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.
Saturday, March 17, 2007
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.
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