Amber deposits

Amber deposits are found worldwide and are reckoned to be firom 300 to 15 million years old. The two best known deposits are those in the Baltic region and in the Dominican Republic. 

Siberia has the world s largest Cretaceous amber deposit. It is thought to be about 100 million years old and lies in the permafrost, so is accessible for only a short period each year when the fixjzen ground thaws. 

Europe has its own Cretaceous amber. Deposits have been found in, among other places, England (the Isle of Wight), France, Denmark and Austria. They date from 130 to 100 million years old. 

Amber is a fossd resin, extremely appreciated for its colom and beauty, and used as a gemstone from very early times. Natmal amber deposits are found all around the world, the most famous being the ones from the Baltic sea, the Dominican republic, Sicily, Borneo, Spain, etc. Amber resources are documented in Romania since the late sixteenth century, around the village of Colli (Buzau County), but they have certainly been exploited only starting with the modern age, after 1828, in the same area (Ghiurca, 1999 Wollmann, 19%). 

Czechowski F, Simoneit BRT, Sachanbinski M, Wolowiec S, Physicochemical structural characterization of ambers from deposits in Poland, Applied Geochem 11 811-834, 1996. 

The term varnish is used to describe the hard, amber-colored coating of fuel oxidation products adhering to engine components. The term sludge is used to describe the heavy, dark-colored deposits which settle from solution out of the fuel. Sludge can accumulate in areas of low turbulence and act as a prime site for initiating corrosion. 

SYNTHESIS To a solution of 14.0 g 4-ethoxy-3-methoxyphenol (see the recipe for MME for the preparation of this starting material) in an equal volume of EtOH, there was added a solution of 5.3 g KOH in 100 mL hot MeOH. This was followed with 9.1 g ethyl bromide, and the mixture was held at reflux for 2 h. The first deposition of KBr was apparent in 5 min, and there was rather severe bumping by the end of the reaction. The mixture was diluted with 3 volumes H20 and 1 volume 5% NaOH, and extracted with 2x200 mL Et20. The extracts were pooled, and the solvent removed under vacuum, yielding 14.3 g of a pale amber oil that set to crystals of 2,5-diethoxyanisole with a mp of 44-45 °C. The compound had been reported in the literature from the action of diethyl sulfate on methoxyhydroquinone. 

Amber can be found in rocks dating back to the Mesozoic era, about 80 million years ago. There undoubtedly were deposits of plant resin before that time, but they have failed to survive to this day. This may be due to the gradual breakdown of the hydrocarbons that constitute most amber, as well as its dehydration after burial. 

Amber can be formed by any plant that produces sap or resin. It is not specific to pine trees, as is commonly believed. The amber found in the Baltic region of Eastern Europe was indeed formed in a huge pine forest that covered that area about 10 million years ago, during the Miocene Epoch. Much of today s commercial amber is mined in Mexico and the Dominican Republic. These deposits are older than the European amber, and were formed by large shrubs in the Pea family. 

Baltic amber is found as secondary deposits in much of Denmark and southern Sweden, in layers laid down 30 000 years ago. It is not mined but turns up when foundations are laid for bridges or buildings. 

Deposits of amber are still being found today, so any list can quickly be out of date. A relatively young amber was recently found in Borneo, and there are known deposits of Canadian amber, but this has been buried in the permafrost and is badly preserved. However, there are a few other types that should be mentioned and described as, though they are rare, they can be found in antique shops and seen in museums. 

Rumanite came from the Carpathian Mountains in Romania. Both Tertiary and Cretacious deposits have been found. Although never plentiftil, it was immensely popular about 100 years ago, but today is seldom seen except in museums and, on rare occasions, in antique jewellery. It occurs in shades of brown, and is very clear except for the mass of small fractures within the material. This is very typical of rumanite and seldom seen in other ambers. 

Japan, which at 100 to 85 million years old is, together with burmite, the oldest amber from which objects have been carved. The largest deposits are north of Tokyo, near the town of Kuji. 

As with amber, copal deposits are found worldwide in subtropical regions, for example Brazil, the Dominican Republic, Columbia, Australia, New Zealand, West and East Africa, and Madagascar, to name but a few. Much of that found is probably no more than a few hundred years old, though some is considerably older. 

The chemical nature of amber is complex. Amber consists of complex mixtures of sesquiterpenoids, diterpenoids, and triterpenoids that have undergone polymerization and molecular reorganization during fossilization. Phenolic units may also be present. Baltic coast deposits, which contain about 8% succinic acid, are often called succinite. Amber is amorphous, and its infrared spectrum closely resembles those of nonvolatile resins from extinct pine trees. It is believed not to be a high polymer, the resinous state being accounted for by the complexity of materials present. Amber also serves as a repository for a variety of extinct species of insects. 

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