Pale yellow amorphous powder or hexagonal or cubic crystals. Odorless. Gradually turns black in contact with air and light. It reacts slowly with boiling concentrated acids but not with hot alkali hydroxide solutions. It is readily soluble in alkali cyanide and alkali iodide solutions, as well as concentrated hydroiodic acid, alkaline bromide, alkaline chloride, thiocyanate, thiosulfate, mercuric nitrate, and silver nitrate solutions. It is virtually insoluble in water, acids other than hydroiodic acid, and ammonium carbonate solutions.
