Colombia's open pit coal mining company Carbones del Cerrejón engages in the exploration, production, transportation and shipment of thermal coal from high-grade coal deposits located in northern Colombia's Guajira department. It operates South America's largest coal mine, Cerrejón Zona Norte, as well as the Cerrejón Zona Central and Patilla mines. Cerrejón also owns the Cerrejón Zona Sur property, which is at the exploration stage. Coal reserves in La Guajira are in the region of 4Bt, according to official estimates. Carbones del Cerrejon is owned equally by Anglo-Australian resource group BHP Billiton, Glencore and Anglo American of South Africa.