Abstract: Disclosed are a composition produced from rubber containing polymeric hydrocarbons and carbon black by pyrolyzing and grinding such rubber with heated balls for a sufficient length of time to vaporize and depolymerize the hydrocarbons and to produce a solid char material having a very fine particle size, said char material being free of nondecomposed rubber and coke and having a benzene discoloration number of greater than 70% and preferably 90%, and the related method of making the composition. If the rubber also contains fiberglass and metal, the solid material produced in the pyrolyzing and grinding step will contain fiberglass and metal. The fiberglass and metal are separated from the solid char particles by mechanical means using no caustic, acid or organic solvents. The resulting char may be used, among other things, as a substitute for carbon black in the production of various products such as tires.