(KDAL) - In an effort to match the production output with a lowered demand, Cliffs Natural Resources will be idling two of the four production lines at Northshore Mining effective January 5, 2013.  The taconite production curtailment will impact about 125 employees.  The President of Global Operations at Cliffs says they will remain operationally flexible in 2013 and will ramp up production volumes again if the demand increases.