py·ro·phor·ic 
(pī′rə-fôrĭk)
(pī′rə-fôrĭk)adj.
1. Spontaneously igniting in air.
2. Producing sparks by friction.
[From pyrophorus, substance that ignites spontaneously : from Greek purophoros, fire-bearing : puro-, pyro- + -phoros, -phorous.]