Cottanello antico 'marble' is a variety of marl limestone commonly referred to as scaglia in Italy. It has a high iron content and is veined in calcite, hence the red and white coloration. It was quarried in only one location at Cottanello near the town of Rieti in the Sabine Hills of Lazio, approximately 40 kilometers northeast of Rome.
The quarry was closed in late antiquity and was only reopened in the early 17th century to provide Gianlorenzo Bernini with columns for the nave of the Basilica of St. Peter's in Rome. However, these columns are much coarser than the stone quarried in antiquity, with the inclusion of brown and pink patches in addition to the red-and-white marbling. The stone quarried at this site in antiquity was from an area closer to the geological fault line that was richer in iron with thin veins of white calcite, as can be seen in the present example. This area of the quarry had been exhausted in antiquity and was unavailable to Bernini and his patron Santi Ghetti in the 17th century.
The labrum is commonly regarded as the basin for cold water in the caldarium or hot room of a Roman bath complex. They were made of marble in order to keep the water cool. They would also have been placed in the atrium of a dwelling in order to collect rain water.
Ambrogi, in her study of ancient labra (Labra di età Romana in marmi bianchi e colorati), has identified eight main forms of profile for the basin. This example falls into her Type VIII. However, within the type, examples with elaborate petals and egg-and-dart are comparatively rare. Ambrogi also identifies two main pedestal profiles, with two subdivisions within each type - with and without fluting. This pedestal would be categorized as Type I(a).
The closest known parallel to the present labrum is the example now in the Museo Pio Clementino in the Vatican, which was excavated at a Roman villa in the Valle dell'inferno, just north of the Vatican, during the reign of Pope Pius VI (1775-1799). The Vatican labrum is of larger dimensions (79 in. diameter) and was sculpted from pavonazzetto marble, pale yellow in color, veined in black, which was quarried in Phrygia, western Turkey. With similar petals and egg-and-dart molding, the Vatican example is now supported on an 18th century pedestal and plinth, the dimensions and style of which are so close to this example that it has been postulated that the Vatican pedestal may have been designed with the knowledge of this one. The labrum still sits in the Vestibolo Rotondo in the Vatican museums, where it was placed by Pius VI in the 18th century. It was engraved in that location by Vincenzo Feoli (1750-1831).
The condition of the present example indicates wear from water over a significant length of time. One large crack follows the vein of white calcite that has shown weakness from water erosion. The crack was clamped in two places, with marble cut away to accommodate the iron clamps set in lead. According to surface studies, the clamps and repairs were made after the basin had already been severely worn, i.e., when the basin was already quite old. Furthermore, analysis of the iron clamps dates them to the 17th century, clearly placing this labrum in use well before the discovery of the Vatican example.