Memorable quote (s) from the movie:
Jack (Thomas Haden Church): I might be in love with another woman.
Miles Raymond (Paul Giamatti): In love? Really? 24 hours with some wine-pourer chick and you're fucking in love? Come on! And you're gonna give up everything?
Jack (Thomas Haden Church): Here's what I'm thinking: you and me, we move up here, we buy a vineyard. You design the wine; I'll handle the business side. You get inspired; maybe write another novel, one that can sell.
Miles Raymond (Paul Giamatti): Oh, my God. No, no.
Jack (Thomas Haden Church): As for me, if an audition comes up, LA's right there, man. It's two hours away, not even.........
Miles Raymond (Paul Giamatti): Jesus Christ, you're crazy. You're crazy. You've gone crazy.
Jack (Thomas Haden Church): All I know is that I'm an actor. All I have is my instinct. You're asking me to go against it.
Sunday, March 25, 2007
Natural Colored Blue Quartz
(via Wahroongai News, Volume 30, No.7, July 1996) Grahame Brown writes:
For many years I have made the general statement in lectures on synthetics that ‘blue quartz is never difficult to identify, for blue quartz does not occur naturally’. It would seem that this statement could, and should, be challenged. The reason for this change of opinion is a small paper that was published in the March-April 1996 issue of The Mineralogical Record.
The paper, titled ‘Blue quartz from the Antequera-Olvera Ophite, Malaga, Spain’, describes the occurrence of attractive dipyramidal blue quartz owing its color to aerinite inclusions.
Apparently blue quartz was first reported from the Antequera region of Spain in 1910. This deposit was rediscovered near the Olvera-Pruna road in Cadiz province—a small province that lies just to the east of the British fortress of Gibraltar. Here a clay-lined fractures in an ophitic (rock with a texture dominated by lath-shaped plagioclase crystals completely included within pyroxene) augite diabase = dolerite (a dark colored intrusive rock, containing major labradorite and pyroxene, which characteristically has an ophitic texture) rock host well crystallized dipyramidal (consisting of equally developed positive and negative rhombohedron) blue quartz crystals of 5mm to 1.5cm size.
The blue quartz crystals are actually colorless quartz crystals that are included by fibrous aerinite. These crystals vary in color from deep blue to sky blue. For the interested reader, aerinite is a monoclinic mineral that commonly adopts a fibrous habit.
Other possible causes of blue quartz are……the inclusion of colorless quartz by:
- Submicroscopic inclusions of rutile, producing a blue color in the quartz by Tyndall scattering of white light, and
- Dumortierite, a bluish to purple orthorhombic mineral.
For many years I have made the general statement in lectures on synthetics that ‘blue quartz is never difficult to identify, for blue quartz does not occur naturally’. It would seem that this statement could, and should, be challenged. The reason for this change of opinion is a small paper that was published in the March-April 1996 issue of The Mineralogical Record.
The paper, titled ‘Blue quartz from the Antequera-Olvera Ophite, Malaga, Spain’, describes the occurrence of attractive dipyramidal blue quartz owing its color to aerinite inclusions.
Apparently blue quartz was first reported from the Antequera region of Spain in 1910. This deposit was rediscovered near the Olvera-Pruna road in Cadiz province—a small province that lies just to the east of the British fortress of Gibraltar. Here a clay-lined fractures in an ophitic (rock with a texture dominated by lath-shaped plagioclase crystals completely included within pyroxene) augite diabase = dolerite (a dark colored intrusive rock, containing major labradorite and pyroxene, which characteristically has an ophitic texture) rock host well crystallized dipyramidal (consisting of equally developed positive and negative rhombohedron) blue quartz crystals of 5mm to 1.5cm size.
The blue quartz crystals are actually colorless quartz crystals that are included by fibrous aerinite. These crystals vary in color from deep blue to sky blue. For the interested reader, aerinite is a monoclinic mineral that commonly adopts a fibrous habit.
Other possible causes of blue quartz are……the inclusion of colorless quartz by:
- Submicroscopic inclusions of rutile, producing a blue color in the quartz by Tyndall scattering of white light, and
- Dumortierite, a bluish to purple orthorhombic mineral.
It’s All In The State Of Mind
Author Unknown.
If you think you are beaten, you are
If you think you dare not, you don’t
If you think you’d like to win, but can’t
It’s almost a ‘cinch’ you won’t
If you think you’ll lose, you’ve lost
For out in the world you’ll find
Success begins with a fellow’s will
It’s all in the state of mind
For many a race is lost
Ere even a race is run
And many a coward fails
Ere ever his work’s begun
Think big and your deeds will grow
Think small and you fall behind
Think that you can, and you will
It’s all in the state of the mind
If you think you’re outclassed, you are
You’ve got to think hard to rise
You’ve got to be sure of yourself before
You can ever win a prize
Life’s battle doesn’t always go
To the strongest or fastest man
But sooner or later the man who wins
Is the man who thinks he can
If you think you are beaten, you are
If you think you dare not, you don’t
If you think you’d like to win, but can’t
It’s almost a ‘cinch’ you won’t
If you think you’ll lose, you’ve lost
For out in the world you’ll find
Success begins with a fellow’s will
It’s all in the state of mind
For many a race is lost
Ere even a race is run
And many a coward fails
Ere ever his work’s begun
Think big and your deeds will grow
Think small and you fall behind
Think that you can, and you will
It’s all in the state of the mind
If you think you’re outclassed, you are
You’ve got to think hard to rise
You’ve got to be sure of yourself before
You can ever win a prize
Life’s battle doesn’t always go
To the strongest or fastest man
But sooner or later the man who wins
Is the man who thinks he can
Geological Laboratory Techniques
By M Allman and D F Lawrence
Arco Publishing Company, Inc
1972 ISBN 0-668-03358-4
Arco Publishing Company writes:
This is the first comprehensive handbook for the geologist, whether amateur or professional, who requires practical information on the basic laboratory techniques essential to the study of geology. It also covers advanced and sophisticated procedures.
The topics described include specimen cutting and grinding, the preparation of thin sections of rock for microscope study, the petrological microscope, microfossil separation from various matrixes, isolation of minerals from mixed powders, moulding and casting methods to reproduce fossils, and modern embedding techniques for specimen display.
The equipment, different methods of working and their results are discussed and compared. In many cases an elementary method using simple equipment is described in addition to the more advanced methods which usually require expensive apparatus.
The text is augmented with nearly 200 illustrations. Of these 48 are in magnificent full color, and include 32 pictures showing the different stages of thin section preparation. The inclusion of a full color interference chart, in an extended, pull-out form, will be of particular value to the laboratory technician.
The authors are experts in the geological techniques and have both held appointments as Chief Technician in the Department of Geolgoy at Queen Mary College, University of London. This eminently practical manual will be indispensable in the laboratory to anyone concerned with geology in the universities, technical colleges and in industry.
Arco Publishing Company, Inc
1972 ISBN 0-668-03358-4
Arco Publishing Company writes:
This is the first comprehensive handbook for the geologist, whether amateur or professional, who requires practical information on the basic laboratory techniques essential to the study of geology. It also covers advanced and sophisticated procedures.
The topics described include specimen cutting and grinding, the preparation of thin sections of rock for microscope study, the petrological microscope, microfossil separation from various matrixes, isolation of minerals from mixed powders, moulding and casting methods to reproduce fossils, and modern embedding techniques for specimen display.
The equipment, different methods of working and their results are discussed and compared. In many cases an elementary method using simple equipment is described in addition to the more advanced methods which usually require expensive apparatus.
The text is augmented with nearly 200 illustrations. Of these 48 are in magnificent full color, and include 32 pictures showing the different stages of thin section preparation. The inclusion of a full color interference chart, in an extended, pull-out form, will be of particular value to the laboratory technician.
The authors are experts in the geological techniques and have both held appointments as Chief Technician in the Department of Geolgoy at Queen Mary College, University of London. This eminently practical manual will be indispensable in the laboratory to anyone concerned with geology in the universities, technical colleges and in industry.
Friday, March 23, 2007
The Cause Of Photoluminescence
(via Wahroongai News, Volume 30, No.5, May 1996) Grahame Brown writes:
Many minerals (gemstones) owe their photoluminescent (fluorescent and phosphorescent) properties to the presence of fluorescence activators in their crystal structure. These activators may be either elemental ionic impurities, metallic radicles, e.g., urinate, or structural defects in the crystal structure. Fluorescence activators function by introducing required properly separated raised energy levels for electrons in the mineral’s crystal structure. It is the presence of these defined energy levels (above the ground state) that will allow the mineral to luminesce when irradiated by short wavelength visible light, ultraviolet and x-ray wavelengths, and cathode rays (accelerated electrons).
Substitution of activator ions into a crystal structure is controlled by both the size (radius) and charge of the substituting ions. If a size or charge mismatch does occur, then smaller size and higher charge will affect ionic substitution in crystal structure.
The energy levels required for luminescence may be either:
- Associated with either a single activator, e.g., the europium ions responsible for the blue fluorescence of fluorite.
- Shared with a second co-activator, e.g., the copper and aluminum impurities in sphalerite that are responsible for its fluorescence.
- Shared between the host mineral and an activator, e.g., the green fluorescence of willemite is the result of shared energy levels between the willemite silicate structure and its manganese activator.
In some minerals, e.g., diamond, non-metals such as nitrogen and hydrogen act as fluorescence activators. While there is no lower limit on the concentration of an activator required to produce fluorescence, typical fluorescence activators are present in quite small concentrations that may vary from 1ppm to several percent. However, higher concentrations of activators can inhibit fluorescence by the process known as concentration quenching. A good example of concentration quenching is provided when the concentration of Cr³+ ions start to absorb their neighbors fluorescent emission, thus eventually quenching the red fluorescence of the ruby. Other causes of fluorescence quenching include heat and the additional presence of ions that poison luminescence.
Certainly fluorescence can be quenched by heat. This occurs because heat increases molecular vibrations in the crystal structure. As a consequence, these additional vibrations can interact with an activator or co-activator (sensitizer) to carry off their luminescence excitation energy as heat.
Fluorescence also can be quenched if certain impurities occur in a mineral that has the potential for photoluminescence. For example, the presence of Fe³+ and to a lesser extent Fe²+ in ruby effectively quenches its fluorescence; for the Fe³+ selectively steals blue to ultraviolet wavelengths from Cr³+ to energize a charge transfer reaction between Fe³+ and its surrounding oxygen atoms. Consequently the Cr³+ ion can’t be energized, and minimal red fluorescence (purely from red and green absorption) will occur.
For more information refer to Robbins, M (1994); Geoscience Press, Phoenix.
Many minerals (gemstones) owe their photoluminescent (fluorescent and phosphorescent) properties to the presence of fluorescence activators in their crystal structure. These activators may be either elemental ionic impurities, metallic radicles, e.g., urinate, or structural defects in the crystal structure. Fluorescence activators function by introducing required properly separated raised energy levels for electrons in the mineral’s crystal structure. It is the presence of these defined energy levels (above the ground state) that will allow the mineral to luminesce when irradiated by short wavelength visible light, ultraviolet and x-ray wavelengths, and cathode rays (accelerated electrons).
Substitution of activator ions into a crystal structure is controlled by both the size (radius) and charge of the substituting ions. If a size or charge mismatch does occur, then smaller size and higher charge will affect ionic substitution in crystal structure.
The energy levels required for luminescence may be either:
- Associated with either a single activator, e.g., the europium ions responsible for the blue fluorescence of fluorite.
- Shared with a second co-activator, e.g., the copper and aluminum impurities in sphalerite that are responsible for its fluorescence.
- Shared between the host mineral and an activator, e.g., the green fluorescence of willemite is the result of shared energy levels between the willemite silicate structure and its manganese activator.
In some minerals, e.g., diamond, non-metals such as nitrogen and hydrogen act as fluorescence activators. While there is no lower limit on the concentration of an activator required to produce fluorescence, typical fluorescence activators are present in quite small concentrations that may vary from 1ppm to several percent. However, higher concentrations of activators can inhibit fluorescence by the process known as concentration quenching. A good example of concentration quenching is provided when the concentration of Cr³+ ions start to absorb their neighbors fluorescent emission, thus eventually quenching the red fluorescence of the ruby. Other causes of fluorescence quenching include heat and the additional presence of ions that poison luminescence.
Certainly fluorescence can be quenched by heat. This occurs because heat increases molecular vibrations in the crystal structure. As a consequence, these additional vibrations can interact with an activator or co-activator (sensitizer) to carry off their luminescence excitation energy as heat.
Fluorescence also can be quenched if certain impurities occur in a mineral that has the potential for photoluminescence. For example, the presence of Fe³+ and to a lesser extent Fe²+ in ruby effectively quenches its fluorescence; for the Fe³+ selectively steals blue to ultraviolet wavelengths from Cr³+ to energize a charge transfer reaction between Fe³+ and its surrounding oxygen atoms. Consequently the Cr³+ ion can’t be energized, and minimal red fluorescence (purely from red and green absorption) will occur.
For more information refer to Robbins, M (1994); Geoscience Press, Phoenix.
Bonnie And Clyde
Memorable quote (s) from the movie:
Bonnie's Mother (Mabel Cavitt): You know Clyde, I read about you all in the papers, and I just get scared.
Clyde Barrow (Warren Beatty): Now Ms. Parker, don't you believe what you read in all them newspapers. That's the law talkin' there. They want us to look big so they gonna look big when they catch us. And they ain't gonna catch us. 'Cause I'm even better at runnin' than I am at robbin' banks! Shoot, if we'd done half that stuff they said we'd done in that paper, we'd be millionaires by now, wouldn't we? But Ms. Parker, this here's the way we know best how to make money. But we gonna be quittin' all this, as soon as the hard times are over. I can tell ya that. Why just the other night, me and Bonnie were talkin'. And we were talkin' about the time we're gonna settle down and get us a home. And uh, she says to me, she says, "You know, I couldn't bear to live more than three miles from my precious Mother." Now how'd ya like that, Mother Parker?
Bonnie's Mother (Mabel Cavitt): I don't believe I would. I surely don't. You try to live three miles from me and you won't live long, honey. You best keep runnin', Clyde Barrow. And you know it. Bye, baby.
Bonnie's Mother (Mabel Cavitt): You know Clyde, I read about you all in the papers, and I just get scared.
Clyde Barrow (Warren Beatty): Now Ms. Parker, don't you believe what you read in all them newspapers. That's the law talkin' there. They want us to look big so they gonna look big when they catch us. And they ain't gonna catch us. 'Cause I'm even better at runnin' than I am at robbin' banks! Shoot, if we'd done half that stuff they said we'd done in that paper, we'd be millionaires by now, wouldn't we? But Ms. Parker, this here's the way we know best how to make money. But we gonna be quittin' all this, as soon as the hard times are over. I can tell ya that. Why just the other night, me and Bonnie were talkin'. And we were talkin' about the time we're gonna settle down and get us a home. And uh, she says to me, she says, "You know, I couldn't bear to live more than three miles from my precious Mother." Now how'd ya like that, Mother Parker?
Bonnie's Mother (Mabel Cavitt): I don't believe I would. I surely don't. You try to live three miles from me and you won't live long, honey. You best keep runnin', Clyde Barrow. And you know it. Bye, baby.
Simulants For Paraiba Tourmalines
Today the 4 different types of simulants for Paraiba tourmaline are still encountered in all shapes and sizes.
(via ICA Early Warning Flash, No.47, September 20, 1991) Deutsche Stiftung Edelsteinforschung writes:
Details
In the last weeks some remarkable simulants for blue and greenish blue Paraiba tourmalines have been observed in Idar Oberstein. In lots of cut stones 4 different types of simulants have been found.
- Blue to greenish blue apatite
- Blue irradiated topaz (unheated)
- Beryl-beryl-triplets with a bright blue cement
- Tourmaline glass doublets
Blue and greenish blue apatite has also been found in lots of rough Paraiba tourmalines.
Identification
1. Apatite possesses refractive indices in the same range as tourmaline but the birefringence is distinctly lower. Furthermore, the absorption spectra are quite different; blue and greenish blue apatite shows absorption lines in the red and yellow, which are caused by certain color centers, while Paraiba tourmalines owe their color to copper and manganese, which cause broad absorption bands in the red and green spectral range.
2. Blue irradiated topaz has lower refractive indices than tourmaline and additionally a lower
birefringence, while the density is higher. The artificial coloration by irradiation has been tested by thermoluminescence measurements.
3. The beryl-beryl-triplets are detectable by the lower refractive indices and birefringence compared to tourmaline. The cementing layer can be easily observed by microscopical studies.
4. The tourmaline-glass-doublets can cause more difficulties because the upper part consists of tourmaline. But microscopical observations attest the composite stone. Routine tests revealed doubling of the back facets of tourmaline and single refraction of glass.
Conclusion
Be careful with lots, and investigate each stone of every lot individually even if or especially when the color is similar or nearly the same.
(via ICA Early Warning Flash, No.47, September 20, 1991) Deutsche Stiftung Edelsteinforschung writes:
Details
In the last weeks some remarkable simulants for blue and greenish blue Paraiba tourmalines have been observed in Idar Oberstein. In lots of cut stones 4 different types of simulants have been found.
- Blue to greenish blue apatite
- Blue irradiated topaz (unheated)
- Beryl-beryl-triplets with a bright blue cement
- Tourmaline glass doublets
Blue and greenish blue apatite has also been found in lots of rough Paraiba tourmalines.
Identification
1. Apatite possesses refractive indices in the same range as tourmaline but the birefringence is distinctly lower. Furthermore, the absorption spectra are quite different; blue and greenish blue apatite shows absorption lines in the red and yellow, which are caused by certain color centers, while Paraiba tourmalines owe their color to copper and manganese, which cause broad absorption bands in the red and green spectral range.
2. Blue irradiated topaz has lower refractive indices than tourmaline and additionally a lower
birefringence, while the density is higher. The artificial coloration by irradiation has been tested by thermoluminescence measurements.
3. The beryl-beryl-triplets are detectable by the lower refractive indices and birefringence compared to tourmaline. The cementing layer can be easily observed by microscopical studies.
4. The tourmaline-glass-doublets can cause more difficulties because the upper part consists of tourmaline. But microscopical observations attest the composite stone. Routine tests revealed doubling of the back facets of tourmaline and single refraction of glass.
Conclusion
Be careful with lots, and investigate each stone of every lot individually even if or especially when the color is similar or nearly the same.
Be On The Lookout For Fake Amber
(via Wahroongai News, Volume 32, Number 3, March 1998) Grahame Brown writes:
This warning follows the recently held North Brisbane Lapidary Show at which one dealer was found to be selling materials clearly marked as amber—yet these materials were not amber. One group of the ambers for sale were manufactured from the amber imitation polyberne; and other pale yellowish ambers were obviously recent copal resin (some of which was attractively included by insect inclusions).
To assist members and students not to be taken in by this scam, the following information is supplied on these two amber imitations and their identification.
Copal Resin
Copal resin is a diaphanous brittle colorless, yellow to brownish recent plant resin that may have an age of up to several tens of thousands of years. Commercial copal resins are often given names such as Kauri gum (a misnomer), Manila, Congo or Colombian copal.
Kauri gum and manila are respectively derived from sap from the gymnosperms Agathis australis from the North Island of New Zealand and Agathis albis from the Philippines and the Indonesian archipelago. There are two major African sources of copal resin which also may be termed congo or Zanzibar resin. East African copal, which comes from Tanzania and island of Zanzibar, is derived from sap exuded from damaged trunks and branches of the leguminous (fruit-bearing) angiosperm (flowering plant) Hymenaea verrucosa; while West African copal from the Congo Republic is derived from the sap of the leguminous angiosperm Copiafera demusi. Most Colombian copal comes from ploughed fields in the Departments of Santander, Boyaca, and Bolivar—specifically near the cities and villages of Bucaramanga, Giron, Bonda, Medellin, Penablanca, Mariquita, and Valle du Jesus. Some Colombian copal has been given the tongue-twisting name of bucarimangite. Age dating of specimens of Colombian copal has yielded ages that ranged from 10 to 500 years. The source resin of Colombian copal is undoubtedly three resin producing trees that are still growing in Colombia—the Hymenaea courbaril, the H. oblongifolia, and the H. parvifolia. In these trees the exuded resin accumulates between the bark and wood, and also under the roots of the tree. Common inclusions in this very recent resin include stingless bees, millipedes, centipedes, ants, moths, beetles, cockroaches, silverfish, and termites.
Precisely how long copal resin takes to convert to amber is unknown. However, this (hardening) time is influenced by such conditions as temperature, pressure, moisture, and perhaps the presence or absence of oxygen. Poinar (1994) suggested that 2-4 million years of burial might be required to convert copal resin into amber.
Copal resin and/or kauri gum are excellent amber look-alikes so with the exception copal’s:
Slightly lower hardness (2 on Mohs scale).
Slightly lower specific gravity (varying from 1.3 to 1.09 with age).
Increased solubility in volatile hydrocarbons.
Increased volatility, with a ‘pine’-like odor being emitted when kauri and/or copal is firmly rubbed in the heel of the hand.
Increased shallow surface crazing, restricted to the outer 2mm of the resin, due to continuing evaporation of volatiles.
………these effective amber imitations have an appearance, gemological properties, sectility (chips on peeling), and pattern of inclusions virtually identical to those of amber.
Practically, the increased solubility of kauri gum/copal resin in volatile organic solvents (a potentially destructive test) may be used to effectively discriminate them from amber, as
1. Surfaces of copal resin become sticky to an applied finger following the judicious application of a drop of volatile organic solvent (e.g. ether, chloroform, acetone, or alcohol) to an inconspicuous area of the suspect resin. This is a very useful test that can be applied before you purchase specimens of ? amber; and,
2. A yellow stain will be deposited on the surface of an alcohol-moistened white cloth or tissue, when an inconspicuous surface of kauri and/or copal is wiped briskly with a moistened cloth or tissue.
Polyberne
Polyberne, a man-made composite imitation of amber consists of fragments of amber embedded in brownish polyester casting resin. Polyberne is a distinctly Polish product that displays evidence of:
- Molding.
- Entrapment of air bubbles between the external surface of the imitation and the mold into which the polyester resin was poured.
- Evidence of two components. That is fragments of amber embedded in a resin of different refractive index.
Hand lens examination, looking for evidence of embedding and molding, and perhaps a test for sectility, are all that is required to positively identify the polyberne imitation of amber.
So beware, these materials are in the marketplace. Do not be caught for want of applying a few simple observations and tests.
This warning follows the recently held North Brisbane Lapidary Show at which one dealer was found to be selling materials clearly marked as amber—yet these materials were not amber. One group of the ambers for sale were manufactured from the amber imitation polyberne; and other pale yellowish ambers were obviously recent copal resin (some of which was attractively included by insect inclusions).
To assist members and students not to be taken in by this scam, the following information is supplied on these two amber imitations and their identification.
Copal Resin
Copal resin is a diaphanous brittle colorless, yellow to brownish recent plant resin that may have an age of up to several tens of thousands of years. Commercial copal resins are often given names such as Kauri gum (a misnomer), Manila, Congo or Colombian copal.
Kauri gum and manila are respectively derived from sap from the gymnosperms Agathis australis from the North Island of New Zealand and Agathis albis from the Philippines and the Indonesian archipelago. There are two major African sources of copal resin which also may be termed congo or Zanzibar resin. East African copal, which comes from Tanzania and island of Zanzibar, is derived from sap exuded from damaged trunks and branches of the leguminous (fruit-bearing) angiosperm (flowering plant) Hymenaea verrucosa; while West African copal from the Congo Republic is derived from the sap of the leguminous angiosperm Copiafera demusi. Most Colombian copal comes from ploughed fields in the Departments of Santander, Boyaca, and Bolivar—specifically near the cities and villages of Bucaramanga, Giron, Bonda, Medellin, Penablanca, Mariquita, and Valle du Jesus. Some Colombian copal has been given the tongue-twisting name of bucarimangite. Age dating of specimens of Colombian copal has yielded ages that ranged from 10 to 500 years. The source resin of Colombian copal is undoubtedly three resin producing trees that are still growing in Colombia—the Hymenaea courbaril, the H. oblongifolia, and the H. parvifolia. In these trees the exuded resin accumulates between the bark and wood, and also under the roots of the tree. Common inclusions in this very recent resin include stingless bees, millipedes, centipedes, ants, moths, beetles, cockroaches, silverfish, and termites.
Precisely how long copal resin takes to convert to amber is unknown. However, this (hardening) time is influenced by such conditions as temperature, pressure, moisture, and perhaps the presence or absence of oxygen. Poinar (1994) suggested that 2-4 million years of burial might be required to convert copal resin into amber.
Copal resin and/or kauri gum are excellent amber look-alikes so with the exception copal’s:
Slightly lower hardness (2 on Mohs scale).
Slightly lower specific gravity (varying from 1.3 to 1.09 with age).
Increased solubility in volatile hydrocarbons.
Increased volatility, with a ‘pine’-like odor being emitted when kauri and/or copal is firmly rubbed in the heel of the hand.
Increased shallow surface crazing, restricted to the outer 2mm of the resin, due to continuing evaporation of volatiles.
………these effective amber imitations have an appearance, gemological properties, sectility (chips on peeling), and pattern of inclusions virtually identical to those of amber.
Practically, the increased solubility of kauri gum/copal resin in volatile organic solvents (a potentially destructive test) may be used to effectively discriminate them from amber, as
1. Surfaces of copal resin become sticky to an applied finger following the judicious application of a drop of volatile organic solvent (e.g. ether, chloroform, acetone, or alcohol) to an inconspicuous area of the suspect resin. This is a very useful test that can be applied before you purchase specimens of ? amber; and,
2. A yellow stain will be deposited on the surface of an alcohol-moistened white cloth or tissue, when an inconspicuous surface of kauri and/or copal is wiped briskly with a moistened cloth or tissue.
Polyberne
Polyberne, a man-made composite imitation of amber consists of fragments of amber embedded in brownish polyester casting resin. Polyberne is a distinctly Polish product that displays evidence of:
- Molding.
- Entrapment of air bubbles between the external surface of the imitation and the mold into which the polyester resin was poured.
- Evidence of two components. That is fragments of amber embedded in a resin of different refractive index.
Hand lens examination, looking for evidence of embedding and molding, and perhaps a test for sectility, are all that is required to positively identify the polyberne imitation of amber.
So beware, these materials are in the marketplace. Do not be caught for want of applying a few simple observations and tests.
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