Amber: Frozen moments in time
Gary Platt (UK).
Amber has a deep fascination for people, both as a gem and as a chance to look back into the past with a remarkable clarity. Its warm, lustrous touch beguiles us and the remarkable inclusions sometimes found within it capture our imagination.
Amber is found all over the world including, nearer to home, the Isle of Wight. This article looks at some aspects of amber that might interest both the casual and the informed reader.
Formation of Amber
Amber begins as resin exuded from trees millions of years ago. Most known deposits of amber come from various tree species that are now extinct. Baltic amber was produced by a tree called Pinites succinifer, a tree sharing many characteristics of the modern genus Pseudolarix. In appearance, it would have looked similar to a pine or spruce tree.
The resin may have originally been used as a defensive mechanism against insect infestation or fungal attack. Once released from the tree, the resin begins to go through a number of stages to become amber.
The first stage involves the evaporation of volatile oils. The oils, called “turpenes”, slowly permeate out of the amber. This may take many thousands of years before the process turns the resin into something approaching the structure of amber. Turpenes give resin its distinctive and powerful odour.
Following the evaporation of the turpene, the next stage is the slow, cross chain linking of the molecular structure within the resin (a kind of polymerisation). This makes the resin hard and brittle compared to its original state of soft plasticity. Once completed, the resin can be called “amber”. Before this final transition stage is complete, the resin may be called “copal”. However, many researchers argue about when resin should be referred to as “copal” or “amber”.
Columbia, in South America, has extensive deposits of copal that are frequently sold as amber. However, recent tests undertaken by G. Poinar have shown that, in some cases, it is less than 250 years old. Madagascar and Kenya also have highly fossiliferous copal mines. Their age is likely to be roughly the same as the Colombian deposits, if not younger.
It is speculated that either one or both of the stages in the formation of amber must take place either in an anaerobic environment (that is, in the absence of oxygen) or it may have to sustain a period of immersion in seawater. Amber, which is exposed to air for several years, undergoes oxidation that causes a distinct darkening and crusting of the gem’s surface. If sustained over many years, the amber can fragment into small splinters and shards. The Isle of Wight amber is amongst the oldest found in the World, an estimated 120 million years old. Not surprisingly, the pieces found are tiny, weighing only a few grams. Lebanese deposits, dating back 125 million years, are similarly found in minuscule sizes and quantities whereas Baltic amber (a mere 40 millions years old) can be found in quite large blocks, in some cases weighing several kilos.
Facts about Amber
The largest known piece of Baltic amber ever found weighed 21.5lbs. It was found near Stettin in Poland in 1860 and now resides in the Museum fur Naturkunde in Berlin. Unconfirmed reports exist of a 4,400lb monster discovered in Samland in 1862, but this may be nothing more than a story.
The largest confirmed piece of amber ever found is not from the Baltic but from Borneo. The stone weighed 150lbs, but was unfortunately broken into four pieces during or after extraction.
The quantity of resin from the Baltic deposits is phenomenal. This can be confirmed simply from the amount of amber that has been extracted from various Baltic mines. For example, in 1925, the Palmnicken factory (a German government-controlled company) extracted a record 1,205,916lbs.
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