gold mine vs horn of plenty

gold mine

noun
  • A mine for gold ore or metal. 

  • A very profitable economic venture. 

  • A plentiful stockpile of something sought after. 

horn of plenty

noun
  • The cornucopia. 

  • An edible chanterelle, Craterellus cornucopioides. 

How often have the words gold mine and horn of plenty occurred in a corpus of books? (source: Google Ngram Viewer )