We have carried out a thorough mineralogical analysis of 16 pottery samples from the Lapita site of Bourwera in Fiji, using micromorphological techniques with optical and polarising microscopes. While the overall mineralogy of all of the samples is similar the samples clearly divide into two groups, namely those with or without the mineral calcite. Our findings are backed up by chemical analysis using SEM-EDX and FTIR. SEM-EDX shows the clear presence of inclusions of calcite in some of the samples; FTIR shows bands arising from calcite in these samples. The study suggests that it is likely that more than one clay source was used for production of this pottery, but that most of the pottery comes from a single source. This finding is in line with previous studies which suggest some trading of pottery between the Fijian islands but a single source of clay for most of the pottery found at Bouwera. We found no evidence for the destruction of CaCO₃ by heating upon production of the pottery in line with the known technology of the 'Lapita' people who produced earthenware pottery but not high temperature ceramics.