Maya Blue is a vibrant blue color believed to have first appeared about 800 AD, and was documented to have still been used in the 16th century. The techniques for its production has since been lost, and it’s found on pottery, palace walls, codices, murals and other artifacts made by the Maya people centuries ago. The color held a strong significance as the color of Chaak - the rain god, and of human sacrifice. When the climate was dry and the skies were cloudless - much like the color of Mayan Blue - human sacrifices may have been made in hopes that rains would follow. But perhaps the most peculiar thing is that this pigment is unusually durable - remaining vibrate after other colors have long faded away in one of the world’s harshest climates. For a long time its chemical stability was a mystery - how was it able to remain almost impervious to age, acid, weather and even modern solvents? It wasn’t until the 1960s, when chemists were able to decipher its components: the plant-based dye indigo, and a clay mineral called palygorskite, which can be melded together with heat to produce the pigment. Researchers found samples of the pigment to have dehydroindigo, which likely formed during oxidation of the indigo when it was heated. The blue indigo turns greenish with the yellow dehydroindigo, creating that signature vibrant hue. In 2008, it was proposed that the indigo and palygorskite was fused by the burning of copal incense along with palyforskite and the leaves of the indigo plant, suggesting that the combination of these three materials were symbolic of the healing power of water for the agricultural peoples.