You've got to be better iron than that.

Pig-iron has no fiber; it breaks instead of bending.

Build a bridge of it and a gale will break it and it will fall into the river.

Some races are pig-iron; Hottentots and Bushmen are pig-iron.

They break at a blow.
They have been smelted out of wild animalism, but they went no further; they are of no use in this modern world because they are brittle.