 Wall painting also occurs on vault capstones, in tombs (e.g., Río Azul), and in caves (e.g., Naj Tunich), usually executed in black on a whitened surface, at times with the additional use of red paint.Yucatec vault capstones often show a depiction of the enthroned lightning deity (e.g., Ek' Balam).A bright turquoise blue colour - 'Maya Blue' - has survived through the centuries due to its unique chemical characteristics; this color is present in Bonampak, Cacaxtla, Jaina, El Tajín, and even in some Colonial Convents.