Amber

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Amber
Chemical composition C-H-O compound (fossil resin)
Crystal system Amorphous
Fracture Conchoidal, brittle
Hardness 2-2.5
Refractive index 1.54
Specific gravity 1.05-1.09
Lustre Resinous
Baltic Amber with insect,
Palmnicken (40-60 Million Years in age)
Photo courtesy of Conny Forsberg
Mexican amber
Photo courtesy of Dave Gibson

Amber image gallery

Amber is the fossil resin from a pine tree that flourished in the Baltic region (and other localities) some 25 to 60 million years ago. Globs of this aromatic sap poured down from prehistoric trees, often trapping insects, twigs, bark and leaves. Amber is one of the few gemstones of organic origin. In ancient India and Egypt, amber was burned as an incense, believed to purify the surrounding area. Amber is abundant along the shores of the Baltic Sea where it is mined extensively from Tertiary glauconite sands that are from 40 million to 60 million years old.


Diagnostics

Amber is often very hard to seperate from its imitations due to overlapping physical and optical properties. When no internal features are diagnostic, one can, usually, only fall back on destructive methods like the hot needle test and ether/aceton.

Color

Blue amber in reflected and transmitted light


Amber occurs in the colors white, yellow, orange, red, brown, blue, black, green and has a typical resinous luster.

Blue and green amber is found only in the Dominican Republic. This blue (or green) color is only seen in reflected light, in transmitted light it will show a more common amber color (such as yellow, orange, red). Under UV light these blue gems give a strong cobalt blue fluorescence.
The cause of color of these blue and green gems is believed to be from fluorescence of UV and violet light from natural sunlight.

Delocalized electrons on organic molecules are the cause of the other colors.

Diaphaneity

Transparent to opaque.

Refractometer

Amber has a refractive index of ~1.54 and is singly refractive.
Copal and some plastics are in the same range of amber gemstones.
Glass and chalcedony also have a similar refractive index to amber.

Specific gravity

The specific gravity varies from 1.05 to 1.09. Amber with many gassbubbles are in the lower range.
Amber floats in a saturated saline solution. This is the reason why amber is found on many shores around the Baltic Sea, it floats on sea water.
As with the refractive index, copal and some plastics fall in the same range.

Hot needle test

When a needle is heated and then brought to a piece of amber, it will give a pine tree odor, while the plastic similants will smell like burned plastic.

Ether

When a small drop of ether or acetone is placed on plastic or copal, it will leave a sticky surface while they have no effect on real amber.

Polariscope

Amber is singly refractive and will show anomalous extinction (ADR) and stress colors between crossed polarizers, as will some plastics.

Magnification

  • Insects (usually extinct species) and other flora and fauna that got trapped by the resin.
(These can be mimiced in plastic)

Electricity

The greek word for amber is "electron" and "electricity" is named after this gemstone.

When rubbed with silk, amber will get a negative electric charge while glass will be positively charged.
Plastics will also be charged negatively like amber.

Treatments

Heat treatment

Alot of amber contains many gas bubbles that give it a hazy appearence. Slow heating between 150-180° C, followed by slow cooling, can diffuse these bubbles out.
When the cooling takes place too rapidly, typical leaf like stress inclusions form (these are know as "sun spangles") and these inclusions are, more than often intentionally, mistaken for prehistoric leaf inclusions.

Another type of heating involves laying the specimens in a sand filled iron pot and heat it over an extensive period to darken the amber. This gives it an "antiqued" look. Natural amber may darken naturally over time due to air oxidation.

Other treatments

  • Dying
  • Coating
  • Foiling

Imitations

Reconstructed amber

One type of amber that one may encounter is reconstructed amber. This type of amber is also marketed as "ambroid".
Clear fragments of amber are carefully selected and heated upto ± 180° C under high pressure of +350 bar in a reducing atmosphere with sometime linseed oil added. Under these conditions the fragments fuse together and some organic dyes may be added to the process to influence the color of the resulting solid block.
These gemstones may whiten over time opposed to natural occuring amber which will darken.

The following inclusions may be seen:

  • flow lines
  • elongated bubbles

A strong bright blue fluorescence might be observed.

Copal

Copal is also a natural occuring fossilized resin which can also be artificially created. The resin has been burried in the earth for a conciderably shorter period and its hardness is lower than that of amber.
The best way of descriminating between copal and amber is by placing a small drop of ether or aceton on the gemstone. This will create a sticky surface on copal, while it has no effect on amber. This is a destructive method though.
The fluorescence of copal is much whiter than that of amber.

Plastic

Plastic is often used to imitate amber. Even complete insects and/or small animals like salamanders are embedded into the mould to mimic natural fauna inclusions.
When the hot needle test is applied to them, it will smell acrid instead of piney.

If you are offered a piece of amber with a complete salamander at low cost, there must be something wrong as they would fetch several ten-thousands dollars when genuine.

Occurrence

  • The areas around the Baltic Sea (Poland, Denmark, Finland, Sweden, Germany, Latvia, Lithuania)
  • The Dominican Republic
  • Mexico
  • Borneo Island (Sarawak and Sabah in Malaysia, Kalimantan in Indonesia, Brunei Darussalam)
  • North America (New Jersey, Arkansas, Alaska, Montana, North Carolina in the USA)
Chiapas Amber,
Very suitable for jewelry as it's hold the polished surface longer enough. Mined from the lignite deposit at the Simojovel, Chiapas, Mexico
Borneo Amber,
Toughest and uniform forms of Borneo amber from Merit-Pila Coal Mine, Sarawak, Malaysia
Borneo Amber,
Toughest and uniform forms of Borneo amber from Sabah, Malaysia
Borneo Amber,
Very brittle and semi-transparent forms of Borneo amber from Sabah, Malaysia
Golling amber,
Rarely cut as cabochon because its extreme rarity. Although Golling amber is very old resin(125 million years old),it is sometime have gem-quality properties and also harder than normal amber.
Lee Creek Amber,
Very difficult to polish and usually keep in raw forms. Have similar properties to Borneo amber. It was found at PCS, North Carolina in the active phosphate mine.
New Jersey Amber,
Very brittle Cretaceous amber. It is found near the Sayreville, New Jersey, USA

A Short Series of Films on Amber

<videoflash>huls7o5L9q8</videoflash> Part 1:
The International Amber Association production. Remarks by Dr. Elzbieta Sontag, scholars & experts Wieslaw Gierlowski & Barbara Kosmowska Ceranowicz plus amber master Lucjan Myrta describes his magnificent magnum opus.

<videoflash>NBC1mbuAa18</videoflash> Part 2:
Explanation of how some amber colors are formed, artworks in the new Museum of Amber, stunning footage of St. Brigid's amber altar Our Lady of Czestochowa with remarks by amber master Mariusz Drapikowski. The famous Lizard of Gdansk fossil inclusion. Whimsical amber jewelry & fashions from contemporary designers, amber artworks & amber inspired sculpture. Inside the amber artist's studio. Buying amber on Mariaska Street in Gdansk. The International Amber Association's efforts to educate the public about amber & identify & stamp out forgeries. Remarks by Dr. Ewa Wagner Wysiecka on scientific amber testing.

<videoflash>5z-oe8fqoOw</videoflash> PART 3:
The role of infrared spectrascopy & an explanation of "The Baltic Curve" & how this chemical signature is used to identify & authenticate Baltic amber. Professor Barbara Kosmowska Ceranowicz of Poland's Museum of the Earth discusses the traits of Baltic ambe. She explains why it is the most highly prized form of amber & specifically why it is the best choice for amber jewelry. Eva Rachon discusses amber fakes & forgeries in the marketplace & explains the unique mission of the International Amber Association & it's role in The role of over 1,000 amber studios are located in the Pomerania (Polish) amber industry, employing over 10,000 workers. The annual value of it's jewelry exports all over the world is over 300 million US dollars. Historic & beautiful Gdansk has again emerged as the center of amber production, earning the name Amber Capitol of the World. The future looks exciting indeed for those who work with, study, wear & love beautiful Baltic amber.

Sources

External links

Museums