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hat is amber?
Amber is fossilised resin,
a viscous liquid that’s
produced by certain plants.
It’s solid but not very
hard, reaching 2.5 on the
10-point Mohs hardness
scale (diamond is 10), the
same as a fingernail. Though
considered a gemstone because it’s used
in jewellery, amber isn’t a ‘natural’ mineral
because it’s formed by organisms, not
geological processes. And despite its name,
colours range from transparent to black and
it can come in rare, desirable forms such as
blue amber.And what’s resin?
Resin is released in response to injury. Most
resins are made by trees and are secreted if
a trunk is gouged open, a branch is snapped
off or an insect bores through wood. Resin
is a liquid bandage for the tree, protecting it
by sealing the wound to prevent invasion by
organisms such as bacteria, fungi or insects.
If resin is like blood flowing from a deep
cut, amber is the dried-up scab.Nice. What’s resin actually made of?
It consists of polymers of hydrocarbon
rings known as terpenes, which account for
around 60 per cent of plant biomolecules.
Turpentine, the fluid artists use to thin
oil paint, is distilled resin. Unlike other
plant fluids you may have heard of, like
sap or gum, resins aren’t water-soluble
and most ambers won’t dissolve. But the
composition determines its properties:
dammar-type amber can be dissolved as its
terpene polymers aren’t linked; witch-hazel
makes resins that also contain ‘styrene’
hydrocarbons, so the resulting amber
includes a dense, plastic-like polystyrene.How does amber form?
Resin becomes more stable over time
through molecular changes like the
formation of links across polymers.
Crosslinks make amber insoluble, strong
and relatively inert, with a melting
point between 200 and 400ºC. Most
organic matter naturally decomposes – a
process soil scientists confusingly call
‘mineralisation’ – but amber doesn’t
mineralise and can’t be dated via decay of
radioactive carbon-14. Amber is arbitrarily
defined as being at least 40,000 years old- the limit of carbon dating. Before then
the substance goes by the name of copal or
sub-fossil resin.
Which plants produce amber?
Most ambers from the ongoing Cenozoic
era, beginning 66 million years ago (MYA),
were produced by conifer trees, thoughsome originate from flowering plants of
the pea family. Almost all amber from
the Mesozoic era, 252-66 MYA, was made
by conifers such as cedars, redwoods
and ancient ‘southern pines’. The oldest
samples, from around 320 MYA, were made
by tree ferns of the Paleozoic era, 541-252
MYA. Amber occurs across the globe, from
the Arctic to Antarctic, and most deposits
are found within the sediments that became
buried in river deltas and lagoons.Why is amber important?
Because it preserves organisms. Resin
surrounds and oozes into living things to
embalm and entomb their bodies. Besides
helping to fossilise the delicate structures
of small creatures – particularly arthropods- in microscopic detail, it can also reveal
lifestyles, showing that ancient spiders
spun webs to catch prey, for instance, and
that ants and termites formed colonies.
Amber is very useful to palaeontologists
because it captures characteristics
that indicate evolutionary change or
relationships, as well as providing
snapshots of prehistoric behaviour.
AMBER?
THE BIG QUESTION
BY JV CHAMARYCan amber preserve DNA, like in
Jurassic Park?
Probably not. In the 1993 Spielberg film,
DNA is extracted from a mosquito that
had drunk dinosaur blood before becoming
encased in amber. Scientific studies have
uncovered a variety of biological materials
in amber, including amino acids from
dinosaur feathers, but amber usually
preserves only a lifelike impression or
trace of an organism, and doesn’t protect
molecules from degradation. DNA is
susceptible to hydrolysis, so any trapped
moisture would cause the genetic material
to break down. “Life, uh finds a way” by
adapting to its environment, but biology
can’t beat chemistry. So it’s highly unlikely
that amber could bring back Mesozoic
reptiles such as Triceratops or T-rex. Sorry!Amber can fossilise
the structures of small
creatures, but, sadly,
can’t bring back the
dinosaursWhat are the special properties of
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