Hafnium boride, gray with metallic luster crystals. The melting point is 3250 degrees Celsius, the conductivity is large, and the chemical properties are stable.
Cuprous oxide is a bright red powder that is almost insoluble in water.It is decomposed into divalent copper and copper in acid solutions,and gradually oxidized into black copper oxide in humid air.
Copper oxide,chemical formula CuO. It is a black oxide of copper,slightly amphoteric and slightly hygroscopic.The relative molecular mass is 79.545,the density is 6.3～6.9 g/cm3,and the melting point is 1026℃.