Fossil
Amber or Fossil Resin
 Amber
is the popular name for fossilized resin of botanical origin.
The proper scientific terminology is fossil resin, but we will
use the terms amber and fossil resin interchangeably. The word
amber also denotes a golden color that amber predominately reflects
(recall that when human eyes see color, it is actually the portion
of the visible light spectrum that an object reflects that is
detected). In fact, amber reflects many frequencies of light,
including red, green and blue that together constitutes the entire
visible spectrum. Archeological findings show that amber was one
of the first materials prehistoric humans used for ornamentation,
with instances dating back as far as 30,000 years. Use of fossil
resin for jewelry and other decoration continues unabated, and
amber is often considered as a gemstone.
Amber
is also valued for its botanical and animal inclusions that are
trapped by the sticky resin as it flows as sap, which is also
organic. Of course, other life is captured including microscopic
bacteria that often produce gas bubbles, and various fungi. Both
the botanical and animal inclusions not only add beauty, but also
are of potential  scientific
value in the study of taxonomy and evolution. Animal inclusions
are usually invertebrates, specifically arthropods, and only extremely
rarely a vertebrate such as a tiny lizard. Fossil resin inclusions
are predominately insects, which should be no surprise since botanical
resin is an evolutionary adaptation of plants that is, in part,
for protection against insects.
Fossil
Amber Chemistry
Fossil resin's molecular constituency is mainly carbon and hydrogen
atoms that readily form hexagonal rings. Molecular bonding between
the rings increases over time (called polymerization), and the
sticky resin becomes hard. There are other types of atoms in trace
to larger amounts that alter physical properties and may be substrates
to certain organic solvents. For all practical purposes, the hardened
resin, or amber, is a "plastic". Just when the resin
becomes amber, or a fossil, is not defined, and is perhaps not
definable. It is even contentious, since fossil resin is a commercial
product in a competitive market. Younger amber is often called
copal, though it is essentially as hard and its physical properties
differ little from older resins.
All
fossil resins are substrates for both hydrophilic (e.g., alcohol
or acetone) and lipophilic (e.g., benzene) organic solvents and
will disolve in them. The solvents will create various weak chemical
interactions with the resin in order to solubilize it. The most
common of these interactions are the relatively weak van der Waals
interactions (induced dipole interactions), the stronger dipole-dipole
interactions, and the even stronger hydrogen bonds (interaction
between O-H or N-H hydrogens with O or N atoms).
Diamonds
(and most mineral based gems) are forever, but fossil resin (amber)
is not. As an unstable organic polymer, amber is biodegradable,
just like a plastic milk jug or fiberglass boat. Its many weak
covalent bonds and weaker hydrogen bonds are easily broken, a
process that is accelerated by electromagnetic radiation of all
frequencies and heat; ultraviolet is especially damaging (do not
expose amber to sunlight), while visible and infrared much less
so. Thus, while amber is, in a sense, the perfect preservative
of fossils, once removed from the environment in which it formed,
it is destined to crumble into dust; the time is long compared
to the human lifespan, but essentially instantaneous on a geological
timespan. Diamonds, on the other hand, go on forever.
Amber,
Natural Selection and Chemical Warfare
Fossil resin (a.k.a., amber) is the result at least in part of
nature's oldest drama, predator versus prey. Science does not
yet know when it appeared in the Kingdom Plantae's arsenal of
survival tactics, but natural section has conserved and probably
diversified its usage. In temperate climates, the pines are prodigious
producers of resin, which is used to make turpentine. In tropic
climates, the genus Hymenaea, a timber tree, is the prolific producer.
The evolutionary advantages of resin are varied. The resin is
exuded to seal wounds such as from wind, fire, lightening or insect
predation. Resin also contains a diversity of chemical defensive
weapons. Some of these repel insects, and others attract insects
that attack harmful insects, or attract parasites of insects that
attack the plant, or are toxic to harmful fungi; in short a diverse
chemical arsenal.
A
Container for the whole Tree of Life
In terms of the Tree of Life, amber is most interesting since
it entombs all three domains, Arachaea, Eubacteria and Eukarya.
Archaea and eubacteria microbes are, of course, everywhere and
surely embedded in the amber at high density. Interestingly, it
is possible that some microbes. Still controversial finding a
decade old claims to have recovered from the gut of a Hymenoptera
from 30 million year old Dominican amber some three-dozen species
of bacteria from ancient spores that grew on culture plates. The
bacteria are from the extant genus Bacillus, a group that go dormant
forming spores. Interestingly, Bacillus thuringiensis is used
in the biological control of insects. Bacillus thuringiensis parasitizes
the caterpillars of some harmful moths and butterflies. Spraying
or dusting plants with its provides some protection against gypsy
moth, tent caterpillar, and the tobacco hornworm. The bacteria
has a gene that produces a toxic chemical warfare. The gene for
this toxin has also been introduced into some crops.
Fossil
Amber Ecosystems
One way to view amber is as a sealed unit containing a cross section
of an ancient ecosystem with all its intricate predator-prey as
well as beneficial symbiotic systems (e.g., termites as the methane
produced by symbiotic bacteria that digest fiber in the termite
gut). Fossil resin is a superb preservative, with organisms such
as insects and spiders preserved in full three-dimensionality
and in living color. To some degree, even, nucleotide sequence
from ancient DNA is preserved, although resurrection of a Jurassic
dinosaur is clearly science fiction.
Amber's
Geographic Dispersion
Amber
comes from throughout the world, even the Arctic. However, in
terms of commercial availability, the Baltic area of Europe produces
vast amounts, followed by the Dominican Republic in a distant
second, with minor amounts coming from Central and South America,
and more specifically, Mexico and Colombia, respectively. Amber
from other localities is miniscule.
Baltic
Amber
An enormous amount of fossil resin is extracted on the shoreline
of the Baltic Sea, and these strata are dated to be Eocene in
age, give or take a few million years, thus making it some of
the oldest amber that is available in commercial quantity. The
largest Baltic amber mine is in Kaliningrad, Russia, but Baltic
amber is also found in Lithuania, Latvia, Estonia, Poland, Russia,
and sometimes washes ashore far away in Denmark, Norway, and England.
Fossil inclusions are relatively rare, almost always in isolation
and usually tiny, and the amber is normally occluded with botanical
debris and bubbles; for this reason, fossil specimens are best
made viewable in pieces cut to small size prior to polishing,
and pictures many times require a trinocular microscope.
Dominican
Amber
Geological data for amber from sedimentary deposits in the Dominican
Republic predict an age dating to the Oligocene, in the range
of 20 to 30 million years old, presuming the resin is a primary
in situ deposit, and not a secondary deposit by transport/erosion
etc. Dominican amber from Cotui, however, is Pliocene or Pleistocene,
has larger and more insects, and is otherwise indistinguishable
from older material from the dated sedimentary deposits. Since
resin-producing trees are still abundant in this tropical island
area, resins of any age are possible. The older fossil resins
are from deep mines in the hillsides, and the extraction can be
a dangerous proposition, with risk of being buried in a cave in.
The insect inclusions in Dominican amber are fairly abundant,
the insects larger, and the amber of higher clarity than found
in Baltic amber. Though uncommon, fossil association are found
more frequently in Dominican amber.
Colombian
Amber
Far and away the most fossiliferous amber originates in Colombia,
albeit it has become fairly widespread that all fossil resin from
Colombia is called copal. The amber versus copal distinction is
lost on many geologists and paleontologists that are aware that
scientific data is unavailable to determine the age of fossil
resins from this region. The consensus age estimate seems to be
Pleistocene (up to 2 million years old), but estimates range to
the Lower Miocene (about 20 million years old). Though geological
studies are unlikely soon in this region that is controlled by
drug cartels, it seems safe conjecture that there is a large range
of age across different deposits, similar to that of the Dominican
Republic. In the Dominican Republic, mine cave-ins are a danger
for some of the older deposites; in Colombia the danger might
be AK47's of the drug producers. Whether amber or copal, young
or old, the fossil insects and other arthropod inclusions and
their associations are truly sublime in Colombian amber. Perhaps
the most impressive aspect of Colombian amber to those with a
scientific propensity is the wonderful fossil associations. So
many species are often in association that the specimen will represent
an ecological cross section of an ancient rainforest.
Amber versus Copal -
Obfuscation not science
A
few more words about the distinction between amber and copal,
both slang terms without scientific basis, is warranted. We absolutely
disdain scientific prostitution, and are therefore compelled to
expose it. Fairly widespread on the Internet and in several popular
and otherwise wonderful "amber" books are statements
that there is no amber from Colombia, and that Colombian amber
is "young" copal, because it has not yet undergone some
mythical transformation that is never described. This is a perfect
example of the old saw: "if you tell a lie enough times,
it becomes (perceptive) reality"; such obfuscation is perhaps
to be expected from commercial interests, but is shameful when
individual scientific credentials are used as justification. Any
polymer chemist studying fossil resin chemistry would quickly
discern that the essential constituents and chemical binding characteristics
are demonstrably the same in all fossil resin, regardless of locality,
and regardless of age, once the material has hardened - there
is no important scientific distinction to be made. Several of
these sources offer as fact a small sample from one locality in
Colombia carbon dated at a couple hundred years old. They then
make the banal extrapolation that the small sample's age can be
extrapolated to all fossil resin in what is a huge country where
trees have been producing resin for as long as anywhere else.
Besides the idiocy of presuming all fossil resin is the same age
as the one sample, they neglect to point out that the evolutionary
adaptation of resin production has not been eradicated from plant
genomes. That is, plants continue to make resin, and thus the
only plausible assumption is that fossil resin exists in a continuum
of ages to present in all places where it is found, unless the
botanical source has disappeared. It is unfortunate that a few
gemologists and others not trained in science continue to promulgate
scientific poppycock. For a few more words on this, Dr. Robert
E. Woodruff, Emeritus Taxonomist, Florida State Collection of
Arthropods, who has collected and studied fossil resin and insects
in fossil resin throughout his career, has several thoughts to
share on the copal
versus amber controversy. Those who draw distinction between
fossil resin, amber and copal are either exhibiting scientific
ignorance, and engaging in deliberate obfuscation for financial
gain.
Internet
sources of information about fossil resin are virtually useless,
and are essentially replicating and cross-linking nonsense masquarading
as science. One of the most conspicuous examples is the assertion
that copal will dissolve in acetone but amber will not. Any chemistry
student by their junior year should be able to refute this, or
they should not graduate. In reality, fossil resin is a substrate
to most solvents. Solubility may, in fact, vary depending on the
chemical constituency of different fossil resins, but any statement
that solubility determines authenticity is putting the cart before
the horse. Another more general falsehood is that age directly
correlates with authenticity due to the time required for cross-linking
of carbon chains depending on diffusion and loss of terpenes.
Yet, Miocene-age coal deposits in Sumatra have yielded resinites
that are wholly unstable to environmental exposure. For decades
now, sellers of amber from the Baltic region in Europe have stated
that the only authentic amber comes from there, and sellers of
amber from both the Baltic and Dominican Republic have said that
fossil resin from Colombia is not authentic amber. This self-serving
disinformation will become truth when swiss chocolate is not chocolote
because it does not come from Hershey, Pennsylvannia.
One
of dumbest statements to be found on several Internet sites is:
"But amber is a true fossil; it has turned to stone";
yea sure it has. Such a transformation would be infinitely harder
than turning lead into gold. I wonder who was dumber, the person
who copied and pasted it, or the person who wrote it in the first
place.
For
decades, the suppliers of abundant fossil resin from the Baltic
and Dominican Republican operated in a cartel-like manner, controlling
the sources, and sustaining prices well above intrinsic value.
The Internet age of global communication and resultant supply
chains broke the cartel. Amber from these sources can now be obtained
at a fraction of the price of years past.
References
Anderson
KB, Crelling JC. (1994) Amber, resinite, and fossil resins. ACS
symposium series (A.C.S. symp. ser.) ISSN 0097-6156
Cano RJ, Borucki MK. Revival and identification of bacterial spores
in 25- to 40-million-year-old Dominican amber. Science. 1995 May
19;268(5213):1060-4.
Kasman
LM, Lukowiak AA, Garczynski SF, McNall RJ, Youngman P, Adang MJ.
Phage display of a biologically active Bacillus thuringiensis
toxin. Appl Environ Microbiol. 1998 Aug;64(8):2995-3003.
Cano
RJ, Poinar HN, Pieniazek NJ, Acra A, Poinar GO Jr. Amplification
and sequencing of DNA from a 120-135-million-year-old weevil.
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