Terra Sigillata - Medicinal Earth

Medicinal Earth

The oldest use for the term terra sigillata was for a medicinal clay from the island of Lemnos. The latter was called "sealed" because cakes of it were pressed together and stamped with the head of Artemis. Later, it bore the seal of the Ottoman sultan. This soil's particular mineralic content was such that, in the Renaissance, it was seen as a proof against poisoning, as well as a general cure for any bodily impurities, and it was highly prized as a medicine and medicinal component. In 1588 English ethnographer and translator Thomas Harriot wrote in A Briefe and True Report of the New Found Land of Virginia that Algonquians of the mid–Atlantic region treated various sores and wounds with wapeih, a kind of terra sigillata that English surgeons and physicians found to be of the same kind "of vertue and more effectuall" than the contemporary European sort.

A sintered or high fired colloidial slip can develop a glaze like surface when fired at temperatures above the earthenware range so the statement that a fusible slip loses its polish when high fired is not technically accurate