Oxidation zone
The part of the weathering zone of ore deposits that extends from the earth's surface to the groundwater level is called the oxidation zone , in which ore minerals weather through contact with oxygen (air), sometimes in connection with water , carbon dioxide , carbonic acid, etc. It mainly contains the corresponding oxides , hydroxides , carbonates and sulfates of the heavy metals contained in the ores. This is particularly noticeable in the weathering of sulphidic ores. A typical mineral of the oxidation zone is for example chrysocolla . When iron ores are weathered, red or reddish-brown colored porous masses often form, which miners refer to as the iron hat .