The sheer volume of granite, diorite, and alabaster that was cut precisely into statues around Luxor attests to the ancient Egyptians' mastery of their craft. The Greeks and Romans did not sculpt statues in igneous rock. Granite was not fashioned into statues until the development of more modern power tools with steel bits. In The Materials of Sculpture, Nicholas Penny writes: Granite had occasionally been worked in shallow relief, for architectural ornament where it was the local building stone, and for the stiff figures of sixteenth-century cavalries in Brittany, but, before the advent of improved metals and power-driven tools in the nineteenth century, the idea of making statues out of it was seldom seriously entertained by sophisticated sculptors.