Petrographic Analysis of Pottery from the White Marl Archaeological Site, St. Catherine Parish, Jamaica, West Indies

Petrographic analysis was conducted on a series of prehistoric pottery sherds from the White Marl archaeological site in Jamaica, as well as raw sediment from the Rio Cobre valley where the site is located. To address the origin of materials from which White Marl pottery was produced, a point count was conducted on twenty pottery sherds which represent the full range of ceramic vessel forms and functions. For each thin section, 300 to 500 points were examined, providing a quantitative percentage of the sherds' mineralogical compositions. Poorly sorted angular grains appear within dark brown to orange clay matrices. The mineralogy is dominated by clay (59.1-60.9%), quartz (12.1-17.4%), and feldspar (4.4-7.2%), with minor opaque minerals (1.6-5.0%), muscovite (0.4-2.9%), and amphiboles (0.4-1.8%). Well weathered rock fragments, including polycrystalline quartz, volcanics, and granitoids also commonly occur within the matrix (7.6-13.8%). Undulose extinction of quartz and sericitic alteration of feldspar indicate exposure to deformation and hydrothermal processes. Raw clay deposits from the Rio Cobre are similar in color to the matrices of observed ceramics. Point counts of Rio Cobre riverbed sands display varying mineralogy depending on sample location, although they are commonly dominated by quartz (35.2-50.4%). These findings indicate that Rio Cobre sediments are weathered from granodiorite of the Above Rocks Inlier and later evolved into the material used in White Marl ceramics. The ceramics are homogenous across samples, suggesting that a standard recipe was followed during production.