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.
The interference colors range from pink or red to blue. Ribbon shaped carbon domains are sometimes called flow structure. Data from coke carbon form analysis is corrected for yield in estimating the coal blend used to produce the coke. The inorganic inerts are allocated to categories of 50 microns. Pyrite-derived minerals are sometimes counted separately.