Crucibles to melt glass are very rare in archaeological contexts in sub-Saharan Africa. Recent archaeological excavations at Igbo Olokun, Ile-Ife (Southwest Nigeria) revealed abundant fragments of glass crucibles from 11th-15th century AD deposits, matching the complete and near complete examples earlier reported from Ile-Ife. This paper provides an in-depth examination of these crucible fragments in order to understand the material quality of the crucibles, their typology, and their functions in glass- working/making. Optical microscopic and scanning electron microscopy (SEM) with energy dispersive spectrometry (EDS) analyses were carried out on ten crucible samples. The composition of ceramic fabrics and the adhering glass are presented and discussed in view of their function. The crucibles were produced from specifically selected highly refractory clay and used for melting glass from its raw materials; colorants were added to the melt in the crucible. The useable capacity of the crucibles varied from 1 to 7 liters, equivalent to about 2.5 to 17.5 kg of finished glass for each crucible. Compositional analysis of a sample of the thousands of glass beads from the excavations indicates that the crucibles were used to melt the glass used in the beads. Archaeological evidence of glass bead making at this scale has not previously been reported from West Africa. The crucibles are unique evidence of indigenous glass-working/making in Sub-Saharan Africa from early through mid-second millennium AD.

The quest for a comprehensive understanding of Africa's indigenous technology has been an important intellectual agenda in Black Studies. In some instances this interest has tended to be speculative and derivative because most Black Studies scholars are not trained in the disciplinary fields that are relevant for investigating Africa's indigenous technology through primary field and laboratory research. Collaboration between Black Studies scholars and those in the physical sciences is therefore important in order to develop new insights into Africa's indigenous technology. One of such collaborations has led to a new archaeological and geochemical evidence for primary glass manufacture in Yorubaland. Based on the recent archaeological finds of glass artifacts from Osun Grove (Osogbo, Nigeria), we present the laboratory data that lead us to the conclusion that the Yoruba of West Africa developed a unique glassmaking technology that lasted till the seventeenth century.