Bismuth(III) iodide is a dark gray solid. It is sometimes pale yellow, though. It does not dissolve in water. It reacts with other iodides to make iodobismuth(III) ions, BiI52-.
It is made by reacting bismuth powder with iodine. It is also made by reacting bismuth(III) oxide with hydroiodic acid. It can also be made by reacting bismuth(III) chloride with any iodide such as potassium iodide.
It was used in a test for bismuth ions. Bismuth ions form a dark gray precipitate when reacted with potassium iodide because bismuth(III) iodide was made.