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Copal
An Immature and Controversial Resin

Copal is not the fossilized, hardened resin that is known as amber, but rather an immature recent resin. Increasingly, copal is being offered for sale, via the online auction services, gem shows, and shops, misrepresented as "amber." The commercial value of amber is related to its scarcity, age, inclusions of extinct species, and durability. Unfortunately, some dealers are more preoccupied with high economic returns, rather than whether or not their resin is fossil or recent. The amber listserv has had an active discussion, beginning in October, 1999, regarding Colombian resin, which was listed for sale as amber at a popular auction website. Many internet sites now exist for amber, from commerical to educational, but only a few include information on copal. Confusion is inevitable. A quick search for "copal" on the internet brought up a site providing images of the Titanic (offered by the Copal Website), the Nicdec Copal business making motors and parts in Malaysia, and a site for immunodiagnostic products?! In response to the listserv discussion and numerous email questions, this addition to the World of Amber will provide some information and references from some amber experts regarding the definition of resins and in particular, copal, an immature and controversial resin.

Patty Rice     David Grimaldi    Barbara Kosmowska-Ceranowicz

George Poinar    Curt W. Beck     Ken B. Anderson    

References     Links

"The oldest known substitute for amber is copal, a resin which is very similar in appearance" (Rice, 1993, p. 219). The term "copal" was derived from "copalli," a Spanish word meaning incense, which is what copal is used for as well as in varnish. Rice (1993) stated copal can occur in a semi-fossilized form or fresh, gum form, usually ranging from 1,000 to 100 years old (p. 220). Copal can fluoresce white under short-wave ultraviolet light (amber usually fluoresces blue or yellow) and it contains inclusions of extant plants and animals (as opposed to extinct forms found in amber). One test for copal vs. amber can be by applying a small drop of ether, which evaporates quickly on amber leaving it unaffected, while it makes copal and other recent resins sticky (Rice, 1995, p. 141).

Rice (1993) distinguishes several type of copal from different geographic regions and trees (p. 222-230). Zanzibar copal from East Africa was possibly produced by the Trachylobium verrucasum (also known as Hymenaea verrucosa), while Kauri copal from New Zealand was produced by the Kauri pine, Agathis australis. Sierra Leone and Congo copal are both from a leguminous tree, Copaifera guibourthiana. Manila copal, produced by trees in the genus Agathis, is found in Indonesia and the Philippines. Dammar resin was produced by dipterocarpaceous trees in southern Asia, i.e., Malaya and Sumatra (Rice, 1993, p. 230). Various tropical trees, such as Hymenaea courbaril or Hymenae protea, produce Colombian and Brazilian copal (Rice, 1993, p. 227). "Radiocarbon testing of a sample of copal from Colombia has indicated that it is younger than 250 years old" (Rice, 1993, p. 227).

Grimaldi (1996) referred to copal as subfossil resin, several hundred to several thousand years old, that may take a high polish, but will craze deeply on the surface after only a few years when the volatiles from the original resin evaporate (p. 16). Grimaldi described the process to change freshly hardened resin into fossil resin as a continuum, with no specific age or consistent length of time in which this occurs. He believed claims of 2 million year old copal in Africa and South America to be suspect. "The oldest copal deposit, from Mizunami, Japan, is approximately 33,000 years old" (Grimaldi, 1996, p. 16). He stated copal deposits from Colombia ..."are sold to amateur collectors as 'Pliocene amber' (about two million years old), even though carbon-14 dating indicates it is only several hundred years old, like all the other Hymenaea copal deposits" (Grimaldi, 1996, p. 19).

Major deposits of copal are produced from tropical legume and araucarian trees (conifers indigenous today to South America and Australia) and are found in tropical or wet temperate regions where these resin producing trees still exist (Grimaldi, 1996, p. 16). To identify copal, Grimaldi (1996) suggested a drop of alcohol or other solvent on the specimen; amber is not effected by the solvent, but copal's surface will become sticky. He also stated that copal will melt next to hot flame, whereas amber will merely soften and blacken (Grimaldi, 1996, p 16).

Kosmowska-Ceranowicz (1999) has used infrared absorption spectroscopy (IRS) to identify and compare geographically varied fossil resin samples from Poland and the rest of Europe. In response to researchers who termed "young amber" from Pleistocene sediment near Gdynia, Poland as copal, Kosmowska-Ceranowicz countered that copal indicated ..."subfossil resins from the southern hemisphere, which are of a different age and botanical origin" (p. 95). "Copal, which is entirely transparent, occasionally lightly clouded, and rich in inclusions, can be worked cold, attaining a good polish" and she also noted that large pieces of Colombian copal have recently been illegally imported into Poland (Kosmowska-Ceranowicz, 1999, p. 95).

Poinar (1999) placed all fossiliferous resin in Quaternary deposits, or those up to 1.6 million years old, into ..."the category of copal since they do not have the chemical or physical properties of amber" (p. 151). Poinar went on to list countries in which copal deposits are common: Colombia, South America; Kenya; Madagascar; Cotui deposits in Dominican Republic; Hymenaea deposits in French Guyana; and the Agathis or Kauri pine deposits in New Zealand, Australia and Fiji. Most copal from these deposits is under 65,000 years and some as young as 50 years (Kenya and Madagascar); all contain extant species of fauna and flora, although some of the species are previously undescribed (Poinar, 1999, p. 151). On a recent amber listserv posting (December 3, 2002), one subscriber related a conversation with Dr. Poinar in which he dated a Columbian copal sample at 250 years old and an East African copal sample from Kenya at 30 to 40 years old.

Beck (1999) has reviewed the chemical evidence for the composition of fossil resins for the last one thousand years. He noted that the chemical composition is "indissolubly intertwined with its botanical origin" and preconceived notions of the amber trees being Pinites succinifer and Pinus succinifera had led to confusion in interpreting the chemistry based on the principal resin acid found in modern pines (Beck, 1999, p. 33). "The latest and most decisive contribution to the chemistry of succinite and other fossil resins has been made by pyrolysis gas chromatography" and combining this with mass spectrometry (Beck, 1999, p. 46). This technique has been used by Anderson and co-workers, who have created the first exclusive chemical classification of fossil resins.

Ken B. Anderson and John C. Crelling edited an American Chemical Society symposium series entitled Amber, Resinite, and Fossil Resins. The volume began with definitions and nomenclature, or an attempt to define what the term "amber" really means. To many people, amber, resin, copal, and the like, are synonymous and interchangable. To other people, the age and maturity of the substance should determine different classifications of fossil resins. Anderson and Crelling (1995) believed the term "resin," when used alone, should be for modern substances, and "amber" or "fossil resin" should be defined as, ..."solid, discrete organic materials found in coals and other sediments as macroscopic or microscopic particles, which are derived from the resins of higher plants" (p. xi-xii). They (Anderson and Crelling, 1995) admit that one of the most controversial and unanswered questions involves when a resin becomes amber (p. xiii). Amber dealers and researchers have complicated the issue with terms such as sub-fossil resin and young amber and there is no clear consensus on ambers and their relationships with modern resins (Anderson and Crelling, 1995, p. xv).

Anderson and Crelling (1995) have proposed the following chemical classification for fossil resins (p. xiii):

Class I The macromolecular structures are derived from polymers of labdanoid diterpenes, which include labdatriene carboxylic acids, alcohols, hydrocarbons
Class Ia ...derived from polymers and copolymers of labdanoid diterpenes with regular configuration, which normally include communic acid, communol, and succinic acid
Class Ib ...derived from polymers and copolymers of labdanoid diterpenes with regular configuration, which often include communic acid, communol, biformene, and succinic acid is not present
Class Ic ...derived from polymers and copolymers of labdanoid diterpenes with enontio configuration, which include ozic acid, ozol, and enantio biformenes
Class II ...derived from polymers of bicyclic sesquiterpenoid hydrocarbons, such as cadinene, and related isomers
Class III natural fossil poylstyrene
Class IV non-polymeric, including sesquiterpenoids based on the cedrane carbon skeleton
Class V non-polymeric diterpenoid carboxylic acid, including abietane, pimarane, and iso-pimarane carbon skeletons

Class I distinguishes between succinite (Class Ia), fossil kauri amber (Class Ib), and the Mexican and Dominican ambers (Class Ic), which have predominantly a labdane skeleton or show a relationship with the Araucariaceae family (Beck, 1999, p. 41, 46). Classes II and III are also polymers, of cadinene and styrene, with II being characteristic of Utah and Indonesian amber and Class III, with siegburgite and some New Jersey amber (Beck, 1999, p. 44). Classes IV and V are not polymeric, characterized by Moravian amber and Bovey-Trace retinite (Class IV) and retinites in European brown coals (Class V); Class V is the only fossil resin with abietane and primarane skeletons (abietic acid is the principal resin acid of the genus Pinus) (Beck, 1999, p. 40, 44).

In spite of the proposed classification, Anderson and Crelling (1995) admit ..."it is basically futile to attempt to determine the chronological age of sedimentary organic matter by chemical analysis alone" because the rate of chemical transformations is determined by the rate constant of a particular reaction and the temperature at which the reaction proceeds (p. xv). Resins could be of the same "age," but have differing "maturities" due to higher temperatures and chemical changes. Therefore a combination of chemical studies and biological studies are paramount in amber/resin studies. [Return to physical properties.]

Conclusions

Copal has been labeled the oldest known substitute for amber and this amber imitator continues to confuse and frustrate the public and professionals. Copal has been referred to as a subfossil resin, semi-fossilized resin, an immature amber, and as a fresh, gum form of resin. Experts vary in their assessment of the age of copal, from 50 years to 1.6 million years, based on the geologic settings in which it is found and other evidence, both chemical and botanical. Commercial dealers selling specimens of copal with inclusions often state the age as several million or tens of millions of years old.

There is agreement among the experts that the inclusions in copal, when present, are of extant, not extinct, species, although some may not have been previously described in the literature. It is believed that the resin trees were and are primarily tropical legume and araucarian trees, such as Copaifera guibourthiana, Hymenacea ourbaril, Hymenacea protea, and Agathis australis or Kauri pine. Geographically, the copal is believed to be recovered today primarily from tropical latitudes and the southern hemisphere. A chemical classification has been proposed for fossil resins although the methodology involves sophisticated equipment and specialized knowledge to interpret results, which is not readily available to the public.

Thus, to conclusively delineate amber from other resins, such as copal, detailed chemical analysis, biological considerations of the inclusions, and the geologic setting in which it is found, should all be considered. Some of the tests the layperson might employ include fluorescence, specific gravity, hot flame, and testing the surface reaction to alcohol (or another solvent such as ether). However, these tests, with the exception of fluorescence, may be destructive to the specimen.

Copal has the same warm glow of amber and a wide range of inclusions, usually with remarkable preservation. Copal has many uses, from incense to varnish, and is important as an avenue in studying past life. Copal should not be misrepresented as amber, a mature fossilized resin, but marketed as copal, a fresh recent resin, with many desirable qualities of its own.


References

  • Anderson, K. B., and Crelling, J. C. (1995). Amber, resinite, and fossil resins. Washington, DC: American Chemical Society.
  • Beck, C. W. (1999). The chemistry of amber. Estudios Del Museo De Ciencias Naturales De Alava, 14(Numero especial 2), 33-48.
  • Grimaldi, D. A. (1996). Amber window to the past. NY: Harry N. Abrams, Inc.
  • Kosmowska-Ceranowicz (1999). Estudios Del Museo De Ciencias Naturales De Alava, 14(Numero especial 2), 73-117.
  • Poinar, G. (1999). Cenozoic fauna and flora in amber. Estudios Del Museo De Ciencias Naturales De Alava, 14(Numero especial 2), 151-154.
  • Rice, P. C. (1993). Amber the golden gem of the ages. NY: Kosciuszko Foundation, Inc.

  • Other websites with a "copal component" include:

    The Kauri Museum located at Matakohe, Northland, New Zealand is an interesting site detailing Kauri copal gum (go to Exhibits) and the copal producing Kauri Tree (go to More Info).

    Professor Brian Stross from the University of Texas wrote Mesoamerican Copal Resins. This look at copal is from an ethnobotany and anthropology lens.

    Wayne Armstrong's page, Volume 7(2), Summer 1998, Nature's Transparent Tomb! Amber from the New World Tropics and Is Your Amber Necklace Real?.

    Tammi Johnson created Amber: Arboreal Gold. The site has a copal section with specific emphasis on the Colombian resin deposits.

    Gary Platt's Amber Home relates techniques to identify types of amber, copal and resin.

    Mark R. Meyer's 3dotstudio has a frequently asked questions section that addresses the difference between amber and copal.

    Doug Lundberg has a page on "Real Amber or Fake?" that highlights copal as well as other imitators.

    The London Natural History Museum has a page on Ancient nucleic acids from amber-preserved insects. An insect in copal (genus Trigona) from the east coast of Africa, several thousand years old, is tested. Their studies concluded DNA is not preserved in abundance in the amber- or copal-preserved insects, nor is it easy to extract, if it is present at all.

    The Amber Gallery, based in Lexington, Kentucky, has an educational section on detecting copal and other amber imitators.

    Leif Brost's Swedish Amber Museum has a section on "Copal, Young Resin" found toward the bottom of the "fact page," entitled Amber, A Fossilized Tree Resin.

    Bob's Rock Shop, Tucson, Arizona, USA, has an amber vs. copal identification section contributed by Gary Platt.

    The Paleo Warehouse, from Ardmore, Oklahoma, USA, advertises "Insects in Amber" of Miocene age from Kenya, Africa and Colombia, South America (page down several times). The viewer may speculate the age of the Colombian "amber" by the dealer's statement: "If the beds are involved in the Andean uplift, the age may well be in the neighborhood of 25 million years."

    Yale Goldman discusses copal, and other amber imitations, such as glass, phenolic resin, celluloid, and casein, from his Dead Bug in Amber Club site.

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    Created February, 2000; updated 16 January, 2004. copyright 2000-2004 © Susan Ward Aber All rights reserved.