Call me sceptical. That would have been astronomically expensive given the enormous supply chain needed to produce charcoal to get that iron in those times. I

Call me sceptical. That would have been astronomically expensive given the enormous supply chain needed to produce charcoal to get that iron in those times. I am sceptical on how they figured out iron stains are pothole fillings. I think much simpler explanation would be everyday items or metal pieces of carts getting stuck between stones.