Used in laboratories as a source of sulfide ions in chemical reactions. Commonly employed in the synthesis of other sulfur-containing compounds. Acts as a reducing agent in certain industrial processes. Found in some solid lubricants due to its layered structure, providing friction reduction in high-temperature environments. Utilized in the production of iron and steel to control sulfur content. Also applied in environmental chemistry for removing heavy metals from contaminated water through precipitation as insoluble metal sulfides.