purple dye murex vs purpure

purple dye murex

noun
  • A species of medium-sized predatory sea snail, Haustellum brandaris, which secrets a substance that can be used to make a long-lasting purple dye- Tyrian purple. 

purpure

noun
  • purpure 

  • A purple colour on a coat of arms, represented in engraving by diagonal parallel lines 45 degrees clockwise. 

adj
  • In blazon, of the colour purple. 

How often have the words purple dye murex and purpure occurred in a corpus of books? (source: Google Ngram Viewer )