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The great hope for a jade supply in the Americas seems to lie in western Canada and Alaska. Early explorers of the coast of Alaska, the Yukon, the country eastward to the Mackenzie River, and the coast of British Columbia came into contact with nephrite jade in general use by local Indians and Eskimos. They found large numbers of jade artifacts. The famous exporers Captain Cook and later Vancouver and La Perouse were impressed by the native use of this incredibly tough green stone. The Alaskan Eskimos, who got most of their nephrite as boulders from the bed of the Kobuk River, flowing westward from the Point Barrow region, knew of the existence of an entire mountain of this green stone along the Kobuk River. By 1883, Lt. George T. Emmons had penetrated the difficult area and rediscovered “Jade Mountain,” thus certifying the Eskimo information. The entire mountain is green, mostly from serpentine scree which covers it, and it does contain enormous deposits of nephrite. These Alaskan nephrites occur in attractive shades of olive-green, yellow-green, gray-green, and blackish-green.
As for British Columbian nephrite, the bulk of the supply has come from the gravels and boulders in an enormous area along the lower reaches of the Fraser River. The deposits are incredibly large, and each spring flood exposes more of what seems to be an unending supply. Sometimes British Columbian and Alaskan nephrites resemble each other rather closely. The British Columbia material also occurs in several shades of green, as well as a grayish-white with green spots. Jadeite is not known in this part of North America and is often used for diamond engagement rings.
Jade has been woven into the fabric of early human technology around the world because it has such unique and utilitarian characteristics. Its sparse, sporadic, but widespread distribution has put enough of it conveniently into the hands of man so that he has it available to fashion for his own purposes. Occurring with the barely adequate supply there has been just enough of the highest quality, best-textured, most-translucent, beautifully colored jade to whet the world’s appetite for at least a few more centuries to come.
Farther south, nephrite is known to have been used for tools by aborigines along the Amazon River. A small nephrite deposit has been found in place in Brazil. Old jade objects are known elsewhere in South America, but there are no obvious sources of the material other than those already mentioned. The original natives of what is now the United States did not develop a jade industry. No artifacts have been reported in spite of the presence of significant jade deposits which have been found in recent years in the western states. By far the most important find in the United States occurred in 1942, in the countryside near Lander, Wyoming. Here the jade was collected as pebbles and boulders, some as large as the nearly 2500-pound piece in the Field Museum of Natural History in Chicago. Most of the jade had remarkably uniform texture and quality which made it ideal for carving.
The color range was wide, including good green, greenish-brown, gray, and jet-black stones that are used for wedding bands. Many tons were gathered, and already the best-quality material seems exhausted. Other sporadic finds of jade in California have maintained a lively interest in prospecting. Both nephrite and jadeite have been found there, but quantities are not large, nor is the quality exceptional. The beaches of Monterey County have yielded numerous pebbles and boulders of rather poor-quality nephrite, with the bulk of the recoveries being made in the late 1940’s and early 1950’s. Jadeite, previously known only in Burma, was discovered in San Benito County in 1936. Subsequent finds led to a jade rush into the area in 1950. These finds predated the rediscovery of Guatemalan jadeite by almost twenty years. Little jade of any value for carving has come from San Benito County, but the discoveries point out the possibility of eventually finding some jadeite at least as good as that used for the best Central American artifacts.
A very small jadeite deposit in Japan and a more recent discovery of mostly dark-green nephrite in Taiwan complete the inventory of jade sources in the eastern part of the world. Some of the Taiwan jade has already made its way into western markets to add to the meager supply from Russia and Burma.
But what of the western world? Surely there must be a more plentiful supply there. In actual fact, a quick survey shows jade to be an uncommon mineral.
As someone once said, “When scientists say jade is geologically fortuitous and the Chinese that it was a gift from Heaven, they agree in all except terminology.”
It is agreed that the arts of jade carving in Central America and China reached their highest artistic levels at about the same period in history. In China, although the jade supply was not native, there were at least some records of possible sources and these have now been pretty well identified. All traces of American sources were lost before and during the Spanish conquest. The great mystery for centuries had been the unexplainable high development of jade carving in Central America with no obvious sources of material. The implication was that somehow jade was imported by long-lost trade routes from other parts of the world. However in 1955 the rediscovery of a jade deposit in Guatemala was reported. This jade was obviously the same kind of green diopside-jadeite used by the Mayas, Aztecs, and others. The problem was solved. Unfortunately, very little jade is added to the world’s current supply from any Central American source. Also check princess diamond earrings.
The only other abundant source of good jade for the use of Chinese carvers was Burma. This jade was not discovered until the thirteenth century and took until the eighteenth to get to China, whose master carvers very likely were puzzled by its properties. It didn’t work like the stone they knew. It had a different set of characteristics and very different colors. However, it was jade and highly acceptable jade, at that. The long-delayed arrival of jadeite into China had finally come about discount diamond stud earrings.
Jade mining in Burma has not changed much since the days of its discovery. The best deposits were found in the hills north of the Uru River. At these Tawmaw mines, just as had been done in Turkestan, fires were built on the rock face to crack the jade, which could then be split out by hammer and wedge. Quantities of jade were also recovered as boulders in loose rock deposits along and in the Uru River. Frequently this was better material, and undamaged by the mining fires. Most of the Burmese jade mined was—and is—very pale green or whitish, sometimes with rather sizeable bright green splotches. Much more rarely have the coveted solid-green pieces—in emerald and darker shades—been recovered, and even more infrequently some of lavender color.
One of the annoying problems in jade appraisal is the practice of dyeing weak-colored or off-colored jadeite to simulate the best-quality green stones. Sometimes the dyeing is obvious. Cheaper dyes will fade in sunlight in a few days. Under magnification the dye often looks like thin, threadlike lines of color where it is trapped between jade grains but does not penetrate the grains themselves. There are dyeing processes more difficult to detect, and some so clever as to require laboratory detection. Fortunately, these pieces are not so common and are usually limited to smaller carvings. Then, too, the collector is protected somewhat in the United States by rulings of the Federal Trade Commission that such material be labeled “dyed jade.”
For the buyer of jade carvings, there remains an important problem: determining the authenticity of age. Richard Gump, long familiar with the merchandising of jade carvings, gives several guidelines for this in his book on jade. Among his suggestions is this: “The style or design of an object would, generally speaking, indicate the period. Check the exact detail of design. If it is a Han vessel with a Ming or Sung design, you know something is wrong. The material used is a good indicator. If the piece is said to be pre-17 84 and of jadeite, look out. If it is labeled Ch’ien Lung and of distinctive spinach-green Russian jade, which came onto the market in 1920, you would again have due cause for suspicion.” The general trend of these remarks indicates the complexity of authenticating a jade carving and the long and detailed experience necessary for this kind of detective work.
Once a working knowledge of jade characteristics is acquired, another pressing question arises: what are the sources of all the rough material worked by so many different cultures in such great quantities? Until recent times it was actually believed by many scholars that all the jades of ancient Middle America came from China. They certainly couldn’t have come from there, for, astounding as it seems, jade was never found in China proper. All the works of four thousand years of Chinese jade carving were executed in imported stone. There has been much speculation that the earliest carvings were done in native stone and that when these deposits ran out a thriving import trade in rough jade from other sources was begun. Check also round diamond earrings.
Tags: diamonds, gems, jade, jewelry
The evidence now very strongly indicates that the bulk of Chinese jade came from mines in eastern Turkestan, now Sinkiang Province in the west of modern China. There are references to this source in Chinese literature as far back as 200 B.C. The river valleys on the south side of the K’unlun mountains, lying between Tibet and Turkestan, are known to have a number of jade mines that operated for at least two thousand years. Marco Polo made mention in 1272 of jade supplies moving through the nearby city of Khotan. Quantities of broken pebbles and boulders of jade also were found in the river beds draining the same mountain areas. There are other jade deposits further to the west, in the vicinity of Yarkand, and especially at the “jade mountain” within one hundred miles of Yarkand. All of this imported jade was nephrite in white, green (mostly of pale shades), and black. Jade is frequently used for anniversary rings
There was another source of nephrite in Siberia. Although close to the ancient Chinese, it was unknown to them until well into the early 1900’s. These deposits are south of Lake Baikal in Siberia, and they yield a very deep spinach-green nephrite with black inclusions of chromite. Nephrite also occurs there in white or cloudy-green masses. The Russians themselves had made use of it as a decorative stone by the late 1800’s, and some of it had even been carved by such great lapidaries as Carl Peter Faberge.
Undoubtedly, the quickest and easiest of the reliable determinations is using a petro-graphic microscope, or a refractometer, to determine the refractive index. A trained micro-scopist can very rapidly differentiate between the varieties of jadeite, between jadeite and nephrite, and between jade and many of the jade-like minerals. Best of all, it takes only a few tiny grains of material, which can be removed easily from some inconspicuous place on a carving. The major drawback is that it requires an operator trained in the techniques of optical crystallography, as well as an expensive piece of equipment.
The most precise jade identification involves the X-ray diffraction powder method. This, too, requires only a very tiny amount of sample. A narrow X-ray beam is passed through the powdered mineral, which diffracts it into a pattern of lines. The pattern is recorded on photographic film, which can then be compared with a standard file of films containing patterns of known nephrite, jadeite, and other minerals. This kind of identification is fundamental because it depends on the fact that every crystalline mineral yields a characteristic pattern stemming from differences in internal structure. More info for diamond rings can be find here 1ct diamond engagement ring
A quick survey of obvious and not-so-obvious jade substitutes—many used innocently and with no intention of fraud—shows the magnitude of the identification problem. Only a very few substances are difficult to distinguish from jade. Jade-like glass, plastics, soapstone, and softer varieties of serpentine are easily separated from true jades because they are scratched readily by a good penknife. Jade carvings from ancient tombs will also scratch because their surfaces have become softened through centuries of exposure to the chemicals of decomposing bodies and soil solutions. Very old, archaic jade pieces may suffer the same alteration. If there is any doubt about these, they are worth an X-ray determination of the powdery surface material, which will show that they are still nephrite. Since jadeite was unknown in China until relatively modern times, all the ancient and altered jade will be nephrite.
Of the harder jade substitutes, the most troublesome to identify are bowenite; a green, fine-grained variety of idocrase known as cali-fornite; some fine-grained pieces of zoisite and diopside, and a few other related silicate minerals. For some, a determination of specific gravity is sufficient evidence. This, coupled with a reading of refractive index, is usually enough. Except in obvious cases, these silicate minerals are best left to trained mineralogists and gemologists for proper identification.
Jadeite is one of a group of minerals known as pyroxenes. Basically it is a sodium aluminum silicate. One variety of it found in Central America has an intermediate composition between jadeite and diopside—a calcium magnesium silicate; it is usually referred to as diopside-jadeite. Still another variety, called chloromelanite, with a strong, dark-green-to-black color, has a composition intermediate between jadeite, diopside, and acmite—a sodium iron silicate. Whether the sample is jadeite, diopside-jadeite, or chloromelaniie, all of these are unquestionably identifiable as pyroxenes and are close enough to jadeite to be recognized as merely slightly variant kinds of the same species.
The crystals of jadeite are not fibrous or matted, as are those of nephrite. However, they are complexly interlocked so as to have a compact, granular appearance. Jadeite, because of this difference, is not as tough as nephrite, but at 7 it is somewhat harder on the Mohs scale. It is measurably denser, too, than nephrite with a specific gravity varying from 3.30 to 3.36. Colors of jadeite tend to parallel those of nephrite, except that a pure-white or near-white jade is almost surely jadeite, as is a vivid emerald green 3 stone ring . Also reserved to jadeite are blue-greens, shades of lavender, and near red.
The challenge to the present-day jade carver and collector is an old one: how can jadeite and nephrite be distinguished from each other and from very similar substitutes? Most of the folklore of jade identification is worthless. For example, jade carvings do feel cool to the touch, as we are told, but so do many other stones. Simple tests can be applied, and long years of experience with jade can be used to make visual identification with a high percentage of success. In difficult cases, even among the experts, simple tests may fail miserably. Of course, there are more sophisticated methods available to the experts using expensive technical equipment and procedures that are just about foolproof.
Hardness is not a good test. Nephrite is 6 to 6i/2, and jadeite 61/2 to 7. Then, too, there is a variety of good green serpentine, called bow-enite, which looks very much like nephrite and has a hardness of 6. These hardnesses are all too close for certainty. The old trick of making a small, inconspicuous scratch with a penknife will not distinguish jadeite from nephrite, and will not eliminate bowenite or other hard species. It is useful for separating out the softer varieties of serpentine, soapstone, etc. Specific-gravity determinations are good, in that they do not require any mutilation of a carving.
The entire piece can be measured. Fortunately, too, jadeite has a specific gravity of 3.3 to 3.5, and nephrite of 2.96 to 3.10. The gap is sufficient to measure and distinguish one from another. But once again, bowenite, with a specific gravity just under 3.0, confuses nephrite identifications. Visual examination sometimes helps, because the expert soon comes to recognize a certain crystallinity in jadeite that is lacking in the other stones. Nephrite and serpentine have an amorphous internal appearance. A polished surface on nephrite seems to look more oily than glassy.
The material which thus came to be called jade was not the same as the mineral of like appearance that the Chinese had known for centuries. Chinese jade was what we now call nephrite, while the stone used by the ancient Americans has the modern name jadeite. Almost all of what is and was known as “true jade” is one of these two minerals. (Alas, the name of the Chinese species is not even of Chinese origin. When the Spanish for kidney stones was translated into Latin it became lapis nephriticus, which later became “nephrite.”) Jadeite and nephrite really have very little in common. At times they may look very much alike and both can be very tough, durable minerals.
Observed closely, the greens are not the same, even when both minerals are of good green color. The Spanish, for example, were able to generate some confusion between jadeite and emerald. This is possible because jadeite and emerald greens may sometimes approximate each other. Such confusion could not exist with the typical spinach green of nephrite. The differences in these hues are explainable because nephrite gets its green from the presence of iron in its composition, while jade-ite’s green—like that of emerald—arises from the presence of chromium. More diamond jewelry.
Nephrite and jadeite both are mineral species arising from special metamorphic conditions. Seldom are these jades found in place. They usually occur as pebbles and boulders in present or ancient stream beds to which they have been carried from their original deposits by strong erosional forces. Nephrite is very often associated with other iron-bearing metamorphic rocks, such as hornblende schists and gneisses, and with its look-alike, serpentine. Jadeite, on the other hand, occurs with a variable suite of minerals that require high pressures and temperatures for their formation. Usually these minerals associated with jadeite include albite and quartz. As with nephrite, serpentine is often present. Jadeite and nephrite are almost never found in proximity with each other, attesting to the different sets of natural conditions under which they are formed.
Nephrite is a calcium magnesium silicate. It is a member of what is called the tremolite-actinolite series of minerals. Tremolite is a pure, white, calcium magnesium silicate, and actinolite is a green calcium magnesium iron silicate. There are any number of mineral samples whose composition falls somewhere between the two, nephrite among them. The tremolite-actinolite series itself is part of a larger family of mineral species known as amphiboles. Jadeite is not even closely enough related to nephrite to be part of the amphibole group. Nephrite differs from the other tremolite-actinolite minerals in that the typical fibrous crystals of the group are very compactly and tightly matted and meshed together. This produces an extremely tough, tufted structure. Check other diamond jewelry
Its hardness is only 6y2, which is not extreme among minerals. However, its toughness, due to the gross structure, is so great that very thin and delicate objects carved from it are not nearly so fragile as they look. It was an ideal material for primitive tools, which in some ways were more durable than the iron implements introduced later in Chinese culture. Nephrite is three times as dense as water, but its specific gravity, due to compositional and impurity differences among selected samples, varies from 2.90 to 3.01. This value, unfortunately, is too close to the density of its most troublesome substitutes, but serves admirably to distinguish it from jadeite. Sometimes nephrite is green. Certainly its best-known and more highly prized pieces are green. Shades of white, brown, yellow, and gray-to-black are just as natural to it. Even blue nephrite is known. Almost all these colors, as suggested earlier, are due to the presence of iron in its composition. Oddly enough, white nephrite has been found with considerable iron content, so that at least part of the reason for coloring in this kind of jade is still a mystery.
Aside from the deposits in Turkestan and Burma, only a few other small occurrences have been noted for all the Orient. Scattered through the Pacific area there are some deposits of jade, and jade artifacts have been discovered widely scattered over the area. A deposit of nephrite exists on New Caledonia. Jadeite is found in place in the Celebes, and even chloromelanite occurs in New Guinea. Jade is perfect 3 stone ring.
The Maoris, when they arrived in their great migration to New Zealand in about the fourteenth century, quickly discovered durable nephrite in several places. Deposits they worked were found primarily on Mount Cook and elsewhere on the South Island. They called the nephrite pounamou, a word which literally means “green stone,” but also connotes value. Most of the jade was a dark green and none of it was ever plentiful. The export of unworked jade from New Zealand has now been prohibited, so that this source adds nothing to the world supply.
The Spanish conquistadores came to Mexico and Central America for various reasons, among them the urge for adventure and exploration. Very likely the booty they desired most was gold diamond jewelry, and they found it. They also found chalchihuitl, which the natives prized even more highly than gold. This stone of great durability and bright green color was revered sufficiently by the Aztecs to be reserved primarily for royalty and high officialdom.
Apparently, even in those times, it was rather rare and limited in its uses and distribution. Soon after the Spanish conquest the high art of American jade carving died. The existing carvings were plundered and dispersed. Native interest in the stone was lost along with the highly organized culture which valued it. Even the locations of the jade deposits were forgotten. There had been sufficient time, however, for the Spanish to import the stone. They identified it as very like the Chinese material then being brought in by Portuguese traders, and they adopted a strange mixture of Chinese and Aztec beliefs about it. One of these had to do with the miraculous curative power which jade could exercise on urinary disorders.
They labeled it “piedra de ijada,” or stone of the loins. Given the similarity in Portuguese and Spanish languages, it is not surprising that the stone from both sources soon became known around the world by the corrupted name “jada.” In French literature it was translated as “pierre de I’ejade.” By repeated error it became “le jade” and in English literature it became simply “jade.”
The ancient Chinese employed the word Yii in a very broad sense for any good hard-stone carvings, including those of what we now recognize as “true jade.” A more specific Chinese name, applied many centuries later in history to bright green jade, is fei-ts’ui. The name means kingfisher, and alludes to the bright green color of the feathers of one species of this bird. There was even a time when the name jasper, which we now use for a variety of quartz, served several kinds of jade that are used for wedding rings.
Strangely enough, despite the close connection between China and jade, the names used for this material come from an opposite corner of the world. The name jade was established before the time Chinese jade and jade carvings were well known in Europe. There are no known references to jade, by any name, in the literature of Europe that predates the discovery of jade in America. It was the Spanish who introduced this “new” stone to Europe and gave it a name.
So much has been written about jade that it should be one of the best publicized and best understood of all the gemstones that are used for gemstone rings. On the contrary, most of what has been written as fact has been embedded in reams of speculation, guesswork, fantasy, fiction, and pure invention, so that jade remains a great mystery. Of course, a gemstone with a continuous popular history running through more than four thousand years is bound to accumulate a voluminous body of confusing lore. This is especially so with gem material that has been put to use for utilitarian, economic, political, and religious purposes along the way.
Jade has become what it is in history, legend, and gemology as a direct result of its inherent characteristics. Consistently, publications about jade dwell on its mystical and potent powers, and on the reverence with which it has been regarded by the Chinese. Actually, the gemstone needs none of this, because its characteristics alone can explain its exalted position. It is very interesting that even today an exquisite Chinese carving, having all the appropriate mystical symbolism, will suddenly lose its magic and market value when it is discovered to be executed in one of the very similar—almost indistinguishable—natural substitutes and not in true jade.
The facts about jade took gemologists a long time to assemble. A good part of the problem lay in the definition of jade. It was so broad that the name—or its equivalent—has been applied to several mineral substances with grossly different characteristics.