Workers in this minor group extract solid minerals from underground or surface mines and quarries, prepare the extracted minerals for distribution or further processing, and erect and operate drilling plant and perform related tasks in the sinking and operation of wells. Operators of earth-moving equipment in mines and quarries are classified in unit group 9-94; crusher-grinder operators employed in chemical and related processing plants in unit group 7-41; well diggers who works with hand tools in unit group 9-59; and riggers (oil and gas well drilling) in unit group 9-72.