A separation-method for dispersed carbonaceous material in rocks and a calculation-method for L_c(002) are presented, and a numerical expression of the graphitizing-degree is newly proposed revising Tagiri and Tsuboi (1979), Graphitizing-degree=[(d₀₀₂-3.70)/log (L_c(002)/1000)]×100. Some examples in the metamorphic aureoles are indicated and it has been clearly shown that the graphitization mainly depends on temperature suffered and that it is useful to investigate a geothermal structure.