black tea vs gunpowder tea

black tea

noun
  • Tea leaves which have been "fermented" (actually, oxidized) before drying to enhance their flavour (cf. green tea). 

  • A cup of tea served without milk. 

gunpowder tea

noun
  • A form of Chinese green tea in which each leaf has been rolled into a small round pellet. 

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