This is a natural iron pigment that has a large percentage of manganese in its composition. Good grades of raw umber are not too reddish but have a pleasing yellowish cast. It is totally lightfast and semi-opaque. This is a crucial pigment for modifying colour in that it darkens and desaturates a colour while only minimally shifting its hue. When blacks are used to desaturate colours, they tend to make reds look bluish, yellows look greenish etc. When placed beside other colours raw umber can look greenish, reddish, or bluish depending on the surrounding colours thus making it a useful neutral pigment. Its slight transparency makes it also useful in mixes for glazing, staining or washes.