A slag heap that was started in 1913 and eventually grew to 200 feet high and 130 blocks around is finally moving on - to the recycling bin.
The heap was formed when rail cars dumped red-hot molten slag, a byproduct of U.S. Steel's operations. The dumping stopped in the 1960s, but the heap remains as a monument to Pittsburgh's industrial past.The slag now is being recycled into material for roads and parking lots while businesses have begun to sprout at its base in this community just south of Pittsburgh.
Slag is a hard, chunky compound of such materials as silicon, phosphorus, manganese and limestone that results from the open-hearth process of steelmaking.