Maya Blue is the name of a hybrid organic and inorganic pigment, used by the Maya civilization to decorate pots, sculpture, codices and panels. While its date of invention is somewhat controversial, the pigment was predominantly used within the Classic period beginning about AD 500. The distinctive blue color, as seen in the murals at Bonampak in the photo, was created using a combination of materials, including indigo and palygorskite (called sak lu'um or 'white earth' in the Yucatec Maya language).
Maya blue was used primarily in ritual contexts, pottery, offerings, copal incense balls and murals. By itself, palygorskite was used for medicinal properties and as an additive for ceramic tempers, in addition to its use in the creation of Maya blue.
Making Maya Blue
The striking turquoise color of Maya Blue is quite tenacious as such things go, with visible colors left on stone stele after hundreds of years in the subtropical climate at sites such as Chichén Itzá and Cacaxtla. Mines for the palygorskite component of Maya Blue are known at Ticul, Yo'Sah Bab, Sacalum, and Chapab, all in the Yucatán peninsula of Mexico.
Maya Blue requires the combination of ingredients--the indigo plant and palygorskite ore--at temperatures between 150 and 200 degrees centigrade. Such heat is necessary to get molecules of indigo incorporated into the white palygorskite clay. The process of embedding (intercalcating) indigo into the clay makes the color stable, even under exposure to harsh climate, alkali, nitric acid and organic solvents. The application of heat to the mixture may have been completed in a kiln built for that purpose--kilns are mentioned in early Spanish chronicles of the Maya. Arnold et al. (in Antiquity below) suggest that Maya Blue may also have been made as a by-product of burning copal incense at ritual ceremonies.
Dating Maya Blue
Using a series of analytical techniques, scholars have identified the content of various Maya samples. Maya Blue is generally believed to have been used first during the Classic period. Recent research at Calakmul supports suggestions that Maya Blue began to be used when the Maya began painting internal murals on temples during the late pre-classic period, ~300 BC-AD 300. However, murals at Acanceh, Tikal, Uaxactun, Nakbe, Calakmul and other pre-classic sites don't seem to have included Maya Blue in their palettes.
A recent study of the interior polychrome murals at Calakmul (Vázquez de Ágredos Pascual 2011) conclusively identified a blue painted and modelled substructure dated to ~150 AD; this is the earliest example of Maya Blue to date.
Scholarly Studies of Maya Blue
Maya blue was first identified by Harvard archaeologist R. E. Merwin at Chichén Itzá in the 1930s. Much work on Maya Blue has been completed by Dean Arnold, who over his 40+ year investigation has combined ethnography, archaeology, and materials science in his studies. A number of non-archaeological material studies of the mixture and chemical makeup of Maya blue have been published over the past decade.
A preliminary study on sourcing palygorskite using trace element analysis has been undertaken. A few mines have been identified in the Yucatán and elsewhere; and tiny samples have been taken from the mines as well as paint samples from ceramics and murals of known provenience. Neutron activation analysis (INAA) and laser ablation-inductively coupled plasma-mass spectroscopy (LA-ICP-MS) have both been used in an attempt to identify the trace minerals within the samples, reported in a 2007 article in Latin American Antiquity listed below.
Although there were some problems with correlating the two methodologies, the pilot study identified trace amounts of rubidium, manganese and nickel in the various sources which may prove useful in identifying the sources of the pigment. Additional research by the team reported in 2012 (Arnold et al. 2012) hinged on the presence of palygorskite, and that mineral was identified in several ancient samples as having the same chemical make up a modern mines at Sacalum and possibly Yo Sak Kab. Chromatographic analysis of the indigo dye was securely identified within a Maya blue mixture from a pottery censer excavated from Tlatelolco in Mexico, and reported in 2012. Sanz and colleagues found that blue coloration used on a 16th century codex attributed to Bernardino Sahagún was also identified as following a classic Maya recipe.
Recent investigations have also centered on the composition of Maya Blue, indicating that perhaps making Maya Blue was a ritual part of sacrifice at Chichén Itzá. See Maya Blue: Ritual and Recipe for more information.
Anonymous. 1998. Ceramic Ethnoarchaeology at Ticul, Yucatán, Mexico. Society for Archaeological Sciences Bulletin 21(1&2).
Arnold DE. 2005. Maya blue and palygorskite: A second possible pre-Columbian source. Ancient Mesoamerica 16(1):51-62.
Arnold DE, Bohor BF, Neff H, Feinman GM, Williams PR, Dussubieux L, and Bishop R. 2012. The first direct evidence of pre-columbian sources of palygorskite for Maya Blue. Journal of Archaeological Science 39(7):2252-2260.
Arnold DE, Branden JR, Williams PR, Feinman G, and Brown JP. 2008. The first direct evidence for the production of Maya Blue: rediscovery of a technology. Antiquity 82(315):151-164.
Arnold DE, Neff H, Glascock MD, and Speakman RJ. 2007. Sourcing the Palygorskite Used in Maya Blue: A Pilot Study Comparing the Results of INAA and LA-ICP-MS. Latin American Antiquity 18(1):44–58.
Berke H. 2007. The invention of blue and purple pigments in ancient times. Chemical Society Reviews 36:15–30.
Chiari G, Giustetto R, Druzik J, Doehne E, and Ricchiardi G. 2008. Pre-columbian nanotechnology: reconciling the mysteries of the maya blue pigment. Applied Physics A 90(1):3-7.
Sanz E, Arteaga A, García MA, Cámara C, and Dietz C. 2012. Chromatographic analysis of indigo from Maya Blue by LC–DAD–QTOF. Journal of Archaeological Science 39(12):3516-3523.
Vázquez de Ágredos Pascual, Doménech Carbó MT, and Doménech Carbó A. 2011. Characterization of Maya Blue pigment in pre-classic and classic monumental architecture of the ancient pre-Columbian city of Calakmul (Campeche, Mexico). Journal of Cultural Heritage 12(2):140-148.