Provenience of eighteenth-century British porcelain sherds from Sites 3B and 4E, Fortress of Louisbourg, Nova Scotia: Constraints from mineralogy, bulk paste, and glaze compositions

Twenty-six British porcelain sherds excavated from two properties at the Fo rtress of Louisbourg were analysed by electron microprobe with the objectiv e of identifying the factories from which they originated (that is, their p rovenience). Nineteen of the samples are phosphatic; seven are magnesian. S ixteen of the phosphatic sherds have paste and glaze compositions consisten t with Bow porcelain (ca. 1747 to 1776). This attribution is supported by u nderglaze blue patterns (Dragon, Cannonball, and Desirable Residence patter ns) and famille rose overglaze polychrome designs that match the decoration used on Bow porcelain. A calcic plagioclase-bearing sherd has a compositio n suggesting derivation from the Gilbody works (Liverpool, ca. 1755 to 1861 ). Another unassigned sherd has a paste composition that resembles products of the Lowestoft factory (ca. 1757 to 1799), but contains plagioclase, a m ineral not known to occur in Lowestoft porcelain, and its glaze contains sm all amounts of tin, a component unknown in analysed Lowestoft glazes. One h ighly porous sample has an anomalous composition (a lower phosphate content than any known bone-ash porcelain), and appears to have been chemically mo dified in the ground. It, too, remains unattributed. The magnesian sherds c ontain diopside and enstatite, and thus are mineralogically similar to anot her type of Liverpool porcelain (late Chaffers [ca. 1756 to 1765]) and its successor, the Christian/Seth Pennington works (ca. 1765 to 1688). Composit ionally, the body and glaze of these samples resemble Chaffers/ChristianSet h Pennington porcelain. This attribution is further supported by their unde rglaze blue patterns, which match some of those (Liver Bird pattern) known to have been used at the Liverpool works. Contemporary documents record the fact that the Bow works exported significant amounts of its wares to North America. The discovery of Chaffers/Christian/Seth Pennington porcelain at Louisbourg and other archaeological sites in Atlantic Canada (Fort Beausejo ur) indicates that some Liverpool factories also supplied colonial markets with porcelain.