GEOLOGICAL OCCURRENCE
Amorphous graphite may occur wherever coal or other carbonaceous beds have undergone regional or igneous metamorphism. Crystalline graphite has two principal geologic occurrences, as flakes in schists and as larger crystals in veins. Flake graphite in schists is usually associated with granitic intrusions which appear to have aided recrystallization of original carbonaceous material in the sediments. Vein graphite in commercial quantities is rather rare. It is found associated with granitic intrusives and generally with graphitic sediments containing the flake variety. Such rocks in most parts of the world have not been prospected enough to make sure that all important bodies of graphite are discovered.