This paper reports the results of scientific research on a fragment of mosa
ic flooring recovered from the Ninfeo of Punta Epitaffio in Baia (Italy). T
he tesserae were made of calcite; the mortar present among the tesserae was
made of slaked lime. Incrustations of mixed carbonatic and silicatic natur
e were found on the surface of the tesserae: silicatic components were also
found in the upper layers of the tesserae. One explanation is that a react
ion involving solution and re-precipitation occurred between the calcium ca
rbonate of the mosaic fragment and the pozzolanic sands present in the Baia
area, during the centuries the tesserae remained submerged under the sea.