... girt is sharp, and Thermal conductivity4 Suitable for grinding Hard alloy, Optical glass, vitrify, gem, agate, honing cylinder sleeve and ... silicon carbideGCgreenOnly no harder than Boron carbideSuitable for grinding Hard alloy, Optical glass, vitrify and other hard friable materials.Black ... metallic and Nonmetallic material, i.e. Leather cutting/splitting/skiving Machine Accessories-Grinding Wheel