Shungite (Black Ocher)

This is a rare form of carbon black that occurs as a natural deposit. Sources assign a pigment code somewhat differently. Artiscreation lists PBk6 as Shungite, while Kremer Pigments lists theirs at PBk8. Kremer describes it as a "very deep, opaque black which may show a slight bluish cast." Usually carbon black is made by burning or calcining something (common sources are vegetable matter like vines, soot from a lamp or natural gas, or even animal bones). Shungite is interesting because it is like a specific kind of extra-hard coal that can be mined. Shungite has been used for ages in Russian Icons, and the most famous deposits are in Karelia, Russia. More information can be found from Kremer here and here.