mullock vs tailings

mullock

noun
  • Tailings: waste rock from which the wanted gold, minerals, opal, etc., has been extracted. 

  • Rubbish, waste matter. 

  • 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. 

tailings

noun
  • The waste that remains after the minerals have been extracted from an ore by ore dressing. 

  • The feints, the last fraction of product obtained at the end of distillation. 

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