Used in laboratory settings to generate hydrogen sulfide gas through acidification, ferrous sulfide serves as a convenient and controlled source of 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 in anaerobic conditions. Additionally, it can be found in some industrial processes where sulfide donation is required, such as in certain types of ore treatment or wastewater remediation.