The texture and properties of carbonaceous mesophase pitch formed from coal tar pitch by treating it at 400 ℃ and 430 ℃ for different times have been studied, using optical microscope with polarized light and measuring mesophase content, volatile matter content, C/H ratio, interlayer spacing （d₀₀₂） and crystalline size (L_c).
The mesophase content and C/H ratio were found to increase with residence time. Heat treatment at 430 ℃ for 5 hours resulted in a coarse mosaic type mesophase, the content of which was 92 %.
About 51 % of asphaltene and 13 % of pre-asphaltene, having mosaic type and bulk type texture, respectively, have been obtained by solvent extraction. However, by mixing the two fractions, the asphaltene was transformed into the bulk mesophase type because of the dominant partner effect of the pre-asphaltene fraction.