Recent excavation and research in the Batan Grande, in the North Coast region of Peru, have revealed a metal-producing community centered around a mine at Cerro Blanco and a smelting and metalsmithing complex at nearby Cerro de los Cementerios. Dating the latter's occupation from ca 1000 AD 1500 AD, the complex was producing arsenical copper (also known as arsenical bronze). The components of this metal, the process used to smelt, produce ingots, and ultimately working the copper -- these are all described. -- AATA