Amber

Amber stones in the rough. Photo credit: Lanzi

Amber is the name for the fossilised resin of prehistoric trees. Although not mineralised, it is classified as a semiprecious gemstone or as an organic gemstone along with coral and pearls.

Amber is formed in three distinct stages over a period of at least 20 million years. Firstly, resin is internally or externally secreted by a tree in response to injury or disease, thereby creating a barrier to further intrusion. Once pooled into a adequate mass, the resin, along with any trapped inclusions (for example insects, plant debris and dirt), undergoes a hardening process called polymerisation, as the volatile oils (terpenes) that occur naturally in the resin begin to evaporate. Millions of years after the original tree is returned to dust, the resin continues to harden as it is buried under successive sedimentary layers and subjected to intense pressure and heat. While in this semi-fossilized state, between the ages of 15 and 20 million years, the material is known as copal. After at least 20 million years, the volatile oils have dissipated and the material may be classified as amber.

The oldest deposits of amber are 345 million years old, dating back to the Carboniferous period of the Palaeozoic Era. The oldest amber containing insects comes from the Lower Cretaceous, approximately 146 million years ago - a time when the very first insects were appearing on earth. Deposits can be found all over the world, in every imaginable colour from white to black and from transparent to completely opaque.

History of Use

Amber was amongst the first gemstones collected by human beings, with beads carved from amber found in tombs and caves dating back to at least 11,000BC. The first amber pieces were found by prehistoric man washed up on Baltic sea shores near mouths of the rivers which transported them downstream, and it is because of this that amber has always been associated with the sea. During these earliest times, amber was thought to be made from preserved sun rays or hardened sea foam. The word amber itself stems from the old Arabic word ambergris, the oily, perfumed substance secreted by sperm whales and often found washed up on beaches.

It was during the Bronze Age at around 3000BC that the first amber trade routes were established - several significant pieces made from amber have been found far from the Baltic, the most notable example being the Hove Cup, a drinking vessel turned entirely in amber and found in a bronze-age barrow at Hove in England. Amber was significant to many subsequent cultures including the Egyptians, Greeks and Romans, and at this time was believed to be a product of the sea gods, specifically their urine or spit. For this reason it was and still is thought by many to have both medicinal and amuletic properties.

Throughout the past 2 thousand years amber has continued to be highly valued, with many priceless artefact's crafted from the substance. The most famous of these is the Amber Room, a series of wall panels commissioned in 1701 for the king of Prussia, then given to Tsar Peter the Great. The room was stolen in it's entirety by the Nazis and is still lost, presumed destroyed.

Today amber is extensively used in jewellery making and ornament crafting and is valued for its unique appearance and aesthetic qualities. It is regarded by the Turks and Viennese as especially valuable for fashioning cigar-holders and the mouth-pieces of pipes as they believe amber to be incapable of transmitting infection. Many modern tribal cultures also hold it in high esteem.

The Characteristics of Amber

Amber may range in colour from palest white (‘butter' amber), yellow and green to deep red (date palm amber) or even brown-black. It can be opaque or completely transparent. These characteristics are all determined by the species of tree, the number and type of inclusions, the amount of air originally trapped in the resin and the age of the material. Amber continues to change minutely in appearance with time, which it is why it is today called the "living stone".

Ancient ant trapped forever in amber

Amber may contain animal and plant fragments, trapped at the very moment the resin was secreted. These are considered to be highly desirable features by geologists and biologists because they provide a snapshot of local conditions at the time the tree was alive. Amber is also unique in that it is able to preserve organic plant matter, small soft-bodied insects, amoebae and even bacteria. Debris and insect containing amber stones are highly sought after by the scientific community and command the highest prices on the international market, leaving very little available to the jewellery industry.

Exquisitely preserved bones and feathers from the tip of a dinosaur tail discovered in a piece of 99-million-year-old amber, found by a palaeontologist hunting for fossils in a Myanmar market in 2015. Photo: Royal Saskatchewan Museum  by RSM/R.C. McKellar

The World's Deposits

Amber is found all over the world, however the most important commercial deposits are found in the Baltic and Dominican Republic.

Baltic amber, which is found over most of northern Europe, is distinguished from other ambers by the presence of succinic acid and can be identified as such by IR Spectroscopy. Traditionally it was harvested from the shores of the Baltic and North Seas, however at this time extensive land mining operations are in place all over the region. Baltic amber can span many millions of years in age and comes in many different colours and transparencies. It is often treated before being sent to market.

Carved Dominican amber

Dominican amber is approximately 40 million years old. It is usually transparent and tends to contain a higher number of fossil inclusions than any other amber in the world. Much of the Dominican amber is sent on to the market without any enhancement. The Dominican Republic is also the home of blue amber, highly regarded because of its distinctive blue fluorescence under natural light and it's rarity - only 100 kilograms are mined per year. Dominican amber is harvested through bell pitting, a primitive and dangerous form of mining in which worm-like tunnels are cut into the sides of hills and mountains.

The oldest amber in the world is found in the USA, while other ancient deposits may be found in Switzerland, Austria, France, Mexico and Nigeria. Distinctive clear red ambers, secreted by date palm trees, are found especially in Burma and Lebanon. Other deposits are located in the Australian-oceanic area, including New Zealand, Sarawak and Indonesia. Copal amber, between 10,000 and 20,000 years old, is found in the coastal countries of East and West Africa.

Treatment

Amber room of the Catherine Palace, Russia.

Amber is a malleable substance that becomes soft and flexible on heating. Small pieces can be joined together by coating the surfaces with linseed oil and then pressing them together with intense hydraulic pressure while hot, forming "ambroid" or pressed amber. This material can then be cut or further pressed into any desired shape. Cloudy amber can be clarified in an oil-bath, inclusions can be made larger or more uniform by the application of heat and the colour of amber can be altered to almost any desired tone. However, all of these treatments do not diminish from the "realness" of the amber, but simply serve to enhance its natural beauty.

Historically amber was imitated by materials such as copal, kauri, celluloid and glass. Today plastic resins are used to counterfeit amber, particularly in China and Indonesia. The amber buyer should be aware that any low priced amber or amber with insect inclusions is likely to be fake or remoulded around a modern insect. A simple test consists of touching the object with a heated pin or the judicious application of a flame - if the resultant odour is of wood resin then the material is real, if it is of plastic then it is not.

Why is amber so expensive? Because as with any fossilised material, it is a non-renewable resource - there is a finite or limited amount of amber in the world, which will one day be exhausted. In addition, the scientific interest in the fossil inclusions of amber mean that there will always be buyers willing to pay the highest market prices.

Care for your amber jewellery by keeping it out of the sun and away from intense heat. A gentle wipe with a cloth should be enough to maintain its natural beauty, however should your amber become cloudy, it can always be re-polished, even with a piece of plastic.

References and Further Reading

Baltic Amber:The Living GemstoneJun 1, 2007.

Bradney, A2004. Amber. Retrieved on 10-5-09. ClearlyExplained.Com

Ward, S 2002 "Welcome to the World of Amber". Emporia State University.

Wikipedia Amber.  Retrieved on 11-5-09.