Petrographic and chemical analyses were undertaken to determine the provenance of a group of Islamic ceramics excavated at Qsar es-Seghir, a late medieval site on the Moroccan coast of the Straits of Gibraltar. The vessels are conical or cuencos of the the Hispano-Moresque commonware tradition and come from the early Marinid (1287-1350) and late Marinid (1350-1458) strata at the site. This is an important historical period in the western Mediterranean which witnessed the definitve shift from Muslim to Christian economic and political control. These stratigraphically excavated vessels are a record of changing craft practices at this time. Some of the conical plates, along with related kiln furnishings, were found in association with a late Marinid pottery workshop. The laboratory investigations were undertaken to characterize these locally produced late wares and to test the hypothesis that the early Marinid conical plates were imported. The analyses show that early and late materials are chemically distinct, suggesting that, as hypothesized, the early period vessels were imported to the site.