaques chrtiennes du IVe au Xe siecle (1924); G. Matthiae, Mosaici medioevali delle chiese di Roma (1967); W. F. Oakeshott, The Mosaics of Rome, from the Third to the Fourteenth Centuries (1967); H. Stern, Les Mosaques de l'glise de Sainte-Constance Rome, Dumbarton Oaks Papers, no. 12 (1958); C. Cecchelli, I mosaici della basilica di S. Maria Maggiore (1956); C. Ricci, Tavole storiche dei mosaici di Ravenna, 4 vol. (193037); F. W. Deichmann, Frhchristliche Bauten und Mosaiken von Ravenna (1958); G. Brusin and P.L. Zovatto, Monumenti paleocristiani di Aquileia e di Grado (1957); J.L. Maier, Le Baptistere de Naples et ses mosaques (1964); B. Brenk, Die ersten Goldmosaiken der christlichen Kunst, Palette (Basel), 38:1625 (1971), a work concerning the earliest use of gold cubes in mosaics. Early Byzantine mosaic G. Brett et al., The Great Palace of the Byzantine Emperors (1947); C. Diehl, M. Le Tourmeau, and H. Saladin, Les Monuments chretiens de Salonique (1918); T. Schmit, Die Koimesis-Kirche von Nikaia (1927); P.A. Underwood, The Evidence of Restorations in the Sanctuary Mosaics of the Church of the Dormition at Nicaea, Dumbarton Oaks Papers, no. 13 (1959); M. Aviyonah and M. Schapiro, Israel: Ancient Mosaics (UNESCO 195460); E. Kitzinger, Israeli Mosaics of the Byzantine Period (1965); K. Weitzmann, The Mosaic in St. Catherine's Monastery on Mount Sinai, Am. Phil. Soc. Proc., 110:392405 (1966); K.A.C. Creswell, Early Muslim Architecture, 2nd. ed., vol. 1 (1969), including K. Van Berchek, The Mosaics of the Dome of the Rock in Jerusalem and the Great Mosque in Damascus; G. Bovini, Mosaici di Ravenna (1956; Eng. trans., Ravenna Mosaics, 1956), and La vita di Cristo nei mosaici di S. Appollinare Nuevo di Ravenna (1959), B.J. Nordhagen, The Mosaics of John VII (705707 AD), Acta, Institutum Romanum Nowegiae, 2: 121166 (1965); Gunilla . Kerstrm-Hougen, The Calendar and Hunting Mosaics of the Villa of the Falconer in Argos (1974). Middle and late Byzantine O. Demus, Byzantine Mosaic Decoration (1948), A. Graber, La Peinture Byzantine (1953; Eng. trans., Byzantine Painting, 1953); T. Whittemore, The Mosaics of Haghia Sophia at Istanbul, 4 vol. (193352); P.A. Underwood and E.J.W. Hawkins, The Mosaics of Hagia Sophia at Istanbul: The Portrait of the Emperor Alexander, Dumbarton Oaks Papers, no. 15 (1961); E.J.W. Hawkins, Further Observations on the Marthex Mosaic in St. Sophia at Istanbul, ibid. 22 (1968); C.A. Mango, Materials for the Study of the Mosaics of St. Sophia at Istanbul, ibid. 8 (1962); P.A. Underwood, The Kariye Djami, 3 vol. (1967); E. Diez and O. Demus, Byzantine Mosaics in Greece, Hosios Lucas, and Daphni (1931); A. Grabar and M. Chaizidakis, Greece: Byzantine Mosaics (UNESCO 1960); V.N. Lazarev, Old Russian Murals and Mosaics: From the 11th to 16th Century (1966). Medieval mosaics in the West W.F. Oakeshott, The Mosaics of Rome, from the Third to the Fourteenth Centuries (1967); O. Demus, The Mosaics of Norman Sicily (1950); E. Kitzenger, The Mosaics of the Cappella Palatina in Palermo, Art Bull., 31:269292 (1949); The Mosaics of Monreale (1960); A. de Witt (ed.), I mosaici del Battistera di Firenze, 4 vol. (195459); H. Kier, Der mittelalterliche Schmuckfussboden (1970); A Prandi, Pietro Cavallini a S. Maria in Trastevere, Rivista dell'Istituto Nazionale d'Archeologia e Storia dell'Arte, 1:282297 (1952); R. Dertel, Wandmalerei und Zeichnung in Italien, Mitteilungen des Kunsthistorischen Institutes in Florenz, 5:217324 (193740), on the technique; F. Forlati, La tecnica dei primi mosaici marciani, Arte veneta, 3:8587 (1949); Hetty Joyce, The Decoration of Walls, Ceilings, and Floors in Italy in the Second and Third Centuries A.D. (1981). Renaissance to modern The best surveys are those contained in E.V. Anthony, A History of Mosaics (1935, reprinted 1968); and P. Fischer, Das Mosaik (1969). Specific instances are discussed in Frank R. DiFederico, The Mosaics of Saint Peter's: Decorating the New Basilica (1983); and Alvar Gonzlez-Palacios, The Art of Mosaics: Selections from the Gilbert Collection (1982).