The disulphide, IrS2, is formed when powdered iridium is heated with sulphur and an alkaline carbonate.
Molybdenum disulphide, MoS 2, is found as the mineral molybdenite, and may be prepared by heating the trioxide with sulphur or sulphuretted hydrogen.
It is a brown powder which on heating in air loses sulphur and leaves a residue of the disulphide.
If excess of a mineral acid be added to a solution of an alkaline thiogermanate a white precipitate of germanium disulphide, GeS2, is obtained.
By heating the disulphide in a current of hydrogen, germanious sulphide, GeS, is formed.