Centuries-old Maya Blue mystery finally solved

Production of the renowned, extremely stable pigment was part of ritual sacrifices at Chichén Itzá

CHICAGO—Anthropologists from Wheaton College (Illinois) and The Field Museum have discovered how the ancient Maya produced an unusual and widely studied blue pigment that was used in offerings, pottery, murals and other contexts across Mesoamerica from about A.D. 300 to 1500.

First identified in 1931, this blue pigment (known as Maya Blue) has puzzled archaeologists, chemists and material scientists for years because of its unusual chemical stability, composition and persistent color in one of the world’s harshest climates.

The anthropologists solved another old mystery, namely the presence of a 14-foot layer of blue precipitate found at the bottom of the Sacred Cenote (a natural well) at Chichén Itzá. This remarkably thick blue layer was discovered at the beginning of the 20th century when the well was dredged.

Chichén Itzá, one of the Seven Wonders of the Ancient World, is an important pre-Columbian archeological site built by the Maya who lived on what is now the Yucatán Peninsula of Mexico.

The findings from this research will be published online Feb. 26, 2008, by the prestigious British journal Antiquity and will appear in the print version of the quarterly journal to be released in early March.

According to 16th Century textual accounts, blue was the color of sacrifice for the ancient Maya. They painted human beings blue before thrusting them backwards on an altar (see below for image) and cutting their beating heart from their bodies. Human sacrifices were also painted blue before they were thrown into the Sacred Cenote at Chichén Itzá. In addition, blue was used on murals, pottery, copal incense, rubber, wood and other items thrown into the well.

The new research concludes that the sacrificial blue paint found at this site was not just any pigment. Instead, it was the renowned Maya Blue – an important, vivid, virtually indestructible pigment.

Maya Blue is resistant to age, acid, weathering, biodegradation and even modern chemical solvents. It has been called “one of the great technological and artistic achievements of Mesoamerica.”

Scientists have long known that the remarkably stable Maya Blue results from a unique chemical bond between indigo and palygorskite, an unusual clay mineral that, unlike most clay minerals, has long interior channels. Several studies have found that Maya Blue can be created by heating a mixture of palygorskite with a small amount of indigo, but they have not been able to discover how the ancient Maya themselves actually produced the pigment.