pyrophoric
/ˌpaɪrəʊˈfɒrɪk/adjective
1- liable to ignite spontaneously on exposure to air（遇空气）易燃的; 发火的, 引火的。
1.1
- (of an alloy) emitting sparks when scratched or struck（合金）（刮或敲打时）生火花的。
词源
mid 19th cent.: from modern Latin pyrophorus, from Greek purophoros 'fire-bearing', from pur 'fire' + pherein 'to bear'.