Cinnabar is a common name for mercuric sulfide (meaning it is made of mercury and sulfur) -- a mineral that can release mercury via the heat from hands. It was a trade item not only in Mesoamerica but also in South America. The most likely area the ancient Maya would have mined cinnabar is the highlands. They would use cinnabar in and of itself and for extracting the mercury from it.
What was the significance of this mineral? The ancient Maya may have thought cinnabar was sacred due to its color red. Red to the ancient Maya may have been associated with the east (which may be connected to the rising sun) and with blood, a sacred substance.
Cinnabar was also used in funeral rites. Skeletons covered with cinnabar (or sometimes hematite) have been discovered, and the ritual seems to vary. In some burials such as Tikal Burial 10, the head seems to be the most important part for the cinnabar covering ritual.
One famous example of cinnabar coated skeleton is lord Pacal. Another instance is of the "Red Queen" who was buried in tomb near lord Pacal's tomb. The reason they did this isn't entirely clear, but this practice may have been done in connection to the sacred color, possibly even meaning resurrection.
Both mercury and cinnabar have been found in places where rituals were performed. According to Robert. J Sharer, "In rituals involving fire, the Maya priests would burn cinnabar, transforming it into metallic mercury with mysterious qualities."
Ancient Maya painters used different kinds of substances to make paints. Among these substances was cinnabar, cinnabar as a kind of paint. However, cinnabar tends to darken. Funerary goods, such as incense burners (and in one instance, lord Pacal's sarcophagus), were also sometimes painted with cinnabar.
Ancient maya craftsmen would sometimes use cinnabar on jade. They would coat the jade with a very thin layer of copal, and then apply cinnabar.
Consideration: Containers of Mercury
At Belize, archaeologists found various items -- including about 0.67 ounces of cinnabar, a container with about 3.5 ounces of hematite -- and and other things on top of a pool of mercury. Two possible areas the mercury for this are the Matapan Formation (located in west Honduras) and the Todos Los Santos Formation (located in Guatemala).
Containers of mercury have also been uncovered from underneath mud. Archaeologists working at Guatemala's Lake Amatitlan uncovered two containers that possessed mercury. These containers are understood to be from the Early Classic period (around 300 AD to 600 AD).
"Encyclopedia of American Indian Contributions to the World: 1500 Years of Inventions and Innovations"; Emory Dean Keoke, Kay Marie Porterfield; 2009
"The Maya and Teotihuacan: Reinterpreting Early Classic Interaction"; Geoffrey E. Braswell; 2003
"Death and the Classic Maya Kings"; James L. Fitzsimmons; 2009
"Exploring Maya Ritual Caves: Dark Secrets from the Maya Underworld"; Stanislav Chládek; 2011
"Archaeomineralogy"; George Robert Rapp; 2009
"Mercury In The Environment: Pattern and Process"; Michael S. Bank; 2012
"Pulltrowser Swamp: Ancient Maya Habitat, Agriculture and Settlement in Northern Belize"; B.L. Turner; 2000