The Collaborative International Dictionary of English v.0.48:

Pyrophoric \Pyr`o*phor"ic\, Pyrophorous \Py*roph"o*rous\, a.
   [Pyro- + Gr. fe`rein to bear.]
   Light-producing; of or pertaining to pyrophorus.
   [1913 Webster]

   Pyrophoric iron (Chem.), finely reduced iron, which ignites
      spontaneously on contact with air.
      [1913 Webster]