Used in laboratory settings to generate hydrogen sulfide gas when reacted with acids, ferrous sulfide serves as a convenient source for this toxic but useful gas in qualitative inorganic analysis. It is also employed in the synthesis of other sulfur-containing compounds. In environmental chemistry, it plays a role in modeling natural processes involving sulfur cycles and metal sulfide formation. Additionally, it can be found in some industrial applications where controlled release of sulfur is needed, such as in the production of certain pigments and in corrosion studies.