Jiao Zha form a flat cake, coal particle is not easy to distinguish between the boundaries of, the surface of clear Silver metallic, silvery sheen on the surface more pronounced under the coke residue.
Pie coke residue formed flat, not easy to distinguish the boundaries of coal particles, silver metallic luster surface significantly lower cinder surface silvery sheen is more obvious.
Cinder form flat cake, limit of coal particle is not easy to distinguish, the surface has obvious argent metallic luster, cinder surface silver white luster more obvious.