Blue Sky Blue

There is a pigment the Mayans made and used for ceremonial purposes which scientists cannot recreate. This pigment color is called Maya Blue and not only can it not be currently recreated, this pigment has unusual qualities--it is extremely durable and in the words of National Georgraphic (who may have been quoting Antiquity magazine), shows "remarkable ability to resist age, acid, weathering, and even modern chemical solvents." We know about this durability from surviving examples of the pigment on bowls.