bismuth subcarbonate

noun

bismuth sub·​car·​bon·​ate -ˌsəb-ˈkär-bə-ˌnāt, -nət 

: a white or pale yellowish white powder that is a basic salt of varying composition obtained by reaction of a carbonate with a bismuth salt and used chiefly in treating gastrointestinal disorders, topically as a protective in lotions and ointments, and in cosmetics