ignescent

IGNES'CENT, a. [L. ignescens, ignesco, from ignis, fire.]

Emitting sparks of fire when struck with steel; scintillating; as ignescent stones.

IGNES'CENT, n. A stone or mineral that gives out sparks when struck with steel or iron.

Many other stones, besides this class of ignescents, produce a real scintillation when struck against steel.