Saturday, June 09, 2007
Prediction: DTC to send formal Sightholder Termination Notices to All 93 Clients
Chaim Even-Zohar writes about the status of new DTC (Diamond Trading Company) sightholders + existing contracts + the uncertainities @ http://www.idexonline.com/portal_FullEditorial.asp?TextSearch=&KeyMatch=0&id=27309
Geology Of Placer Gem Deposits
Here is an experts view on placer deposits and its commercial significance in gem producing countries around the world + the geological and gemological characteristics that are important in identifying the particularities of placer deposits.
James M Prudden (Prudden GeoScience Services, Nevada, USA) writes:
Placer gem depositional environments consist of colluvial, fluvial, and beach deposits. The weathering of primary gem-bearing deposits forms overlying eluvial deposits, and the down-slope migration of the residual gems by both gravity and water creates colluvial deposits. Fluvial systems range from youthful through mature and old-age sedimentological regimes with associated channel geometrics that determine the hydraulic energy and therefore the locations of gem deposition. Fluvial systems commence with straight steep-channel gradients, with low depth-to width ratios containing unsorted clasts and large gems. This evolves into to the downstream, low-energy, old-age fluvial systems with low channel gradients that host bedded, well-sorted smaller clasts deposited in a meandering fashion within a broad flood plane. Gems in this environment are smaller and more rounded. At the point where the river enters a marine or lacustrine environment, the resulting abrupt gradient change is very favorable for gem deposition. Wave energy and long shore currents further winnow and transport gems in beach environments. Alpine and continental glaciers are nature’s bulldozers and the braded fluvial streams that are fed from their melt water effectively concentrate the contained gems from the glacial rubble.
Gem characteristics such as specific gravity, hardness, shape and durability will influence their related depositional environments and survivability, thus favoring the economic concentrations of certain gems in the fluvial milling environment.
Select case histories of a variety of placer deposits illustrate the practicality of applying detailed geology and sedimentology to placer gem exploration:
1. Australian Tertiary modified paleo-colluvial type sapphire deposits, derived from the weathering of alkaline basalts, have been a major global source of sapphires.
2. Namibian long-shore diamond distribution along the Atlantic Ocean coast constitutes the world’s most valuable diamond deposit, extending westward 100km to the continental shelf edge and 200km northward. The diamonds were originally liberated from the South African kimberlites (and possibly more distant sources) by post-Gondawana erosion of the southern African craton, which commenced in the humid Middle Cretaceous with the formation of the ancient Karoo and Kalahari Rivers. Subsequent erosion of these diamondiferous placers was accomplished by the Orange River in the Miocene. Prolonged winnowing of the diamonds increased their value by about 500%.
3. Fluvial reworking of glacial sediments in British Colombia, Canada, concentrated sapphires and garnets from several cubic kilometers of glacial material.
4. A fluvial diamond deposit in China’s Hunan province was deposited on completely weathered karst bedrock, which presents challenges to sampling and mining.
James M Prudden (Prudden GeoScience Services, Nevada, USA) writes:
Placer gem depositional environments consist of colluvial, fluvial, and beach deposits. The weathering of primary gem-bearing deposits forms overlying eluvial deposits, and the down-slope migration of the residual gems by both gravity and water creates colluvial deposits. Fluvial systems range from youthful through mature and old-age sedimentological regimes with associated channel geometrics that determine the hydraulic energy and therefore the locations of gem deposition. Fluvial systems commence with straight steep-channel gradients, with low depth-to width ratios containing unsorted clasts and large gems. This evolves into to the downstream, low-energy, old-age fluvial systems with low channel gradients that host bedded, well-sorted smaller clasts deposited in a meandering fashion within a broad flood plane. Gems in this environment are smaller and more rounded. At the point where the river enters a marine or lacustrine environment, the resulting abrupt gradient change is very favorable for gem deposition. Wave energy and long shore currents further winnow and transport gems in beach environments. Alpine and continental glaciers are nature’s bulldozers and the braded fluvial streams that are fed from their melt water effectively concentrate the contained gems from the glacial rubble.
Gem characteristics such as specific gravity, hardness, shape and durability will influence their related depositional environments and survivability, thus favoring the economic concentrations of certain gems in the fluvial milling environment.
Select case histories of a variety of placer deposits illustrate the practicality of applying detailed geology and sedimentology to placer gem exploration:
1. Australian Tertiary modified paleo-colluvial type sapphire deposits, derived from the weathering of alkaline basalts, have been a major global source of sapphires.
2. Namibian long-shore diamond distribution along the Atlantic Ocean coast constitutes the world’s most valuable diamond deposit, extending westward 100km to the continental shelf edge and 200km northward. The diamonds were originally liberated from the South African kimberlites (and possibly more distant sources) by post-Gondawana erosion of the southern African craton, which commenced in the humid Middle Cretaceous with the formation of the ancient Karoo and Kalahari Rivers. Subsequent erosion of these diamondiferous placers was accomplished by the Orange River in the Miocene. Prolonged winnowing of the diamonds increased their value by about 500%.
3. Fluvial reworking of glacial sediments in British Colombia, Canada, concentrated sapphires and garnets from several cubic kilometers of glacial material.
4. A fluvial diamond deposit in China’s Hunan province was deposited on completely weathered karst bedrock, which presents challenges to sampling and mining.
Role Of Beryllium In The Coloration Of Fe and Cr-doped Synthetic Corundum
Thailand is perceived as one of the gemstone refineries of the world. The experts from GIT shares their opinion (s) on the pros and cons of beryllium treatment in natural and synthetic corundum.
Visut Pisutha Arnond, Tobias Hager, Pornsawat Wathankul, Wilawan Atichat, Jitrin Nattachai, Chakkaphant Sutthirat, and Bootawee Sriprasert writes:
X-radiation and Be-diffusion heating experiments were performed on an iron-doped (colorless) synthetic corundum and a chromium-doped (pink) synthetic corundum to evaluate the role of beryllium in causing color in the Be-Fe-Al2O3 and Be-Cr-Al2O3 systems.
The iron-doped corundum, containing around 140-170 ppm by weight of Fe with negligible concentrations of other trace elements, was irradiated with X-rays (60 kV, 53 mA) for 30 minutes, then the color was faded for one hour with a 100-watt light bulb, and finally the sample was heat treated in a crucible with ground chrysoberyl in an electric furnace at 1780ºC in an oxidizing atmosphere for 50 hours. The chromium-doped corundum, containing around 160-210 ppm by weight of Cr with negligible concentrations of other trace elements, was also irradiated with X-rays (80 kV, 4mA) for 4 hours, then faded for 4 hours with a 100-watt light bulb, and subsequently heat treated with ground chrysoberyl at unspecified conditions by a Thai treater. At each stage of the experiments, the samples were photographed and UV-Vis absorption spectra were recorded.
Both the irradiation and Be-diffusion experiments on the iron-doped synthetic corundum created defect centers that had similar UV-Vis absorption curves and produced yellow coloration. The yellow color was unstable when induced by irradiation, but was stable after Be-diffusion.
Experiments on the chromium-doped synthetic corundum produced orange coloration (and similar UV-Vis absorption patterns) by both irradiation and Be-diffusion heating methods. Again, the orange color was unstable when induced by irradiation (and quickly faded to pink), but remained stable after Be-diffusion. These results confirm that divalent Be acts as a stabilizer of defect centers or color centers in iron-doped and chromium-doped synthetic corundum. Hence, the spectrum produced by the irradiation of Fe-doped or Cr-doped synthetic corundum was attributed to metal-related unstable color centers, while that produced in synthetic corundum doped with Be + Fe + or Be + Cr was caused by Be²+ + metal-related stable color centers.
Visut Pisutha Arnond, Tobias Hager, Pornsawat Wathankul, Wilawan Atichat, Jitrin Nattachai, Chakkaphant Sutthirat, and Bootawee Sriprasert writes:
X-radiation and Be-diffusion heating experiments were performed on an iron-doped (colorless) synthetic corundum and a chromium-doped (pink) synthetic corundum to evaluate the role of beryllium in causing color in the Be-Fe-Al2O3 and Be-Cr-Al2O3 systems.
The iron-doped corundum, containing around 140-170 ppm by weight of Fe with negligible concentrations of other trace elements, was irradiated with X-rays (60 kV, 53 mA) for 30 minutes, then the color was faded for one hour with a 100-watt light bulb, and finally the sample was heat treated in a crucible with ground chrysoberyl in an electric furnace at 1780ºC in an oxidizing atmosphere for 50 hours. The chromium-doped corundum, containing around 160-210 ppm by weight of Cr with negligible concentrations of other trace elements, was also irradiated with X-rays (80 kV, 4mA) for 4 hours, then faded for 4 hours with a 100-watt light bulb, and subsequently heat treated with ground chrysoberyl at unspecified conditions by a Thai treater. At each stage of the experiments, the samples were photographed and UV-Vis absorption spectra were recorded.
Both the irradiation and Be-diffusion experiments on the iron-doped synthetic corundum created defect centers that had similar UV-Vis absorption curves and produced yellow coloration. The yellow color was unstable when induced by irradiation, but was stable after Be-diffusion.
Experiments on the chromium-doped synthetic corundum produced orange coloration (and similar UV-Vis absorption patterns) by both irradiation and Be-diffusion heating methods. Again, the orange color was unstable when induced by irradiation (and quickly faded to pink), but remained stable after Be-diffusion. These results confirm that divalent Be acts as a stabilizer of defect centers or color centers in iron-doped and chromium-doped synthetic corundum. Hence, the spectrum produced by the irradiation of Fe-doped or Cr-doped synthetic corundum was attributed to metal-related unstable color centers, while that produced in synthetic corundum doped with Be + Fe + or Be + Cr was caused by Be²+ + metal-related stable color centers.
Friday, June 08, 2007
The Hidden Transparency
Chaim Even-Zohar writes about supplier of choice contracts + DTC's problems communicating with the sightholders @ http://www.idexonline.com/portal_FullEditorial.asp
Subjectivity In Gemology
How true! In a way gemology is a magic blend of subjectivity + objectivity + the expert who knows how to connect with the world makes all the difference in a day. Can anyone express the allure, fineness, attraction and glamor in alpha numerical notation? I doubt it.
Ronald Ringsrud (Ronald Ringsrud Co, California) writes:
The analytical mind cannot encapsulate the full experience of viewing a beautiful gem. The detailed objective perceptions of the intellect are supplemented by another style of perception—that of subjective perception. It is holistic and devoid of the mental activity of analysis.
Connoisseurs of gems develop the ability, during a lifetime of viewing fine gems, to go beyond the boundaries of the intellect and witness the glorious aesthetics that a fine gemstone has to offer. From a physiological standpoint, this could be called shifting from brain activity dominated by the left hemisphere (responsible for analysis and discrimination) to that of the right hemisphere (contextual and nonverbal functions).
Gemology’s fullest expression as a discipline is exemplified when both objective and subjective approaches are used. Therefore, physics, optics, and chemistry are taught in gemological institutes alongside history, romance, and folklore. The work of gemologists Dr Edward Gubelin expressed not only objective science but also subjectivity; gemstone certificates from his laboratory had the usual page of objective determinations for the gemstone, but also a page of subjective description outlining the beauty, uniqueness, rarity of the gem.
Dr Gubelin went to encourage work in the use of poetry to describe gemstone aesthetics, which, in an industry sustained by the romancing sale of gemstones, should be recognized as worthy of the highest endeavor.
Fredrick Kunz decried the arbitrary alteration of the birthstone chart by an association of jewelers in 1912. He recognized the multicultural reality that gemstones are special to people born on certain months. Modern understanding of an ancient eastern astrological system sheds new light on this. Practitioners of traditional Asian medicine prescribed gems not only as talismans but also as pharmaceuticals.
Gemology is perhaps more suited to address subjectivity than other sciences simply because its focus, gemstones, involves the complete expressions of the highest subjective qualities: allure, fineness, attraction, glamour, and charm. The role of subjectivity in gemology is interdisciplinary and should elevate our expectations of future gemologists and gemstone dealers.
Ronald Ringsrud (Ronald Ringsrud Co, California) writes:
The analytical mind cannot encapsulate the full experience of viewing a beautiful gem. The detailed objective perceptions of the intellect are supplemented by another style of perception—that of subjective perception. It is holistic and devoid of the mental activity of analysis.
Connoisseurs of gems develop the ability, during a lifetime of viewing fine gems, to go beyond the boundaries of the intellect and witness the glorious aesthetics that a fine gemstone has to offer. From a physiological standpoint, this could be called shifting from brain activity dominated by the left hemisphere (responsible for analysis and discrimination) to that of the right hemisphere (contextual and nonverbal functions).
Gemology’s fullest expression as a discipline is exemplified when both objective and subjective approaches are used. Therefore, physics, optics, and chemistry are taught in gemological institutes alongside history, romance, and folklore. The work of gemologists Dr Edward Gubelin expressed not only objective science but also subjectivity; gemstone certificates from his laboratory had the usual page of objective determinations for the gemstone, but also a page of subjective description outlining the beauty, uniqueness, rarity of the gem.
Dr Gubelin went to encourage work in the use of poetry to describe gemstone aesthetics, which, in an industry sustained by the romancing sale of gemstones, should be recognized as worthy of the highest endeavor.
Fredrick Kunz decried the arbitrary alteration of the birthstone chart by an association of jewelers in 1912. He recognized the multicultural reality that gemstones are special to people born on certain months. Modern understanding of an ancient eastern astrological system sheds new light on this. Practitioners of traditional Asian medicine prescribed gems not only as talismans but also as pharmaceuticals.
Gemology is perhaps more suited to address subjectivity than other sciences simply because its focus, gemstones, involves the complete expressions of the highest subjective qualities: allure, fineness, attraction, glamour, and charm. The role of subjectivity in gemology is interdisciplinary and should elevate our expectations of future gemologists and gemstone dealers.
Three Days Of The Condor
Memorable quote (s) from the movie:
Kathy (Faye Dunaway): You... you have a lot of very fine qualities. But...
Joe Turner (Robert Redford): What fine qualities?
Kathy (Faye Dunaway): You have good eyes. Not kind, but they don't lie, and they don't look away much, and they don't miss anything. I could use eyes like that.
Joe Turner (Robert Redford): But you're overdue in Vermont. Is he a tough guy?
Kathy (Faye Dunaway): He's pretty tough.
Joe Turner (Robert Redford): What will he do?
Kathy (Faye Dunaway): Understand, probably.
Joe Turner (Robert Redford): Boy. That is tough.
Kathy (Faye Dunaway): You... you have a lot of very fine qualities. But...
Joe Turner (Robert Redford): What fine qualities?
Kathy (Faye Dunaway): You have good eyes. Not kind, but they don't lie, and they don't look away much, and they don't miss anything. I could use eyes like that.
Joe Turner (Robert Redford): But you're overdue in Vermont. Is he a tough guy?
Kathy (Faye Dunaway): He's pretty tough.
Joe Turner (Robert Redford): What will he do?
Kathy (Faye Dunaway): Understand, probably.
Joe Turner (Robert Redford): Boy. That is tough.
Wine Pirates
I think the colored stone and diamond industry should learn a lot from the wine industry. Though subjective, they do have grading standard (s) that's understood worldwide + the identification of fake wines via high tech, user-friendly gadgets should be a wake up call for the gem and jewelry industry.
Bottle Tech Aims To Foil Wine Pirates
Michelle Locke (AP) writes:
At Colgin Cellars, a kiss is not just a kiss.
For years, vintner Ann Colgin has sealed bottles of her sought-after wine headed for auction with a bright-red lipsticked kiss on the label, a charming, and undeniably personal, certificate of authenticity.
But with concerns growing about counterfeiters, she and other Napa Valley vintners are turning to high-tech fraud prevention so customers can feel confident they're taking home genuine wine.
Colgin, who hasn't yet had someone attempt to fake her wine and hopes to keep it that way, recently signed a deal with Eastman Kodak Co. on a system that employs invisible markers added to inks and other packaging components.
"Our wine is essentially a luxury good and I do believe that these rare and collectible luxury goods are targets," said Colgin, whose ultra-premium wines can fetch hundreds of dollars a bottle at auction.
With the new system, buyers at auctions and other secondary markets can ask the winery to scan their labels if they have any doubts, although the measures are primarily intended to put off counterfeiters.
It's hard to gauge how wide a problem counterfeits are in the U.S. wine industry, which according to a recent industry commissioned study pumps $162 billion a year into the economy, including grape-growing, tourism and other related impacts.
Wine Spectator magazine has reported that some experts believe as much as 5 percent of wines sold in secondary markets such as auctions may be counterfeit, although others consider that figure too high.
Unlike CD and DVD counterfeiting, wine piracy hasn't become a noticeable drain on the industry yet, so U.S. vintners are acting defensively.
There have been cases of counterfeit wines reported in Europe and China, and this spring there were reports that federal authorities in New York were investigating whether counterfeits were passed off as rare vintages, including some said to be part of Thomas Jefferson's collection. According to a lawsuit believed to have partly prompted the investigation, five bottles of wine — including four said to be owned by Jefferson — sold for $500,000.
Regardless of how many phony pinots are out there, it seems clear that interest in preventing fraud has spiked as new technology has become available, said Daniel Welty, marketing manager for Petaluma-based John Henry Packaging, which prints labels for wineries as well as other clients.
"It's more of a case the tools are becoming more available to combat the problem," he said. Anti-fraud measures being explored include tamper-proof seals, radio-frequency identification chips sunk into corks and using inks that only show up under special lights.
The Kodak technology used by Colgin and three other high-end Napa wineries involves putting proprietary markers, which Kodak will describe only as a "forensically undetectable material" into things such as printing inks, varnishes, paper, etc. that can only be detected by a Kodak handheld reader, also proprietary, which incorporates laser technology.
The idea is to come up with something easy to use and hard to detect, meaning it's that much harder for counterfeiters to figure out and copy, said Steve Powell, general manager and director for Security Solutions, Kodak's Graphic Communications Group.
The John Henry packaging company is using technology developed by Hewlett-Packard Co. to develop multicolored codes or graphics into labels. Colors and character combinations can be constantly changed to thwart copycats, Welty said.
The codes can be microprinted, so they're visible only with magnification, or in type that can be easily read.
"It's really cool. It's really simple, and nobody can know what the next codes are," he said. Fine wine can be expensive straight from the shelf, but when it comes to charity affairs, such as the Napa Valley annual wine auction going on this week, prices can go sky high.
Last year's high bid was $1.05 million for five large-format bottles of Staglin Family Vineyard Meritage blend, along with a trip to France. Like Colgin, the Staglins haven't run across fakes so far, but they decided to take a preemptive step and use the Kodak system on large bottles that are likely to end up being traded, said Garen Staglin.
"We want to be sure that we can give our customers the assurance of the integrity of our brand and label after we spent so much time and effort to try to accomplish what we've done over the years," he said.
In San Francisco, Jerome Zech, CEO of WineBid.com, which had $22.5 million in sales last year, doesn't think wine fraud is prevalent.
But with some high-end wines starting at $500 a bottle for pre-release prices, he's all for the industry's move toward anti-counterfeiting measures. "It'll help them and it'll help us as well."
WineBid's officials authenticate wine by only dealing with people they trust and checking bottles against a vast database, Zech said. If something seems off, "we just don't even question whether or not we would put it on our site. We would just reject the bottle."
So when someone showed up with two bottles of a famous French wine — and the glass was different for each bottle, "We go, Are you joking? Where did you get these things," Zech said. "He had some story, and we just said, "Sorry."
More info @ http://news.yahoo.com/s/ap/20070606/ap_on_bi_ge/genuine_wine
Bottle Tech Aims To Foil Wine Pirates
Michelle Locke (AP) writes:
At Colgin Cellars, a kiss is not just a kiss.
For years, vintner Ann Colgin has sealed bottles of her sought-after wine headed for auction with a bright-red lipsticked kiss on the label, a charming, and undeniably personal, certificate of authenticity.
But with concerns growing about counterfeiters, she and other Napa Valley vintners are turning to high-tech fraud prevention so customers can feel confident they're taking home genuine wine.
Colgin, who hasn't yet had someone attempt to fake her wine and hopes to keep it that way, recently signed a deal with Eastman Kodak Co. on a system that employs invisible markers added to inks and other packaging components.
"Our wine is essentially a luxury good and I do believe that these rare and collectible luxury goods are targets," said Colgin, whose ultra-premium wines can fetch hundreds of dollars a bottle at auction.
With the new system, buyers at auctions and other secondary markets can ask the winery to scan their labels if they have any doubts, although the measures are primarily intended to put off counterfeiters.
It's hard to gauge how wide a problem counterfeits are in the U.S. wine industry, which according to a recent industry commissioned study pumps $162 billion a year into the economy, including grape-growing, tourism and other related impacts.
Wine Spectator magazine has reported that some experts believe as much as 5 percent of wines sold in secondary markets such as auctions may be counterfeit, although others consider that figure too high.
Unlike CD and DVD counterfeiting, wine piracy hasn't become a noticeable drain on the industry yet, so U.S. vintners are acting defensively.
There have been cases of counterfeit wines reported in Europe and China, and this spring there were reports that federal authorities in New York were investigating whether counterfeits were passed off as rare vintages, including some said to be part of Thomas Jefferson's collection. According to a lawsuit believed to have partly prompted the investigation, five bottles of wine — including four said to be owned by Jefferson — sold for $500,000.
Regardless of how many phony pinots are out there, it seems clear that interest in preventing fraud has spiked as new technology has become available, said Daniel Welty, marketing manager for Petaluma-based John Henry Packaging, which prints labels for wineries as well as other clients.
"It's more of a case the tools are becoming more available to combat the problem," he said. Anti-fraud measures being explored include tamper-proof seals, radio-frequency identification chips sunk into corks and using inks that only show up under special lights.
The Kodak technology used by Colgin and three other high-end Napa wineries involves putting proprietary markers, which Kodak will describe only as a "forensically undetectable material" into things such as printing inks, varnishes, paper, etc. that can only be detected by a Kodak handheld reader, also proprietary, which incorporates laser technology.
The idea is to come up with something easy to use and hard to detect, meaning it's that much harder for counterfeiters to figure out and copy, said Steve Powell, general manager and director for Security Solutions, Kodak's Graphic Communications Group.
The John Henry packaging company is using technology developed by Hewlett-Packard Co. to develop multicolored codes or graphics into labels. Colors and character combinations can be constantly changed to thwart copycats, Welty said.
The codes can be microprinted, so they're visible only with magnification, or in type that can be easily read.
"It's really cool. It's really simple, and nobody can know what the next codes are," he said. Fine wine can be expensive straight from the shelf, but when it comes to charity affairs, such as the Napa Valley annual wine auction going on this week, prices can go sky high.
Last year's high bid was $1.05 million for five large-format bottles of Staglin Family Vineyard Meritage blend, along with a trip to France. Like Colgin, the Staglins haven't run across fakes so far, but they decided to take a preemptive step and use the Kodak system on large bottles that are likely to end up being traded, said Garen Staglin.
"We want to be sure that we can give our customers the assurance of the integrity of our brand and label after we spent so much time and effort to try to accomplish what we've done over the years," he said.
In San Francisco, Jerome Zech, CEO of WineBid.com, which had $22.5 million in sales last year, doesn't think wine fraud is prevalent.
But with some high-end wines starting at $500 a bottle for pre-release prices, he's all for the industry's move toward anti-counterfeiting measures. "It'll help them and it'll help us as well."
WineBid's officials authenticate wine by only dealing with people they trust and checking bottles against a vast database, Zech said. If something seems off, "we just don't even question whether or not we would put it on our site. We would just reject the bottle."
So when someone showed up with two bottles of a famous French wine — and the glass was different for each bottle, "We go, Are you joking? Where did you get these things," Zech said. "He had some story, and we just said, "Sorry."
More info @ http://news.yahoo.com/s/ap/20070606/ap_on_bi_ge/genuine_wine
Amethyst Mining In Zambia
Here is an insider's view on amethyst mining in Zambia. Amethyst is found worldwide, but new localities can be always full of surprises.
Bjorn Anckar (European Union Mining Sector Diversification Programme, Lusaka, Zambia) writes:
One of the world’s largest producers of amethyst is Republic of Zambia in south-central Africa. Amethyst mining takes place in several parts of the country, but only three localities have any significance in the gem trade. The most important occurrence is the Mapatizya mining area in the Kalomo District of southern Zambia. Amethyst has been mined here since its discovery in the late 1950s. At present there are about 60 registered mining plots but only about 10 can be considered active producers. Currently, there is one large operator and a few moderate-scale operations. There are also a number of small scale mining operations as well as an abundance of artisanal miners and illegal diggers. About 5000 people have settled in the immediate area and depend on amethyst mining for their livelihood. The local climate is very arid, and agriculture is at the subsistence level or lower. The poverty of the area is striking.
Amethyst mining by the large and moderate scale operators is accomplished in open pits using bulldozers and excavators. Small scale operators dig pits and tunnels using only picks and shovels. Processing is very labor intensive, and includes washing, sorting, cobbing, sawing and final sizing/grading of large amounts of mineral material.
Production in Zambia over the last decade averaged about 1000 tonnes of amethyst annually. The vast majority of this production is low grade and mostly exported to China for carving and bead making. A small portion of the total production constitutes facet grade with a vivid purple Siberian hue. Faceted amethyst from Zambia ranges from melee to >50 carats. Heat treatment is not performed, as the material turns an unattractive grayish green. Frequent bush fires and intense sunlight in the area have turned all surface exposed amethyst veins to this color.
Amethyst mines are also located in central Zambia, in Chief Kaindu’s area north-northwest of Mumbwa. The area is most noted for its production of specimens of attractive amethyst druses; some are quite large and weigh several tones. The crystals are generally large, ranging from 2 to 13cm. One locality, the Lombwa mine, produces material that shows patchy portions of distinct citrine and amethyst, but the two colors tend to blend and the material is difficult to cut into attractive pieces of ametrine.
A vast area with several amethyst mines is located along the border of Zambia and the Democratic Republic of Congo, between Solwezi and Mwinilunga in northwestern Zambia. The material is often very clear but tends to be pale and is mainly exported to China for carving and bead making. Amethyst from this area responds well to heating, and a large portion of the production is treated to citrine. The Chafukuma mine is considered the producer of the best quality amethyst in this area.
Bjorn Anckar (European Union Mining Sector Diversification Programme, Lusaka, Zambia) writes:
One of the world’s largest producers of amethyst is Republic of Zambia in south-central Africa. Amethyst mining takes place in several parts of the country, but only three localities have any significance in the gem trade. The most important occurrence is the Mapatizya mining area in the Kalomo District of southern Zambia. Amethyst has been mined here since its discovery in the late 1950s. At present there are about 60 registered mining plots but only about 10 can be considered active producers. Currently, there is one large operator and a few moderate-scale operations. There are also a number of small scale mining operations as well as an abundance of artisanal miners and illegal diggers. About 5000 people have settled in the immediate area and depend on amethyst mining for their livelihood. The local climate is very arid, and agriculture is at the subsistence level or lower. The poverty of the area is striking.
Amethyst mining by the large and moderate scale operators is accomplished in open pits using bulldozers and excavators. Small scale operators dig pits and tunnels using only picks and shovels. Processing is very labor intensive, and includes washing, sorting, cobbing, sawing and final sizing/grading of large amounts of mineral material.
Production in Zambia over the last decade averaged about 1000 tonnes of amethyst annually. The vast majority of this production is low grade and mostly exported to China for carving and bead making. A small portion of the total production constitutes facet grade with a vivid purple Siberian hue. Faceted amethyst from Zambia ranges from melee to >50 carats. Heat treatment is not performed, as the material turns an unattractive grayish green. Frequent bush fires and intense sunlight in the area have turned all surface exposed amethyst veins to this color.
Amethyst mines are also located in central Zambia, in Chief Kaindu’s area north-northwest of Mumbwa. The area is most noted for its production of specimens of attractive amethyst druses; some are quite large and weigh several tones. The crystals are generally large, ranging from 2 to 13cm. One locality, the Lombwa mine, produces material that shows patchy portions of distinct citrine and amethyst, but the two colors tend to blend and the material is difficult to cut into attractive pieces of ametrine.
A vast area with several amethyst mines is located along the border of Zambia and the Democratic Republic of Congo, between Solwezi and Mwinilunga in northwestern Zambia. The material is often very clear but tends to be pale and is mainly exported to China for carving and bead making. Amethyst from this area responds well to heating, and a large portion of the production is treated to citrine. The Chafukuma mine is considered the producer of the best quality amethyst in this area.
Subscribe to:
Posts (Atom)