Siena

brownish-ochre color, by 1760 (terra-sienna), from Italian terra di Sienna "earth of Siena," region in Italy where the coloring material first was produced from a type of earth mined there. It is used as a pigment in both oil and watercolor painting. See Siena.

Burnt sienna is the raw material roasted in a furnace before powdering. By this means the color is changed to a warm reddish brown similar to old mahogany. It is, like raw sienna, translucent in body. [Century Dictionary]