Digging that Maya blue

Before plucking the hearts from humans and tossing the bodies into the sacred cenote, the sacrificial well, the Maya of Chichén Itzá painted their offerings blue—Maya blue. The process for making the unusual pigment, also found on pottery, sculpture, and murals from roughly 400 to 1519, has long puzzled researchers.

Now an analysis of a 600- to 700-year-old pot (above) found in the well suggests that the pigment was made on the spot during ceremonies honoring the rain god Chaak. Indigo and palygorskite, a mineral clay, were probably heated over a fire of copal, a gummy incense derived from tree resin, says Dean Arnold of Wheaton College in Illinois, who led the study, which appears in the March Antiquity.