Copper is a chemical element with the chemical symbol Cu (from Latin: cuprum) and atomic number 29. pure copper is a soft metal, with a reddish-orange surface with a metallic sheen when it is freshly cut, good ductility, high thermal and electrical conductivity, and is therefore the most commonly used material in cables and electrical and electronic components, and can also be used as a building material, as well as making up a large number of alloys. Copper alloys have excellent mechanical properties and low electrical resistivity, the most important of which are bronze and brass. In addition, copper is a durable metal that can be recycled many times without losing its mechanical properties. Copper and its alloys have been used by humans for thousands of years. During the Roman period copper was mainly mined in Cyprus, hence the initial name cyprium (meaning metal of Cyprus), which later became cuprum, which is the source of the English word: copper, the French word: cuivre, and the German word: Kupfer. Divalent copper salts are common copper compounds, often blue or green in color, and are the source of the color of minerals such as bluish chalcopyrite and turquoise, which have been widely used as pigments throughout history. Copper green (copper alkali carbonate) is produced when copper architectural structures are corroded. The decorative arts primarily use metallic copper and copper-containing pigments. Copper is an essential trace dietary mineral for all living organisms, as it is a key component of the respiratory enzyme complex cytochrome c oxidase. Mollusks and crustaceans contain copper in the blood pigment hemocyanin. In fish and other mammals, the blood is hemoglobin, an iron-containing complex. Copper is found in the human body mainly in the liver, muscles and bones. Copper compounds are used as bacteriostatic agents, fungicides and wood preservatives.