BRN 9-3 - Flipbook - Page 70
But resin was not enough. No, this
was not resin, it was pre-amber. The
nodules, two shown below, did not
have insects or other items of interest
trapped inside. An unfortunate
Þnding because had they been
included I would have had an
excellent basis for an article about
how insects in amber are now
revealing more than the taxonomic
relationships of old. Something along
the lines of, ÒFossil Amber Preserves
Ecological Interactions between
Ancient Ants and Other OrganismsÓ,
which discusses how amber including
more than one species can hint at
ancient ecology. That would have
been a great article, how pre-amber
from the Black Range led to the deep
and profound understanding of.É
That was not happening, so I held
those chunks of pre-amber in my hand
and wondered how they would lose
the Òpre-Ò of their name. How did
resin become amber. The thought
experiments which ran through my
mind were not satisfying, demanding
a bit of literature research.
Wikipedia is often a good starting
point for a subject overview. There I
learned that there are Þve classes of
amber which are generally deÞned
based on chemical composition,
which will vary depending on the tree
species the resin came from and a few
other things; that amber has a
hardness of 2 to 2.5 on the Mohs scale
(so scratch it with a Þngernail if you
wish to deface a work of natural art);
that amber melts when heated above
392¡ F.; and that it has a speciÞc
gravity of just over 1, so it will sink in
water - but just barely. All very
interesting, but I was not getting to
what I wanted to know - how does it
form.
mindat.org notes that ÒIn order to
qualify as ÔamberÕ, it is NOT sufÞcient
for a tree resin merely to harden by
losing its volatiles. The molecules
have to polymerize, which can take
millions of years (or at least 100,000
years). After polymerization, amber
becomes signiÞcantly less soluble in
common organic solvents, and so will
not become sticky if wetted with
alcohol, acetone, or gasoline. Much
of the material marketed as ÔamberÕ
(especially that from Colombia and
Madagascar) is far too young to be
considered amber and is in reality just
dried tree resin.Ó
The oldest amber dates to the Upper
Carboniferous period (320 million
years ago).
A survey of mining literature did not
result in listings of amber from the
Black Range. The closest listings were
from the San Juan Basin in New
Mexico, Alpine in Texas, and Baja.
These listings did not include preamber at all.
Wikipedia describes the formation of
amber in this way: ÒMolecular
polymerization, resulting from high
69
pressures and temperatures produced
by overlying sediment, transforms the
resin Þrst into copal. Sustained heat
and pressure drives off terpenes and
results in the formation of amber.Ó
That is an explanation, but I did not
Òget itÓ, in particular, the emphasis on
high pressure. And to be more
speciÞc, how were inclusions (insects,
for instance) so perfectly preserved if
they had been subjected to high
pressures. These inclusions are
perfect in their three-dimensional
form. In some manner, the pressure
would seemingly have to be applied
on all sides of the pre-amber material
evenly. If not, would not the inclusion
be distorted? There seemed a bit of
logic there, enough when you are
lounging under a Pi–on Pine. Later,
my son who is a former SCUBA diver,
pointed out that when diving at more
than 30 meters you donÕt get crushed
on one side.
So step by step, how does amber
form? First of all, we are not dealing
with tree sap. Tree sap does not
become amber. The Red-naped
Sapsucker, Sphyrapicus nuchalis,
picture top left on the next page
(Hillsboro, November 1, 2016), eats
sap, sap that will never be amber.
When a tree is damaged in some way
it excretes resin, like that of the
Ponderosa Pine at the center left on
the next page. Resin is not sap. The
resin shown here will congeal and
