Amber inclusions

Copal is sometimes sold as amber and can be difficult to distinguish, especially for people not used to handling the materials. It is also used as filler or glue in the manufacture of faked amber inclusions, as it has the same colour and specific gravity as amber, and is therefore less easily detected than other materials. 

Amber is fossilized tree resin that hardened over millions of years and now is valued as a gem. Baltic amber is thought to be hardened sap from pine trees. It is normally yellow-brown in color, but the shades vary from almost white to almost black. Although sometimes completely clear, amber often contains inclusions of insects or other matter, often considered desirable. Much amber is obtained along the shores of the Baltic Sea, but it is also found along the coasts of Sicily, Romania, and Myanmar. 

Amber is soft, has a low melting point, and a very low density. Most amber will float in saturated salt water. It may be transparent, translucent or opaque, and varies in color. Most often it is yellow or brown, but specimens of red, blue, and green are known. Inclusions of insects, plant parts, dust, and other debris are sometimes found in amber formed from resin that was extruded onto the outside of a plant. There is lots of amber, however, that formed on the inside of plants, and this material rarely carries inclusions. Amber is very important to paleontologists because it preserves organisms, both plant and animal, that are far too delicate to be preserved by the normal fossilization processes of burial and dehydration. 

The cloudiness in some amber specimens is due to the presence of many very tiny air bubbles. In an effort to produce the more commercially desirable transparent amber, this material is often cleared by heating. This has the effect of driving off the air bubbles, and may achieve a better-looking product. At the same time, however, water is also driven off, leaving a more brittle, and sometimes less lustrous material. Heating done too quickly or at too high a temperature can also result in the formation of flat ovoid structures within the amber. These flying saucers are often exploited by dealers as natural inclusions. 

Possibly, as presumed by Frausto Da Silva and Williams (2001), some hitherto essential elements lost their biocatalytic functions altogether or are about to do so (ibid.) yet, this issue is open to speculations only because there is no way to determine former biocatalytic functions in fossil samples even if they are fully preserved, like inclusions in amber (with chitin retaining the metals) or dry mummies. Moreover, very few such samples date back beyond the Cretaceous (dinosaur xeromummies from Mongolia, Arabic amber) whereas most of the changes we consider here took place far back in the Precambrian. Changes of enviromnental conditions may also contribute to stabilization of changes by substitution of some redox-inert ion with 3 func-... 

While many gem materials contain inclusions, amber is unique in that it can contain inclusions of plant and animal matter - flora and fauna. These have become stuck to the sticky surface of the resin as it oozed from the tree. They may have inadvertently landed on it, or they may have been blown onto it by the wind. In the case of stingless bees, it is thought that they gathered the resin for nest building. Other trapped creatures have included termites, ants, flying ants, butterflies, moths and damsel flies, or anything too small or weak to be able to extricate itself. 

Baltic amber is rich in inclusions and over 1000 varieties of flora and fliuna have been discovered embedded in the resin. Unique to Baltic amber are hairs fi"om oak flowers and tiny crystals of the mineral pyrite. Other inclusions are flowers, leaves or pieces of bark, and various insects, the most common being termites and ants. Most of these things are now extinct, but a few species are very closely related to insects or plants alive today (Fig. 1.2). 

An opaque, white matter is often present around an insect inclusion. This is thought to be a ftmgus formed by the partial decay of the insect, and is unique to Baltic amber (Fig. 1.1). 

Burmite is harder than other ambers and can contain many insect inclusions. 

Simetite is also very rarely seen today. It is between 35 and 25 million years old and was found in Sicily near the River Simeto. It is predominantly orange to red in colour, sometimes appearing in a greenish hue. It is transparent, has few inclusions, and reflects light better than other ambers. 

With the exception of burmite all the ambers mentioned so far are from the Tertiary period. There are many finds of amber from the Cretaceous period, 140 to 65 million years ago, but the vast majority of these are of little use as decorative material as they are far too brittle to work. They are usually found in very small pieces and tend to be a dull, opaque brown. They are, however, of great scientific interest, especially as some contain plant and animal inclusions. 

Modem plastics are today used to fake amber. To give the impression of sun spangles, tiny slivers of metal are added to the plastic. When examined under a lOx lens these are seen to be too regular, often too thick, and without any radiating stress lines. They are often more easily discernible as fakes when they are photographed. Modem plastics are also used to fake pieces of amber with insect inclusions. The amber is often very clear and the insect beautifully placed in the middle of the piece. The insect normally proves to be of an extant species as opposed to an extinct one (Fig. 13.7). 

Doublets. More worrying and harder to discern are the faked insect inclusions that have been carefully placed on a piece of amber and capped with plastic. Careful inspection will probably show joins, and the piece is likely to sink in salt water because it has a higher specific gravity (a measurement of the mass of a substance) than natural amber (see Tests ). Again, the insect species will most likely be extant. 

A piece that is very even in colour and totally clear may indicate plastic. Although it does occur, totally clear natural amber that is free of any form of colour variation, crack or inclusion is unusual. 

Natural amber can have inclusions of plant debris, dirt, small animals and minerals. 

Copal is generally paler than amber, and is often the pale yellow colour of dry sherry (Fig. 1.34). Having been produced in the same way as amber it, too, can contain lots of flora and fauna inclusions. Copal is less stable than amber and the surface deteriorates relatively quickly, displaying the typical crazing which produces a whitish powder, sometimes referred to as dandruff (Fig. 1.35). The surface of amber can also craze with time, but the pattern is darker and does not produce white powder. 

Kauri gum is of a darker colour than most copals (Fig. 1.34), and, like the Japanese copal, some of it is turning into amber. It is mosdy transparent and it contains few inclusions. Insect inclusions are extremely rare. It has been successfully worked into a variety of decorative objects and jewellery. 

This copal, like the local amber, is from the genus Hymenaea. It is the typical pale yellow colour of most copals, and is extremely rich in plant and animal inclusions which are beautifully preserved and very distinct in the clear, pale material. It is usually sold cut and polished to show off these inclusions (Figs 1.34 and 1.3). 

Inclusion An item or cavity enclosed in a specimen, e.g. an insect inclusion in amber. 

Amber, a resin with unusual inclusions in his Metamorphoses the Roman poet Ovid (43 B.C. - 17 A.D.) describes the adventure of Phaethon, the son of the sun god Helios. Helios agreed to his son s request that he be allowed to drive the sun chariot. Phaethon had no experience, the horses ran wild, the chariot touched the heavens and the earth and left a track of fire in its wake. Zeus put an end to the chaos by means of a thunderbolt which catapulted Phaethon out of the chariot and down to the underworld Hades. Phaethon s sisters, the Heliads, wept for their brother they were turned into dolls and their tears to amber. 

Amber is by no means a uniform substance, but a mixture of resins. Most of it was formed in the tertiary period, an era which began about 65 million years ago and ended about 2 million years ago. The resin exudated by the plants attracted insects which were trapped by the sticky mass. Thus the inclusion of these insects and plants gives palaeontologists the rare possibility of studying extinct life forms in their natural state. About a thousand types of insects have been discovered in amber, which is mainly found on beaches in East Prussia. ... 

Table I gives Freundlich parameters for selected additional systems where the isotherm was established with many data taken over a wide concentration range. Most of these isotherms are nonlinear. Inspection of Figure 2a and Table I reveal the following. /) Nonlinearity applies to both polar and apolar compounds, ii) Nonlinearity applies to soils both high and low in NOM. Hi) Nonlinearity is a characteristic of sorption to humic materials because it occurs even in soils with very little mineral content. Many of our studies have been carried out on Pahokee peat soil, a high-organic ( -7% ash), well-humified reference material. This material consists of jagged amber-like translucent particles containing opaque inclusions, and is absent of undecomposed plant fibers. Furthermore, nonlinearity persists in cases where the mineral component of the peat has been stripped by HF/HCl treatment (cf., entry 1 vs entry 15, Table I), iv) Nonlinearity is not an artifact of insufficient equilibration time, since isotherms typically become increasingly nonlinear with time.

With the wide commercial availability of the last class of compound and sophisticated artwork, convincing imitations of large transparent amber pieces with a wide variety of inclusions (ants, bees, lizards, mosquitos, etc.) have been prepared. Py-GC provides a simple test for unmasking of such fakes, and Py-GC/MS can identify quite precisely the structures of the materials used for these purposes. 

---