Scientists have identified the origins of the blue color in one of Jackson Pollock’s paintings with a little help from chemistry. In the painting called “Number 1A, 1948,” scientists had previously characterized the reds and yellows splattered across the canvas, but the source of the rich turquoise proved elusive. In a new study, researchers took scrapings of the blue paint and used lasers to measure how its molecules vibrated. They pinpointed it as manganese blue. It’s the first confirmed evidence of Pollock using this specific shade. The research was published Monday in the journal Proceedings of the National Academy of Sciences.