Ash

n. The incombustible matter remaining after a fire, often composed of minerals, sand, and other inorganic materials.  

 

  • Discussion

 

The traditional combustion science definition of ash includes only the noncombustible material.  For wood, this is generally less than 2 percent of the fuel mass.  However, because combustion is often not complete in wildland fire, the ash from naturally burning fires includes a substantial amount of carbon.