Joint Venture Deal - big open pit nickel mine Cerro MatosoCordoba Minerals enters into definitive joint venture agreement with South32 ( BHP Billiton's) to develope the Cerro Matoso. Cerro Matoso is a big open pit nickel mine and smelter located in the Cordoba area of northern Colombia, consisting of an open-cut mine and an industrial processing. Just 20 km away from Cordoba 's "San Matias" sits the worlds third largest nickel mine, Cerro Matoso, owned by BHP Billiton, which has operated there for 30 years and has another 30 years of reserves to mine through. During its 33 years of operation, Cerro Matoso has become a major world producer of ferronickel and nickel iron alloy with a low content of impurities.