MCS 2026 cover background image

MCS 2026 cover background image: Molten copper being poured into anode molds at Freeport-McMoRan Inc.'s smelter in Miami, AZ. Each solidified copper anode weighs approximately 390 kilograms and is about five centimeters (cm) thick, 90 cm wide, and 110 cm tall. Cast anodes, which consist of 99.8% copper, are shipped to an electrolytic refinery to be further processed into cathodes with a copper purity of >99.99%. The green and blue gases visible over the flowing molten copper are a result of fine copper oxide particles or trace amounts of copper vapor and impurities reacting with moisture, oxygen, and other chemical compounds (like carbon dioxide) in the atmosphere to form various copper salts. Copper (p. 72–73) has the lowest resistivity and highest electrical conductivity of all non-precious metals. It is widely used in electrical applications across a broad range of products, such as appliances, automobiles, building wire, data transmission lines, generators, lighting, microprocessors, motors, personal electronic devices, power and telecommunications cables, renewable energy systems (geothermal, solar, and wind), and transformers. In 2025, copper was designated as a critical mineral by the U.S. Geological Survey. The United States was the sixth-ranked global producer of both mined and refined copper.