black coal vs carbon

black coal

noun
  • coal 

  • high-quality coal 

carbon

noun
  • A fossil fuel that is made of impure carbon such as coal or charcoal. 

  • carbon dioxide, in the context of climate change. 

  • A plate or piece of carbon used as one of the elements of a voltaic battery. 

  • A carbon copy. 

  • A sheet of carbon paper. 

  • A carbon rod or pencil used in an arc lamp. 

  • An atom of this element, in reference to a molecule containing it. 

  • The chemical element (symbol C) with an atomic number of 6. It can be found in pure form for example as graphite, a black, shiny and very soft material, or diamond, a colourless, transparent, crystalline solid and the hardest known material. 

verb
  • To cause (someone) to receive a carbon copy of an email message. 

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