Brown patina on Parthenon fragment baffles scientists

A sculptural fragment from the south side of the Parthenon depicting the Centauromachy, the mythical battle between the Lapiths and the Centaurs, currently housed at the National Museum of Denmark, is partly coated by a thin brown film that baffles scientists to this day. First studied by German chemist Justus von Liebig in the mid-19th century, who found that the film contains oxalates - salts of oxalic acid - the substance is the focus of a new study published earlier this month in Heritage Science journal. The researchers said the patina is unlikely to have a biological origin, but they did not arrive at a conclusive answer.