Amber is an interesting gem material from a number of view points. For example, it has long been assumed to have a definite medicinal value, particularly for the alleviation of goiter. Perhaps this belief was derived from the fact that it has unusual electrical qualities (i.e., it can be electrified by friction) in fact, the Greek name for it, "elektron" is the word from which our word electricity was derived. Amber, according to ancient records, has been used by mankind since earliest times. The Greeks had the romantic thought that it was solidified sunshine that floated in from the sea, believing that solidification occurred when pieces were broken off as the sun sank into the sea. Some of the earliest trading done by various civilizations involved amber. The Phoenicians made some of their first voyages to bring it back from the Baltic Sea, along with tin from England.
Amber was valued so highly by the Romans that, according to Pliny, a small figure carved from the material would "fetch more than a healthy slave. During one period, Roman women were in the habit of carrying a small piece of amber in the hand, for the sake of the delicate balsamic odor it emitted when warmed in this way.
During the thirteenth century, and later, amber was used extensively for ornaments, the work being done primarily by "turner's guilds" in northern Europe. Graceful powder boxes and smelling bottles were brought into existence, often carved from a single chunk and studded with gold or silver filigree and precious stones. The baroque age influenced the amber art, also; quaint jewel cases and millinery chests even cupboards with pillars, walls and doors of different colors, date back to this period. Other costly articles made of amber included mirror frames and goblets and vases inlaid with gold or silver or enamel. Museums in Berlin, Dresden and Moscow contain wonderful specimens of artistic amber products of earlier days.
Amber is not a mineral but an organic product. It is fossilized resin of ancient trees that includes a number of related resins. As a non mineral, its composition varies greatly. The formula for succinite (SUCK-sin-ite), one of the principal resins composing amber, is approximately C40H64O4, with a small amount of hydrogen sulphide. An average sample is about 79% carbon, 10 1/2% hydrogen and 10 1/2% oxygen by weight. When heated, succinite produces succinic acid, oil of amber, a watery fluid, and a black residue. The name succinite is derived from the original Latin word for amber, "succinum" which itself was taken from the word meaning "juice". Colors range from pale yellow to dark brown and even red (orange colors often oxidize to red). It may also be whitish, greenish, bluish or violetish. Very rarely is it green or blue. Colors other than whitish, yellow, orange, brown and red are often caused by fluorescence or by interference of light as it passes through bubbles of air within the stone. In addition, amber can be stained various colors, as well as heated and plunged into dye, which is drawn into resultant "stress cracks".
The so-called Baltic amber, which is found on the southern shores of the Baltic Sea, is sometimes considered to include not only succinite but also another fossil resin called gedanite (GED-an-ite). This resin, because it contains no succinic acid, is classed by some authorities as a gum, not as a true amber. The name is derived from "Gedanum", the Latin name for Danzig. All of the types listed below are usually referred to by the general term block amber.
- Sea Amber
Amber found in the sea, either floating on the surface of the water or under it. It is also called "seastone" or "scoopstone."
- Pit Amber
This type, which is mined, includes the greater amount of the Baltic material produced. In the 1920's, it was second only to diamonds in U.S. gem imports.
- Clear Amber
Highly transparent material.
- Massive Amber
Compact, almost colorless to dark reddish yellow.
- Fatty, or Flohmig Amber
This type resembles goose fat and is full of tiny bubbles; however, it is not as opaque as cloudy amber.
- Cloudy, or Bastard, Amber
The appearance of cloudy material is caused by a multitude of small bubbles. The clarity can sometimes be increased by heating it gently with rapeseed oil.
- Foamy, or Fronthy, Amber
An opaque, chalky type that will not take a polish.
- Bone, or Osseous, Amber
More opaque and softer than the cloudy variety, contains many bubbles, and is white to brown in color, resembling bone or ivory. It takes a poor polish.
In addition to the Baltic Sea material described above, they are three other principal kinds of block amber; these are usually classified as follows:
- Sicilian Amber, or Simetite
This kind is red to orange and usually dark in tone. Fluorescence sometimes occurs, which changes the color to yellowish green and induces other colored effects, including bluish overtones. It may also be yellow or brown, but usually darker than Baltic amber.
- Chinese Amber, or Burmite
These are names-that are sometimes used dishonestly for amber substitutes. Genuine amber from Burma is usually brownish yellow to dark brown; sometimes it is almost colorless to pale yellow to orange, but ages to red. Although it comes from Burma, it was usually marketed through China in the past. It is slightly harder than Baltic amber and often has many calcite filled cracks. Only the pale Varieties are transparent.
- Roumanian Amber, or Roumanite
This type is brownish yellow to brown; it may also be brownish red or even black. It contains more sulphur than Baltic amber.
A final type, known as reconstructed or pressed amber (also sometimes called "amberoid"), is made by melting small pieces of amber and compressing it into blocks by hydraulic pressure, usually with the addition of linseed oil. It is easily stained various colors, but the color distribution is often uneven. An oil of similar R.I. to that of amber is sometimes forced into the air bubbles, thus clarifying cloudy amber. Different colors may be induced by using colored oils.
The major source of amber is along the southern shores of the Baltic Sea, in Poland (formerly East Prussian). It is also found in marine deposits along the shores of East Germany; in Sicily; in the Mediterranean Sea off Sicily; and in Upper Burma and Romania. In the Polish deposits, it occurs in a dark bluish, earthy stratum that represents the present evidence of once luxurious forests of extinct species of pipes and cypres. It is mined both by tunneling and open pit methods. Similar strata exposed beneath the sea are disintegrated by the waves and amber is released to wash up on the shore, since its S.G. is less than that of sea water. It is found in similar deposits in Sicily and beneath the sea off Sicily.
Amber is amorphous, occurring in irregular lumps varying in size from small grains to pieces weighing many pounds. The luster is resinous in the rough and resinous to almost vitreous in the polished state. With a hardness of only 2 to 2 1/2, it is easily cut with a pocket knife. Its toughness is poor, the fracture is conchoidal, and the S.G. of transparent material varies from about 1.05 to 1.096; cloudy material with a multitude of bubbles may be as low as 1.0, however. The R.I. varies somewhat, but it is usually very close to 1.54; it may be as low as 1.539 and as high as 1.545. As an amorphous substance, it is isotropic and has no cleavage, pleochroism nor birefringence. Gedanite is distinguished by a lack of tenacity, powdery inclusions, a greasy luster, a glassy fracture, and an inability to take a high polish. Inclusions in the form of insects, seeds and other foreign objects that were caught in the resin before it hardened are often present. The Germans call amber "Bernstein" ("stone that burns"), because it burns at very low temperatures; for that reason, it has often been used as incense.
Amber is usually identified by its very low S.G. and hardness. In addition, its R.I. is fairly characteristic. One useful test is to place the unknown material in a saturated salt solution, in which amber will float and most substitutes will sink. This test is usually sufficient to separate bakelite and most of the other plastic substitutes, but R.I. is also useful, since bakelite has an R.I. in the 1.60's, Bakelite gives off a strong carbolic acid odor when an small shaving is heated gently, and celluloid emits a camphor odor. Amber and copal bum with the smell of resin. Amber is difficult to separate from such recent resins as copal, kauri gum and dammar resin. Copal and kauri gum swell and soften when immersed in ether from five to twenty minutes. Also, a hot needle will melt copal or kauri gum more readily than amber, but the difference is slight enough to require comparison with known amber. Ethyl acetate is required to soften dammar resin. A cut stone is best tested by placing a small drop of ether on an inconspicuous place and allowing it to stand for a few minutes. When the ether is wiped off, a spot will appear on the surface of the substitute, if it has been attacked by the chemical. Ether evaporates so rapidly that a fairly large drop may be necessary, or else the drop must be replenished from time to time. Reconstructed amber can be separated by its appearance in transmitted light, where it shows a flow like structure similar to that of cheap, pressed glass. The bubbles in pressed amber are elongated or flattened, whereas in block amber they are round. The reconstructed material often appears flaky and shows separation planes that may be bluish between the layers of amber. It is attacked by ether, unlike the genuine. A fairly useful test for amber is to apply a knife blade or razor blade to an inconspicuous spot and check the sectility, or "cutability". Amber, pressed amber and copal break away in powdery splinters or chips. Bakelite resists the blade, but tends to peel off in rather large chips. Other plastic imitations tend to make curled peelings when cut. The insects or seeds that occur in genuine amber are often imitated in substitutes; therefore, they cannot be relied on as proof of natural material.
At the present time amber is not too highly regarded as a gem material, but it is in demand by antique collectors and there are still many persons who appreciate its beauty and its light weight for a necklaces. Moreover, many are firmly convinced of its value in the treatment and prevention of goiter, as mentioned previously. In general, Baltic Sea amber is of better quality than that recovered by mining on the shore. Sicilian amber is especially in demand by connoisseurs. Fine greens and translucent reds are the most valuable: transparent, flawless, intense yellows are the most desired of the more usual colors. The most transparent varieties are in greatest demand. Most amber used today is rather inexpensive and is used to make cigarette boxes, beads, rosaries, carved ornamental objects, and stones for rings and pendants. Amber darkens very gradually with age, becoming reddish or brownish. Such old pieces are quite desirable to collectors, although some specimens may be aged somewhat by immersing them for several weeks in salt water. Pressed amber turns white rather rapidly with age, and for this reason it should always be sold with the explanation that it is pressed. The price of amber in 5 to 15 carat sizes may vary from $4 to $120 per stone, depending on quality.