Research reveals Romans’ use of mother of pearl to decorate Hispano-Roman villas

Nacre or mother of pearl, a hard, highly iridescent substance found on the inside of the shells of certain molluscs, was used for decorative effect in the homes of wealthy and important Romans in ancient times. A group of researchers from the archaeology unit of Spain’s IE University, working in collaboration with experts from Flashback Archaeologica and specialists in molluscs from Spain’s National Natural Sciences Museum, have published an article in the latest issue of leading Spanish research journal Oppidum in which they highlight the widespread use of mother of pearl, for ornamental purposes in Roman architecture.

In issue No. 12 of Oppidum, experts examined the presence of mother of pearl in rural Hispano-Roman residential complexes from the 4th century AD. More specifically, they documented slabs of the exotic material found in the Las Pizarras excavation site in the town of Coca (Segovia), which served as the base of Theodosius the Great, the last Roman Emperor of both East and West.

The study reveals that molluscs have held an interest for many since ancient times, both for nutritional reasons, and because the properties of their shells made them useful for a range of purposes, including being used as currency, as musical instruments, for personal adornment, as components in rituals, or even as charms to protect the user against the evil eye.

Although the iridescence of mother of pearl was much appreciated by the Romans and Visigoths, there is scant mention of it in classical texts, while the use of pearls as adornment is well documented. “Mother of pearl is something that is largely unknown among archaeological materials from Roman times” says Cesáreo Pérez, who heads IE University’s archaeology unit.

Not all mollusc shells contain mother of pearl, the result of secreting an organic substance made up of crystalized calcium carbonate in the form of aragonite which is deposited on the inside of their shells. Researchers involved in this project have pointed out that this natural element played a key role in the decoration of the most sumptuous Hispano-Roman villas.

Malacological (related to the study of molluscs) analysis of the mother of pearl found at the Las Pizarras site revealed it belongs to a sole family of bilvalve molluscs (Pteriidae). Experts have also been able to identify the specific marine species used to decorate the residential complex in Coca as a pearl-bearing oyster called pinctada margaritifera. Experts say that it was sent from its place of origin in the Red Sea, or the Persian Gulf, around the Roman Empire to provide decorative detail in luxury residences.

Researchers were surprised by the extent to which the nacre was used for the decoration of a residence of marked architectural value located so far inland, thereby establishing a link between mother of pearl and the decoration of Hispano-Roman villas in the 4^th century, a golden age for that style of architecture.

According to the study, the mother of pearl was used extensively to provide detail on the walls and on the marble floors. It brought a touch of elegance and prestige to the main rooms of the suburban villa situated in Las Pizarras, a complex which experts believe covered a surface area of around a hectare. The presence of the remains of slabs of mother of pearl at the Roman residential complex suggests that entire slabs were transported to wherever they were going to be used, and were worked on in situ. The study concludes, however, that it is not possible to be certain whether or not only one species of pearl oyster was used to provide nacre, even if it was the only type used to line and decorate parts of the Hispano-Roman building in Coca.

Researcher Olivia Reyes says that the finding that mother of pearl was used to decorate Hispano-Roman villas still requires further investigation. Researchers underscore the need to evaluate the presence of nacre when considering links between Roman residences in inland Spain, including the Roman palaces found in Carranque (Toledo) and in El Saucedo (Talavera de la Reina), both of which provide excellent pointers to the way of life and styles of residence of Hispanic aristocracy in Roman times.

Doctor Cesáreo Pérez talked about how it is the first time that real remains from an excavation of a Hispanic-Roman site have been analyzed and synthesized. “There is no doubt this research is a great place to start and provides an excellent guide to distinguishing and isolating the remains of this mollusc in different Roman and Visigoth sites on the Iberian Peninsula, where they have lain undiscovered until now, making it impossible to know the extent of their use in architecture.”