... composition for pyroxene, plagioclase, a few olivine, black mica and trace magnetite, black color, the precise structure, after ... gloss, precise construction,even character, nice stability, high strength and hardness, but also no rust, acid&alkali-proof, ... precision at heave duty. It is suitable for industrial production and measuring works at laboratory.Proportion,2970-3070kg/m3Compression strength ...