A vivid, fade-resistant blue pigment used by the ancient Maya people. Maya blue is a mix of organic indigo and an inorganic clay mineral, palygorskite. The mixture was heated with copal, a resin extracted from the copal tree, that acted as a binding agent. Web resource here.

Procession of musicians. Structure 1, room 1, east wall. Bonampak, Chiapas, Mexico. Late Classic Mayan. 792 CE. Photo: Ricardo David Sánchez.