[quarks22]

Iron is the only metal which is talked of as having come down to earth as meteorites so its source is outerspace originally but why arnt other heavy metals not included such as lead?

Thanks a bunch

[Arkcon]

Virtually all of the composition of Earth was formed from the debris cloud that formed the solar system.  Very heavy elements were formed in a supernova that predated the formation of that debris cloud.  The addition of small amounts of iron or nickel from meteorites is a minimal contribution -- especially compared to the mantle and core of the Earth, the substance of which is outside our exploitation, yet still there.

Meteorites are important as sources of iron for pre-industrial civilizations, so that may be the source of your confusion.