Emerald jewelry emeralds gemstones beryl emerald bracelet...

	Emerald jewelry is also the traditionally selected gift for anniversary celebrations for the 20th, 35th, and 55th years of marriage. Emeralds are believed to have a strong effect on the conscious and the subconscious mind, causing strengthened memory and increased psychic awareness. And now, add a piece of this eternal goodness to your jewelry collection. The symbolic idea of an emerald is the promise of new life, growth, integrity, flourishing, and of prosperity. Unlike other stones, the color of an emerald cannot be precisely defined. Emeralds may be a blue-green or just green color, but the most valuable color for an emerald is typically a blue-green. When searching for that perfect emerald, you want the color to be uniform throughout the stone.
	Emerald rings are superior in every way and words alone cannot begin to describe it. In the princess cut emerald rings the top of the stone is cut in a square or rectangular shape and the overall shape is similar to that of an inverted pyramid with four beveled sides. Most square or rectangular cuts just don't live up to the round brilliant for sparkle, but the Princess Cut was designed for getting maximum brilliance from a square cut. You can`t help but be attracted to this stunning stone. You can be assured that you will get an emerald ring at an affordable price from any genuine online dealer. You sure will be be ecstatic with your purchase and without a doubt you are going to be more than satisfied. Most online stores have the full money-back guarantee on your purchase. The great color of a princess cut emerald ring, maybe surrounded by some beautiful diamonds signifies freshness, calmness, constant love and beauty. Surprise your loved one by treating her to something beautiful. With elegance, femininity and celebration in mind, share an expression of love. As divine and romantic as it is sparkling, a princess cut emerald ring is filled with magnificent beauty. A princess cut emerald ring is both sophisticated and elegant, and can still show off sparkle and fire with more dramatic prisms of light. Modern brides are embracing emerald rings with diamonds in designs that highlight richly hued emeralds with diamonds and an emerald bracelet with diamonds express a woman's unique personality. Make sure you go for a rich green color emerald with a darker shade in a princess cut emerald ring. www.diamondsonweb.com has an experienced and knowledgeable staff waiting to assist you with your purchase and any questions you may have.	Emerald jewelry - emerald bracelet and emerald ring

- About Emeralds - the four 'C's for Emerald Gemstones

Emeralds are more than simply the birthstone for the month of May. They are ancient stones of beauty, power, and wonder. They have long been one of the most sought after and admired precious gems to be found on this earth. Fascination and demand for this precious jewelry stone has a lot to do with its captivating and beautiful green color, but it is spurred on even further by its scarcity. For these same reasons, emerald jewelry may sometimes be considered even more precious than diamonds. You may find that statement difficult to believe, but arguably, it is often true in some of the finer emerald specimens. There are many things about emeralds such as this that are often misunderstood or even unknown to the casual emerald admirer. In this section we hope to change that. Read on to find a great deal of interesting facts and information about emeralds. We have provided links in this section to allow you to jump to the parts you may want to read about most.

- Color

When someone speaks of diamonds, they often mention the "4 C's" of Color, Cut, Clarity, and Carat when they assess the quality and value of the stone. All of these characteristics are considered when one looks at an emerald, but they looked at in a much different way. For most colored stones, the most important trait, by far, is color. This is one reason why Colombian emeralds are more highly prized over all others. Their rich and superior green to bluish green colors are unparalleled by emeralds from any other source. This is the 'trademark' color for which Colombian emeralds are known, but the color range for Colombian stones is actually quite varied, even within the same mine. You'll find Colombian emeralds with colors that range from a pale yellow green to a dark blue-green that's almost surreal. Or from a bright grassy color to a milky green jade-like appearance. You get the idea...They vary a great deal, but they are easily recognized if placed amongst emeralds from other countries. Valuation differences will also be just as obvious. But as the old rule says...you get what you pay for.

Color is one of the most important considerations in buying an emerald. The richer greens and blue-greens tend to be the most expensive and highly regarded emerald colors, but this should never sway you from buying a lighter colored stone that you fancy. After all, beauty is very subjective. It is not determined by some arbitrary quality standard or grading system, but by how you feel about it. If you think it's beautiful.. that's all that matters. We receive just as many questions about our lighter colored stones as we do for some of the more expensive specimens with deeper color.

An interesting fact on the subject of color that we have to mention is that the beautiful rich blue-green color that you may see in some Colombian emeralds is almost certainly indicative that it comes from the famed Muzo mine. This mine is perhaps the most well known gem-producing mine in the world. Its name is synonymous with the outstanding quality emeralds it produces.

- Cut

The quality of the diamond cut plays an important role in assessing a stone's value, but it is not an exact science. There is no single cut that is valued more than another, but well cut, matched pairs and sets will cost more because of the difficulty in finding and cutting multiple stones to match not only in color, but size and overall appearance.

Different gemstones may sometimes have certain cuts associated with that gem. For example, you will often see diamonds in a round brilliant cut or a princess cut. Emeralds are no different in that regard, with the emerald cut being by far the most common. There are reasons for this, as you will read about in the next paragraph. But overall, the most common cuts in which you will find emeralds are: emerald cut, round and oval cuts, pear or teardrop cut, and cabochon. To a lesser extent you will find princess cuts, brilliants, trilliants, and various fancy cut variants to include hearts and carvings. Some of these cuts are rather self-explanatory, so we'll only comment further on those that are not as obvious.

The emerald cut may be square or rectangular in shape and is easily recognizable by its shape, large face, and chopped corners. It is used so often for emeralds that it took its name from them. A big reason why emerald cuts are so common for emeralds is that it yields more saleable product from the rough crystal. This is an important consideration because a significant portion of the rough crystal is already lost in the cutting process... Approximately thirty percent. When this cut is used on any other gemstone, it is still referred to as an 'emerald cut'.

Cabochon is an ancient cut that has a convex, rounded surface that is polished. Finer stones are not often cut in the cabochon style, but do turn out to be quite elegant when they are. Cabochons are not as brilliant as other cuts, but instead project a quiet, tasteful beauty that features the stones natural color. Other gemstones use the cabochon cut more frequently with great results. Notable examples are: cat's eyes (chrysoberyl), star rubies and sapphires, many opaque stones such as opal, turquoise, and moonstone.

Fancy cut is a term that may be used to describe custom carving-type cuts or non-typical cuts which would often be used for custom settings. Gem cutters, will inevitably cut unusually shaped stones to make the most of the gem crystal they have to work with. But for a dealer, carrying a large inventory of unusually cut stones is probably unwise. If a client plans to make a custom piece of jewelry, it may be unlikely that the design could incorporate the fancy cuts you'd have on hand. Because there will inevitably be these fancy cut stones produced and with perhaps a much less predictable demand, the prices of these stones will often be lower than if they were cut in the typical shapes. Herein lies opportunity. A savvy buyer, who may be looking create a custom-made piece, could find some real bargains. They would just have to be willing to work with what's available.

- Clarity

Clarity is one of the essentials in selecting diamonds, but in colored stones such as used in emerald jewelry, this characteristic can be considerably less important...but not always. This is especially true when it comes to emeralds because of what is often referred to as the 'garden'. A garden is a natural feature internal to the stone that may appear like a silky web trapped within. Gardens are as varied as snowflakes and fingerprints and should be thought of in much the same way. Dense gardens may have an affect on clarity, but clarity alone should not sway one's opinion of a particular stone. The degree to which clarity affects a stone,s appeal and value is a very subjective consideration. Many emerald buyers will often place greater emphasis on color.

- Carat

One carat is a unit of weight measurement equivalent to 1/5th of one gram. Most gemstones are priced and sold based on their carat weight. For average sized stones, this price is based primarily on their color, cut, and clarity which we've already discussed. But as you begin to look at larger stones, and particularly larger stones of high quality, the 4th 'C' begins to play a much bigger role in pricing the stone. This is because the larger stones are rarer, and thus command a higher price per carat than smaller stones of the same quality. During a recent visit to colombia, we were shown a 180 carat stone of rather poor color and clarity with large, obvious inclusions. A one carat stone cut from this material would be priced at less than $200. But a stone of this size is rare and commands a much higher price. In the case of this stone, our source had a buyer for it at $1,000/carat.

About the Author Garrett Fifer
Embassy Emeralds was founded in 2005 with the goal of building a successful business by bringing high quality Colombian emeralds at good prices to those who share the same appreciation for these captivating green treasures. My vision for Embassy Emeralds is simple. I intend for us to become your trusted source for Colombian emeralds. Quality stones, pricing, service, and attention to the customer will be the things you remember about your buying  

- Archaeological geology of the world's first emerald mine

Emerald, a green transparent variety of beryl, was one of the most highly prized gemstones for jewelry in antiquity. The earliest known emerald mine is located in the mountain valley of Wadi Sikait in Egypt's Eastern Desert, where mining probably began toward the end of the Ptolemaic period in the first century BC. Most of the mining activity for emeralds for jewelry , however, dates to the Roman and Byzantine periods, from the late first century BC through the sixth century AD.

The Romans referred to emerald as smaragdus

and named the Sikait region Mons Smaragdus or Emerald Mountain. An archaeological geology survey of Wadi Sikait was undertaken for the purpose of mapping the distribution of ancient mine workings, deducing the ancient mining methods, and describing the geological occurrence of emerald. It was found that emerald and other green beryls occur within the contact zone between phlogopite schist and intrusive quartz and pegmatite veins. The workings, which were excavated in the softer phlogopite schist with flat-edged chisels and pointed picks, are mostly shallow, open-cut trenches that follow the quartz/ pegmatite veins. Some workings continue as much as 100 m underground and are still largely unexplored. It is noteworthy that the geological occurrence of beryl in Wadi Sikait, the world's oldest emerald mine, is essentially the same as for the world's newest emerald discovery at Regal Ridge in Canada's Yukon Territory.

INTRODUCTION

The study of ancient quarries and mines lies at the interface of geology and archaeology. It is one aspect of the broader discipline of 'archaeological geology' or, as it is also known, 'geoarchaeology' (Herz and Garrison, 1998; Rapp and Hill, 1998). Simply defined, archaeological geology is the application of geological principles and methods to archaeological objects and sites. In ancient Egypt, as with most other early civilizations, much of what remains consists of stone. There are building stones for temples and pyramids; ornamental stones for vessels, stelae, sarcophagi, statues and other sculptures; and precious stones for jewelry. The archaeological geologist may investigate not only the petrology and uses of these stones, but also the quarries and mines that supplied them, including their layout and operation, extraction and transport technologies, and geologic setting. For Egypt, the study of archaeological stones is well advanced (e.g., Aston et al., 2000; for further information on the quarries and mines see the author's web site at http:// www.eeescience.utoledo.edu/egypt/).

As an example of the application of archaeological emerald geology, the present paper looks at emerald mining in ancient Egypt. This review also serves to provide a historical perspective on Canada's own emerald deposit on Regal Ridge in the Pelly Mountain range (near Finlayson Lake) of southeast Yukon Territory. Emeralds were discovered here in 1998 on land owned by Expatriate Resources Ltd. of Vancouver, the property is now being developed by True North Emerald Exploration In Canada

	Emeralds	Gems Inc., also of Vancouver (Groat et al., 2002). Regal Ridge is the world's youngest emerald discovery, but the world's first emerald mine was in Egypt's Wadi Sikait (Fig. 1, 2). The word 'wadi' means 'valley' in Arabic and 'Sikait' is a Bedouin corruption of the ancient name for the site, 'Senskete' or 'Senskis.' Egypt was probably the only source of emerald and other green beryl for the ancient civilizations of Europe and the Mediterranean region. Although it has been suggested that the emerald deposit at Habachtal near Salzburg, Austria was worked as early as the Roman period, there is no conclusive evidence that it was known prior to the Middle Ages (Sinkankas, 1981, p. 371-77). However, Giuliani et al. (1998, 2000) have shown that the green beryls from Egypt and Austria are distinguishable by their oxygen-isotopic composition, and such testing, if applied to Roman jewelry, may yet reveal Habachtal's true historical significance. Egyptian emerald mining occurred not only in Wadi Sikait but also at several other sites within 15 km of this valley, including Gebel Zabara to the northwest, Wadi Nugrus and Wadi Abu Rusheid to the west, Wadi Umm Kabu and Wadi Umm Debaa to the southeast, and Wadi Gimal to the southwest. Mining
	began first in Wadi Sikait sometime during the Ptolemaic period (late 4th through mid-1st centuries BC) with most of the activity occurring in the subsequent Roman (late 1st century BC through 4th century AD) and Early Byzantine (5th through early 6th centuries AD) periods. All the other mining sites are strictly Roman-Byzantine or Islamic (mid-6th century AD onward) in date. Beryl mining ceased in Egypt with Spain's discovery of superior-quality Colombian emeralds in the 16th century AD. It is commonly reported in the literature (e.g., Giuliani et al., 2000, p. 631) that emeralds were used in Egypt as early as the 18th dynasty (16th through 14th centuries BC) of the New Kingdom. This claim, however, is based on the misidentification by archaeologists of amazonite (a green variety of microcline) as emerald (Lucas and Harris, 1962, p. 389-390). The earliest unequivocal evidence for emerald mining in Egypt dates to Ptolemaic times, and even for this period the evidence is scant. It was the Romans who were primarily responsible for developing the mines, and it was they who gave the mining district its ancient name, Mons Smaragdus or 'Emerald Mountain'. EMERALD AND OTHER BERYLS Beryl is a beryllium alumino-silicate mineral with the chemical formula. Ordinary beryl is colorless but the presence of various trace impurities gives the gemstone varieties of this mineral their distinctive colors: green emerald, blue to bluish-green aquamarine, pink morganite, red bixbite, and yellow to yellowish-orange heliodor  Emerald jewelry, emerald bracelet and emeral pendant
	(Sinkankas, 1981, p. 206-235). Beryl almost always occurs as elongated crystals with a hexagonal cross-section. It has a Mohs scratch hardness of 7.5-8, which is exceeded by only a few other gemstones such as chrysoberyl at 8.5, ruby and sapphire corundum at 9, and diamond at 10. Although highly resistant to grinding and cutting, beryl does have a weakly developed basal cleavage. Ancient stonecutters could thus cleave it perpendicular to the crystal axis to produce hexagonal prisms of any desired length. The name 'beryl' comes from the Roman naturalist Pliny the Elder who, writing in the 1st century AD, used beryllus to refer to a variety of minerals having long, prismatic crystals with hexagonal cross-sections. His smaragdus included the Egyptian beryl among other green stones, but he also recognized its relationship with beryllus: "many people consider the nature of berulli to be similar to, if not identical with, that of smaragdi" (Pliny's Natural History 37.16-20 in Eichholz, 1962, p. 212-227; Healy, 1999, p. 202-203, 241-245). The modern name 'emerald' is derived from the ancient smaragdus, a word that can be traced back at least as far as the late 4th or early 3rd century BC when it was used by the Greek writer Theophrastus as a catchall for green gemstones (Theophrastus' On Stones 23-27 in Caley and Richards, 1956, p. 50-51, 97-109). The Egyptian green beryl, however, was almost certainly unknown to him. The first mention of beryl (smaragdos) mining in Egypt was by the Greek geographer Strabo about 24 BC (Strabo's Geography 17.1.45 in Jones, 1959, p. 120-121). When mining began in Wadi Sikait is not known precisely but, given the almost total absence of green beryl in Ptolemaic jewelry, it must have been late in the Ptolemaic period and probably not much before Strabo wrote about it. True emerald has a bright, uniform, medium to dark green color and is transparent, but the best is a emeralds and diamonds composition. Beryls of this quality are very rare not only in Wadi Sikait but throughout the surrounding beryl-mining region. The Egyptian green beryl almost always has a pale color and a cloudy translucency (due to abundant fluid inclusions), and it also commonly contains minute mineral inclusions (usually phlogopite or actinolite, or their weathered clay-mineral equivalents). It is ironic, therefore, that Egypt's famous 'emerald mines' produced very few true emeralds. emeralds and diamonds The poor quality of Egyptian green emerald has been attested to repeatedly in both the ancient and modern literature (for a partial summary see Sinkankas, 1981, p. 542-548). For example, Pliny the Elder complained that the "Ethiopian [i.e., Egyptian] smaragdus is ... rarely flawless or uniform in tint" (Pliny's Natural History 37.18.69 in Eichholz, 1962. Although Egypt's ordinary green beryl may not have been highly esteemed by the Romans, it was still clearly much valued by them for jewelry. It was the hardest green gemstone available to them and it also had the added mystic of coming from fabled Egypt. Perhaps another appeal of beryl was its naturally faceted hexagonal prisms that mimicked the more costly cut gemstones. Unlike in recent centuries, when beryl has been ground into faceted stones, the Romans used the natural hexagonal prisms cleaved from crystals. These were either fixed into metal settings or drilled along the prism axis and strung as bead.. - Geology of Wadi Sikat emerald mines. Much has been written about the geology of the Wadi Sikait region (e.g., MacAlister, 1900; Hume, 1934, p. 109-125; EGSMA, 1951, p. 82-94; Basta and Zaki, 1961; El Shazly and Hassan, 1972; Hassan and El Shatoury, 1976; EGSMA, 1992, p. 31-83; and Abdalla and Mohamed, 1999). The map in Figure 2 is based on both this literature and fieldwork by the author. This is the first map of Wadi Sikait to combine topographic and geologic information, and also to show the distribution of ancient mine workings. The rock units in the map legend are listed chronologically downward from youngest to oldest. Not shown on the map are numerous diabase dikes that postdate the granite and intrude all other rock units. The schist melange also contains some small pockets of metadiorite-metagabbro as, for example, around the Middle Village. All the rock units date to the Late Proterozoic era and belong to the Pan-African Series except for the granite-granodiorite gneiss, which dates to an earlier part of the Proterozoic (Hassan and Hashad, 1990). The geologic occurrence of emerald in Wadi Sikait has been well described by Basta and Zaki (1961) and Abdalla and Mohamed (1999), and their findings are consistent with what is known generally about the origins of beryl deposits elsewhere (Sinkankas, 1981, p. 339-356). For green beryl tn form, two relatively rare elements need to be present: beryllium and chromium. Beryllium-bearing minerals are most commonly associated with hydrothermal veins that are offshoots of silicic magma bodies. At Wadi Sikait, such a magma body produced dae granite with its quartz and pegmatite veins. These veins generally vary from a few centimetres up to one metre in thickness, and have intruded all older rock units in the area. The veins are now much deformed and so commonly appear as discontinuous lenticular bands and pods. The occurrence of beryl is intimately linked with these Be-enriched veins, especially those of milky quartz, which are the most plentiful (Fig. 4). Only minute amounts of Cr substituting for A1 in the beryl crystal structure are needed to give the mineral a green emerald color, with darker shades produced by higher Cr concentrations. Although V can also color beryl green, chemical analyses have shown that Cr is the colorant for Wadi Sikait beryl. Unpublished analyses of five beryl specimens from Wadi Sikait reveal Cr concentrations ranging from 150 to 1013 ppm, and averaging 552 ppm (EGSMA, 1992, Table 3.4; A. El Dougdoug, Geology Dept., Cairo University, Egypt, pers. comm.). Chromium is commonly found in rocks of mafic composition, where it occurs as an impurity in mica and amphibole minerals through substitution for the Al and Fe in their crystal structures. In Wadi Sikait, these rocks are represented by phlogopite and actinolite schists in the schist melange. The actinolite schist occurs as thin sheets and lenses within the much more abundant phlogopite schist. Beryl or emeralds occurs mainly in the phlogopite schist and quartz/pegmatite veins, and is restricted to within tens of centimetres of their contact. It is found as individual crystals and, more often, as small clusters of crystals. Crystals can be up to 3 cm in length but most are much shorter. The beryl in the quartz/ pegmatite veins varies from colorless or white to light green but in the phlogopite schist the color ranges from light to dark green. Given that the schist is a source of Cr, it is not surprising that this rock would have the greener beryl, including true emerald. The geologic occurrence of green beryl at Wadi Sikait is very similar to that at Canada's Regal Ridge. Here the green beryl, which is colored by Cr, occurs within mica schist close tn its contact with quartz veins spawned by a nearby granite intrusion (Groat et al., 2002, p. 1330). Contrary to what Giuliani et al. (1998, p. 513-514) claim, Wadi Sikait is not a Type II emerald deposit, where Be-bearing hydrothermal fluids permeated Cr- or V-bearing rocks along thrust faults or shear zones. Both Wadi Sikait and Regal Ridge classify as Type I emerald deposits, where Be-bearing quartz or pegmatite veins from a granitic pluton intruded Cr- or V-bearing mafic or ultramafic rocks.

ANCIENT BERYL MINING

Beryl and emerald mining in Wadi Sikait with three ancient mining settlements that date to the Roman and early Byzantine periods (Foster et al., in press; Sidebotham et al., 2004). The largest of these is the so-called South Village, and this is the only one where archaeological excavations have been undertaken. The buildings here, as in the other two settlements, are constructed from slabs of quartz-muscovite schist (Fig. 5, 6). The well-preserved late Roman structure in Figure 6 is probably an administrative building, but could also be a temple. The South Village is particularly notable for its rock-cut temple, which is carved out of talc schist (Fig. 7). From conservation work done on this structure, it is known that it goes back at least as early as the 1st century AD, and poorly preserved Greek and hieroglyphic inscriptions hint at an earlier Ptolemaic date. Both the quartz-muscovite and talc schists are common lithologies in the schist melange unit. The next largest settlement is the Middle Village, which is perched midway up the west side of the mountain known as Gebel Sikait (Fig. 8). Here there is also a well-preserved, ancient roadway leading down to Wadi Sikait.

Modern prospecting and small-scale emerald mining occurred in Wadi Sikait during the first three decades of the last century. Most traces of this activity are found around the Middle and North villages, where modern workings occur amongst the ancient ones. Past attempts at reopening the Wadi Sikait mine were all unsuccessful because of the generally poor quality and, hence, low market value of the beryl.

Prospecting and Extraction Methods

The ancient emerald mine workings are mostly open-cut trenches of up to a few metres in depth. These follow the quartz/ pegmatite veins within the phlogopite schist. Many adits, shafts and tunnels, some extending over 100 m, pursue these veins deep underground. Where less than a few tens of centimetres thick, the vein together with 1-2 m of schist on both sides was removed, but for the thicker veins the schist was generally extracted along just one side. From the tool marks preserved in the schist, it is clear that the Roman miners used flat-edged chisels and, to a lesser extent, pointed picks for their excavations (Fig. 4). None of these tools, which were presumably cast from iron, have yet to be found in Wadi Sikait. It is likely that the quartz and pegmatite veins, which are too hard for such tools, were removed by stoping with the actual digging occurring only in the much softer phlogopite schist.

	The underground portions of the Wadi Sikait emerald mine have not yet been studied but anyway from time to time great emeralds are discovered. There are instead only a few passing comments from earlier visitors. For example, MacAlister (1900, p.544) says "the mining is of a most primitive character ... the ancients simply excavated ... a network of long and very tortuous passages just large enough to allow the body being dragged through, and only in a very few cases was any attempt made at ... excavating the entire seam." An unpublished report from the Egyptian Geological Survey and Mining Authority (EGSMA, 1951, p. 86) provides additional details: "some mines are very elementary, the galleries are very narrow and tortuous, that one has to creep all the time ... [whereas] other mines are nearly perfect; [their] walls were cleanly cut, shafts and levels were systematically dug, tunnels are [so] wide and high that it is easy to walk comfortably through ... [and] steps were carved in the floor of some inclined tunnels... [and] in all cases, one can notice the presence of big pillars of country rock being left for roof support."	Emeralds
	The ancient emerald miners knew that beryl was to be found along the contact between the quartz/pegmatite veins and phlogopite schist, and so probably rested every such association where visible on the surface (Fig. 4). The fact that not all the vein-schist contacts in Wadi Sikait have been mined is an indication that either the beryl deposits are erratic in their occurrence or they were never fully exploited.

Although emerald occurs in the quartz/pegmatite veins, it could not have been extracted from these hard rocks without great effort and large losses of crystals through breakage. Given this as well as the generally inferior color of beryl in the veins, the ancient miners were probably interested only in the more easily worked phlogopite schist. The beryl crystals were presumably cut out of this rock with a sharp-pointed metal tool, perhaps an iron blade or burin. From the great piles of fine-grained tailings around many of the workings, it appears that the removal of beryl crystals from the schist was done at the mine site.

CONCLUSIONS

In Egypt's Wadi Sikait, ancient miners extracted emerald and other green beryl from the contact zone between phlogopite schist and intrusive quartz and pegmatite veins. This is essentially the same geologic occurrence as the beryl on Canada's Regal Ridge. The world's oldest emerald mine (Wadi Sikait) and youngest emerald discovery (Regal Ridge) are separated by two millennia, yet are linked by not only their similar geology but also their common purpose--to satisfy people's desire for emerald jewelry. It is through the practice of archaeological geology that such links are made.

ACKNOWLEDGEMENTS

The author wishes to thank Steven E. Sidebotham, Professor of Roman Archaeology at the University of Delaware (USA) and Director of the Wadi Sikait Project, for permission to publish the present paper. This ongoing project, for which the author is the site geologist, has been supported by grants from the National Geographic Society. Thanks are also due to A. P. Sabina and especially J.D. Greenough for their comments on an earlier draft of this paper.

RESUME

L'emeraude qui est une variete de beryl vert transparent, etait l'une des pierres precieuses les plus prisees dans l'Antiquite La plus vieille mine d'emeraude connue est situee dans la vallee de montagne de Wadi Sikait dans le desert oriental de l'Egypte, ou l'extraction a probablement debutee vers la fin de la periode ptolemaique durant le premier siecle A.C. Cependant, le gros des travaux d'extraction date des periodes romaines et byzantines, de la fin du premier siecle avant J.C. jusqu'au sixieme siecle apres J.C. Les Romains utilisaient le mot smaragdus pour designer l'emeraude et designait la region de Sikait par l'expression Mons Smaragdus ou la montagne d'emeraude. Une etude de geologie archeologique de Wadi Sikait a ete entreprise dans le but de cartographier les anciens sites d'extraction, d'en deduire

les anciennes methodes d'extraction utilisees et de circonscrire la distribution des gisements d'emeraude. On a decouvert que les gisements d'emeraude et autres beryls verts sont localises dans la zone de contact separant une zone de schistes a phlogopite et de veines intrusives de quartz, d'une zone de pegmatites. Les excavations pratiquees dans la formation plus tendre du schiste a phlogopite a l'aide de ciseaux a pointe aplatie et de pics pointus, sont peu profondes pour la plupart, et forment des tranchees a ciel ouvert qui longent les zones de veines de quartz et de pegmatites. Certaines d'entre-elles qui se prolongent en soussol jusqu'a 100 m de profondeur sont peu explorees. Il est interessant de noter que le cadre geologique du beryl de Wadi Sikait, la plus vieille mine d'emeraude au monde, est essentiellement le meme que celui du plus recent gisement decouvert a Regal Ridge dans les Territoires du Yukon au Canada.

REFERENCES

Aston, B.G., Harrell, J.A. and Shaw, I., 2000, Stones, in Nicholson, P. T. and Shaw, I. (eds.), Ancient Egyptian Materials and Technology: University of Cambridge Press, Cambridge, UK, p. 5-77.

Abdalla, H.M. and Mohamed, F.H., 1999, Mineralogical and geochemical investigation of emerald and beryl mineralization, Pan-African Belt of Egypt--genetic and exploration aspects: Journal of African Earth Sciences, v. 28, n. 3, p. 581-598.

Basta, E.Z. and Zaki, M., 1961, Geology and mineralisation of Wadi Sikeit area, South-Eastern Desert: Journal of Geology of the United Arab Republic (later Egyptian Journal of Geology), v. 5, n. 1, p. 1-36.

Caley, E.R. and Richards, J.F.C., 1956, Theophrastus On Stones: Ohio State University Press, Columbus, Ohio, 238 p.

EGSMA, 1951, Report on the Prospecting Expedition in Wadi El Gemal Area, 1950-1951 (unpublished internal report): Egyptian Geological Survey and Mining Authority, Cairo, Egypt, 95 p. Geoscience Canada by James A. Harell

New technique discerns emerald jewelry beginnings - Gemstone

Once someone buy an emerald and the gemstone leaves its country of origin and circulates around the world and becomes emerald jewelry, the gem's provenance becomes murky. Scientists have now developed a nondestructive method for determining the source of emerald jewelry, even down to the mine from which it was extracted. That information can affect the gem's price and make it easier for historians to reconstruct ancient trade routes.

An emerald buying tracking procedure that measures the ratio of two oxygen isotopes in a microscopic sample from a gem has been available for a few years . Unfortunately, that method is not foolproof, says Philippe de Donato of the Ecole Nationale Superieure de Geologie in Vandoeuvre-les-Nancy, France.

Emeralds from Russia, Pakistan, and Madagascar often have the same ratio of oxygen isotopes, making them indistinguishable from one another.

A new analysis technique focuses on water trapped in an emerald's minute channels, de Donato and his colleagues reported last week at the Materials Research Society meeting in Boston. These channels, distributed throughout the stone, are just wide enough to fit one or two water molecules. The researchers homed in on a naturally occurring form of water in which an atom of deuterium, a doubly heavy isotope of hydrogen, replaces an atom of the more common hydrogen.

In the new technique, de Donato's team shines infrared light on an emerald. Oxygen-deuterium bonds in the gem's water molecules absorb specific wavelengths of the light, yielding an absorption spectrum that serves as an optical signature. The investigators used this signature to link various emeralds with their known sites of origin. "Because this method is completely nondestructive, we can make all the measurements we want," de Donato says.
Not only could the researchers distinguish between an emerald jewelry from Russia and one from Madagascar, they could pinpoint the specific mine in each country from which the emerald jewelry came. So far, the scientists have distinguished among emeralds from 10 mines in seven countries. They have also discriminated between natural emeralds and synthetic ones.

Why water molecules in emeralds from different parts of the world produce different optical signatures is unclear. De Donato says it may have to do with the presence of soil nutrients, such as sodium and potassium, whose concentrations vary from region to region and that seep into an emerald's crystal structure. The proximity of these elements to water in the gem's channels could influence the spectrum, he says.

The method could also be useful for documenting new emerald jewelry, he says. For example, if gem dealers can confirm that a stone is from Muzo, Colombia, the most famous emerald mine, they can sell it at a premium. Geography Science News, by A. Goho COPYRIGHT Science Service, Inc. & Gale Group.

Thailand's Chanthaburi the trading place in Asia for precious and semi precious stones.