Iodine green, is an iminium salt composed of (4-{[4-(dimethylamino)-3-methylphenyl][4-(trimethylazaniumyl)phenyl]methylidene}cyclohexa-2,5-dien-1-ylidene)(dimethyl)ammonium and chloride ions in a 1:2 ratio. A histological dye used for staining chromatin and amyloid.