In Madagascar the graphite is mainly disseminated in a Graphitic schist, though to some extent it is present in the form of veins and in gneiss.
"The Economic Aspect of Geology"
C. K. Leith
The silica of the compound has been driven off, leaving a shell of Graphitic substance formed from the coke.
"Electricity and Magnetism Nature's Miracles, Vol. III."
Elisha Gray