section_path: Lifecycle/Extraction
section_name: Extraction
paragraph_text: Extraction
  
  Metallic elements are often extracted from the Earth by mining ores that are rich sources of the requisite elements, such as bauxite. Ores are located by prospecting techniques, followed by the exploration and examination of deposits. Mineral sources are generally divided into surface mines, which are mined by excavation using heavy equipment, and subsurface mines. In some cases, the sale price of the metal(s) involved make it economically feasible to mine lower concentration sources.
  
  Once the ore is mined, the elements must be extracted, usually by chemical or electrolytic reduction. Pyrometallurgy uses high temperatures to convert ore into raw metals, while hydrometallurgy employs aqueous chemistry for the same purpose.
  
  When a metallic ore is an ionic compound, the ore must usually be smelted —heated with a reducing agent—to extract the pure metal. Many common metals, such as iron, are smelted using carbon as a reducing agent. Some metals, such as aluminum and sodium, have no commercially practical reducing agent, and are extracted using electrolysis instead.
  
  Sulfide ores are not reduced directly to the metal but are roasted in air to convert them to oxides.