Copper Chromite Black. The pigment in Gamblin's famous Black Spinel- a pigment not often found in oil paints. There are different varieties of this pigment and they vary a bit in undertone. Like PBk26 (another black spinel) it has a blue-black color. PBk28 is near infra-red absorbent and is recommended for opaque paints.
The precautions for working with copper and chrome would apply- see the Artist's Guide to Health and Safety for the health issues associated with Copper and Chrome in pigments. Her updated writings can be found through her site.
This black pigment does not contain carbon, and Gamblin describes their paint as drying matte.
