... powder or crystalline particles (monoclinic crystals). Relative density 6.315, melting point 1446 °C, Mohs hardness 3-4, dielectric constant 18 ... materials and other electronic industries, glass, ceramic, enamel, paint industry, agent for take away, fungicides, solar heat absorber surface, reducing tobacco ... ---Acid insoluble ≤%0.010.20.2Cl¯ ≤%0.010.20.2 High quality black copper oxide plating grade