Scientists have long known the two chief ingredients of the intense blue pigment: indigo, a plant dye that’s used today to color denim; and palygorskite, a type of clay. But how the Maya cooked up the unfading paint remained a mystery. Now Spanish researchers report that they found traces of another pigment in Maya Blue, which they say gives clues about how the color was made.
“We detected a second pigment in the samples, dehydroindigo, which must have formed through oxidation of the indigo when it underwent exposure to the heat that is required to prepare Maya Blue,” Antonio Doménech, a researcher from the University of Valencia, said in a statement.
Story: Megan Gannon, LiveScience | Photo: Heather Hurst, National Geographic Society