Copal, Bursera jorullensis, a sacred tree that exudes a resin that provides the fragrant incense used in many Native American religious ceremonies.  The tree is related to East Indian Frankenincense.

Copal has pale green leaves and shedding bark may be found growing in arid regions, dry hills near Cuernavaca, Zochicalco and Taxco.

Copal may be mixed with pine resins for a more potent fragrance.  It is used today in Mexican Christian and Native American religious ceremonies. 

The smoke is used for smudging.

Mexican Medicine   Also see myrr a close relative.
Same photo as above, lightened.

Native American Medicine:  Copal, called Copaiba in Brazil, is used as a treatment for respiratory conditions such as a cold.   Modern uses include a disinfectant, laxative, stimulant and diuretic.  Copal derivative is used to coat teeth that have been drilled for a cavity.  The copal solution is painted in the hole to seal dentine tubules before the filling is placed.

According to Mark Plotkin in his book, Tale of a Shaman's Apprentice, Viking Press, a copal tree can produce up to ten gallons of copal oil each year.  The oil burns in diesel engines.