Ashford Black Marble is the name given to a dark limestone, quarried from mines near Ashford-in-the-Water, in Derbyshire, England. Once cut, turned and polished, its shiny black surface is highly decorative. Ashford Black Marble is a very fine-grained sedimentary rock, and is not a true marble in the geological sense. It can be cut and inlaid with other decorative stones and minerals, using a technique known as pietra dura.