Amber is fossilized tree resin, which has been appreciated for its color and natural beauty since Neolithic times. Much valued from antiquity to the present as a gemstone, amber is made into a variety of decorative objects. Amber is used in jewelry. It has also been used as a healing agent in folk medicine.
There are five classes of amber, defined on the basis of their chemical constituents. Because it originates as a soft, sticky tree resin, amber sometimes contains animal and plant material as inclusions. Amber occurring in coal seams is also called resinite, and the term ambrite is applied to that found specifically within New Zealand coal seams.
Baltic AmberThe main deposits of the Baltic amber are not in the former amber forests where resins had formed and got in the soil. At present it is supposed that amber forests had existed gore 15-20 million years in Fen Scandia and maybe in the middle and the north part of the Baltic Sea.
In the Eocene period amber forests were overflowed, by the tertiary period mowing from the West. The main part of amber was washed out from the soil of those forests and brought together into Eocene and Oligocene sediments – settlings of the south coast of the sea, from the Sambian peninsula to Chlopov near Dancing (Gdansk). In these deposits the so-called “blue soil” (clayey sand with glaucomatous admixtures) was so much filled with amber that it that been mind here for more than 100 years. These are famous amber mines near Palmnicken (today Yantarny) in Russia. The thickness of the stratum of the blue soil is about 7-8 meters, and there are approximately 2,5 kg of amber in one cubic meter. Primary deposits were totally and secondary partly destroyed. At present the Baltic amber can be found from England in the West to Ukraine in the East, south Sweden and south Finland in the North.
Molecular polymerization, resulting from high pressures and temperatures produced by overlying sediment, transforms the resin first into copal. Sustained heat and pressure drives off terpenes and results in the formation of amber.
For this to happen, the resin must be resistant to decay. Many trees produce resin, but in the majority of cases this deposit is broken down by physical and biological processes. Exposure to sunlight, rain, microorganisms (such as bacteria and fungi), and extreme temperatures tends to disintegrate resin. For resin to survive long enough to become amber, it must be resistant to such forces or be produced under conditions that exclude them.
Fossil resins from Europe fall into two categories, the famous Baltic ambers and another that resembles the Agathis group. Fossil resins from the Americas and Africa are closely related to the modern genus Hymenaea, while Baltic ambers are thought to be fossil resins from Sciadopityaceae family plants that used to live in north Europe.
Amber is globally distributed, mainly in rocks of Cretaceous age or younger. Historically, the Samland coast west of Königsberg in Prussia was the world’s leading source of amber. The first mentions of amber deposits here date back to the 12th century. About 90% of the world’s extractable amber is still located in that area, which became the Kaliningrad Oblast of Russia in 1946.
Pieces of amber torn from the seafloor are cast up by the waves, and collected by hand, dredging, or diving. Elsewhere, amber is mined, both in open works and underground galleries. Then nodules of blue earth have to be removed and an opaque crust must be cleaned off, which can be done in revolving barrels containing sand and water. Erosion removes this crust from sea-worn amber.
Blue amber from Dominican Republic
Caribbean amber, especially Dominican blue amber, is mined through bell pitting, which is dangerous due to the risk of tunnel collapse.
Amber occurs in a range of different colors. As well as the usual yellow-orange-brown that is associated with the color “amber”, amber itself can range from a whitish color through a pale lemon yellow, to brown and almost black. Other uncommon colors include red amber (sometimes known as “cherry amber”), green amber, and even blue amber, which is rare and highly sought after.
Yellow amber is a hard, translucent, yellow, orange, or brown fossil resin from evergreen trees. Known to the Iranians by the Pahlavi compound word kah-ruba (from kah “straw” plus rubay “attract, snatch”, referring to its electrical properties), which entered Arabic as kahraba’ or kahraba (which later became the Arabic word for electricity, كهرباء kahrabā’), it too was called amber in Europe (Old French and Middle English ambre). Found along the southern shore of the Baltic Sea, yellow amber reached the Middle East and western Europe via trade. Its coastal acquisition may have been one reason yellow amber came to be designated by the same term as ambergris. Moreover, like ambergris, the resin could be burned as an incense. The resin’s most popular use was, however, for ornamentation—easily cut and polished, it could be transformed into beautiful jewelry. Much of the most highly prized amber is transparent, in contrast to the very common cloudy amber and opaque amber. Opaque amber contains numerous minute bubbles. This kind of amber is known as “bony amber”.
Although all Dominican amber is fluorescent, the rarest Dominican amber is blue amber. It turns blue in natural sunlight and any other partially or wholly ultraviolet light source. In long-wave UV light it has a very strong reflection, almost white. Only about 100 kg (220 lb) is found per year, which makes it valuable and expensive.
Sometimes amber retains the form of drops and stalactites, just as it exuded from the ducts and receptacles of the injured trees. It is thought that, in addition to exuding onto the surface of the tree, amber resin also originally flowed into hollow cavities or cracks within trees, thereby leading to the development of large lumps of amber of irregular form.
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