Copal

What copal is

Copal is an immature recent resin, unlike amber, which is fossilized, hardened resin. More generally, the name covers resinous substances at a stage of polymerization and hardening between gummier resins and amber. Partly mineralized copal is known as copaline. In its natural condition, copal can be told from old amber by its lighter citrine colour and by a surface that turns tacky with a drop of acetone or chloroform. The word copal comes from the Nahuatl copalli, meaning incense.

Sources

Protium copal, commonly known as the copal tree, is a species of tree endemic to Mexico and Central America. It is found in wet tropical forests, preferring heavy shade. The genus Bursera has around 100 species throughout the American continent, of which 80 are distributed in Mexico. Bursera bipinnata is commonly known as copal chino and is considered a source of high-grade copal resin used in ceremonies and offerings. Copal resin from Hymenaea verrucosa, a member of Fabaceae, is found in East Africa and is used in incense. The sap of Hymenaea courbaril, called animé, is similar to copal in its nature and appearance. Subfossil copal is well known from New Zealand (as kauri gum from Agathis australis), Japan, the Dominican Republic, Colombia and Madagascar. It often has inclusions and is sometimes sold as young amber.

Chemistry

The resins of Bursera species contain principally triterpenes with ursane, oleanane and lupane skeletons. In the resin of Bursera bipinnata, α-amyrin and 3-epilupeol represent more than 67.90 percent of the resin. Of 15 compounds identified by GC/MS in the total resin of Bursera bipinnata, four triterpenes accounted for 79.48 percent and seven monoterpenes for 12.69 percent. The chemical profile of B. bipinnata differs from that of other copal resins such as B. copallifera in the presence of a greater variety of triterpenes. Residues of copal resins in archaeological Aztec samples showed triterpenes, of which 3-epilupeol, 3-epi-α-amyrin and α-amyrone were the most abundant. The essential oil of a commercial copal resin identified as possibly Bursera bipinnata contained 14.52 percent α-copaene and 13.75 percent germacrene D. East African copal is a diterpenic resin containing ozic acid, an enantiomer of communic acid, which polymerises as soon as it is exuded from the tree and comes into contact with air and light.

Uses

Copal can be sold as a varnish or molded into figurines. Copal resins are also used for medicinal purposes, such as an anti-inflammatory poultice, to plug dental cavities and to treat pneumonia. A number of indigenous peoples of Mexico and Central America still use copal as an incense, during sweat lodge ceremonies and sacred mushroom ceremonies. Aztec priests are believed to have packed incense pots with coal, copal and other aromatic substances for use in ceremonies. More than 300 copal objects from the offerings of the Great Temple of Tenochtitlan were studied, and they fall into six formal groups: bars, spheres, conglomerates, bases of sacrificial knives, anthropomorphic figurines and miscellaneous fragments. The resin was brought to Tenochtitlan as crude feedstock and transformed there into such objects. Two types of copal are produced by the same tree: gum, stone or wild copal, and santa, white or penca copal.

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Related: Amberwood · Andiroba · Bakhoor · Balsamic Notes · Benzoin · Benzoin Resinoid · Benzyl Benzoate · Benzyl Salicylate