I have a side by side refrigerator with the ice dispenser in the door. We bought this used. I am seeing black flakes in the ice. Any ideas why?

I have seen the part that pushes the ice cubes out start to rust and as you use it thin small pieces of rust fall off and get on the ice. Are you sure that your problem is the black in in the cube or on the out side of it?

It could also be a water mineral building up on the inside of the aluminim tubing in the frig itself. Do you use a water filter on the line coming to the frig?