Lead is much heavier than iron. A uranium asteroid is pretty bad too. But that aside, we have plenty of iron right here on earth. There is zero reason to mine

Lead is much heavier than iron. A uranium asteroid is pretty bad too. But that aside, we have plenty of iron right here on earth. There is zero reason to mine iron in space unless you need it in space. An asteroid of pure gold on the other hand… But setting all that aside, you get to choose the size! And the trajectory! And the arrival point! Like if you toss a 100kg asteroid and get 1kg of gold out of it, no you won’t kill the planet. You get to choose all the variables.