The presence of calcite in archeological ceramics

Abstract The present work describes the methods for detecting and classifying calcite in archeological ceramics, the forms of calcite and their interpretation in archeometric terms. Calcite appears in form of coarse granules and fine particles, and its origin can be primary or secondary. Coarse granules can be polycrystalline or mono-crystals of calcite. Fragments of shells, fossils or microfossils are also found. Primary calcite is the initial calcite preserved in low-fired pottery. Secondary calcite, formed after the ceramic firing, may be reformed (re-carbonated) calcite, precipitated calcite or calcite from alteration. The firing can cause the formation of a ‘reaction rim’ around coarse granules of calcite, while strong decomposition of coarse calcite causes the formation of ‘calcite ghosts’. The identification of the forms of calcite gives information on raw materials, the firing temperature and the manufacturing technology of the pottery.