Sienna (from , meaning "Siena earth") is an earth pigment containing iron oxide and manganese oxide. In its natural state, it is yellowish brown and is called raw sienna. When heated, it becomes a reddish brown and is called burnt sienna. It takes its name from the city-state of Siena, where it was produced during the Renaissance. Along with ochre and umber, it was one of the first pigments to be used by humans, and is found in many cave paintings. Since the Renaissance, it has been one of the brown pigments most widely used by artists. The first recorded use of sienna as a color name in English was in 1760. The normalized color coordinates for sienna are identical to kobe, first recorded as a color name in English in 1924. Earth colors Like the other earth colors, such as yellow ochre and umber, sienna is a clay containing iron oxide, called limonite, which in its natural state has a yellowish colour. In addition to iron oxide, natural or raw sienna also contains about five percent of manganese oxide, which makes it darker than ochre. When heated, the iron oxide is dehydrated and turns partially to haematite, which gives it a reddish-brown colour. Sienna is lighter in shade than raw umber, which is also clay with iron oxide, but which has a higher content of manganese (5 to 20 percent) which makes it greenish brown or dark brown. When heated, raw umber becomes burnt umber, a very dark brown. History The pigment sienna was known and used in its natural form by the ancient Romans. It was mined near Arcidosso (formerly under Sienese control, now in the province of Grosseto) on Monte Amiata in southern Tuscany. It was called terra rossa (red earth), terra gialla (yellow earth), or terra di Siena. During the Renaissance, widely-read painting technique author Giorgio Vasari made note of it under the name terra rossa. Along with umber and yellow ochre, sienna became one of the standard browns used by artists from the 16th to 19th centuries, including Caravaggio (1571-1610) and Rembrandt (1606-1669), who used all three earth colors in his palette. By the 1940s, the traditional Italian sources were nearly exhausted. Much of today's sienna production is carried out in the Italian islands of Sardinia and Sicily, while other major deposits are found in the Appalachian Mountains, where it is often found alongside the