In the mineral sector, metals mainly occur as chemical compounds with oxygen (oxides) or with sulphur (sulphides); only very rarely are they found in pure form. Among these exceptions – besides the precious metals gold and silver – is copper.  Copper with its chemical symbol Cu (from cuprum) is found in the periodic system of elements in the first subgroup together with silver and gold. This is because copper has similarities with both metals: copper and gold are the only two coloured metallic elements, and copper and silver are the two best conductors of heat and electricity.

Since the requirements for the copper quality used for wire production and for applications in electronics, low-temperature and vacuum technology are much higher than those for the production of copper alloys, a distinction is nowadays made between the two types of cathode Cu- CAT-1 (“higher grade” cathode) and Cu-CAT-2 (normal cathode). The term “copper” also usually includes, in addition to pure copper, oxygenated copper grades that contain controlled amounts of oxygen in the form of copper(I) oxide, as well as deoxidised oxygen-free copper grades with and without a residual content of a deoxidising agent (preferably phosphorus). The different properties of these different types of copper also largely determine their areas of application.