Several
factors affect the production of amber from resin, a process known as
amberization. Once the resin is exuded it hardens. Resin contains liquids such
as oils, acids and alcohols, including the aromatic compounds that produce the
distinctive resinous smell – two examples of highly aromatic resins are
frankincense and myrrh. Scientists call these liquids volatiles and they
dissipate and evaporate from the resin. The resin then undergoes a process
known as polymerization, whereby the organic molecules join to form much larger
ones called polymers. Hardened resin is known as copal. Copal becomes
incorporated into soil and sediments where it remains long after the tree dies.
It continues to polymerize and lose volatiles until the resultant amber is
completely polymerized, has no volatiles and is inert.
 |
| Frankincense tree |
Many
scientists thought that time was important in the fossilization of resin to
produce amber, and the amberization process was estimated as taking between 2
and 10 million years. However, it now appears that many more factors are
involved. Most amber in deposits around the world was not formed where it is
found – the copal or amber has been eroded from the soil, transported by rivers
and deposited elsewhere. For instance, amber from Borneo
is 12 million years old and comes from sand and clay sediments that were
deposited in a deep ocean. The fossilized resin from Borneo
that comes from beds of sandstone is completely inert and undoubtedly amber. However,
resin that comes from beds of clay still contains volatile components, which
means that it is still copal. So, the type of sediment in which the resin is
deposited is much more important than time for amber formation. But what is not
so clear is the effect of water and sediment chemistry on the resin.
 |
| Resin oozing from under the bark of a cedar tree, where a branch has been sawn off |
From Amber:
The Natural Time Capsule
By Andrew
Ross
