Researchers at Wheaton College and the Field Museum said the pigment, known as Maya Blue, was integral to the performance of rituals at Chichen Itza, including painting human sacrifices from head to toe with it.

The pigment, which is resistant to age, acid, weathering, biodegradation and even modern chemical solvents, has been described as one of the great technological and artistic achievements of Mesoamerica, Wheaton College said Tuesday in a news release.

"These sacrifices were aimed at placating the rain god Chaak," anthropologist Dean E. Arnold said.

The pigment was cooked in ceramic bowls over burning incense. Arnold said the ritual combination of indigo, copal incense and palygorskitethese, which were considered healing elements, had great symbolic value and ritualistic significance.

The report, published online in the journal Antiquity, said Maya Blue was symbolic of the healing power of water in an agricultural community.