The ancient tufa quarry is located northeast of the ancient theater of Hephaistia.

Tufa is generally found on the shoreline of the Hephaistia archeological site. These are deposits made up of porous limestone sandstone mosaic, and lattice that include fragments of the underlying molassic formation. The multitude of shells in the shallow water is characteristic of these Pleistocene deposits. The deposits, having accumulated on the underlying molassic rocks, have a thickness of more than 50m in certain locations.

Hephaistias’ open ancient quarry once operated in the coastal region. The enormity of the site shows the scale of the mining. The quarry was in operation during the Classical and Hellenistic times.