Amber—Frozen Moments in Time
by Garry Platt
Amber has a deep fascination for people both as a gem & 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 the Isle of Wight. This short narrative looks at some aspects of amber, which 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 which are now extinct. Baltic amber was produced by a tree called Pinites succinifer, a tree sharing many characteristics of the currently living genus Pseudolarix. In appearance it would have looked something 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 would begin to go through a number of stages in order to become amber.
The first stage involves 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 and plastic. Once completed the resin can be called copal.
Columbia in South America has extensive deposits of copal which is frequently sold as amber, but 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.
Following the polymerisation the next stage is the evaporation of volatile oils. The oils, called turpenes slowly permeate out of the amber. This second stage may take millions of years before the process turns the copal into something approaching the structure of amber.
It is speculated that either one or both of these stages in the formation of amber must take place in an anaerobic environment, or it may have to sustain a period of immersion in sea water. Amber which is exposed to air for several years undergoes oxidation which causes a distinct darkening and crusting of the gems surface. If sustained over many years the amber can fragment and breakdown into small tiny splinters and shards. The IoW amber is amongst the oldest found in the world, an estimated 120 Million years. Not surprisingly the pieces found are small and tiny weighing only a few grams. Lebanese deposits dating back 125 million years are similarly found in minuscule sizes and quantities. Baltic amber (a mere 40 millions years old) can be found in quite large blocks, in some cases weighing several kilos.
The largest known piece of Baltic amber ever found, weighs 21.5 pounds, it was found near Stettin, Poland in 1860 and now resides in the Museum fur Naturkunde in Berlin. Unconfirmed reports exist of a 4400 pound monster discovered in Samland in 1862 but it 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 150 pounds, but was unfortunately broken into 4 pieces during or after extraction.
Facts About Amber
The quantities of resin which must have been generated in the Baltic deposits was phenomenal. This can be confirmed simply from the amount of amber that has been extracted from various Baltic mines. The Palmnicken factory, a German government controlled company extracted in 1925 a record 1,205,916 pounds.
Commercial mining and gathering activities have been recorded from as early as 1264 AD and in various guises continue to this day. Imagine, how much amber has been extracted over a period of 700+ years? It is also true to say that the majority of this extraction was subsequently turned into varnish and shellac. We will never know what wonders have been lost.
The amber from the Samland Peninsula in the Baltic is actually a secondary deposit. The original amber forest was probably located further South. The resin was subsequently carried South probably by two great rivers from its original site and deposited in a great estuarial drift of silt and clay. (At the moment this is still speculation as many scientists disagree on this point). This deposit site extends some way out under the sea. This is also the likely source of amber washed up onto the Norfolk, Suffolk beaches. Autumn and Spring storms together with complimenting tides tears pieces of raw amber from the sea bed and strands them on the shore line. If you look for amber it is usually mixed in with the stranded seaweed, litter and of course obligatory dead seagull.
The chemical structure of Amber is not consistent, not even within a single fragment let alone a single deposit. Consequently numerous chemical formulas have been attributed to it: C10H16O - 13C40H64O14 - 12C12H20O. The reason for this wide variation is simply because amber is not a true mineral, it is an organic plastic with variable mixtures, consequently no precise quantification can be made with any exactitude. Some aspects of amber are fairly consistent. On Moh’s scale of hardness it lies between 2 and 2.5. It has a refraction index of 1.54 and a melting point between 150 - 180oC.
The colour range is extremely varied, ranging from near white (osseous) through all shades of yellow, brown and red. There are even examples of blue and green amber. Blue - Green amber is thought to have two possible causes; the permeation of raw resin by mineral deposits present either in the soil into which it fell, or the settling of volcanic dust and ash onto the resin when it was first secreted. By what ever process, the resin is impregnated with unusual compounds and given its distinct hue.
The claim of strong fluorescence in amber is often exaggerated. Generally, the fluorescence is weak and photographs which show glowing pieces of amber are usually achieved with exposure times in excess of 2 minutes under strong UV lamps, quite misleading.
Inclusions in Amber
One of the most exciting and interesting aspects of amber are the inclusions which are found within it, both flora and fauna.
The most frequent inclusions to be found in amber, particularly Baltic are examples of the order Diptera, or true flies. Quite often these are species of the superfamily Sciaroidea, commonly referred to as fungus gnats. These tiny little flies would have lived on the fungus growing on the rotting vegetation of the amber forest of which no doubt there was enough to support an enormous population.
It is this aspect of amber, these frozen moments in time which give us an insight into the ecology of ancient times which makes it so fascinating and compelling to study. It should also be recognised that amber gives us a skewed view of this ancient world. For example, it is unusual to find cockroaches in amber. But, Blattoidea most certainly did exist as every stage of moult development is present within the amber record, but why so few fully formed adults? The reason is quite simple; cockroaches were big enough and large enough to pull themselves out of the resin. Analysis therefore of the amber deposits needs to be done with a high degree of circumspection, research and reasoned insight.
There are some unusual and extraordinary things which infrequently turn up in amber. Occasionally a small lizard will be found, trapped and encased in amber, particularly from the Dominican Republic deposits. The American Natural History Museum has a famous example of a 25,000,000 year old gecko. Lizards are extremely rare in European deposits. The author believes there have only been two known and verified instances of lizards preserved in Baltic amber. One has since been lost to science, the other...[is no longer available for viewing].
Another unusual find are the remains of a frog discovered in a piece mined in the Dominican Republic. At first it was thought to be just one animal with some tissue preserved. The distinct shape of the frog can be seen but most of the flesh has deteriorated and several bones are exposed, some broken. Under closer scrutiny a count of the bones suggested that this particular frog must have had at least 6 legs. Palaeontologists speculate that a bird who ate the frogs may have had a feeding site, perhaps on a branch directly above an accumulating pool of resin. Hence the numerous bones present. The complete frog was perhaps an unlucky drop by the bird when it alighted on the branch.
Mammalian animals have left their mark in the amber record. Their hair can infrequently be found trapped as tufts or single strands. When found in Baltic amber it is often attributed to Sloths who lived within the ancient forest. The author has in his possession a piece of amber which has strands of hair which have been tentatively identified as that of a mole. One can only guess how they came to be trapped within the amber.
Doctor Kosmowska-Ceranowicz has describe a set of mammalian molars (possibly a pigs) which were discovered encased in Polish amber. The teeth have been perfectly ‘amberised’ and it is thought that the dead animal lay with its face partially lying in a bed of resin. The resin seeped in and around the decaying jaw of the animal thus preserving the set of teeth.
Resin whilst in the process of hardening usually develops a skin whilst the interior is still soft. Occasionally amber of this nature has impressions stamped on its surface and thus becomes a trace fossil. In one such piece the impression of a cats paw has clearly been left in a piece of Baltic amber.
During 1996 the spine and ribs of a mouse were discovered in amber from one of the Dominican Republic sites. This discovery has completely re-written the standing theory of the population of the West Indian islands by land animals. Yet again another remarkable insight into the ancient evolution and development of life through the window of amber.
The Isle of Wight amber deposit has so far yielded several identified insects, these include a chironomid, a Diptera midge, and a very interesting Hymenoptera (wasp). As at the time of writing the current site is partially covered with a mud flow and further collection is problematic. However, it is almost certain to be the case that further discoveries have yet to be made.
The faking of inclusions of amber has been a major cottage industry since the earliest times. This perhaps reached its height in the early 1900’s and a major source was from New Zealand. The North Island has some major deposits of Kaori Gum, and at the turn of the 19th century some was used to fake and imitate true amber. The digging of Kaori Gum was such a major industry the workers even had their own newspaper; ‘The Gum Diggers Gazette’.
The Kaori Gum would be melted gently and suitable inclusions placed into the matrix, this was frequently some kind of colourful insect. Colour is always a dead give away of a bogus amber fossil. Truly ancient amber fossils have no colour pigmentation left at all and are usually monotone. However, beetle colour is often an effect of light refraction, i.e. the light being broken into its spectral elements, the resin however prevents this. By removing the amber from the back of amberised beetles it has been reported that the original colour returns after 40 million years, quite amazing.
One of the cleverest fakes the author has encountered involves the use of a true piece of amber. The amber had a section cut from one end of the piece. A hole was then drilled into the main block. Inside this cavity was placed the insect which was in fact alive at the time of faking. The offending insect was then surrounded by molten resin and the previously sawn off section placed back in position and glued with the same liquid resin. The result was externally a perfect piece of amber which passed all tests for true amber.
Most of our understanding, beliefs and research on amber have been based upon the work of European and American cultures. The Chinese shared our fascination with amber and the earliest written references go back to AD 92. They believed that amber was the soul of a tiger which had died and passed into the earth and the Tibetans had perhaps the most beautiful name for this gem; pö-she, which meant perfumed crystal.
Amber is a strange and attractive gem. Its golden transparency lends it a quality which even diamonds do not share. For the artisan it provides a remarkable medium to work with and create some of the most beautiful objects for us to enjoy. For the scientist it provides a glimpse into the past, a window into history.
The author would like to acknowledge the suggestions and revisions made by Dr Edward Jarzembowski of Maidstone Museum in the development of this article.
The author is always interested in discussing & listening to stories about amber. Please feel free to contact him through any of the following:
81 Buxton Road
Furness Vale, High Peak
Derbyshire. SK23 7PL
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