ash vs scoria

ash

noun
  • Fine particles from a volcano, volcanic ash. 

  • The wood of this tree. 

  • A gray colour, like that of ash. 

  • The nonaqueous remains of a material subjected to any complete oxidation process. 

  • Human (or animal) remains after cremation. 

  • What remains after a catastrophe. 

  • A shade tree of the genus Fraxinus. 

  • The traditional name for the ae ligature (æ), as used in Old English. 

  • The solid remains of a fire. 

verb
  • To hit the end off (a burning cigar or cigarette). 

  • To reduce to a residue of ash. See ashing. 

  • To hit the end off of a burning cigar or cigarette. 

scoria

noun
  • Rough masses of rock formed by solidified lava, and which can be found around a volcano's crater. 

  • The slag or dross that remains after the smelting of metal from an ore. 

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