The term "shungite" was originally used in 1879 to describe a mineraloid with more than 98 percent carbon. More recently the term has also been used to describe shungite-bearing rocks, leading to some confusion.[3] Shungite-bearing rocks have also been classified purely on their carbon content, with shungite-1 having a carbon content in the range 98-100 weight percent and shungite-2, -3, -4 and -5 having contents in the ranges 35-80 percent, 20-35 percent, 10-20 percent and less than 10 percent, respectively.[3] In a further classification, shungite is subdivided into bright, semi-bright, semi-dull and dull on the basis of their luster (the terms lustrous and matte are also used for bright and dull).[4]

Shungite has two main modes of occurrence, disseminated within the host rock and as apparently mobilised material. Migrated shungite, which is bright (lustrous) shungite, has been interpreted to represent migrated hydrocarbons and is found as either layer shungite, layers or lenses near conformable with the host rock layering, or vein shungite, which is found as cross-cutting veins. Shungite may also occur as clasts within younger sedimentary rocks.[3