Ancient artistic technique that uses cut marbles to create inlaid flooring and wall decorations, also called later, marble or semi-precious stone salesman

The opus sectile is considered one of the most refined and prestigious marble ornamentation techniques, both for the materials used (marbles among the rarest and therefore expensive) and for the difficulty of realization, having to dissect the marble into very thin sheets ("crustae "), shape it with great precision, and use the most diverse qualities of marble in order to obtain the desired chromatic effects. It differs from the mosaic in that it does not use small geometric tiles (opus tessellatum or even opus vermiculatum, due to the very small tiles arranged according to the contours of the figures). The opus sectile instead carves larger pieces, chosen for color, opacity, brilliance and shades of the veins, creating a figurative design.

A variant of this technique is the glass paste opus sectile, commonly referred to as "architectural glass". In this case, the material is not made up of sheets of marble, but of slabs of glass paste, which in the case of use as a coating were colored in imitation of marble.

A relevant example of these sectilia is represented by the approximately 30,000 slabs from the Villa of Lucio Vero at the Acqua Traversa on the Via Cassia and belonging to the Gorga Collection. In this case, the material is not made up of sheets of marble, but of slabs of glass paste, which in the case of use as a wall covering were colored in imitation of marble.

opusA relevant example of these sectilia is represented by the approximately 30,000 slabs from the Villa of Lucio Vero at the Acqua Traversa on the Via Cassia and belonging to the Gorga Collection [1]. Detail of the opus sectile of the insula of Jason in Cyrene, Libya Pliny the Elder describes this technique in book XXXVI, VI-IX of his Naturalis historia, indicating its invention in Caria and the first application in the Mausoleum of Halicarnassus (4th century BC ). The introduction to Rome of the wall decoration in opus sectile is much later and is due, according to Pliny, to the Formian knight Mamurra, who had been chief of Caesar's engineers in Gaul - therefore dates back to the 1st century BC. [2].

Quickly, and despite the moralistic deplorations of Pliny [3] and other nostalgics of republican austerity, the decorations in opus sectile of floors and walls spread, as well as in public buildings, even in the most sumptuous private environments, to magnify the wealth and the refinement of the owners. Initially the scales made up coverings with geometric motifs (as the works of the Cosmati will later be), but over time more and more refined and varied in size naturalistic iconographic modules developed, ranging from large hunting scenes to ornamental panels with floral motifs, to covering of entire rooms, developing a real "stone painting".

The characteristics that measured the quality of the opus sectile were the continuity of the marble fabric (whose joints had to be invisible) and the richness of the colors, to vary which different marbles were used, but also modifying treatments, such as the burning of the antique yellow to create shades with volumetric effects.

Finally, a very important feature of this technique is the two-dimensional rendering of the figures. The technique will be used in the West for the entire duration of the Roman Empire and will continue to find application, in the East, in the Byzantine basilicas. An extraordinary example of an entire room decorated in opus sectile and reconstructed in a museum exhibition is the hall of the domus of Porta Marina di Ostia, currently (2009) exhibited at the Museum of the Early Middle Ages in Rome.

The environment, found in 1949 and whose first restoration was carried out between 1959 and 1966, comes from a domus in Ostia, and can be dated to the last years of the fourth century. Its relative integrity (which allowed its exceptional restoration) is due to the fact that the walls collapsed while construction work was still in progress, as evidenced by the existence of areas not yet paved but whose materials had already been prepared on site, and the presence of two pits to extinguish lime in the work area. Altar to "Commesso Florentine" in the Church of Santa Corona in Vicenza, work by Domenico Corbarelli The technique of "commesso in semi-precious stones", also known as "Florentine mosaic", was promoted in the sixteenth century by the Medici and was perfected over the centuries thanks to the establishment, in 1588, of the Opificio delle Pietre Dure by the Grand Duke Ferdinando I de 'Medici. The drawings, flowers, landscapes and figures, can be performed with this technique using parts of colored stone, assembled one next to the other, to obtain chromatisms of particular effect, similar to a painting, as Vasari defined it in 1550.

The term "committed" derives from the Latin committere (to join) stone pieces cut from a metal wire according to an initial design, starting from which a cardboard section was made that served as a composition. The various pieces were fixed with glue on a rigid support and then polished. The most famous Prague manufactories were born on the Florentine model, at the behest of Rudolph II of Habsburg and the Gobelins by Louis XIV of France, in 1668. At the end of the seventeenth century the Corbarellis, an important Florentine family of stone inlayers hard workers who worked in Brescia, Padua, Vicenza, Modena and Mantua, introduced the art of the “Florentine salesman” with naturalistic inlay in sacred architecture (decoration of altars).

They were commissioned to decorate the altar for the lost church of San Domenico in Brescia. Other Brescian sculptors were masters in this technique, in particular those belonging to the Gamba family [4]. At the beginning of the seventeenth century, a new technique was invented, called scagliola, able to imitate the appearance of marble inlay, through the use of poor and cheap materials (a mixture of the same plaster, combined with natural glues and colored pigments).