The word texture relates to the carbons' optical properties, while structure relates to the amount and size of coke pores and walls. Many properties of carbons such as their graphitizability, their electrical resistivity, reactivity to CO 2 at elevated temperatures and strength are related to the optical properties of the coke carbon forms.
Cokes consist of binder and filler phases.
Binder phase carbons are produced from vitrinite, exinite, resinite, and reactive semifusinite which soften during carbonization. Filler phase carbon forms are derived from inert semifusinite, fusinite, possibly micrinite, macrinite and inertodetrinite macerals which do not soften appreciably during carbonization. The binder phase carbons from high volatile coals consist of isotropic, incipient and circular forms. Isotropic carbon is derived form vitrinoid V-Type 7 or lower and remains pink to purple when the specimen is rotated using polarized light and a tint plate. Some systems refer to lenticular domains as leaflet.