pyrophoric

 
Pronunciation: /ˌpʌɪrə(ʊ)ˈfɒrɪk/

adjective

  • liable to ignite spontaneously on exposure to air: several boranes are pyrophoric and toxic
  • (of an alloy) emitting sparks when scratched or struck.

Origin:

mid 19th century: from modern Latin pyrophorus, from Greek purophoros 'fire-bearing', from pur 'fire' + pherein 'to bear'