kaolin vs pottery

kaolin

noun
  • A fine clay, rich in kaolinite, used in ceramics, paper-making, etc. 

pottery

noun
  • Fired ceramic wares that contain clay when formed. 

  • The potter's craft or art: making vessels from clay. 

  • A potter's shop or workshop, where pottery is made. 

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