一種天然大地棕顏料，顏色範圍從深黃到深紅棕，含有矽石、黏土、氧化鐵混合物以及少量的氧化錳。根據顏色的不同，另稱為「赭土」或「茶紅色料」。A natural earth brown pigment ranging in color from a dark yellow to a deep reddish brown, containing silica, clay, and a mixture of iron oxides along with small amounts of manganese dioxide. It may be called "umber" or "sienna," depending on its color.