Amber is a fossil resin of trees that lived tens of millions of years ago. Its chemical composition varies because it is a mixture of organic compounds, including succinic acid and succinic resins. originating from the polymerization of terpenes and resinous acids.

Crystal system Noncrystaliine.
Appearance From transparent to translucent to semi- opaque. yellow to honey, brown or reddish brown, it sometimes has a dusty, friable reddish-brown, light brown, orgray crust, clue to alteration, It is found in variously shaped nodules—swollen blobs, due to an accumulation of drops, “icicles.” runs. or large lumps, like those formed by the resin of present-day trees. although in tar greater masses. when present in alluvial sand or gravel, amber no longer has the opaque coating and is often rounded into pebbles or grains.

Physical properties Amber is singly refractive, with an index of about 1.54, and has a very low density of around 1.06-T .08 g/cm3, so that it floats in a concentrated solution of kitchen salt. It has a hardness of around 2.5, but is reasonably tenacious and workable. even though it splinters when cut, showing signs of brittleness, It softens and starts to decompose at 150° and melts at about250°C. On
contact with the usual red-hot piece of wire, it gives off an aromatic smell as it decomposes, almost like the resin of present-day pine trees.

Genesis Amber originated from species of now-extinct plants. capable of producing enormous quantities of resin, which fell to the ground or filled large cracks and holes in the trunk and bark.

Subsequently, over a geological time span. it lost most of its more volatile components, then polymerized and hardened. The normal processes of erosion and sedimentation subsequently caused it to be deposited in deltaic sands on the shores and bed of what is now the Baltic Sea, or in other continental alluvial deposits, where it is found today.

Occurrence It is mainly found along the Baltic coasts of the Soviet Union and Poland, and in the Dominican Fiepublic in the Antilles. Other European sources include Czecho- slovakia, Romania. and Sicily. It is also found in the United States, Canada, and Chile; and in Burma.

The name has come down, probably through French, from the Arabic anbar. The Flomans called it succinum. as it was rightly believed to be from tree sap. Its use as an ornamental material dates from Neolithic times. It was brought to the foothills of the Alps from the Baltic coast. The distances that had to be covered to obtain it, enormous for those days. give an idea of its importance.

Appearance It is typically yellow to honey-colored. or yellow brown to brown, with good transparency, revealing glimpses of opaque brown to black frustules on the inside. almost disc-shaped surfaces with types of radial veins and sometimes animal remains, especially of arthropods (mainly insects, arachnids, and miriapodsl. Small gnats. wasps and ants are sometimes clearly recognizable, because whole and perfectly preserved in every detail. Some amber, however, is quite "cloudy"—-from translucent to semiopaqueeand lemon yellow to orange yellow or brownin color.

The semiopaque brown color is the least valuable. The opaque varieties are sometimes treated to make them transparent. Amber takes an excellent polish and is used in irregular, polyhedral pieces, similar to slightly elongated tetrahedra, polished and threaded into necklaces, and in spherical or oval disc-shaped and globular pieces with polyhedral faceting, likewise threaded into necklaces, bracelets and other types of jewelry. Pieces several centimeters in size (though not easy to find) are sometimes used as well. because having such a low density, this material is very light. In the recent past, it was used, in the West, the Arab world. and the Far East, for carved items, figurines, small perfume bottles, cigarette holders and pipe parts. brooches. buckles. and pendants. The semitransparent or opaque varieties are often used for carving and engraving.

Distinctive features There is another semifossil natural resin, of limited value and importance, called copal, which looks very much like amber at first sight. Numerous artificial, plastic materials are also widely employed as excellent, inexpensive substitutes for amber. To be sure of distinguishing them, the following procedure should be used. First, a quick check of the density should be made. using a very concentrated solution of kitchen salt in water. Only amber. copal. and polystyrene float in this; all other types of plastic sink, unless they have large cavities inside, which will be clearly visible. Next, two common organic liquids are used: benzole, which dissolves polystyrene fairly rapidly, making it go soft and "stringy," and ethyl alcohol {ordinary denatured alcohol), which softens the surface of
copal in less than half a minute, so that if the specimen is rubbed against a piece of white cloth, it leaves a distinct mark, the friction also producing visible signs of abrasion.

In this way, amber can be quite rapidly and positively identified, because it is not attacked by either benzole or alcohol. Partial immersion in alcohol also helps make another distinction: pieces are often found which have the basic characteristics of amber, but in fact consist of an agglomeration of numerous small fragments of amber (offcuts or pieces that were too small to begin with) that have been heated and compressed. In this case, a type of mosaic is visible with a lens on polished surfaces, because the contiguous pieces have slightly different hardnesses and show different relief when polished. Immersion in alcohol for between half a minute and two minutes causes the parts that have been softened by heat to turn slightly opaque, still further emphasizing the mosaic effect. Amber's famous ability to develop an electric charge and pick up pieces of paper if rubbed is not a useful means of distinction, as copal and nearly all plastics have the same property.

Occurrence In the past, most amber came from the southern coastal areas of the Baltic, which are now part of Poland and the Soviet Union. Other areas, such as Romania and Sicily. were much less important." Amber usable for ornamental purposes has also been found in Burma--home of many of the principal gemstones—and large quantities of very fine amber have also been obtained for more than a decade from the Dominican Republic.

Value Nowadays it is quite low, or at any rate, muchlower than it must have been many centuries ago. Obviously, antique and/or finely worked pieces are an exception to this rule. but they are not often seen.

Stimulants Ever since production of plastics began several decades ago. they have nearly all been used to imitate amber. Large amounts of old-fashioned jewelry, therefore, are in circulation which are believed to be amber but are, in fact. plastic. In the Orient (mainly India and China) various sculpted or engraved objects have been produced, some of them quite large. which are now coming onto the market as old or antique. but which are made of plastic fashioned like amber. Many modern pieces of silver ieweiry of Arabic or African origin are now set with pieces of plastic instead of amber. Copal is sometimes used for these as well. Although less valuable because it is unstable and liable to deteriorate, it is at least a natural material. The tremendous confusion on the market and the difficulty of distinguishing amber readily from many types of plastic, not to mention agglomerated amber and oopal, have greatly diminished the respect this material enjoyed in the past.