si·en·na 
(sē-ĕnə)
(sē-ĕnə)n.
1. A special clay containing iron and manganese oxides, used as a pigment for oil and watercolor painting.
2.
a. Raw sienna.
b. Burnt sienna.
[Short for terra-sienna, from Italian terra di Sienna, earth of Siena, after Siena.]