junkyard vs mullock

junkyard

noun
  • A place where rubbish is placed. 

  • A business that sells used metal or items. 

mullock

noun
  • 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. 

  • Overburden: waste material generated while searching for minerals or while mining, such as when sinking a shaft. 

verb
  • To clear waste material out of a mine. 

How often have the words junkyard and mullock occurred in a corpus of books? (source: Google Ngram Viewer )