The 632-carat natural uncut emerald of Colombian origin gets its name from the daughter of the mine owner in Chivor, in the southeastern region of the Colombian emerald belt, high up in the Andes Mountains, where the rare bi-hexagonal crystal was discovered, in the year 1920. Chivor and Muzo emerald mines are ancient emerald mines worked by the indigenous Aztecs, but later re-discovered by the Spanish in 1537 and 1559 respectively. Production from both these mines have taken place intermittently since then and continues to this day. Fritz Klein, who discovered the Patricia Emerald in 1920, had taken the Chivor Emerald Mine on short term lease from the Colombian Government
It was Fritz Klein who donated the rare emerald crystal to the American Museum of Natural History. The emerald came to be known as the "Patricia Emerald" after his daughter, but according to a different point of view, the emerald was actually named after the Patron Saint of Ireland, St. Patrick, venerated by Catholics, Anglican, Lutheran and Orthodox Churches, and was originally known as "Patrizius" in the Spanish Language, which subsequently became the "Patricia Emerald."
© AMNH, New York City
The "Patricia Emerald" is one of the largest gem-quality emeralds in the world, still preserved in its original natural crystalline-state. Emeralds usually crystallize in the hexagonal crystal system, forming flattened or elongated hexagonal (six-sided) prisms with pinacoidal terminations. But, the "Patricia Emerald" is unique in that it is di-hexagonal or twelve-sided. One of the characteristic features of emeralds produced in the Chivor mines is that the crystals tend to be more elongated than those of other mines like Muzo and Coscuez, and the "Patricia Emerald" exhibits this character. The crystal has a length of 6.35 cm and a width of 2.54 cm. The weight of the crystal is 126.4 g equivalent to 632 carats. The color of the emerald is a deep green with a slightly bluish caste characteristic of Chivor emeralds. Chivor emeralds also have much less inclusions than either Muzo or Coscuez emeralds, but they are slightly lighter in color. The combination of the unique di-hexagonal elongated shape, deep green color and the size of the crystal, makes the "Patricia Emerald" one of the most famous emeralds in the world. The emerald is the property of the American Museum of Natural History.
Emeralds belong to the group of minerals called Beryls, which are actually Beryllium Aluminum Silicates having the formula Be3Al2(SiO3)6. Beryls belong to a sub-class of silicates, called cyclosilicates, in which six tetrahedral silicate ions (SiO4)‾ link together to form a hexagonal ring-shaped structure, which is finally reflected in the crystal habit, which is a hexagonal-shaped crystal. The negative charges on the hexagonal rings are balanced by the positive charges on the aluminum and beryllium ions, which hold the rings together. The deep green color of emeralds is caused by traces of chromium and/or vanadium atoms in the crystal structure which replaces the aluminum atoms. The green color of Colombian emeralds seem to vary with the source. The Muzo emeralds are a deep grass-green color, the Chivor emeralds are a deep-green color with a bluish undertone, the Coscuez and Penas Bancas emerlads are deep-green with a yellowish undertone and the Gachala emeralds are pale green in color.
The presence of flaws and inclusions, known as "Jardin" is a characteristic feature of all natural emeralds, and reflects their turbulent genesis, formed in hydrothermal veins, pegmatites and the contact zones of igneous intrusions invading the aluminous schist, shale and impure limestone. The turbulent conditions in which emeralds are produced, prevents the formation of large flawless crystals, and thus emeralds usually contain cracks and fissures. The Chivor and Muzo emeralds have three phase inclusions containing gas, fluid and crystals of halite. The Chivor emeralds also contain pyrite and albite inclusions. It is because of the presence of cracks and fissures in natural emeralds, that oil treatment of emeralds is generally accepted in the trade, in which the oil fills the cracks and fissures, and if the refractive index of the oil used is very close to that of the emerald, the cracks and fissures become invisible. It is because of this treatment, that ultrasonic cleaning and the use of soaps and detergents for cleaning emeralds is not recommended.
The presence of inclusions make emeralds quite brittle in spite of their hardness, which is 7.5 to 8.0 on the Mohs scale. Thus cutting of emeralds is a difficult task even for the most skilled gem-cutters, and the special cut known as the emerald-cut, which is a rectangular or square shaped step-cut, with beveled corners has been developed, to protect the gemstone from mechanical strain, while bringing out its intrinsic beauty.
The specific gravity and refractive index of emeralds are quite low. The specific gravity varies between 2.67 and 2.78, and the refractive index between 1.565 and 1.599, and both of them seem to vary with the mine of origin. The Chivor emeralds have a slightly lower specific gravity and refractive index. The specific gravity is equal to 2.69 and the refractive index 1.571. The Muzo emeralds have a specific gravity of 2.71 and refractive index of 1.578.
The dispersion of emeralds is also low, equal to 0.014. The low dispersion and refractive index of emeralds decrease their "fire" and brilliance, which is to some extent compensated by the deep green color, the vitreous luster and transparency of the stone.
Emeralds have a distinct dichroism from blue-green to yellow-green. In ultra-violet light natural emeralds do not show any fluorescence, but artificial emeralds show a dull-red fluorescence. The low specific gravity and refractive index, distinct dichroism and the absence of fluorescence are the distinguishing properties of natural emeralds.
The Patricia emerald was discovered in the ancient Chivor mines of Colombia in 1920. Chivor, which is a historic and ancient emerald mining district of Colombia is situated northeast of Bogota, high up in the Andes. The region is rugged and inaccessible with thick forest vegetation. Chivor and Gachala mines are the two major mines situated in the district. The Chivor mine is situated 2,300 meters above sea level on a mountain side. These mines were originally mined by the Chibcha Indians, who traded the stones for other goods from Peru and Mexico. The rocks in this district are black shale and sandstone. Emeralds occur in sparse veins with pyrite, quartz and albite.
The three most ancient emerald mines in Colombia that had been worked for a long time by the indigenous Indian tribes prior to the arrival of the Spaniards in the New World, are the Muzo, Somondoco (Chivor) and Coscuez mines. These mines seem to have been worked for at least 500 years before the arrival of the Spanish, but archaeological evidence seem to suggest that the Incas had used emeralds at least a thousand years before Christ. The Geological age of the Chivor emerald deposits date back to about 65 million years ago during the cretaceous period. Somondoco was the original name used for the Chivor mines. The Spaniards first saw the brilliant green stones in Peru and Mexico used as ornaments by the Indian tribes or offered to their Gods in temples, as the emeralds were considered as sacred stones. Emeralds were also used in their burial rites, and the green stones were buried together with their dead. But, the Spanish colonizers were not aware of the actual source of the emeralds, but now we know that the only source of all the emeralds, that appeared to be widely distributed throughout northwest South America at that time, were the three ancient mines of Muzo, Somondoco and Coscuez in Colombia.
In 1537, Gonzalo Jimenez de Quesada conquered the interior of Colombia and subsequently entered the valley of Guacheta, the heart of the Chibcha domain, where he was warmly received by the Chibcha Indian chief, who also gifted him with nine large emeralds. Gonzalo Jimenez was marveled by the gifts he received, but pretended not to be overenthusiastic, as any expression of interest would have aroused the suspicions of his host. He knew immediately that the valuable emeralds he received as gifts, must have been sourced locally and knowing fully well that the Chibcha Indians would never voluntarily reveal the source of their emeralds, assigned some of his soldiers to comb the country side in an attempt to locate the site, without arousing the suspicions of the Indians. Finally after more than a year of relentless and painstaking search, two of his captains succeeded in locating the source, in a wild region situated about 95km southwest of Tunja, the main settlement in that region. The soldiers found that the mines had been exploited by the Indians for quite some time, and that they worked there mainly during the rainy seasons. The area where these mines were located, subsequently came to be known as Somondoco and later as Chivor.
In spite of this major breakthrough, the Spaniards did not immediately undertake any systematic exploitation of these deposits due mainly to the inhospitable terrain and the inaccessibility of the region. However in the 1540s the Spanish colonial government based in Bogota, did commence exploitation of these mines. The Chivor mines were said to be developed and operated under incredibly cruel conditions. Mining operations in the Chivor mines were intermittent, and the mines were closed from time to time due to various reasons such as the barbaric cruelty towards the workers resulting in frequent work stoppages, the lack of proper equipment for mining, and blatant corruption. Eventually conditions in the Chivor mines became so brutal and unbearable that the mine had to be closed down indefinitely in 1675, by royal decree issued by King Charles II. The abandoning of the mines led to the surrounding jungle reclaiming the area. The Chivor mines were once again brought back into full production only in 1911.
A gruesome account of the atrocities committed by the Spanish Conquistadors during the conquest of the Americas is given by Bartolome de Las Casas, who was a missionary and conquistador himself. Going into details of such atrocities may not be relevant to the central theme of this web page, suffice it to say that this period may be one of the darkest pages in the history of mankind, which perhaps might elevate modern day despots like Idi Amin or Saddam Hussein to the status of saints. Modern day opinion about the Spanish conquest of the Americas as expressed by Spanish humanists, intellectuals, clergymen and writers, state that the conquest is an unfortunate fact of history, morally questionable, driven by the greed for gold and other valuable minerals, with the destruction and disappearance of cultures of native peoples, an unparalleled event which stands out above all other consequences of the Conquistador's actions.
After Columbia gained its independence from Spain in 1819, the emerald holdings mainly the Muzo mines, became the property of the new-born republic, but the Republican Government lacked the organization and expertise to run these mines. Nevertheless, the Government realizing the potential of the mines as a source of revenue, gave them out on lease from 1828 to 1848, with the condition that 10% of the profits from the mines should go to the government. In 1848, the Congress in Bogota decreed that all emerald deposits in the country should be worked under the direction of the state, thus bringing in tighter controls of the industry. However private companies could operate under lease with their entire production being taxed. From 1848 to 1909 there seem to be a general decline in the production due to government intervention, mismanagement, corruption and the lack of scientific guidance in the exploitation. In 1909, the Government entered into a partnership with an English company, the Colombian Emerald Mining Co. Ltd. and the emerald deposits of the Muzo mine, were actively exploited for some time.
In 1896, the mining engineer Don Francisco Restrepo was able to re-discover the site of the abandoned Chivor mines, in the Andes mountain range, 2,300 meters above sea level, 70 miles northeast of Bogota, in a rugged and inaccessible region covered with thick forest, after studying documents written by a Spanish priest. In 1901, Francisco Restrepo and his associate Fritz Klein, successfully negotiated a deal with the government that bestowed perpetual title of the area to them. The agreement stipulated that title for the land would be conveyed to them only after the payment of an amount equivalent to the total of twenty years of taxes on the land. Accordingly, after the payment of the said amount, Francisco Restrepo and Fritz Klein were granted perpetual title for the area. The clearing of the jungle in the mine area and its immediate environs then began, and the mine was reopened under the name "Compania de Minas de Chivor" and operations commenced in 1911. When production in the mines increased significantly, the government reneged on its own agreement and tried to impose additional taxes on the company. The company sued the government in 1912, and the Colombian Supreme Court in 1913 upheld the original agreement. The Supreme Court nullified efforts by the government to tax the company, and reaffirmed that the property was forever free of taxation. The Supreme Court also forbid any further attempts by government to tax or obtain control of the property.
In 1915, "Compania de Minas de Chivor" was dissolved, and a new venture known as the "Sociedad Ordinaria de Minas des Esmeraldas de Chivor, SA" was formed, but subsequently, the rights to Chivor were sold to Wilson E, Griffith and Carl K. Mcfadden, representing the Colombian Emerald Development Corporation of New York, which in the year 1919 was reorganized as Chivor Emerald Mines Inc. In 1931, production at Chivor was drastically curtailed, and later suspended due to political strife, and the mines remained close until 1936. In 1937, Chivor Emerald Mines Inc.resumed operation, but on a restricted scale. Again in 1948 production in Chivor was reduced or suspended but later resumed. In 1951, the Chivor Emerald Mines Inc. declared bankruptcy and production was suspended. The Chivor mines were again in operation from time to time from 1960 onwards, under lease, by different companies, and whenever production was suspended illegal mining continued at the mines.
In 1996, the Chivor Emerald Corporation, a Canadian Company, purchased an 80% stake in the Colombian emerald mining company, Empresa Chivorena de Minas Ltda. The company used computer aided modern mining methods, that plots mining moves with three-dimensional diagrams. Initially, they found about $ 250,000 worth of emeralds by this method.
In the past exploration for emeralds mainly depended on intuition, and was a hit and miss operation that depended on one's luck. There have been instances where companies have gone bankrupt after sinking deep mines that unfortunately had not yielded a single emerald. But today, scientific exploration methods adopted have discovered emerald deposits that previously would have been missed. Today mining companies use sophisticated orbital and airborne remote sensing techniques to discover new emerald deposits, based on detailed investigations of the geology, geophysics, and geochemistry of mine sites. Besides, initial core drilling can give an assessment of the mineable reserves available. In Chivor, mechanized bulk mining have been introduced for the mass extraction of gemstones.
At the first World Emerald Congress held in Bogota in February 1998, reports had emerged that two of the three most important Colombian emerald mines are running out of rough. Opinions had been expressed that unless modern scientific exploration techniques are adopted soon, the world renowned premier quality emeralds from Colombia will soon be extinct, and dealers would have to seek for new sources of emeralds elsewhere. It was revealed at the conference that Colombia had not yet adopted most of the modern sophisticated techniques available for identifying new reserves. The following were identified among the factors militating against the adoption of such modern techniques :- 1) The lack of funds 2) Political instability 3) Physical dangers of working in violence-prone areas. 4) Reluctance of foreign investors to invest because of volatile political environment in the country.
According to the above account on the production history of the Chivor mines, Fritz Klein and Francisco Restrepo, had already sold their rights to the Chivor mines in 1915, and in the year 1920, when the "Patricia Emerald" was apparently discovered in Chivor, the mines were actually under the control of Colombian Emerald Development Corporation of New York. Thus an apparent contradiction arises between the actual facts and the generally accepted version of the discovery of the "Patricia Emerald," according to which the emerald was discovered in 1920, when the mines were under the control of Fritz Klein, who later donated the rough crystal to the American Museum of Natural History in New York, and called it the "Patricia Emerald" after his own daughter. Thus it is quite possible that the date of discovery of the emerald was actually somewhere between 1911 and 1915, when the mines were under the control of Fritz Klein and Fransico Restrepo, but was donated to the AMNH only in the year 1921.
The Chivor emerald crystals are longer than emeralds from other Colombian mines, and are bluish-green in color. The emeralds are also cleaner than the emeralds from Muzo and Cosquez, and sometimes do not require oiling with cedar wood oil. Besides the three phase inclusions found in all emeralds of Colombian origin, the characteristic inclusions found in the Chivor emeralds are pyrite and albite.
The specific gravity of the Chivor emeralds is 2.69, which is towards the lower side of the general specific gravity range for emeralds, that lies between 2.67 and 2.78. The refractive index of Chivor emeralds is 1.578, which is also towards the lower side of the general refractive index range of 1.565 to 1.599.
After the "Patricia Emerald" was presented to the American Museum of Natural History in New York, it was displayed in the Morgan Memorial Hall of Gems on the first floor, together with other famous gemstones such as the 563-carat "Star of India," of Sri Lankan origin, the world's largest and most famous blue star sapphire, the 100.32-carat "De Long Star Ruby" of Burmese origin, the 116.75-carat "Midnight Star Sapphire" a deep purple-violet star sapphire of Sri Lankan origin, and other cut as well as rough and famous gemstones. The "Patricia Emerald" has become one of the most prominent exhibits in the Hall of Gems. It is not known whether the "Patricia Emerlad" was among the 22 gemstones stolen on October 29, 1964, in the infamous burglary carried out by Jack Murphy, Allan Kuhn and others, which came to be known as the biggest jewel heist in the History of America. All the gem stones were eventually recovered except for the 16.25-carat "Eagle Diamond."
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4.The Gemstone Forecaster Vol 16, No. 2 - Part Two
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13. Precious Stones - Emeralds - minelinks.com
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