Volcanic ashes from Pozzuoli, in Italy, used in the manufacture of a kind of mortar which hardens under water.
volcanic dust mixed with lime and used in mortar by the Romans
the volcanic ash of central Italy, named after the region where its properties were first recognized and, when mixed with lime, the material which gave Roman concrete its strength and ability to harden in water
A rust colored volcanic ash, found in the regions in central Italy around the town of Pozzuoli, which was a crucial component in Roman concrete.
volcanic earth from the region of Pozzuoli, near Naples, which sets like hard cement after mixing with water and gives Roman concrete its strength
A type of volcanic ash used for mortar or for cement that sets underwater.
Pozzolana, also known as pozzolanic ash, is a fine, sandy volcanic ash, originally discovered and dug in Italy at Pozzuoli in the region around Vesuvius, but later at a number of other sites. Vitruvius speaks of four types of pozzolana. It is found in all the volcanic areas of Italy in various colours: black, white, grey and red.