Source : Webster's Revised Unabridged Dictionary (1913)

Ignescent \Ig*nes"cent\, a. [L. ignescens, p. pr. of ignescere
   to become inflamed, fr. ignis fire: cf. F. ignescent.]
   Emitting sparks of fire when struck with steel;
   scintillating; as, ignescent stones.

Source : WordNet®

ignescent
     adj : can emit sparks or burst into flame