Almost a synthetic Cassel earth, cold, dark, bituminous...think a wet November evening about 5pm, when it should be light but it isn't. In masstone it is a bit like Burnt Umber but much cooler.
This has no red undertone, so it is excellent for cool shadows.
It also has some wonderful, rich grey tones when tinted with some white. So all in all a useful paint, and after all without dark there would be no light.
Pigment - Synthetic Iron Oxide, PBr6 / PBk11
Vehicle - Linseed Oil, Consistency - Butter