The stone in quarries is found to be of different and unlike qualities. In some it is soft, in others it is medium, in still others it is hard as in lava quarries. There are also numerous other kinds: for instance, in Campania, red and black tufas in Umbria, Picenum, and Venetia, white tufa which can be cut with a toothed saw like wood.
Marcus Vitruvius Pollio
