What type of reaction is #FeS + HCl -> FeCl_2 + H_2S#?
It's a double displacement reaction.
These commonly occur when the reactant species are both binary compounds. You might want to balance it though if you have to do any further calculations.
#FeS(s) + 2HCl(aq) -> FeCl_2(aq) + H_2S(g)#