It's wrong, since "non-ferrous natural resources" includes a lot of things lighter than iron, notably aluminum, but it's not really misleading, it's got the right general idea. Before the Earth formed a solid crust, heavier elements settled out of the outermost layer of liquid and fell inward toward the core. Only where convection plumes have brought magma to the surface from deeper in the mantle do we find high concentrations of heavier elements in the Earth's crust.