Overburden: waste material generated while searching for minerals or while mining, such as when sinking a shaft.
Rubbish, waste matter.
Tailings: waste rock from which the wanted gold, minerals, opal, etc., has been extracted.
Nonsense, rubbish.
A mess; the result of a blunder.
To clear waste material out of a mine.
The slag or dross that remains after the smelting of metal from an ore.
Rough masses of rock formed by solidified lava, and which can be found around a volcano's crater.