Sinopia (also known as Sinoper, after the present-day Turkish city of Sinop) is a dark reddish-brown natural earth pigment whose reddish color comes from hematite, a dehydrated form of iron oxide. It was used extensively in painting in antiquity and the Middle Ages, and in the Renaissance it was often used over the first rough layer of plaster to emphasize a fresco. The word is used for both the pigment and the preliminary drawing itself, which is revealed when a fresco is removed from the wall for transfer. In medieval times, Sinopia simply means red ocher in Latin and Italian. It has entered the English language as Sinoper, meaning an earthy red colour. Sinopia is a color in various modern color systems.