What? You need it to be more explicit? Just pore mars dust (15% iron, found everywhere) into this furnace (wear oxygen mask or space suit.) From muffin tin, break off iron from dross and do it again to purify. Sand (or mars dust compacted) works if you don't have a muffin tin.
During planetary formation all of its iron went to its core. All of the iron in the dust is from later planetary bombardment. You knew this, right?
Before doing this, extract the water first at much lower temperatures. Settling mars is going to be a blast [furnace.]