Slag

The Third Doctor described Earth in the 30th century as "slag, ash, clinker." (TV: The Mutants)

In 2006, the Passameer-Day Slitheen plotted to start a nuclear war on Earth, which would reduce the planet to molten slag. Knowing that the radioactive chunks were capable of powering every cut-price starliner and budget cargo ship, the Slitheen intended to sell them piece by piece as raw fuel for a bargain, exploiting the current recession in space. Ultimately, however, this plot was thwarted by the Ninth Doctor. (TV: World War Three)