Copper(II) oxide (also known as cupric oxide) is the inorganic compound with the formula CuO. A black solid, it is one of the two stable oxides of copper, the other being Cu2O. As a mineral, it is known as tenorite. It is a product of copper mining and the precursor to many other copper-containing products and chemical compounds.
Most commonly the copper oxide is produced by the process of pyrometallurgy, as one stage in extracting copper from its ores (copper mining). These ores are then treated with a watered down mixture of ammonium carbonate, ammonia, and oxygen to give copper(I) and copper(II) ammine complexes, which can be extracted from solid. These complexes are decomposed with steam to give CuO.
Copper oxide is often the starting point of production of many copper salts and other chemicals that consist of copper.
Ceramics and woodworking
In woodworking, copper oxide is used as a wood preservative. In ceramics, it can be found as a pigment in different coloured glazes.
Because of its color while being burned, copper oxide is used as a coloring agent in glue flame compositions. For the crackling effect, it is present in strobe effects and compositions to give off an impression of the blinking stars.