Ore be processed and what ore is of too low a grade to be worth mining. Metal ores are generally oxides, sulfides, silicates, or native metals (such as native copper) that are not commonly concentrated in the Earth's crust, or noble metals (not usually forming compounds) such as gold. The ores must be processed to extract the elements of interest from the waste rock and from the ore minerals. Ore bodies are formed by a variety of geological processes. The process of ore formation is called ore genesis. An ore deposit is an accumulation of ore. This is distinct from a
Southeast Missouri Lead District sphalerite, and chalcopyrite. Gangue minerals associated with the economic minerals include pyrite, calcite, dolomite, and quartz. Specimens from the Lead Belt are highly prized by gem and mineral collectors and are found in museums worldwide. The ore minerals of the Lead Belt are primarily hosted by bacterial stromatolite reefs and associated oolitic rocks of the dolomitic Bonneterre Formation. This Cambrian age formation was deposited in a shallow sea around the Precambrian age St. Francois Mountains, which formed an island archipelago. Ore mineralization most likely occurred during the late Pennsylvanian and/or Permian periods when warm metal and petroleum bearing fluids from