malachite vs virescent

malachite

adj
  • Of a colour ranging from olive-taupe to a mild to deeply-rich (at times seemingly translucent) green, like that of the mineral which is present on oxidized copper. 

noun
  • A bright green mineral, a basic copper carbonate, Cu₂CO₃(OH)₂; one of the principal ores of copper. 

  • A mild green colour, like that of the mineral. 

virescent

adj
  • Green-like, greenish. 

  • Becoming green. 

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