(via Wahroongai News, Volume 32, Number 7, July 1998)
Table of absorption lines for gems and minerals: This section deals with the absorption spectra of gemstones by using the spectroscope. The units are measured in Angstrom units (A), (One Angstrom = one ten millioneth of a millimeter), all figures are in Angstrom units. The gem spectroscope is used on transparent materials but thin slices of opaque materials can be used as long as light passes through it. Strong absorption lines are bracketed and weak lines have no brackets.
Color bands for the spectroscope
Red: 7800 – 6400
Orange: 6400 – 5950
Yellow: 5950 – 5700
Green: 5700 – 5000
Blue: 5000 – 4500
Purple: 4500 – 3800
Agate, dyed yellow: (7000), 6650, 6350
Actinolite: 5030, 4315
Alexandrite, green direction: (6805), 6785, 6650, (6550), 6490, 6450, (6400), (5550)
Alexandrite, red direction: 6805, (6785), 6550, 6450, 6050, 5400, (4720)
Almandine: 6170, (5760), (5270), (5050), 4620, 4380, 4280, 4040, 3930
Amethyst: 5500, 5200
Andalusite: 5535, (5505), 5475, 5250, 5180, 5060, 4950, (4550), 4475, (4360)
Apatite, yellow green: 6053, 6025, 5975, (5855), (5772), 5335, 5295, 5270
Aventurine: 6820, 6490
Axinite: 5320, (5120), (4920), (4660), 4400, 4150
Azurite: 5000
Beryl, dyed blue: 7050, 6850, 6450, 6250, 6050, 5870
Calcite: (5820)
Chalcedony, dyed blue: 6900, 6600, 6270
Chalcedony, dyed green: 7050, 6700, 6450
Chrysoberyl: 5040, 4950, 4850, (4450)
Chrysoprase, dyed: 6320, 4439
Chrysoprase: 4439
Danburite: 5900, 5860, (5845), 5840, 5830, 5820, 5805, 5780, 5760, 5730, 5710
Demantoid: (7100), 6930, (6400), (6220), 4850, 4640, 4430
Diamond, colorless to yellow: (4780), 4650, 4510, 4350, 4230, (4155), 4015, 3900
Diamond, brown to green: 537-, (5040), 4980
Diamond, yellow to brown: 5760, 5690, 5640, 5580, 5500, 5480, 5230, 4935, 4800, 4600
Diamond, artificial color yellow: (5940), 5040, (4980), 4780, 4650, 4510, 4350, 4230, 4155
Diamond, artificial color green: (7410), (5040), (4980), 4650, 4510, 4350, 4230, 4155
Diamond, artificial color brown: (7410), 5940, (5040), (4980), 4780, 4650, 4510, 4350, 4230, 4155
Diopside: (5470), 5080, (5050), (4930), 4560
Chrome diopside: 6700, 6550, 6350, 5080, 5050, 4900
Dioptase: 5700, 5600, 4650-4000
Ekanite: 6651, 6375
Emerald: (6835), (6806), 6620, 6460, (6370), 6060, 5940, (6300-5800)
Emerald, synthetic: 6830, 6805, 6620, 6460, (6375), 6300-5800, 6060, 5940, 4774
Enstatite: (5475), 5090, (5058), 5025, 4830, 4720, 4590, 4490, 4250
Chrome Enstatite: 6880, 6690, 5060
Epidote: 4750, (4550), 4350
Euclase: (7065), (7040), 6950, 6880, 6600, (6500), (6390), 4680, 4550
Fluorite, green: 6400, 6006, (5850), 5700, 5530, 5500, 4520, 4350
Fluorite, yellow: 5450, 5150, 4900, 4700, 4520
Gahnite: (6320), 5920, 5770, 5520, 5080, (4800), (4590), 4430, 4330
Grossular: 6300
Hematite: 7000, 6400, 5950, 5700, 4800, 4500, 4250, 4000
Hessonite: 5470, 4900, 4545, (4350)
Hiddenite: (6905), (6860), 6690, 6460, (6200), (4375), 4330
Hypersthene: 5510, (5475), (5058), 4820, 4485
Idocrase, green: 5300, 4870, (4610)
Iolite: 6450, 5930, 5850, 5350, (4920), (4560), 4360, 4260
Jadeite, green: (6915), 6550, 6300, 4950, 4500, (4375), 4330
Jadeite, artificial green: 6650, 6550, 6450
Kornerupine: 5400, (5080), 4630, (4460), 4300
Kyanite: 7060, 6890, 6710, (4460), 4330
Nephrite: 6890, (5090), 4900, 4600
Obsidian: 6800, 6700, 6600, 6500, 6350, 5950, 5550, 5000
Opal, fire: 7000-6400, 5900-4000
Orthoclase: 4480, 4200
Peridot: 6530, 5530, 5290, (4970), (4950), (4930), (4730), 4530
Petalite: 4540
Pyrope: (6870), (6850), 6710, 6500, (6200-5200), 5050
Quartz, synthetic blue: 6450. 5850, 5400, 5000-4900
Rhodochrosite: 5510, 4545, 4100, 3910, 3830, 3780, 3630
Rhodonite: 5480, 5030, 4550, 4120, 4080
Ruby: (6942), (6928), 6680, 6592, 6100-5000, (4750), (4685)
Sapphire, blue: (4710), (4600), 4550, (4500), 3790
Sapphire, yellow: (4710), (4600), (4500)
Sapphire, green: 4710, 4600-4500
Scheelite: (5840)
Serpentine: 4970, 4640
Sillimanite: 4620, 4410, 4100
Sinhalite: 5260, 4925, 4760, (4630), 4520, 4355
Scapolite, pink: 6630, 6520
Spessartite: 4950, (4845), 4810, 4750, (4620), 4570, 4550, 4400, 4350, 4320, 4240, 4120, 4060, 3940
Sphalerite: 6900, 6650, (6510)
Sphene: 5900, (5860), (5820), 5800, 5750, 5340, 5300, 5280
Spinel, red: (6855), 6840, (6750), (6650), 6560, 6500, 6420, 6320, (5950-4900), 4550
Spinel, blue: (6350), (5850), (5550), 5080, (4780), (4580), 4430, 4330
Spinel, synthetic blue: 6340, 5800, 5440, 4850, 4490
Spinel, synthetic green: 6200, 5800, 5700, 5500, 5400
Taaffeite: 5580, 5530, 4780
Tanzanite: 7100, 6910, (5950), 5280, 4550
Topaz, pink: (6828)
Tremolite: (6840), 6500, 6280
Turquoise: 4600, 4320, 4220
Tourmaline, red: 5550, 5370, 5250-4610, (4560), (4510), 4280
Tourmaline, green: (4970), (4610), 4150
Variscite: 6880, 6500
Willemite: 5830, 5400, 4900, 4425, 4315, (4210)
Zircon, normal: 6910, 6890, 6625, 6605, (6535), 6210, 6150, 5895, 5620, 5375, 5160, 4840, 4600, 4320
Zircon, low: (6530), 5200
Monday, March 19, 2007
What Is An Antique
(via Wahroongai News, Volume 32, Number 5, May 1998)
The following definition of an antique was discovered in the first newsletter of 1998 from the Queensland Antique Collector’s Society Inc.
Definition of Antiques
One of the strengths of the Society is the very wide range of subjects that can be covered under the definition of antiques, e.g. porcelain, silver, furniture, art. What is clear is that definition (of what is an antique) has suffered changes.
Until quite recently, the accepted opinion in England was that antique applied to articles made before about 1830, i.e. not including Victorian items. In view of the factors of supply and demand, English dealers have accepted the international convention that antique means more than 100 years old. This includes basically all Victorian pieces, but excludes Edwardian and most Art Nouveau.
American dealers have taken the view that antique refers to pieces made more than 30 years ago, and so would include original material of the Beatles and Elvis Presley. While this concept may appear startling to traditional conventions, the definition can change depending on personal perspective.
In other cultures, goods may be described as a little bit old referring to wares that were in use by grandparents. There are collectors who seek items because their grandma had one of those. The differing age of collectors, from 20 to 70 plus means that the time-frame for defining the previous two generations becomes flexible.
Most antique dealers take pragmatic view that antique refers to articles no longer made, for which there is demand. If pushed, they may limit the scope of the definition to items made before the Second World War, thus including Art Deco.
The following definition of an antique was discovered in the first newsletter of 1998 from the Queensland Antique Collector’s Society Inc.
Definition of Antiques
One of the strengths of the Society is the very wide range of subjects that can be covered under the definition of antiques, e.g. porcelain, silver, furniture, art. What is clear is that definition (of what is an antique) has suffered changes.
Until quite recently, the accepted opinion in England was that antique applied to articles made before about 1830, i.e. not including Victorian items. In view of the factors of supply and demand, English dealers have accepted the international convention that antique means more than 100 years old. This includes basically all Victorian pieces, but excludes Edwardian and most Art Nouveau.
American dealers have taken the view that antique refers to pieces made more than 30 years ago, and so would include original material of the Beatles and Elvis Presley. While this concept may appear startling to traditional conventions, the definition can change depending on personal perspective.
In other cultures, goods may be described as a little bit old referring to wares that were in use by grandparents. There are collectors who seek items because their grandma had one of those. The differing age of collectors, from 20 to 70 plus means that the time-frame for defining the previous two generations becomes flexible.
Most antique dealers take pragmatic view that antique refers to articles no longer made, for which there is demand. If pushed, they may limit the scope of the definition to items made before the Second World War, thus including Art Deco.
Bewitching Jewelry
By Carl H Giles & Barbara Ann Williams
A.S.Barnes and Co, Inc
1976 ISBN 0-498-01654-4
A S Barnes and Co writes:
Bewitching Jewelry opens the occult showcase of amulets and talismans. It examines the glittering and mystic trappings of the supernatural. Lean what the well-dressed witches are wearing—and why! Rip away the ritual robe and peek at the pendants, bracelets, rings, and necklaces of witchcraft.
Amulets and talismans are among the most powerful of all psychic baubles. Mysticism is universal, and amulets are common to all people. Talismans act more as lures to make things happen; amulets are usually used as shields, to safeguard the wearer from misfortunes.
Psychics claim that an amulet possesses supernatural powers, while a talisman may be a piece of jewelry or any object that has been endowed with special powers through occult ceremonies. Almost any object may become a talisman. Choosing the right amulet and talismans for your black arts jewelry box may help you become happier, healthier, and wealthier.
This witch’s jewel case exhibits the ornamental wonders that may help you achieve goals and fulfill ambitions. Learn how to recognize the pieces of bewitching jewelry that many men and women are wearing. You will know what people are trying to accomplish just by observing their occult jewelry.
Is your closest friend trying to revitalize her mate by wearing that special medallion? Should you wear a certain item to stop gossip? Will the piece of jewelry and the right ritual words really get rid of a headache? Is it possible for some occult jewelry to increase your confidence? Amulets and talismans may do all these things.
Some occult stones and metals may be used for solving romantic problems. Regardless of what one wants to obtain or accomplish, there seems to be some jewelry appropriate to the situation. Would you wear a voodoo doll for love or hate? You can take one for whatever scheme you need after reading the chapter on how to choose talismans.
Should you wear a witch’s belt? You may make one with the directions outlines in this volume. Find out how you can fashion some special creations. Inventory your wishes and wants, and select psychic designs that will complement your wardrobe.
Bewitching Jewelry may improve your life by giving you a detailed look at all the occult ornaments needed for an occult jewelry box. The supernatural charms and jewelry will radiate a great, new betwitching you on the outside and may generate a beautiful new mental you on the inside. Start doing your betwitching best.
A.S.Barnes and Co, Inc
1976 ISBN 0-498-01654-4
A S Barnes and Co writes:
Bewitching Jewelry opens the occult showcase of amulets and talismans. It examines the glittering and mystic trappings of the supernatural. Lean what the well-dressed witches are wearing—and why! Rip away the ritual robe and peek at the pendants, bracelets, rings, and necklaces of witchcraft.
Amulets and talismans are among the most powerful of all psychic baubles. Mysticism is universal, and amulets are common to all people. Talismans act more as lures to make things happen; amulets are usually used as shields, to safeguard the wearer from misfortunes.
Psychics claim that an amulet possesses supernatural powers, while a talisman may be a piece of jewelry or any object that has been endowed with special powers through occult ceremonies. Almost any object may become a talisman. Choosing the right amulet and talismans for your black arts jewelry box may help you become happier, healthier, and wealthier.
This witch’s jewel case exhibits the ornamental wonders that may help you achieve goals and fulfill ambitions. Learn how to recognize the pieces of bewitching jewelry that many men and women are wearing. You will know what people are trying to accomplish just by observing their occult jewelry.
Is your closest friend trying to revitalize her mate by wearing that special medallion? Should you wear a certain item to stop gossip? Will the piece of jewelry and the right ritual words really get rid of a headache? Is it possible for some occult jewelry to increase your confidence? Amulets and talismans may do all these things.
Some occult stones and metals may be used for solving romantic problems. Regardless of what one wants to obtain or accomplish, there seems to be some jewelry appropriate to the situation. Would you wear a voodoo doll for love or hate? You can take one for whatever scheme you need after reading the chapter on how to choose talismans.
Should you wear a witch’s belt? You may make one with the directions outlines in this volume. Find out how you can fashion some special creations. Inventory your wishes and wants, and select psychic designs that will complement your wardrobe.
Bewitching Jewelry may improve your life by giving you a detailed look at all the occult ornaments needed for an occult jewelry box. The supernatural charms and jewelry will radiate a great, new betwitching you on the outside and may generate a beautiful new mental you on the inside. Start doing your betwitching best.
Sunday, March 18, 2007
If We Learn To Appreciate What Mines Produce, There Will Be Enough Rough
(via ICA Gazette, April 1990) E Julius Petsch writes:
“We have no rough stones available.”
“There is no more rough.”
“This is the last lot from this mine.”
How many times have I heard these arguments? And in almost every case the people using them were wrong.
There have always been rough gemstones available. I can look back on thirty years of experience in the rough colored gemstone business and during each buying trip those years I found that were more rough stones available than money to pay for them.
During these years I have also collected a great deal of experience in mining and it is very rare to hear about a mine that is actually depleted. What most often disturbs the steady flow of rough is the lack of long term planning and lack of capital to finance proper mining. In fact, even today, only a very few mines are being exploited with the expertise and knowledge of experienced mining engineers and geologists. Many mining enterprises are also handicapped by lengthy quarrels about mining rights or legal possession of the claims. Mines are invaded by prospectors who only dig holes in the ground instead of carrying out a proper mining plan. There are also unrealistic or exaggerated price demands from inexperienced mine owners or prospectors which discourage buyers from trying to create a market for a product.
It also must not be forgotten that in some gemstone producing countries the existence of very rigid laws concerning the export of rough constrains the market. In other producing countries, the uncertain political situation impedes the production of rough gemstones or the government interferes with free trade and mining, often imposing unsupportable conditions on those who would be willing to work in this industry.
Most of the mines and mining areas which are producing today are not recent discoveries. Many mines have been producing for decades without interruption, some even for a century. The number of genuinely new discoveries of gemstone deposits is very small.
If research and prospecting for gemstone deposits were carried out more systematically, we would find that there are still vast reserves available. Most of the mining areas I know are rich with gemstone deposits. The Carnaiba emerald mine in Brazil, for example, has been proven to extend for 12 kilometers. The tourmaline bearing pegmatite of the Cruzeiro area, also in Brazil, in the State of Minas Gerais, measures many square kilometers in area. This deposit has been exploited steadily for more than fifty years. I could give very many more examples of the richness of existing deposits, not only in Brazil, but also in Australia, Africa, and the United States.
No gemstone mine produces only the best and finest qualities. The majority of the production is always the lower qualities. But this does not mean that this material is not beautiful or useful to the jewelry industry: this is a matter of taste and fashion. Cabochons, beads and tumbled stones are very often cut from the lower qualities. Although they are not clean and show inclusions instead of being transparent, they are often of beautiful color and show interesting layers, veins, and patterns. These stones are not as valued primarily because they are found in large quantities. Very often, jewelry set with a cabochon cut stone can be as fashionable, attractive, and impressive as jewelry set with its faceted counterpart.
If we could adjust the demand from the designers and manufacturers of jewelry to fit the availability of the various qualities of rough gemstones, we would always have sufficient material at our disposal to cover the demand for cut gemstones. Demand determines the price for each quality.
If however, we insist on only selling clean gemstones with intense pure colors, the availability of suitable rough is artificially decreased. I am convinced that the concentration of demand in narrow range of material has been created unnecessarily. The consumer always appreciates the natural beauty of a gemstone, be it transparent or translucent, faceted or cabochon cut, bead or tumbled. It is the gemstone itself with its natural beauty that the buyer loves, even more when that beauty is complemented by a fine gold or silver setting.
I am sure that colored gemstone rough—and therefore cut colored gemstones—will always be available, provided we can finally accept the wide range of qualities naturally produced by the world’s gemstone mines.
“We have no rough stones available.”
“There is no more rough.”
“This is the last lot from this mine.”
How many times have I heard these arguments? And in almost every case the people using them were wrong.
There have always been rough gemstones available. I can look back on thirty years of experience in the rough colored gemstone business and during each buying trip those years I found that were more rough stones available than money to pay for them.
During these years I have also collected a great deal of experience in mining and it is very rare to hear about a mine that is actually depleted. What most often disturbs the steady flow of rough is the lack of long term planning and lack of capital to finance proper mining. In fact, even today, only a very few mines are being exploited with the expertise and knowledge of experienced mining engineers and geologists. Many mining enterprises are also handicapped by lengthy quarrels about mining rights or legal possession of the claims. Mines are invaded by prospectors who only dig holes in the ground instead of carrying out a proper mining plan. There are also unrealistic or exaggerated price demands from inexperienced mine owners or prospectors which discourage buyers from trying to create a market for a product.
It also must not be forgotten that in some gemstone producing countries the existence of very rigid laws concerning the export of rough constrains the market. In other producing countries, the uncertain political situation impedes the production of rough gemstones or the government interferes with free trade and mining, often imposing unsupportable conditions on those who would be willing to work in this industry.
Most of the mines and mining areas which are producing today are not recent discoveries. Many mines have been producing for decades without interruption, some even for a century. The number of genuinely new discoveries of gemstone deposits is very small.
If research and prospecting for gemstone deposits were carried out more systematically, we would find that there are still vast reserves available. Most of the mining areas I know are rich with gemstone deposits. The Carnaiba emerald mine in Brazil, for example, has been proven to extend for 12 kilometers. The tourmaline bearing pegmatite of the Cruzeiro area, also in Brazil, in the State of Minas Gerais, measures many square kilometers in area. This deposit has been exploited steadily for more than fifty years. I could give very many more examples of the richness of existing deposits, not only in Brazil, but also in Australia, Africa, and the United States.
No gemstone mine produces only the best and finest qualities. The majority of the production is always the lower qualities. But this does not mean that this material is not beautiful or useful to the jewelry industry: this is a matter of taste and fashion. Cabochons, beads and tumbled stones are very often cut from the lower qualities. Although they are not clean and show inclusions instead of being transparent, they are often of beautiful color and show interesting layers, veins, and patterns. These stones are not as valued primarily because they are found in large quantities. Very often, jewelry set with a cabochon cut stone can be as fashionable, attractive, and impressive as jewelry set with its faceted counterpart.
If we could adjust the demand from the designers and manufacturers of jewelry to fit the availability of the various qualities of rough gemstones, we would always have sufficient material at our disposal to cover the demand for cut gemstones. Demand determines the price for each quality.
If however, we insist on only selling clean gemstones with intense pure colors, the availability of suitable rough is artificially decreased. I am convinced that the concentration of demand in narrow range of material has been created unnecessarily. The consumer always appreciates the natural beauty of a gemstone, be it transparent or translucent, faceted or cabochon cut, bead or tumbled. It is the gemstone itself with its natural beauty that the buyer loves, even more when that beauty is complemented by a fine gold or silver setting.
I am sure that colored gemstone rough—and therefore cut colored gemstones—will always be available, provided we can finally accept the wide range of qualities naturally produced by the world’s gemstone mines.
Magnolia
Memorable quote (s) from the movie:
Jim Kurring (John C Reilly): Let me tell you something, this is not an easy job. I get a call on the radio, dispatch, it's bad news. And it stinks. But this is my job and I love it. Because I want to do well - in this life and in this world, I want to do well. And I want to help people. And I might get twenty bad calls a day. But one time I can help someone and make a save - correct a wrong or right a situation - then I'm a happy cop. And as we move through this life we should try and do good. Do good... And if we can do that, and not hurt anyone else, well... then...
Jim Kurring (John C Reilly): Let me tell you something, this is not an easy job. I get a call on the radio, dispatch, it's bad news. And it stinks. But this is my job and I love it. Because I want to do well - in this life and in this world, I want to do well. And I want to help people. And I might get twenty bad calls a day. But one time I can help someone and make a save - correct a wrong or right a situation - then I'm a happy cop. And as we move through this life we should try and do good. Do good... And if we can do that, and not hurt anyone else, well... then...
Five Different Types Of Synthetic Diamond
(via The Canadian Gemmologist, Volume XIV, Number 1, Spring, 1993) Kurt Nassau writes:
Essentially all the apprehension felt in the diamond trade about the threat of synthetic diamonds is unjustified. It is largely the result of confusion about five groups of synthetic diamond that have quite different growth characteristics. Even scientists themselves often make statements which may be true of one of the five groups of synthetic diamond, but seem to apply to all synthetic diamonds.
As one example, it is true that yellow synthetic diamond can be grown in large, good quality crystals at a relatively low cost by the high pressure technique. Yet this statement does not generally apply to colorless or blue synthetic diamond made by the same process.
As another example, it is true that polycrystalline diamond films can be grown by the low pressure techniques to be a millimeter or more in thickness. Yet it is important to realize that these films are usually neither colorless nor transparent by diamond grading standards when approaching a millimeter in thickness. In addition, millimeter thickness is not achievable at present for single crystal synthetic diamond films even when grown on an existing diamond.
And lastly, there are a whole series of synthetic ‘diamond-like films’ which are too frequently labeled ‘synthetic diamond’, a totally incorrect and misleading usage. These films are usually neither clear nor transparent when of significant thickness. Moreover, they are definitely not diamond, any more than graphite or charcoal could properly be designated ‘diamond’ even though all are forms of carbon.
Confusion also arises from three additional points, which may need clarification. When a crystal grower claims that his crystals have ‘excellent’ quality or are ‘flawless’, he does not mean that they are flawless by gemological standard; usually it means that he can see through the layers or perhaps even read print with the crystal set on the paper, which may not be difficult when the layer is only a fraction of a millimeter in thickness.
The second point involves the definition of ‘diamond’ which is strictly defined as the cubic form of carbon. There is also a hard hexagonal form of carbon, properly designated lonsdaleite ‘hexagonal diamond’ which is erroneous because it means ‘hexagonal cubic caron’. So in the diamond thin-film business ‘diamond’ may not always mean diamond, but may also mean lonsdaleite or amorphous carbon.
Finally, a statement such as ‘a growth rate of one inch per week has been achieved’ does not mean that one inch has been grown; it may mean only that one thousandth of one inch was grown in one-thousandth of a week, that is in ten minutes. But growth rates do not always scale up.
The best way to understand the present rather confusing situation is to consider briefly the high-and low-pressure techniques and the five groups of synthetic diamond products.
Synthetic High Pressure Diamond
The high pressure technique for growth of synthetic diamond was discovered by H Tracy Hall at General Electric in 1955, using temperatures about 2000°C (3623°F) and pressure over one million pounds per square inch. At first, only grit could be made; GE announced gem size crystals in 1970.
Group 1: Synthetic High Pressure Yellow Diamond
Yellow synthetic diamond, colored by traces of nitrogen absorbed from the air during the growth, is readily grown by using a variety of metal solvents; crystals over 12mm across and over 14 carats in weight have been reported. By growing several layers with several small crystals per layer at one time, synthetic diamond slices used as heat sinks for transistors and integrated circuits can be produced economically. Several companies have the capability of doing this, including De Beers, GE and Sumitomo. The gemological properties of such synthetic high pressure yellow diamond have been described for example by Shigley et.al (1987). Identification should present no serious problems.
Group II: Synthetic High Pressure Colorless and Blue Diamond
For the colorless product, nitrogen must be excluded, and boron is additionally used to obtain a blue color. In both instances, special conditions must be used, such as aluminum in the solvent to remove nitrogen. This makes it more difficult to grow many crystals at one time. The characteristics of the products have been discussed by Koivula and Fryer (1984), and Shigley et.al (19860, and identification would probably present no serious problems if and when routine production, and therefore, a standardized product should happen.
Colorless and blue synthetic diamonds suitable for faceting have, indeed, been grown only on an experimental basis so far, and one can estimate that cost of production is not very different from that of natural diamond. To put this statement into perspective, synthetic colored gemstones, such as flux grown emerald, ruby, and so on, appear to be viable at a cost of less than one-tenth that of the equivalent quality natural material, but experience has shown that the market is very restricted except at even lower prices.
Thin Film Carbon Deposition
Various low pressure techniques using carbon-containing gases such as methane or acetylene and temperatures of 1200°C (2192°F) or below are used to grow a variety of types of diamond and other carbon-containing films under non-equilibrium conditions. Even acetylene torches have been used. For reviews of thin film work, see DeVries (1987), Angus and Hayman (1988), and Bachman and Messier (1989).
Group III: Synthetic Polycrystalline Diamond Films
When conditions are carefully controlled, polycrystalline diamond film s can be grown quite rapidly to become a millimeter or more in thickness. When very thin, these would not be readily detected, even by a thermal probe, and would probably not serve any useful purpose in gemology. Weight gain would be negligible and the surface hardness would not be changed significantly.
This last statement may be surprising, but a scratch test applied to a very thin diamond film covering a soft material would merely result in distortion of the substrate, and tearing and detaching of the film. If the film is thick, so that it could give a diamond reaction on a thermal probe ad provide a hard surface for a soft material, it would be visible during a gemological investigation. Moreover, adhesion of such polycrystalline diamond film is extremely poor to substances other than silicon, silcon carbide (moissanite), or diamond itself.
Group IV: Synthetic Single Crystal Diamond Films
This type of film appears to be great concern to some, because it seems to provide the threat of increasing the size of a natural diamond. Single crystal diamond films can indeed be grown on diamond surface by suitable adjustments of the low pressure techniques. Yet, a curious phenomenon occurs: the film only seems to reach a certain thickness, depending on the techniques used. If one tries to force it to continue to grow, then it either stops, turn polycrystalline (when the remarks under Group III apply), or something else happens.
Such films often contain stacking faults and may then be not diamond but lonsdaleite. It is of course possible that someone may discover someday how to keep the films growing, but work on this topic has been underway for over 30 years; a solution just does not seem easy to find. Adhesion is a problem on materials other than those listed above.
One interesting possibility is that a very thin synthetic crystal blue diamond film coating could enhance the appearance of yellow cape-series diamonds. This has been done experimentally (see Fritisch, 1991). Such a film should be as easily detected as a thin blue lacquer layer, by standard gemological testing: the concentration of color in the surface layer can be seen by immersion even in water. The acceptability of such an overgrowth would depend on the nomenclature; it might well be decided that this must be called a ‘natural-synthetic composite diamond.’
Group V: Diamond-like Films
A wide variety of different films which are not diamond but are often so labelled can be deposited quite rapidly and to millimeter thickness by various modifications of the low pressure technique. Some of these are non-crystalline amorphous or glassy films. Some contain significant amounts of hydrogen, up to one hydrogen per carbon, and should then be called hydrocarbon films. Some are partly crystalline but, instead of containing only sp-3 bonding as does diamond, also contain some sp-2 bondings as does graphite. Some have stacking sequences leading to hexagonal lonsdaleite. The materials considered in this group do not have the cube symmetry of diamond.
Additional names that have been used include amorphous carbon, amorphous hydrocarbon, dense (hydro) carbon, hard or superhard carbon, and non-diamond carbon films. All of these names may be appropriate for some such films, but the name ‘diamond’ is definitely incorrect. The hardness may vary from less than 8 to over 9, the color may be black, grey, or near colorless (particularly if very thin), and adhesion is a problem on most materials. It is difficult to visualize any application of such films in the gem field.
The Lessons From Other Synthetics
It is worth examining briefly what happens when usable synthetic gemstones first arrived in the trade. The result was the same each time, whether the product was synthetic ruby in 1905, synthetic sapphire in 1910, synthetic star corundum in 1947, synthetic emerald in 1950, synthetic alexandrite in 1972, and so on. At first there was considerable apprehension, both with respect to the effect on the trade, and also with respect to the ability to distinguish the new synthetic from natural. Each time, this stage was followed by the realization that synthetic could be distinguished from the natural with little trouble, and that synthetic filled a different niche from the natural.
In each instance there was essentially no long term effect on the market for the natural material. It is perhaps worth repeating that synthetics have only been successful in their own niches at a price less than one tenth that of the natural material. Overgrowth of a synthetic over the surface of a natural gemstone has been possible since about 1960, when Lechleitner grew a thin layer of very dark green synthetic emerald over pale natural beryl performs. This has not been a successful product in the market place to date.
In conclusion, there is no significant impact to be expected from synthetic diamond, whether produced in bulk form by the high pressure technique or in the thin film form by the low pressure technique. As always, a steady improvement of growth technology must certainly be anticipated. Significant future breakthroughs are always a possibility and would then change the present status. But they should be of concern only when they happen.
For example, there is little likelihood of D flawless synthetic diamond in carat and larger sizes and at a production cost to make it viable as a synthetic as discussed above for many years to come. After all, someone might just discover next week a new diamond mine containing huge quantities of large flawless stones; while such a discovery is not impossible, it is merely highly improbable.
Essentially all the apprehension felt in the diamond trade about the threat of synthetic diamonds is unjustified. It is largely the result of confusion about five groups of synthetic diamond that have quite different growth characteristics. Even scientists themselves often make statements which may be true of one of the five groups of synthetic diamond, but seem to apply to all synthetic diamonds.
As one example, it is true that yellow synthetic diamond can be grown in large, good quality crystals at a relatively low cost by the high pressure technique. Yet this statement does not generally apply to colorless or blue synthetic diamond made by the same process.
As another example, it is true that polycrystalline diamond films can be grown by the low pressure techniques to be a millimeter or more in thickness. Yet it is important to realize that these films are usually neither colorless nor transparent by diamond grading standards when approaching a millimeter in thickness. In addition, millimeter thickness is not achievable at present for single crystal synthetic diamond films even when grown on an existing diamond.
And lastly, there are a whole series of synthetic ‘diamond-like films’ which are too frequently labeled ‘synthetic diamond’, a totally incorrect and misleading usage. These films are usually neither clear nor transparent when of significant thickness. Moreover, they are definitely not diamond, any more than graphite or charcoal could properly be designated ‘diamond’ even though all are forms of carbon.
Confusion also arises from three additional points, which may need clarification. When a crystal grower claims that his crystals have ‘excellent’ quality or are ‘flawless’, he does not mean that they are flawless by gemological standard; usually it means that he can see through the layers or perhaps even read print with the crystal set on the paper, which may not be difficult when the layer is only a fraction of a millimeter in thickness.
The second point involves the definition of ‘diamond’ which is strictly defined as the cubic form of carbon. There is also a hard hexagonal form of carbon, properly designated lonsdaleite ‘hexagonal diamond’ which is erroneous because it means ‘hexagonal cubic caron’. So in the diamond thin-film business ‘diamond’ may not always mean diamond, but may also mean lonsdaleite or amorphous carbon.
Finally, a statement such as ‘a growth rate of one inch per week has been achieved’ does not mean that one inch has been grown; it may mean only that one thousandth of one inch was grown in one-thousandth of a week, that is in ten minutes. But growth rates do not always scale up.
The best way to understand the present rather confusing situation is to consider briefly the high-and low-pressure techniques and the five groups of synthetic diamond products.
Synthetic High Pressure Diamond
The high pressure technique for growth of synthetic diamond was discovered by H Tracy Hall at General Electric in 1955, using temperatures about 2000°C (3623°F) and pressure over one million pounds per square inch. At first, only grit could be made; GE announced gem size crystals in 1970.
Group 1: Synthetic High Pressure Yellow Diamond
Yellow synthetic diamond, colored by traces of nitrogen absorbed from the air during the growth, is readily grown by using a variety of metal solvents; crystals over 12mm across and over 14 carats in weight have been reported. By growing several layers with several small crystals per layer at one time, synthetic diamond slices used as heat sinks for transistors and integrated circuits can be produced economically. Several companies have the capability of doing this, including De Beers, GE and Sumitomo. The gemological properties of such synthetic high pressure yellow diamond have been described for example by Shigley et.al (1987). Identification should present no serious problems.
Group II: Synthetic High Pressure Colorless and Blue Diamond
For the colorless product, nitrogen must be excluded, and boron is additionally used to obtain a blue color. In both instances, special conditions must be used, such as aluminum in the solvent to remove nitrogen. This makes it more difficult to grow many crystals at one time. The characteristics of the products have been discussed by Koivula and Fryer (1984), and Shigley et.al (19860, and identification would probably present no serious problems if and when routine production, and therefore, a standardized product should happen.
Colorless and blue synthetic diamonds suitable for faceting have, indeed, been grown only on an experimental basis so far, and one can estimate that cost of production is not very different from that of natural diamond. To put this statement into perspective, synthetic colored gemstones, such as flux grown emerald, ruby, and so on, appear to be viable at a cost of less than one-tenth that of the equivalent quality natural material, but experience has shown that the market is very restricted except at even lower prices.
Thin Film Carbon Deposition
Various low pressure techniques using carbon-containing gases such as methane or acetylene and temperatures of 1200°C (2192°F) or below are used to grow a variety of types of diamond and other carbon-containing films under non-equilibrium conditions. Even acetylene torches have been used. For reviews of thin film work, see DeVries (1987), Angus and Hayman (1988), and Bachman and Messier (1989).
Group III: Synthetic Polycrystalline Diamond Films
When conditions are carefully controlled, polycrystalline diamond film s can be grown quite rapidly to become a millimeter or more in thickness. When very thin, these would not be readily detected, even by a thermal probe, and would probably not serve any useful purpose in gemology. Weight gain would be negligible and the surface hardness would not be changed significantly.
This last statement may be surprising, but a scratch test applied to a very thin diamond film covering a soft material would merely result in distortion of the substrate, and tearing and detaching of the film. If the film is thick, so that it could give a diamond reaction on a thermal probe ad provide a hard surface for a soft material, it would be visible during a gemological investigation. Moreover, adhesion of such polycrystalline diamond film is extremely poor to substances other than silicon, silcon carbide (moissanite), or diamond itself.
Group IV: Synthetic Single Crystal Diamond Films
This type of film appears to be great concern to some, because it seems to provide the threat of increasing the size of a natural diamond. Single crystal diamond films can indeed be grown on diamond surface by suitable adjustments of the low pressure techniques. Yet, a curious phenomenon occurs: the film only seems to reach a certain thickness, depending on the techniques used. If one tries to force it to continue to grow, then it either stops, turn polycrystalline (when the remarks under Group III apply), or something else happens.
Such films often contain stacking faults and may then be not diamond but lonsdaleite. It is of course possible that someone may discover someday how to keep the films growing, but work on this topic has been underway for over 30 years; a solution just does not seem easy to find. Adhesion is a problem on materials other than those listed above.
One interesting possibility is that a very thin synthetic crystal blue diamond film coating could enhance the appearance of yellow cape-series diamonds. This has been done experimentally (see Fritisch, 1991). Such a film should be as easily detected as a thin blue lacquer layer, by standard gemological testing: the concentration of color in the surface layer can be seen by immersion even in water. The acceptability of such an overgrowth would depend on the nomenclature; it might well be decided that this must be called a ‘natural-synthetic composite diamond.’
Group V: Diamond-like Films
A wide variety of different films which are not diamond but are often so labelled can be deposited quite rapidly and to millimeter thickness by various modifications of the low pressure technique. Some of these are non-crystalline amorphous or glassy films. Some contain significant amounts of hydrogen, up to one hydrogen per carbon, and should then be called hydrocarbon films. Some are partly crystalline but, instead of containing only sp-3 bonding as does diamond, also contain some sp-2 bondings as does graphite. Some have stacking sequences leading to hexagonal lonsdaleite. The materials considered in this group do not have the cube symmetry of diamond.
Additional names that have been used include amorphous carbon, amorphous hydrocarbon, dense (hydro) carbon, hard or superhard carbon, and non-diamond carbon films. All of these names may be appropriate for some such films, but the name ‘diamond’ is definitely incorrect. The hardness may vary from less than 8 to over 9, the color may be black, grey, or near colorless (particularly if very thin), and adhesion is a problem on most materials. It is difficult to visualize any application of such films in the gem field.
The Lessons From Other Synthetics
It is worth examining briefly what happens when usable synthetic gemstones first arrived in the trade. The result was the same each time, whether the product was synthetic ruby in 1905, synthetic sapphire in 1910, synthetic star corundum in 1947, synthetic emerald in 1950, synthetic alexandrite in 1972, and so on. At first there was considerable apprehension, both with respect to the effect on the trade, and also with respect to the ability to distinguish the new synthetic from natural. Each time, this stage was followed by the realization that synthetic could be distinguished from the natural with little trouble, and that synthetic filled a different niche from the natural.
In each instance there was essentially no long term effect on the market for the natural material. It is perhaps worth repeating that synthetics have only been successful in their own niches at a price less than one tenth that of the natural material. Overgrowth of a synthetic over the surface of a natural gemstone has been possible since about 1960, when Lechleitner grew a thin layer of very dark green synthetic emerald over pale natural beryl performs. This has not been a successful product in the market place to date.
In conclusion, there is no significant impact to be expected from synthetic diamond, whether produced in bulk form by the high pressure technique or in the thin film form by the low pressure technique. As always, a steady improvement of growth technology must certainly be anticipated. Significant future breakthroughs are always a possibility and would then change the present status. But they should be of concern only when they happen.
For example, there is little likelihood of D flawless synthetic diamond in carat and larger sizes and at a production cost to make it viable as a synthetic as discussed above for many years to come. After all, someone might just discover next week a new diamond mine containing huge quantities of large flawless stones; while such a discovery is not impossible, it is merely highly improbable.
Jewelry
History & Technique from the Egyptians to the Present
By Guido Gregorietti
Chartwell Books, Inc
1979 ISBN 089009-231-1
Chartwell Books writes:
A jewel has many meanings. It is a work of art, an ornament denoting rank, a statement of dress, a treasure, a sign of power, an investment, an ethnic clue, an ostentation.
One of the most famous and dependable Parisian jewelers, whose base is in Place Vendome, makes it a professional rule never to reveal the identity of his customers. One exception was made, however, when the firm was put in charge of preparing the ceremonial crown for the Empress of Iran. It would have been difficult to keep it anonymous: 1469 diamonds, 36 rubies, as many emeralds and 105 pearls were mounted on the crown in Teheran, after a year’s work.
Why jewels are never enough to satisfy is a problem for anthropologists and psychologists to explain. A bouquet of 6000 diamonds was shown at the Great Exhibition of 1851 in London; perhaps satisfying enough? Between 1884 and 1917 the Tsar of Russia presented members of his family with fifty Easter eggs with surprises in them, created by the famous Faberge in enamel and precious stones.
If we pause to think of the quantity of jewels worked into gold dug up at Troy, in Mesopotamia, in Egypt and Peru, we see the ancients could compete favorably with modern craftsmen. Also—and a curious thing to have to admit with today’s technology—the ancients had techniques which no one since has known how to repeat.
The history of jewelry, too, has a certain amount of unknown meaning. It even sometimes has a superstitious aura of occult magic.
Guido Gregorietti’s narrative of the fabulous history of jewelry places it in context in the history of art, while interweaving many aspects of the evolution of culture.
About the author
Guido Gregorietti is the author of the Jewelry entry in the Encyclopedia Britannica, and was called upon to take part in judging the 1977 Diamond Award in New York.
By Guido Gregorietti
Chartwell Books, Inc
1979 ISBN 089009-231-1
Chartwell Books writes:
A jewel has many meanings. It is a work of art, an ornament denoting rank, a statement of dress, a treasure, a sign of power, an investment, an ethnic clue, an ostentation.
One of the most famous and dependable Parisian jewelers, whose base is in Place Vendome, makes it a professional rule never to reveal the identity of his customers. One exception was made, however, when the firm was put in charge of preparing the ceremonial crown for the Empress of Iran. It would have been difficult to keep it anonymous: 1469 diamonds, 36 rubies, as many emeralds and 105 pearls were mounted on the crown in Teheran, after a year’s work.
Why jewels are never enough to satisfy is a problem for anthropologists and psychologists to explain. A bouquet of 6000 diamonds was shown at the Great Exhibition of 1851 in London; perhaps satisfying enough? Between 1884 and 1917 the Tsar of Russia presented members of his family with fifty Easter eggs with surprises in them, created by the famous Faberge in enamel and precious stones.
If we pause to think of the quantity of jewels worked into gold dug up at Troy, in Mesopotamia, in Egypt and Peru, we see the ancients could compete favorably with modern craftsmen. Also—and a curious thing to have to admit with today’s technology—the ancients had techniques which no one since has known how to repeat.
The history of jewelry, too, has a certain amount of unknown meaning. It even sometimes has a superstitious aura of occult magic.
Guido Gregorietti’s narrative of the fabulous history of jewelry places it in context in the history of art, while interweaving many aspects of the evolution of culture.
About the author
Guido Gregorietti is the author of the Jewelry entry in the Encyclopedia Britannica, and was called upon to take part in judging the 1977 Diamond Award in New York.
Saturday, March 17, 2007
(How to) Heating Zircon
(via Wahroongai News, Volume 33, Number 7, July 1999) Mark Liccini writes:
Here is how to heat zircon. You place them flawless……must be real clean or they will crack, and even then some may crack….in a (fire-clay) crucible with activated charcoal. This can be bought from any chemical supply company for about US$30 for a small container. Activated charcoal is the best to use, but there is another way to avoid using of reductive gas. Importantly, activated charcoal will work without creating any smoke. The other way is to put sugar in the crucible, but it starts to put out a lot of smoke when you get up to temperatures of 600°C or more. Although the smoking of sugar stops around 800°C, lots and lots of smoke will be generated. Boy! I mean a lot of smoke!
Then, you then must fill the crucible with zircon and seal the crucible. A good way is window screen and just a layer of plaster (plaster-of-Paris) over the top of the screen. Let it dry; then fill in any cracks after the plaster has dried. You then take the temperature of the crucible up slowly. The slower you go, less breakage will occur….all the way to 1000°C. Hold the temperature there for 2 hours or so. The controlled rise in temperature, depending on your furnace could take all day or longer. Following heating it can take 5-6 hours to cool the crucible down to cold (room temperature). Don’t open the door while the crucible and its contents are hot, or all will crack.
Now here are some tricks of the trade.
You will observe precisely in the bottom of a sealed crucible the best blues will be found. Near the top the heat treated zircons may be white. If you rotate the zircon rough imposition and repeat the heating and cooling cycle again, the white zircons will turn blue. If you overheat the zircons (and bleach them), you can do them again and they will come back blue. Even light blues done again will change to dark blues.
Now there is a trick to produce orange and red colors. You might obtain some oranges and red on the top of a sealed crucible. Indeed, when you first open a sealed crucible you will go crazy. The whole top will be covered with red and oranges. However, beware, for after a few minutes in the air all oranges and reds will revert to white and/or light blue—except a stone or two. These are stable reds and oranges. Now to ensure a high percentage of reds and oranges do the same heat treatment without sugar (or activated charcoal) and in an open crucible.
Note: With both heat treatment methods, you will get better results with a full crucible of zircon rough. Although I have never heat treated Cambodian zircons, I have run tonnage of Nigerian and some from Tanzania and Australia.
Here is how to heat zircon. You place them flawless……must be real clean or they will crack, and even then some may crack….in a (fire-clay) crucible with activated charcoal. This can be bought from any chemical supply company for about US$30 for a small container. Activated charcoal is the best to use, but there is another way to avoid using of reductive gas. Importantly, activated charcoal will work without creating any smoke. The other way is to put sugar in the crucible, but it starts to put out a lot of smoke when you get up to temperatures of 600°C or more. Although the smoking of sugar stops around 800°C, lots and lots of smoke will be generated. Boy! I mean a lot of smoke!
Then, you then must fill the crucible with zircon and seal the crucible. A good way is window screen and just a layer of plaster (plaster-of-Paris) over the top of the screen. Let it dry; then fill in any cracks after the plaster has dried. You then take the temperature of the crucible up slowly. The slower you go, less breakage will occur….all the way to 1000°C. Hold the temperature there for 2 hours or so. The controlled rise in temperature, depending on your furnace could take all day or longer. Following heating it can take 5-6 hours to cool the crucible down to cold (room temperature). Don’t open the door while the crucible and its contents are hot, or all will crack.
Now here are some tricks of the trade.
You will observe precisely in the bottom of a sealed crucible the best blues will be found. Near the top the heat treated zircons may be white. If you rotate the zircon rough imposition and repeat the heating and cooling cycle again, the white zircons will turn blue. If you overheat the zircons (and bleach them), you can do them again and they will come back blue. Even light blues done again will change to dark blues.
Now there is a trick to produce orange and red colors. You might obtain some oranges and red on the top of a sealed crucible. Indeed, when you first open a sealed crucible you will go crazy. The whole top will be covered with red and oranges. However, beware, for after a few minutes in the air all oranges and reds will revert to white and/or light blue—except a stone or two. These are stable reds and oranges. Now to ensure a high percentage of reds and oranges do the same heat treatment without sugar (or activated charcoal) and in an open crucible.
Note: With both heat treatment methods, you will get better results with a full crucible of zircon rough. Although I have never heat treated Cambodian zircons, I have run tonnage of Nigerian and some from Tanzania and Australia.
Gigi
Memorable quote (s) from the movie:
Gigi (Leslie Caron): I don't know what you want. You told Grandmama...
Gaston (Louis Jourdan): I know what I told your grandmother. We don't have to repeat it. Just tell me simply what you don't want... and tell me what you do want.
Gigi (Leslie Caron): Do you mean that?
Gaston (Louis Jourdan): Of course.
Gigi (Leslie Caron): You told Grandmama that you wanted to take care of me.
Gaston (Louis Jourdan): To take care of you beautifully.
Gigi (Leslie Caron): Beautifully. That is, if I like it. They've pounded into my head I'm backward for my age... but I know what all this means. To take care of me beautifully means I shall go away with you... and that I shall sleep in your bed.
Gaston (Louis Jourdan): Please, Gigi. I beg of you, you embarrass me.
Gigi (Leslie Caron): You weren't embarrassed to talk to Grandmama about it. And Grandmama wasn't embarrassed to talk to me about it. But I know more than she told me. To take care of me means that I shall have my photograph in the papers. That I shall go to the Riviera. To the races at Deauville. And when we fight, it will be in all the columns the next day. And then you'd give me up, as you did with InÈs des CÈvennes.
Gaston (Louis Jourdan): Who's been filling your head with all these old stories? How do you know about that?
Gigi (Leslie Caron): Why shouldn't I know? You're world famous. I know about the woman who stole from you; the Contessa who wanted to shoot you; the American who wanted to marry you. I know what everybody knows.
Gaston (Louis Jourdan): These aren't the things we have to talk about together. That's all in the past, over and done with.
Gigi (Leslie Caron): Yes, Gaston. Until it begins again.
Gigi (Leslie Caron): I don't know what you want. You told Grandmama...
Gaston (Louis Jourdan): I know what I told your grandmother. We don't have to repeat it. Just tell me simply what you don't want... and tell me what you do want.
Gigi (Leslie Caron): Do you mean that?
Gaston (Louis Jourdan): Of course.
Gigi (Leslie Caron): You told Grandmama that you wanted to take care of me.
Gaston (Louis Jourdan): To take care of you beautifully.
Gigi (Leslie Caron): Beautifully. That is, if I like it. They've pounded into my head I'm backward for my age... but I know what all this means. To take care of me beautifully means I shall go away with you... and that I shall sleep in your bed.
Gaston (Louis Jourdan): Please, Gigi. I beg of you, you embarrass me.
Gigi (Leslie Caron): You weren't embarrassed to talk to Grandmama about it. And Grandmama wasn't embarrassed to talk to me about it. But I know more than she told me. To take care of me means that I shall have my photograph in the papers. That I shall go to the Riviera. To the races at Deauville. And when we fight, it will be in all the columns the next day. And then you'd give me up, as you did with InÈs des CÈvennes.
Gaston (Louis Jourdan): Who's been filling your head with all these old stories? How do you know about that?
Gigi (Leslie Caron): Why shouldn't I know? You're world famous. I know about the woman who stole from you; the Contessa who wanted to shoot you; the American who wanted to marry you. I know what everybody knows.
Gaston (Louis Jourdan): These aren't the things we have to talk about together. That's all in the past, over and done with.
Gigi (Leslie Caron): Yes, Gaston. Until it begins again.
A Timely Warning: Pakistani Fakes
(Via Wahroongai News, Volume 33, Number 6, June 1999)
The letter reproduced below was first published in the January – February 1999 issue of The Mineralogical Record.
“I have recently returned from Northern Areas, Pakistan, where I encountered several sophisticated fake specimens. In fact, I am now the proud owner of several, having not recognized them at the time of the purchase. All of the fakes were apparently made of material from Chumar Bakhoor Nagar (the source of the specimens of aquamarine crystals on muscovite crystals). One such specimen consisting of a fairly nice green fluorite octahedron with aquamarine was obtained in the bazaar of Karimabad, Hunza. The fluorite and aquamarine is surrounded by a band of iron stained fine-grained material. This became obvious when the specimen was cleaned. Another consisted of a tabular beryl with an aquamarine crystal which, on examination, could have not grown where it was sited. This specimen fell apart, allowing me to salvage the nice tabular beryl. Another was a specimen of a pink apatite crystal in a matrix of quartz and muscovite. These last two were obtained from the site on the Karakoram Highway known as Rakaposhi Main Point. Get only photos of Rakaposhi here—the summit is 19000 feet above and seven miles horizontally from you. At last fake is really good, consisting of a fine aquamarine crystals on muscovite obtained from the hotel shop at the Riveria Hotel, Gilgit. It should be noted that some of the dealers volunteered the information that certain specimens were fake. It is likely that the dealers from whom I got some of the fakes were also conned by their sources. So all material allegedly from Chumar Bhakoor Nagar should be examined with care.”
This letter clearly reveals that even the experts get conned by the locals of the Hunza Valley. So beware.
The letter reproduced below was first published in the January – February 1999 issue of The Mineralogical Record.
“I have recently returned from Northern Areas, Pakistan, where I encountered several sophisticated fake specimens. In fact, I am now the proud owner of several, having not recognized them at the time of the purchase. All of the fakes were apparently made of material from Chumar Bakhoor Nagar (the source of the specimens of aquamarine crystals on muscovite crystals). One such specimen consisting of a fairly nice green fluorite octahedron with aquamarine was obtained in the bazaar of Karimabad, Hunza. The fluorite and aquamarine is surrounded by a band of iron stained fine-grained material. This became obvious when the specimen was cleaned. Another consisted of a tabular beryl with an aquamarine crystal which, on examination, could have not grown where it was sited. This specimen fell apart, allowing me to salvage the nice tabular beryl. Another was a specimen of a pink apatite crystal in a matrix of quartz and muscovite. These last two were obtained from the site on the Karakoram Highway known as Rakaposhi Main Point. Get only photos of Rakaposhi here—the summit is 19000 feet above and seven miles horizontally from you. At last fake is really good, consisting of a fine aquamarine crystals on muscovite obtained from the hotel shop at the Riveria Hotel, Gilgit. It should be noted that some of the dealers volunteered the information that certain specimens were fake. It is likely that the dealers from whom I got some of the fakes were also conned by their sources. So all material allegedly from Chumar Bhakoor Nagar should be examined with care.”
This letter clearly reveals that even the experts get conned by the locals of the Hunza Valley. So beware.
A Rare Biological Gem Material: Aromatic Resin (Myrrh) Necklace
(via Wahroongai News, Volume 30, May 1996) Grahame Brown writes:
Myrrh, one of the three gifts to the baby Jesus by the three wise men of the Bible, is an aromatic resin produced by the desert tree Commiphora myrrha. In Western Africa the hardened resin from this tree has been hand shaped into beads to be worn for decorative or other purposes.
As determined by Robert Kammerling, and described in the Fall 95 issue of Gems & Gemology (p.210), this very rare biological gem material has the following properties.
Hardness: scratched with fingernail (<2½)
Fracture: granular
Color: yellowish brown to brown
Diaphenity: translucent
Specific gravity: 1.27
Spot refractive index: 1.40
Fluorescence: LW UV (moderate, even, chalky yellow); SW UV (weak, even, chalky yellow)
Absorption spectrum (visible): cut off at 430nm
Absorption spectrum (infrared): broad peaks at 5180, 4778, 4000 cm ¯¹, sharp peaks at 4339 and 4252 cm ¯¹
Thermal stability: readily melts
Characteristic odor: sweet and spicy odor following abrasion and / or rubbing.
Myrrh, one of the three gifts to the baby Jesus by the three wise men of the Bible, is an aromatic resin produced by the desert tree Commiphora myrrha. In Western Africa the hardened resin from this tree has been hand shaped into beads to be worn for decorative or other purposes.
As determined by Robert Kammerling, and described in the Fall 95 issue of Gems & Gemology (p.210), this very rare biological gem material has the following properties.
Hardness: scratched with fingernail (<2½)
Fracture: granular
Color: yellowish brown to brown
Diaphenity: translucent
Specific gravity: 1.27
Spot refractive index: 1.40
Fluorescence: LW UV (moderate, even, chalky yellow); SW UV (weak, even, chalky yellow)
Absorption spectrum (visible): cut off at 430nm
Absorption spectrum (infrared): broad peaks at 5180, 4778, 4000 cm ¯¹, sharp peaks at 4339 and 4252 cm ¯¹
Thermal stability: readily melts
Characteristic odor: sweet and spicy odor following abrasion and / or rubbing.
Rocks, Minerals & Gemstones
By I.O.Evans
The Hamlyn Publishing Group Ltd
1972 ISBN 0-600-37537-4
The Hamlyn Publishing Group writes:
Everybody, at one time or another, has stopped in their tracks, bent down and picked up a beautifully colored or curiously shaped fragment of stone and marveled at the artistry of nature. Prehistoric man was no exception and it was not long before he realized too, the many uses to which he could put the rocks, their minerals and the gemstones. Since then man has become more and more dependent on the minerals he extracts from the Earth’s crust and today these and their derivatives make up a bewildering variety of familiar everyday objects—from out nuts and bolts and diamond rings to our computers and supersonic jet aircraft. In fact civilization as we known it is completely reliant on rocks and minerals and so their importance in our lives, and the effect that the depletion of mineral resources could have on our future, is considerable.
This book presents a broad illustrated survey of the rocks, their constituent minerals and the gemstones. The nature of the rocks, their composition and the way in which they affect the build of the countryside is discussed first (including a consideration of rocks from outer space), and then the extraction techniques of the more important mineral ores are explained, together with a summary of mineral characteristics and the various crystal systems in which minerals form. A selection of the most important and most interesting minerals then follows and details are given for each of its properties, mode of occurrence, characteristics and uses. Gemstones are discussed at length and interesting aspects range from fascinating details of diamond extraction and cutting to descriptions of gemstones of organic origin. A final very useful section deals with the practical possibilities for the rock and mineral enthusiast and includes much advice on how to collect, identify and enjoy mineral specimens.
A very readable, non-technical text is supplemented by a fine collection of over one hundred excellent photographs, thirty of which are in full color.
The Hamlyn Publishing Group Ltd
1972 ISBN 0-600-37537-4
The Hamlyn Publishing Group writes:
Everybody, at one time or another, has stopped in their tracks, bent down and picked up a beautifully colored or curiously shaped fragment of stone and marveled at the artistry of nature. Prehistoric man was no exception and it was not long before he realized too, the many uses to which he could put the rocks, their minerals and the gemstones. Since then man has become more and more dependent on the minerals he extracts from the Earth’s crust and today these and their derivatives make up a bewildering variety of familiar everyday objects—from out nuts and bolts and diamond rings to our computers and supersonic jet aircraft. In fact civilization as we known it is completely reliant on rocks and minerals and so their importance in our lives, and the effect that the depletion of mineral resources could have on our future, is considerable.
This book presents a broad illustrated survey of the rocks, their constituent minerals and the gemstones. The nature of the rocks, their composition and the way in which they affect the build of the countryside is discussed first (including a consideration of rocks from outer space), and then the extraction techniques of the more important mineral ores are explained, together with a summary of mineral characteristics and the various crystal systems in which minerals form. A selection of the most important and most interesting minerals then follows and details are given for each of its properties, mode of occurrence, characteristics and uses. Gemstones are discussed at length and interesting aspects range from fascinating details of diamond extraction and cutting to descriptions of gemstones of organic origin. A final very useful section deals with the practical possibilities for the rock and mineral enthusiast and includes much advice on how to collect, identify and enjoy mineral specimens.
A very readable, non-technical text is supplemented by a fine collection of over one hundred excellent photographs, thirty of which are in full color.
Friday, March 16, 2007
An Alternative African Source Of Vegetable Ivory
(Wahroongai News, Volume 30, No.7, July 1996) Grahame Brown writes:
Vegetable ivory, a long used effective imitation for elephant ivory, is derived from the dried nuts of several species of palm tree. The common commercial source of vegetable ivory is the Corozo or Tagua palm (Phytelephas macrocarpa) from Central America and northern South America. This ivory colored vegetable material (nut) has a hardness of 2½, a specific gravity of 1.40 – 1.43, a spot refractive index of 1.54, and in hand specimen displays the polygonal outlines of its component plant cells.
Another source of African vegetable ivory was suggested by Webster to be the Doum or Gingerbread palm (Hyphaene thebaica) of north and central Africa. According to the 5th edition of Webster’s Gems, the rounded nuts of this palm have a reddish brown skin, and edible underlying spongy layer which is commonly converted into an alcoholic beverage, and a hard inner seed (the source of vegetable ivory).
A recent purchased guide, The Shell Field Guide to the Common Trees of the Okavango Delta and the Moremi Game Reserve, by Veronica Roodt, has provided some additional details about the African source of vegetable ivory.
According to Dr Roodt, the source of vegetable ivory in the Okavango Delta—a wildlife and vegetation-rich area of 18000 km² that is the terminus of the Cubango River in Botswana—is the Real Fan Palm (Hyphanae petersania). This majestic tree grows to a height of 20m, and has a bare stem crowned by arched fan-shaped green leaves.
The tennis ball sized fruits of this palm take 2 years to mature, and up to 2 years to fall. Consequently, this palm is decorated with fruit throughout the year. The nuts of the Real Fan Palm yield a whitish milk, that resembles and tastes like coconut milk, once the hard exocarp of the nut has been fractured. The external pulp of the nut is edible, and tastes like gingerbread. It may be fermented into a very potent palm wine. The hard, hollow internal endosperm of the nut is the source of vegetable ivory.
Elephants play a major role in the dispersion of the seeds of this palm, for elephants love the taste of these nuts. The endosperm (vegetable ivory) passes through the elephant’s digestive tract unscathed and may be collected from the animal’s faeces (as large brownish furry tennis balls). If the nuts are not harvested, the faeces act as a natural fertilizer to hasten the germination of seeds.
So, there you have it; an African source of vegetable ivory confirmed, and correctly assigned to source.
Vegetable ivory, a long used effective imitation for elephant ivory, is derived from the dried nuts of several species of palm tree. The common commercial source of vegetable ivory is the Corozo or Tagua palm (Phytelephas macrocarpa) from Central America and northern South America. This ivory colored vegetable material (nut) has a hardness of 2½, a specific gravity of 1.40 – 1.43, a spot refractive index of 1.54, and in hand specimen displays the polygonal outlines of its component plant cells.
Another source of African vegetable ivory was suggested by Webster to be the Doum or Gingerbread palm (Hyphaene thebaica) of north and central Africa. According to the 5th edition of Webster’s Gems, the rounded nuts of this palm have a reddish brown skin, and edible underlying spongy layer which is commonly converted into an alcoholic beverage, and a hard inner seed (the source of vegetable ivory).
A recent purchased guide, The Shell Field Guide to the Common Trees of the Okavango Delta and the Moremi Game Reserve, by Veronica Roodt, has provided some additional details about the African source of vegetable ivory.
According to Dr Roodt, the source of vegetable ivory in the Okavango Delta—a wildlife and vegetation-rich area of 18000 km² that is the terminus of the Cubango River in Botswana—is the Real Fan Palm (Hyphanae petersania). This majestic tree grows to a height of 20m, and has a bare stem crowned by arched fan-shaped green leaves.
The tennis ball sized fruits of this palm take 2 years to mature, and up to 2 years to fall. Consequently, this palm is decorated with fruit throughout the year. The nuts of the Real Fan Palm yield a whitish milk, that resembles and tastes like coconut milk, once the hard exocarp of the nut has been fractured. The external pulp of the nut is edible, and tastes like gingerbread. It may be fermented into a very potent palm wine. The hard, hollow internal endosperm of the nut is the source of vegetable ivory.
Elephants play a major role in the dispersion of the seeds of this palm, for elephants love the taste of these nuts. The endosperm (vegetable ivory) passes through the elephant’s digestive tract unscathed and may be collected from the animal’s faeces (as large brownish furry tennis balls). If the nuts are not harvested, the faeces act as a natural fertilizer to hasten the germination of seeds.
So, there you have it; an African source of vegetable ivory confirmed, and correctly assigned to source.
The Thomas Crown Affair
Memorable quote (s) from the movie:
The Psychiatrist (Faye Dunaway): I want you to talk about women. Mr. Crown?
Thomas Crown (Pierce Brosnan): I'm sorry?
The Psychiatrist (Faye Dunaway) : Women. You get to talk about women.
Thomas Crown (Pierce Brosnan): Oh, I enjoy women.
The Psychiatrist (Faye Dunaway): Enjoyment isn't intimacy.
Thomas Crown (Pierce Brosnan): And intimacy isn't necessarily enjoyment.
The Psychiatrist (Faye Dunaway): How would you know? Has it occurred to you that you have a problem with trust?
Thomas Crown (Pierce Brosnan): I trust myself implicitly.
The Psychiatrist (Faye Dunaway): But can other people trust you?
Thomas Crown (Pierce Brosnan): Oh, you mean society at large?
The Psychiatrist (Faye Dunaway): I mean women, Mr.Crown.
Thomas Crown (Pierce Brosnan) : Yes, a woman could trust me.
The Psychiatrist (Faye Dunaway): Good. Under what extraordinary circumstances would you allow that to happen?
Thomas Crown (Pierce Brosnan): A woman could trust me as long as her interests didn't run too contrary to my own.
The Psychiatrist (Faye Dunaway): And society? If its interests should run counter to your own?
The Psychiatrist (Faye Dunaway): I want you to talk about women. Mr. Crown?
Thomas Crown (Pierce Brosnan): I'm sorry?
The Psychiatrist (Faye Dunaway) : Women. You get to talk about women.
Thomas Crown (Pierce Brosnan): Oh, I enjoy women.
The Psychiatrist (Faye Dunaway): Enjoyment isn't intimacy.
Thomas Crown (Pierce Brosnan): And intimacy isn't necessarily enjoyment.
The Psychiatrist (Faye Dunaway): How would you know? Has it occurred to you that you have a problem with trust?
Thomas Crown (Pierce Brosnan): I trust myself implicitly.
The Psychiatrist (Faye Dunaway): But can other people trust you?
Thomas Crown (Pierce Brosnan): Oh, you mean society at large?
The Psychiatrist (Faye Dunaway): I mean women, Mr.Crown.
Thomas Crown (Pierce Brosnan) : Yes, a woman could trust me.
The Psychiatrist (Faye Dunaway): Good. Under what extraordinary circumstances would you allow that to happen?
Thomas Crown (Pierce Brosnan): A woman could trust me as long as her interests didn't run too contrary to my own.
The Psychiatrist (Faye Dunaway): And society? If its interests should run counter to your own?
How Can You Take Good Care Of Your Pearl
(Wahroongai News, Volume 28, No.6, June 1994) H Komatsu writes:
How to take good care of pearl can be summarized into the following 4 points:
1. After wearing your pearl, you make it a custom to clean and dry it with a soft cloth, and keep it in a jewelry box. This is to prevent from the dullness of pearl luster from perspiration or cosmetic.
2. Your pearl should not touch with other jewelries such as diamonds, precious stones, gold jewelry, etc otherwise, some flaws might occur on the surface of your pearl.
3. Your pearl should not be exposed to light while it is kept, because light might make it yellowish after many years.
4. Your pearl should avoid extreme dryness and humidity; otherwise, cracks might occur after many years.
What is most important among the above 4 points is (1), that is, to clean and dry your pearl with a cloth after you wear it.
A pearl is far stronger than a marble.
The principle ingredient of a pearl and a marble consist of calcium carbonate, or a sort of calcium crystallization. It is reported that a marble is damaged by acid rain in Europe. Grand edifices and sculptures made of marbles are exposed to weather in ancient European cities, such as Paris, Rome, etc. And those historical structures are deformed, being melted by acid rain caused by waste gas from automobiles. Calcium carbonate is strong and solid crystallization, but it is melted by chemical reaction when influenced by acidity. On the other hand, the principal ingredient of a pearl is calcium carbonate, but the structure of its principal ingredient is greatly different from a marble. A marble is simply a mass of crystallization, but a pearl appears to be tiny bricks which are visible only with an electron microscope. Pearl nacre composes of many, many brick-looking materials. As a matter of fact, a pearl of 7mm composes of 220, 000, 000, 000 bricks. To our further surprise, every brick is covered up with a protein film. Generally speaking, protein is strong against acidity, and a pearl covered with a protein film is much stronger than a marble.
The surface of a pearl will become clouded with perspiration.
Since a brick near the surface of a pearl is exposed to the air and touches with your skin, its protein film may be damaged and it may become melted with acidity, such as perspiration and cosmetic. When a brick becomes melted, the surfaces of a pearl become uneven, though it is a micron in size, and loses its luster, which is called ‘cloudy phenomenon’. The same principle applies for a frosted glass which becomes clouded when a flaw or unevenness is found on the surface of a transparent glass.
It is easy to make clouded surface clean by cutting and polishing its surface.
Cloudy surface appears to be very serious when you notice it one day. You will be shocked to find powdery materials or white cloud on the surface of your pearl. However, it is easy to solve the above problem. By principle, we can remove one brick with flaws on the surface, and take out a new brick below the old one. You can restore pearl luster by polishing its surface with a cloth containing an ordinary abrasive. Since the thickness of a brick is 0.5 micron, you can feel relieved that cutting off such thickness does not reduce the size of your pearl.
To clean and dry your pearl with a cloth is the fundamental rule regarding how to take good care of your pearl.
We advise you not to have your pearl clouded, though you will be able to restore it. There will be two methods:
- To stay away from acidity. In case of a pearl jewelry, it is impossible to do so unless it is coated with special chemical, because you wear it on your skin.
- To remove acidity. The only method will be to remove perspiration and cosmetic on the surface of a pearl. Any soft cloth will do, but strictly speaking, the cloth which is suitable for soaking up the chief ingredient of perspiration, that is, water and oil, will be the best.
A pearl is one of the softest gems.
According to Mohs hardness index, a pearl is harder than a marble, but it is softer than any other gems. It is true that the hardness index of a pearl, which is 4.5, creates its unique luster, but we advise you not to mix it with other gems in a jewelry box.
Let’s not get your pearl sunburnt.
As we told you, pearl brick is covered up with a protein in film. This protein film will become yellowish and get sunburnt. This is the same principle with human beings becoming sunburnt in the sun. However, in case of a pearl, it takes many decades before it becomes discolored. You need not worry much about it so far as your pearl is carefully kept in a jewelry box.
A pearl is breathing.
Furthermore, water inside a pearl is actively moving around. When water inside becomes dry, it will get outside. Then, a pearl will become dry up, and lose its transparency, and may get cracked. On the other hand, when water becomes wet, it will get inside. Then, the protein film will get melted. Therefore, your pearl should be kept at a certain moderate state, not in too high nor too low humidity.
In conclusion, we would like to advise you to keep your pearl in a jewelry box which is designed to function, adjusting humidity naturally.
How to take good care of pearl can be summarized into the following 4 points:
1. After wearing your pearl, you make it a custom to clean and dry it with a soft cloth, and keep it in a jewelry box. This is to prevent from the dullness of pearl luster from perspiration or cosmetic.
2. Your pearl should not touch with other jewelries such as diamonds, precious stones, gold jewelry, etc otherwise, some flaws might occur on the surface of your pearl.
3. Your pearl should not be exposed to light while it is kept, because light might make it yellowish after many years.
4. Your pearl should avoid extreme dryness and humidity; otherwise, cracks might occur after many years.
What is most important among the above 4 points is (1), that is, to clean and dry your pearl with a cloth after you wear it.
A pearl is far stronger than a marble.
The principle ingredient of a pearl and a marble consist of calcium carbonate, or a sort of calcium crystallization. It is reported that a marble is damaged by acid rain in Europe. Grand edifices and sculptures made of marbles are exposed to weather in ancient European cities, such as Paris, Rome, etc. And those historical structures are deformed, being melted by acid rain caused by waste gas from automobiles. Calcium carbonate is strong and solid crystallization, but it is melted by chemical reaction when influenced by acidity. On the other hand, the principal ingredient of a pearl is calcium carbonate, but the structure of its principal ingredient is greatly different from a marble. A marble is simply a mass of crystallization, but a pearl appears to be tiny bricks which are visible only with an electron microscope. Pearl nacre composes of many, many brick-looking materials. As a matter of fact, a pearl of 7mm composes of 220, 000, 000, 000 bricks. To our further surprise, every brick is covered up with a protein film. Generally speaking, protein is strong against acidity, and a pearl covered with a protein film is much stronger than a marble.
The surface of a pearl will become clouded with perspiration.
Since a brick near the surface of a pearl is exposed to the air and touches with your skin, its protein film may be damaged and it may become melted with acidity, such as perspiration and cosmetic. When a brick becomes melted, the surfaces of a pearl become uneven, though it is a micron in size, and loses its luster, which is called ‘cloudy phenomenon’. The same principle applies for a frosted glass which becomes clouded when a flaw or unevenness is found on the surface of a transparent glass.
It is easy to make clouded surface clean by cutting and polishing its surface.
Cloudy surface appears to be very serious when you notice it one day. You will be shocked to find powdery materials or white cloud on the surface of your pearl. However, it is easy to solve the above problem. By principle, we can remove one brick with flaws on the surface, and take out a new brick below the old one. You can restore pearl luster by polishing its surface with a cloth containing an ordinary abrasive. Since the thickness of a brick is 0.5 micron, you can feel relieved that cutting off such thickness does not reduce the size of your pearl.
To clean and dry your pearl with a cloth is the fundamental rule regarding how to take good care of your pearl.
We advise you not to have your pearl clouded, though you will be able to restore it. There will be two methods:
- To stay away from acidity. In case of a pearl jewelry, it is impossible to do so unless it is coated with special chemical, because you wear it on your skin.
- To remove acidity. The only method will be to remove perspiration and cosmetic on the surface of a pearl. Any soft cloth will do, but strictly speaking, the cloth which is suitable for soaking up the chief ingredient of perspiration, that is, water and oil, will be the best.
A pearl is one of the softest gems.
According to Mohs hardness index, a pearl is harder than a marble, but it is softer than any other gems. It is true that the hardness index of a pearl, which is 4.5, creates its unique luster, but we advise you not to mix it with other gems in a jewelry box.
Let’s not get your pearl sunburnt.
As we told you, pearl brick is covered up with a protein in film. This protein film will become yellowish and get sunburnt. This is the same principle with human beings becoming sunburnt in the sun. However, in case of a pearl, it takes many decades before it becomes discolored. You need not worry much about it so far as your pearl is carefully kept in a jewelry box.
A pearl is breathing.
Furthermore, water inside a pearl is actively moving around. When water inside becomes dry, it will get outside. Then, a pearl will become dry up, and lose its transparency, and may get cracked. On the other hand, when water becomes wet, it will get inside. Then, the protein film will get melted. Therefore, your pearl should be kept at a certain moderate state, not in too high nor too low humidity.
In conclusion, we would like to advise you to keep your pearl in a jewelry box which is designed to function, adjusting humidity naturally.
Mtorolite
(via Wahroongai News, Vol 30, No.4, April, 1996) Grahame Brown writes:
Mtorolite is a rare green chrome chalcedony that occurs in one location in the world: Zimbabwe. Here it occurs as horizontally pitched veins that intrude decomposed serpentine bordering the Great Dyke. Although commercially mined out, it is considered that significant reserves remain to challenge the diligent fossicker. Better quality mtorolite can be faceted; but mostly this attractive chrome chalcedony is cabochoned or carved.
According to Ian Campbel (pp 19-23) in the October 95 issue of The South African Gemmologist, mtorolite was named for the Mtoroshanga of Zimbabwe, the district that hosts the only known occurrence of this gem material in the world. The greenish hues possible in this chalcedony depend on its Cr:Ni content, while the saturation of its green color depends of its Cr content. For example, dark green good quality evenly colored mtorolite has 0.04% Cr and 0.02% Ni, while pale green variegated mtorolite has 0.205 Cr and <0.01% Ni.
Mtorolite has colors that vary from a saturated chrome green to pale grayish green hue; a specific gravity of 2.57 – 2.60; a spot RI of 1.54. It has a pinkish to reddish Chelsea Filter reaction and is inert to both LW and SW UV.
Mtorolite is a rare green chrome chalcedony that occurs in one location in the world: Zimbabwe. Here it occurs as horizontally pitched veins that intrude decomposed serpentine bordering the Great Dyke. Although commercially mined out, it is considered that significant reserves remain to challenge the diligent fossicker. Better quality mtorolite can be faceted; but mostly this attractive chrome chalcedony is cabochoned or carved.
According to Ian Campbel (pp 19-23) in the October 95 issue of The South African Gemmologist, mtorolite was named for the Mtoroshanga of Zimbabwe, the district that hosts the only known occurrence of this gem material in the world. The greenish hues possible in this chalcedony depend on its Cr:Ni content, while the saturation of its green color depends of its Cr content. For example, dark green good quality evenly colored mtorolite has 0.04% Cr and 0.02% Ni, while pale green variegated mtorolite has 0.205 Cr and <0.01% Ni.
Mtorolite has colors that vary from a saturated chrome green to pale grayish green hue; a specific gravity of 2.57 – 2.60; a spot RI of 1.54. It has a pinkish to reddish Chelsea Filter reaction and is inert to both LW and SW UV.
The World’s Finest Minerals And Crystals
By Peter Bancroft
The Viking Press, Inc
1973 SBN 670-79022-2
The Viking Press writes:
The collecting, cutting and polishing of minerals is one of the largest and fastest growing hobbies in the world. In spite of the wide popularity of this activity and the generations of scientific study devoted to mineralogy, there is no known formula for determining the best example of a particular mineral species. Rare and valuable specimens of legendary beauty are scattered n collections around the world. Some are in museums where they may be enjoyed by those people lucky enough to be able to travel to see them; others are in private hands and are seldom seen by the public.
In The World’s Finest Minerals and Crystals, Dr Peter Bancroft has brought together a series of magnificent photographs of outstanding minerals nominated for acclaim by enthusiasts all over the world. A distinguished international panel of judges has participated in choosing the very finest examples for inclusions in the Gallery of plates. In his text, Dr Bancroft tells just how this gallery was selected. He explains how minerals are formed and where they are found, and how some of the world’s finest collections were begun. Modern methods of collecting and conservation are also discussed. Fine minerals are growing increasingly rare, and Dr Bancroft reviews the dangers that threaten both natural sources and specimens already housed in important collections. The notes that accompany each plate describe the history and characteristics of the pictured specimen, tell where other fine examples may be seen, and describe the locations around the globe in which these minerals originate.
The book provides a unique opportunity to view the world’s greatest mineral treasures brought together in a superb gallery of photographs that bring out all the rich glow and sparkle of the originals, and the text takes the reader adventuring abroad to exotic locations in the fascinating realm of mineral collection.
About the author
Dr Peter Bancroft is a collector of minerals, and has lectured in mineralogy in the United States, Bolivia, Brazil, and Australia and has contributed articles to Lapidary Journal and other magazines in this field.
The Viking Press, Inc
1973 SBN 670-79022-2
The Viking Press writes:
The collecting, cutting and polishing of minerals is one of the largest and fastest growing hobbies in the world. In spite of the wide popularity of this activity and the generations of scientific study devoted to mineralogy, there is no known formula for determining the best example of a particular mineral species. Rare and valuable specimens of legendary beauty are scattered n collections around the world. Some are in museums where they may be enjoyed by those people lucky enough to be able to travel to see them; others are in private hands and are seldom seen by the public.
In The World’s Finest Minerals and Crystals, Dr Peter Bancroft has brought together a series of magnificent photographs of outstanding minerals nominated for acclaim by enthusiasts all over the world. A distinguished international panel of judges has participated in choosing the very finest examples for inclusions in the Gallery of plates. In his text, Dr Bancroft tells just how this gallery was selected. He explains how minerals are formed and where they are found, and how some of the world’s finest collections were begun. Modern methods of collecting and conservation are also discussed. Fine minerals are growing increasingly rare, and Dr Bancroft reviews the dangers that threaten both natural sources and specimens already housed in important collections. The notes that accompany each plate describe the history and characteristics of the pictured specimen, tell where other fine examples may be seen, and describe the locations around the globe in which these minerals originate.
The book provides a unique opportunity to view the world’s greatest mineral treasures brought together in a superb gallery of photographs that bring out all the rich glow and sparkle of the originals, and the text takes the reader adventuring abroad to exotic locations in the fascinating realm of mineral collection.
About the author
Dr Peter Bancroft is a collector of minerals, and has lectured in mineralogy in the United States, Bolivia, Brazil, and Australia and has contributed articles to Lapidary Journal and other magazines in this field.
Thursday, March 15, 2007
How Do You Value A "Free" Customer?
Sometimes a valuable customer may be the person who never buys a thing, but in a networked setting a free customer may have considerable influence.
Read on to learn more @ http://hbswk.hbs.edu/item/5595.html
Read on to learn more @ http://hbswk.hbs.edu/item/5595.html
The Aviator
Memorable quote (s) from the movie:
Professor Fitz (Ian Holm): Well, the cumulonimbus formations about which you speak that look like...
Howard Hughes (Leonardo DiCaprio): Giant breasts full of milk. I want clouds, damn it.
Professor Fitz (Ian Holm): Yes, clouds that look like giant breasts full of milk, cannot exactly be guaranteed for any particular occasion. So you might have to... to wait.
Howard Hughes (Leonardo DiCaprio): Then we'll wait. Look, whatever they pay you at UCLA I'm doubling it, all right? You work for me now. Find some clouds. Find some clouds! Find me some clouds!
Hell's Angels Pilot (Justin Shilton): Welcome to Hell's Angels.
Professor Fitz (Ian Holm): Well, the cumulonimbus formations about which you speak that look like...
Howard Hughes (Leonardo DiCaprio): Giant breasts full of milk. I want clouds, damn it.
Professor Fitz (Ian Holm): Yes, clouds that look like giant breasts full of milk, cannot exactly be guaranteed for any particular occasion. So you might have to... to wait.
Howard Hughes (Leonardo DiCaprio): Then we'll wait. Look, whatever they pay you at UCLA I'm doubling it, all right? You work for me now. Find some clouds. Find some clouds! Find me some clouds!
Hell's Angels Pilot (Justin Shilton): Welcome to Hell's Angels.
Subscribe to:
Posts (Atom)