grinding stone vs quern

grinding stone

noun

  • A stone tool, used with a quern, to grind cereals 

quern

noun

  • A mill for grinding corn, especially a hand-mill made of two circular stones. 

verb

  • To grind; to use a quern. 

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