A pitch with a complex mixture of numerous essentially aromatic hydrocarbons. It does not contain anisotropic particles detectable by optical microscopy. Mesogenic pitch is low in quinoline-insoluble fractions and capable of transforming into mesophase pitch during continuous heat treatment above 750 K by the formation of optically detectable carbonaceous mesophase.
Source:
PAC, 1995, 67, 473. 'Recommended terminology for the description of carbon as a solid (IUPAC Recommendations 1995)' on page 496 (https://doi.org/10.1351/pac199567030473)