dross vs tailings

dross

noun
  • A waste product from working with metal. 

  • Worthless or trivial matter. 

  • The impurities in metal. 

  • Waste or impure matter. 

  • Residue that forms on the surface of molten metal from oxidation. 

verb
  • To remove dross from. 

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 dross and tailings occurred in a corpus of books? (source: Google Ngram Viewer )