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 Fortress of Louisbourg were analysed by electron microprobe with the objective of identifying the factories from which they originated (that is, their provenience). Nineteen of the samples are phosphatic; seven are magnesian. Sixteen of the phosphatic sherds have paste and glaze compositions consistent with Bow porcelain (ca. 1747 to 1776). This attribution is supported by underglaze blue patterns (Dragon, Cannonball, and Desirable Residence patterns) and famille rose overglaze polychrome designs that match the decoration used on Bow porcelain. A calcic plagioclase-bearing sherd has a composition suggesting derivation from the Gilbody works (Liverpool, ca. 1755 to 1761). Another unassigned sherd has a paste composition that resembles products of the Lowestoft factory (ca. 1757 to 1799), but contains plagioclase, a mineral not known to occur in Lowestoft porcelain, and its glaze contains small amounts of tin, a component unknown in analysed Lowestoft glazes. One highly porous sample has an anomalous composition (a lower phosphate content than any known bone-ash porcelain), and appears to have been chemically modified in the ground. It, too, remains unattributed. The magnesian sherds contain diopside and enstatite, and thus are mineralogically similar to another type of Liverpool porcelain (late Chaffers [ca. 1756 to 1765]) and its successor, the Christian/Seth Pennington works; ca. 1765 to 1799). Compositionally, the body and glaze of these samples resemble Chaffers/Christian/Seth Pennington porcelain. This attribution is further supported by their underglaze 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 Beauséjour) indicates that some Liverpool factories also supplied colonial markets with porcelain.