When combined with barium sulfate, zinc sulfide forms lithopone. The combination of barium sulfate and zinc sulfide (ZnS) is the inorganic pigment called lithopone. Lithopone was discovered in the 1870s by DuPont. It is also a precursor to the pigment lithopone. Lithopone is produced by coprecipitation of barium sulfate and zinc sulfide. By the early 1930s lithopone titanium and zinc oxides were being marketed as non-poisonous. Lithopone is rather nontoxic, due to the insolubility of its components. Lithopone is allowed to be in contact with foodstuffs in the US and Europe.