Black Rock Mine Operations (BRMO) Assmang Proprietary Limited is a joint venture mining company that operates in South Africa. In total, it excavates and produces million tons of iron and manganese ore per year across its three separate mine shafts.
Mine drainage forms from a chemical reaction between water and rocks containing sulfurbearing minerals. The resulting waters become rich in sulfuric acid and dissolved iron. As the iron settles out of the water, it can form red, orange, or yellow sediments in the bottom of streams.