ignescent

from WordNet (r) 3.0 (2006)

ignescent
    adj 1: can emit sparks or burst into flame

from The Collaborative International Dictionary of English v.0.48

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.
   [1913 Webster]