Certain earths were recognized by the Greeks and Romans to have therapeutic properties, whether as antidotes, astringents, or desiccants. As clays, they were ingested as an alexipharmic against poisons and venomous bites, applied to wounds to contract or dry them, used as a collyrium or salve for the eyes, and treated any number of other ailments. Black earth from Samos, for example, was prescribed by Hippocrates in the fourth century BC to treat a "fixed" (possibly retroverted or prolapsed) uterus, which otherwise was believed to move throughout the body (Nature of Women, L). Writing a hundred years later, Theophrastus suggests that Samian earth was kaolin, which was taken from a vein of white clay so narrowly deposited that the miner had to lie on his back or side to extract it (On Stones, §62). By the first century AD, earth from the Aegean island of Lemnos had come to be regarded as especially beneficial. Pliny relates that terra Lemnia was esteemed as a red ochre (rubrica) in painting and "never sold except in sealed packages [signata], a circumstance to which it was indebted for its additional name of sphragis" (Greek, "seal"). As a medicine, it was applied as a liniment or taken internally, especially to counteract poison and snake bites, and to control excessive menstruation (Natural History, XXXV.xiv.33–34; XXIX.xxxiii.104, where goose blood mixed with the "red earth of Lemnos" was made into lozenges "as an antidote for all kinds of noxious drugs"). Samian earth also was used to treat the eyes (XXXV.liii.191) and, like all the medicinal earths mentioned by Pliny, first was washed and dried in the sun, finely ground, and placed in water again, where the particles were allowed to settle. The resulting clay then was divided into pastilles or tablets (XXXV.lv.193).
His contemporary, the Greek physician Dioscorides writes that Lemnian earth was mixed with the blood of a sacrificial goat and made into tablets that were stamped or sealed with the figure of the animal and used as a "very powerful antidote against deadly poisons" (Materia Medica, V.113). Samian earth, too, was used as a poultice for the eyes, an antidote, and for menstruation (V.172). When Galen, physician to Marcus Aurelius, visited the island a century later to witness for himself the ritual extraction of the soil under the auspices of a priestess, blood no longer was being used as an admixture but wheat and barley. Formed into tablets or troches (Greek, "little wheel") and impressed with a seal bearing the likeness of Artemis, terra Lemnia was used for the treatment of ulcers, wounds, and poisonous snake bites (with alum, an astringent and bactericide, being the active ingredient). By the early third century AD, the efficacy of Lemnian clay was such that, when the Greek warrior Philoctetes, having been bitten by a snake, was left on nearby Lemnos on his way to Troy (Iliad, II.822ff), the festering wound was immediately cured by the soil of that island (Philostratus, On Heroes, XXVIII.5).
In the Middle Ages, these small cakes of embossed clay were known as terra sigillata. Writing in the 1240s, Bartholomaeus Anglicus relates that "A Certaine veine of the earth is called Terra Sigillata" and was used to treat nose bleed, swollen feet, and gout (Batman upon Bartholome, XVI.98). Sigillatus means "decorated with figures or patterns in relief" (Oxford Latin Dictionary) and is used in the same sense that a sigillum is the embossed impression left by the stamp of a signet ring.
Terra sigillata has a completely different meaning in archaeology. Instead of figured or sealed clay tablets, it identifies a type of fine glossy-red tableware manufactured in Gaul and exported throughout the western Roman empire from the first to the third century AD. Production centered around La Graufesenque in the south and then at Lezoux in the central part of the province, both of which were renown for their pottery. (Production eventually shifted to eastern Gaul and the Rhineland.) Terra sigillata is a term used more often on the Continent (Germany, in particular) than in Britain, where it usually is described as Samian ware, after the Aegean island of Samos, which once was known for its tableware. Pliny declares that "For the service of the table, the Samian pottery is even yet held in high esteem" (Natural History, XXXV.xlvi.160). Indeed, according to Isidore of Seville, writing in the seventh century AD, "Ceramic dishes are said to have been first invented on the island of Samos, made from white clay and hardened by fire, hence 'Samian dishes.' Afterwards it was discovered how to add red earth and to fashion vessels with red clay" (Etymologies, XX.iv.3). Because terra sigillata pottery is not always decorated, to describe it as such is thought a misnomer. But Samian ware, imported from Gaul, is no less so.
Whatever the nomenclature, the advantage to the archaeologist is that Samian ware was mass produced. Known manufacturing sites, standardized forms and decorative motifs, as well as the names of work shops and the potters themselves (both mold maker and decorator) make it possible to date the pieces and determine their place of manufacture—which provide chronological evidence for the sites where they are found. In 1895, this standardization in production allowed the German scholar Hans Dragendorff to classify pottery of similar shape, size, and decorative style by type, even if the sherds were found in different locations. Fifty-five forms were identified, which established the first systematic basis for later study. It was followed in 1904 by Joseph Déchelette's review of pottery from Roman Gaul (who added additional types, such as Déchelette 72 above), and in 1908 by H. B. Walters' catalog of Roman pottery in the British Museum (which, because it was so early, has some mistaken attributions). Another early and important work was by Oswald and Pryce in 1920, who illustrated most of the known types.
Samian ware was wheel thrown or cast from a mold. If molded, delicate stamps of fired clay were impressed on the inner wall of the mold to form a decorative motif, their curved profile allowing the impression to follow the shape of the vessel. Additional details could be incised by hand using a stylus, adding stems and tendrils, for example, to stamped leaves and rosettes. Motifs that needed to be repeated were made by a "roulette" wheel rolled around the inside of the mold. After it had been fired, soft clay was pressed firmly against the inside of the hardened clay mold to capture the impression in relief. The embossed piece was removed, the rim turned and trimmed, and a foot ring added. Finally, it was dipped in slip (an extremely fine mixture of water and clay), allowed to dry further, and put into the kiln.
Red-slip pottery is not the same as slip casting, which was invented in Europe in the early eighteenth century and likely was not used in antiquity. In this technique, slip is poured into a plaster mold, allowed to set, and the excess poured out again, leaving behind a clay shell. As it dries, the water in the slip is absorbed by the mold, the clay shrinks and so can be pulled away. A mold of fired clay, however, is not sufficiently porous to absorb all the water in the slip. Pliny writes that medicinal earths should be "well washed in water, and then dried in the sun; after which, they are again triturated [ground to a fine powder] in water, and left to settle" (XXXV.lv.193). If the preparation of slip is at all analogous to that of clay, it would not seem commercially viable for a vessel to be made of the same slip that otherwise was intended only to provide its shiny and vibrant red coat.
By the end of the second century AD, barbotine decoration began to replace molded ornamentation. A paste of thick clay slip (French barbotine) was applied by piping (slip trailing), much as a cake is decorated with icing, to form tendrils and scrolls in low relief. The slip also could be cast in molds to create figures in decorative relief that then were applied separately (French appliqué). Or the two techniques were combined. Slip was applied and the piece fired in a kiln, emerging with its characteristic red gloss—beautiful, to be sure, but the thin walls also were fragile. Plautus, writing in the early second century BC, has a character in one of his comedies complain "you know how soon a Samian vessel is wont to break" (Bacchides, II.ii.202), and another chides a visitor who knocks too gently on the door, "You're afraid, I think, that the doors are made of Samian" (Menæchmi, I.ii.178). In Britain, an entire dinner set of imported Samian ware was found discarded in a ditch at Vindolanda on the northern frontier of the Roman empire, all the pottery having been broken in transit from Gaul.
The gloss of Samian ware derives from its slip, which contains illite, an iron-bearing mineral (hence the reddish color) that has a lower sintering temperature (about a thousand degrees centigrade), at which point the clay "sinters" or partially melts, fusing into a solid mass during firing. Illite is formed from weathered mica, which itself is composed of very fine crystalline particles of aluminum silicate, the crystals of which are arranged in sheets of silicon dioxide and aluminum hydroxide. There are two sheets of silica, one on each side of a sheet of alumina, although iron has replaced some of the aluminum (and so differentiates illite from muscovite, for example, which has less iron or glauconite, which has more). It is this structure that allows mica to be cleaved into thin flexible sheets—and which gives illite its natural sheen. The word, in fact, was coined in 1937 from "Illinois" to describe this mica clay. Because the boundary between the two layers inhibits the introduction of water into the structure, illite also has the advantage of being non-expanding.
This fine example of a hound chasing a stag was found at Felixstowe (Suffolk) and now is in the British Museum (number 1881,0626.9) where it is described as a "Samian ware pottery jar with barbotine decoration." (Walters catalogs the piece as M2366.) Thrown on a wheel, the animals are modeled in slip, the tendrils added en barbotine, and the appliqué vine leaves produced from molds, The bulbous form and everted rim (turned outward) corresponds to Déchelette 72, a type that invariably evokes mention of "the magnificent but sadly shattered, vase from Cornhill" (M2365), which also is in the British Museum (number 1856,0701.454) but not on display.
Imported from central Gaul, the Felixstowe vase dates to the time of the Antonines (AD 138–180), when Antoninus Pius and his heir Marcus Aurelius ruled, and the Roman empire still was enjoying, in the words of Edward Gibbon, "the period in the history of the world, during which the condition of the human race was most happy and prosperous" (Decline and Fall of the Roman Empire, I.3). It was then, for example, that the importation of Samian ware from Lezoux to Britain reached its height.
This piece was found in a Roman villa in Germany and now is in the German National Museum (Nuremberg), where it is described as terra sigillata mit Barbotinedekor. Here, the reddish-brown color is attributed to the firing process and not the slip or clay. The introduction of oxygen into the kiln during firing produces red ferric oxide; less oxygen and more smoke, black ferrous oxide—the same technique used by the ancient Greeks to produce Attic black- and red-figure pottery.
By the mid-second AD, as imports of Samian ware from Gaul began to decline, a native Romano-British pottery industry developed around the Roman garrison town of Durobrivae (Water Newton) in the lower Nene valley. Castor ware, or more correctly but no less ponderously, Nene Valley Colour Coated Ware (LNVCCW), takes it name from Castor, now a small village just across the river Nene where, from the mid-second to the fourth century AD there was a thriving pottery industry. Castor derives its own name from a nearby Roman fort (Latin castrum) that once protected a major river crossing or possibly from the large municipal building in Castor itself (the so-called Praetorium, from the name of the commander's tent in a castrum). Castor ware varies in color, depending upon the slip applied before firing, but typically is a yellowish gray or slate blue. Unlike more luxurious Samian ware, which was used as fine tableware, Castor ware does not have the same polished appearance. And, although decorations were based on classical motifs and mythology that would have been regarded as Roman by the provincial Britons, both it and Samian ware display native Celtic influences as well.
This hunt scene is depicted on a beaker found in the Roman settlement of Corinium (Cirencester), almost a hundred miles southwest of Castor. It now is in the Corinium Museum there.
The predecessor to Samian ware was Arretine pottery, named after the ancient town of Arretium (Arezzo) in Tuscany. Not only was Samian tableware still esteemed, says Pliny, but "that, too, of Arretium in Italy, still maintains its high character" (Natural History, XXXV.xlvi.160). Isidore of Seville writes that "Arretine dishes [vasa] are named for the Italian city Arretium, where they are made, and they are red" (Etymologies, XX.iv.5). The fact that Isidore uses the present tense suggests that his source (possibly Pliny) wrote at a time when Arretine ware still was being produced. By the middle of the first century AD, however, production had shifted to Gaul and the Rhineland. It is not found in Britain simply because Claudius did not invade that island until AD 43. By the late second century AD, pottery also was being produced at Colchester, but the clay was inferior and distribution limited to local markets.
References: "Medicinal terra sigillata: A Historical, Geographical and Typological Review" (2013) by Arthur MacGregor, in A History of Geology and Medicine, edited by C. J. Duffin, R. T. J. Moody, and C. Gardner-Thorpe; "Geotherapeutics: The Medicinal Use of Earths, Minerals and Metals from Antiquity to the Twenty-first Century" (2017) by Spyros Retsas, in Geology and Medicine: Historical Connections, edited by C. J. Duffin, C. Gardner-Thorpe, and R. T. J. Moody; "Terra Lemnia" (1909/1910) by F. W. Harris, The Annals of the British School at Athens, 18, 220-231; Galen's visit to Lemnos is embedded in Volume XII (of twenty-two) of his collected works, Claudii Galeni Opera Omnia, a monument of nineteenth-century German scholarship in the original Greek and a Latin translation; Batman vppon Bartholome his booke De proprietatibus rerum [etc.] (1582), translated by Stephen Batman; Hippocrates: Nature of Women (Vol. X) (2012) translated by Paul Potter (Loeb Classical Library); "Lemnian Earth, Alum and Astringency: A Field-based Approach" (2014) by Effie Photos-Jones and Allan J. Hall, in Medicine and Healing in the Ancient Mediterranean World, edited by Demetrios Michaelides; Flavius Philostratus: On Heroes (n.d.) translated by Ellen Bradshaw Aitken and Jennifer K. Berenson Maclean; The Iliad (1990) translated by Robert Fagles; Terra Sigillata: Ein Beitrag zur Geschichte der Griechischen und Römischen Keramik (1895) by Hans Dragendorff; Les Vases Céramiques Ornés de la Gaule Romaine (2 vols.) (1904) by Joseph Déchelette; Catalogue of the Roman Pottery in the Department of Antiquities, British Museum (1908) by H. B. Walters; "A Samian Sherd from New Street, London" (1973) by Catherine Johns, The British Museum Quarterly, 37(3/4), 151-154; The Etymologies of Isidore of Seville (2006) by Stephen A. Barney, W. J. Lewis, J. A. Beach, and Oliver Berghof; The Comedies of Plautus (1880) translated by Henry Thomas Riley; An Introduction to the Study of Terra Sigillata (1920) by Felix Oswald and T. Davies Pryce; Arretine and Samian Pottery (1971) by Catherine Johns; Theophrastus: On Stones (1956) translated by Earle R. Caley and John F. C. Richards.
