also: すいせき
noun
flint; firestone
A hard stone used to produce sparks when struck against steel, traditionally for starting fires. In modern contexts, may also refer to the flint in lighters.
昔の人は火打石と火打金で火を起こした。
People in the old days started fires with flint and steel.
ライターの火打
The flint in the lighter is wearing down.