Historical Reading List: Emeralds from Colombia

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Emerald crystal in white and smoky calcite from the Coscuez Mine in Colombia. Courtesy of Bill Larson. Photo: Robert Weldon/GIA

For hundreds of years, the mines of Colombia have yielded many of the world’s finest emeralds. They were known to the Indian inhabitants prior to the arrival of the Spanish Conquistadors in the 1500s. After being introduced to emeralds in the spring of 1537 as a gift from the Boyacá Indians, over the following decades it was the Spanish who began to send them from what they called “New Grenada” back to Europe. Although emeralds had previously been known from Egypt and a small mining area in Austria (and perhaps from Central Asia), the material from Colombia was of much better quality. There are three main mining areas in the country – Muzo, Coscuez, and Chivor – located in two mountain belts 50 to 80 kilometers northeast of Bogotá.


This reading list was compiled to give you an opportunity to learn more about the history of emeralds from Colombia. A number of the articles were published in the 1800s and early 1900s – when many classical gem deposits of historical importance were discovered – and gemology and mineralogy became sciences. The list is presented in chronological order to emphasize the development of ideas over time. The list is not comprehensive, but a compilation of the some interesting gemological information that has often been forgotten or overlooked.

Many of the articles exist in the public domain and can be found online at digital libraries such as Hathitrust, Internet Archive, or other digital repositories. More recent publications can often be found in libraries, including the Richard T. Liddicoat Gemological Library. Abstracts of these articles can usually be found on the website of the original journal or magazine, and the article itself is often available for purchase from the publisher.

Regarding the GIA library’s holdings and on-site access, please contact the GIA library in Carlsbad.

Examen Chimique de l’Émeraude du Pérou [Chemical Examination of the Emerald from Peru (Colombia)], M.H. Klaproth, Annales de Chimie et de Physique, Series 1, Vol. 23, pp. 68-73, (1797). One of the first published chemical analyses of Colombian emerald (described incorrectly as coming from Peru).

De l’Aique Marine, ou Béril; et Découverte d’une Terre Nouvelle dans Cette Pierre [The Aquamarine, or Beryl; and the Discovery of a New Earth (Element) in the Stone], L.N. Vauquelin, Annales de Chimie, Vol. 26, pp. 155-169, (1798), and Analyse de l’Émeraude du Pérou [Analysis of an Emerald from Peru (Colombia)], Annales de Chimie, Vol. 26, pp. 259-265, (1798). The announcement made by a famous French chemist of the discovery of a new element (beryllium) in beryl, and the detection of chromium in an emerald from Colombia.

Recherches sur la Formation et al Composition des Émeraudes [Studies of the Formation and Composition of Emeralds], B. Lewy, Comptes Rendus Hebdomadaires des Séances de l’Académie des Sciences, Vol. 45, pp. 877-881, (1857). Using emeralds collected in Muzo, Colombia, the author chemically analyzed several samples but did not detect the presence of chromium, but found an amount of some organic substance. A more detailed version of the study is published in Annales de Chimie et de Physique, Vol. 53, pp. 5-20, (1858).

Researches on Emeralds and Beryls – Part 1: On the Colouring-Matter of the Emerald, G. Williams, London, Edinburgh, and Dublin Philosophical Magazine, 4th Series, Vol. 46, No. 306, pp. 314-326, (1873). Based on chemical analyses of beryl samples, and his experiments to fuse chromic oxide to create a green color in beryls, the author confirms the conclusion of Vauquelin on chromium being the coloring agent in emerald.

The Emerald, A.C. Hamlin, Lippincott’s Magazine, Vol. 11, No. 41, pp. 688-696, (1873). The history, lore, and sources of emeralds are discussed in this article.

Ueber die Columbischen Smaragden [On Colombian Emeralds], H.A. Schumacher, Zeitschrift der Gesellschaft für Erdkunde zu Berlin, 3rd Series, Vol. 10, pp. 38-62, (1875). The author presents a detailed history of the Colombian emerald.

[Curious Emerald Crystals], E. Bertrand, Bulletin de la Société Minéralogique de France, Vol. 2, p. 31, (1879). The first brief description of trapiche emeralds from Muzo is given.

Smaragdgruben von Muzo [Emerald mines of Muzo], W. Bergt, Geologische Studien in der Republik Colombia, Vol. 2, pp. 43-48, (1899). A review is given of Colombian emeralds, to include a list of published articles on the material.

Emerald Mines of Muzo and Coscuez, Author unknown, Monthly Bulletin of the Bureau of the American Republics, Vol. 10, No. 6, pp. 1074-1079, (1901). This article summarizes the conditions of the national government for private companies who wish to apply for leases to operate the emerald mines.

Emerald Mining in the Republic, Author unknown, Monthly Bulletin of the International Bureau of the American Republics, Vol. 13, No. 5, pp. 1349-1350, (1902). This is a summary report on the operation of the emerald mines in 1901.

Sur une Émeraude Étoilée de Muso [On a Starry Emerald from Muzo], W. Prinz, Académie Royale de Belgique – Bulletin de la Classe des Sciences, No. 2, pp. 283-289, (1903). A description of what is now called a “trapiche” emerald, and of some of the dark inclusions found in this material.

Emerald Mines of Colombia, Author unknown, Daily Consular and Trade Reports, No. 2325 (August 3), pp. 10-12, (1905). A brief description is given of the status of emerald mining around Muzo.

Sur les Minéraux Associés à l’Émeraude dans le Gisement de Muso (Nouvelle Grenade) [On the Minerals Associated with Emerald at the Muzo Deposit (New Grenada)], H. Hubert, Bulletin de Muséum d’Histoire Naturelle, No. 4, pp. 202-208, (1904). Information is provided on calcite, quartz, pyrite, parisite, and several other associated minerals.

The Emerald Mines of Colombia, Author unknown, Journal of the Society of Arts, Vol. 54, No. 2772, pp. 200-201, (1906). A brief description is given of the Muzo mines, which were owned at the time by the Colombian government.

The Emerald-Mines of Colombia, M. Watson, Chambers’s Journal, Vol. 86, No. 577, pp. 38-41, (1908). The author discusses the operation of the emerald mines beginning under the Spanish in the mid-1500s.

The Emerald Mines of Colombia, Author unknown, Pan-American Magazine, Vol. 8, No. 3, pp. 151-157, (1909). The history, geological setting, and operation of the emerald mines are described. The same article appears in Bulletin of the International Bureau of the American Republics, Vol. 28, No. 6, pp. 1027-1039, (1909).

The Newly Discovered Emerald Mines of Somondoco, E.B. Latham, School of Mines Quarterly, Vol. 32, No. 3, pp. 210-214, (1911). The author recounts the rediscovery of the long-lost Somondoco (Chivor) emerald mines in 1896.

Emeralds: Their Mode of Occurrence and Methods of Mining and Extraction in Colombia, C. Olden, Transactions of the Institution of Mining and Metallurgy, Vol. 21, pp. 193-209, (1911). The author gives a detailed description of the history and operations of the major emerald mines. The same article appeared in the Journal of the Royal Society of Arts, Vol. 63, No. 3264, pp. 685-690, (1915).

The Emerald – Its History and its Place Among Gems with some Facts about its Production, M.R. Ward, Jewelers’s Circular Weekly, Vol. 64, No. 18, pp. 61, 63, 65, 67 and No. 19, pp. 57, 59, (1912). The author provides some general information on emeralds.

Emerald Fields of Colombia, F.P. Gamba, Mining and Scientific Press, Vol. 107, No. 9, p. 345, (1913). A brief description is given of the Muzo and Chivor mines.

The Emerald Mines of Colombia, Author unknown, Bulletin of the Pan American Union, Vol. 38, (No. 6), pp. 839-843, (1914). A short description of the mines is presented. The article appeared in the Journal of Geography, Vol. 13, No. 1, pp. 16-17, (1914), and in the Journal of the Royal Society of Arts, Vol. 62, No. 3228, pp. 943-944, (1914).

The Emerald in Spanish America, J.E. Pogue, Bulletin of the Pan American Union, Vol. 43, No. 6, pp. 706-720, (1916). The author recounts the conquest of the emerald mines and their operation by the Spanish.

Beiträge zur Mineralogie von Columbien – Die Mineralien von Muzo [Contributions to the Mineralogy of Colombia – The Minerals of Muzo], M. Bauer, Zentralblatt für Mineralogie, Geologie und Paläontologie, pp. 481-485, (1916). The author gives information on the minerals in addition to beryl (emerald) found in the Muzo mine.

The Emerald Deposits of Muzo, Colombia, J.E. Pogue, Transactions of the American Institute of Mining Engineers, Vol. 55, pp. 910-934, (1917). Based on a visit to the mines in 1915, the author presents a detailed description of the geological setting of the emerald deposits. A summary of the article appeared in Mining and Scientific Press, Vol. 114, No. 8, p. 268, (1917), and in the Jewelers’ Circular Weekly, Vol. 74, No. 1, pp. 155, 157, (1917).

Emerald Mining in Colombia, Author unknown, Journal of the Royal Society of Arts, Vol. 66, No. 3440, pp. 757-758, (1918). Some brief information on emerald mining is presented.

The World’s Greatest Emerald Mine, L.E. Zeh, Southern Workman, Vol. 48, No. 2, pp. 73-76, (1919). The author discusses the Spanish conquest of Colombia and the emerald mines.

Die Smaragdlagerstätte von Muzo (Kolumbian) und Ihre Nähere Umgebung [The Emerald Deposits of Muzo (Columbia) and Its Nearby Surroundings], R. Scheibe, Neues Jahrbuch für Mineralogie, Geologie und Paläontologie, Vol. 54B, pp. 419-447, (1926). Article not seen.

The Chivor-Somondoco Emerald Mine of Colombia, P.W. Rainier, Transactions of the American Institute of Mining Engineers, Vol. 90, pp. 204-221, (1930). Article not seen.

Emerald Mining in Colombia, C.K. MacFadden, Gems & Gemology, Vol. 1, No. 6, pp. 149-154, (1934). A summary is presented of the history of the emerald mines and their production.

The Emerald Mines of Muzo, Colombia, South America, T. Clements, Gems & Gemology, Vol. 3, No. 9, pp. 130-138, (1941). The author reviews the geologic setting of the deposits and the mining methods used to recover emeralds.

“Green Fire”, P.W. Rainier, John Murray Publishers, London, (1943). This book is an adventure story of an explorer who came to Colombia in the early 20th century in search of emeralds.

The Muzo Emerald Zone, Colombia, South America, V. Oppenheim, Economic Geology, Vol. 43, No. 1, pp. 31-38, (1948). Based on a visit the previous year, the author describes the operations of the mine that did not appear to have changed much over the past four centuries.

Colombian Emerald Sources, R.L. Ives, Rocks & Minerals, Vol. 24, No. 7/8, pp. 339-345, (1949). A brief description of the main emerald deposits is presented.

Mineral Resources of Colombia – Emeralds, Q.D. Singewald, United States Geological Survey Bulletin, Vol. 964-B, pp. 115-120, (1950). A brief description of the emerald mines is presented in this resource survey.

Emeralds of Chivor, M. Lentz, Lapidary Journal, Vol. 5, No. 3, pp. 172-176, (1951). A brief report is given of a visit to the Chivor mine.

Emerald Mining in Colombia, G.H. Spence, The Gemologist, Vol. 27, No. 327, pp. 197-198, and No. 28, pp. 215-218, (1958). General information is presented on emerald mining.

The Emeralds of Chivor Today, P.W. Johnson, Lapidary Journal, Vol. 13, No. 4, pp. 516, 518-520, 522, 524, (1959). The author discusses a visit to the Chivor mine.

The Chivor Emerald Mine, P.W. Johnson, Journal of Gemmology, Vol. 8, No. 4, pp. 126-152, (1961). The history of the mine and a description of the deposit are discussed.

Trapiche Emeralds from Colombia, H.L. McKague, Gems & Gemology, Vol. 11, No. 7, pp. 210-213 and 223, (1964). The author discusses features of the unusual trapiche emeralds from Muzo.

The Present Status of Colombian Emerald Mining, R. Anderton, Lapidary Journal, Vol. 19, No. 3, pp. 374-377, (1965). A status report is presented on the emerald mining industry.

Trapiche Emeralds from Chivor and Muzo, Colombia: Nature and Origin, K. Nassau and K.A. Jackson, American Mineralogist, Vol. 55, No. 3/4, pp. 416-427, (1970), and in Lapidary Journal, Vol. 24, (April), pp. 82-86, and (June), p. 489, (1970). The authors present a description of trapiche emerald crystals and suggest a two-stage mechanism for their formation. They later published a correction in American Mineralogist, Vol. 55, No. 9/10, pp. 1808-1809, (1970).

Emerald Mining in Colombia: History and Geology, T. Feininger, Mineralogical Record, Vol. 1, No. 4, pp. 142-149, (1970). The history of emeralds is recounted, and the geological setting of each of the major mines, are discussed by the author.

The Lure of Chivor, P. Bancroft, Lapidary Journal, Vol. 25, No. 1, pp. 128-131, (1971). Some general information is given on Colombian emeralds.

Muzo Emerald Mine: A Visit, J.W. Tenhagen, Gems & Gemology, Vol. 14, No. 3, pp. 77-81, (1972). This short article describes a visit to the mine.

Sodium – A Geochemical Indicator of Emerald Mineralization in the Cordillera Oriental, Colombia, A.A. Beus, Journal of Geochemical Exploration, Vol. 11, No. 2, pp. 195-208, (1979). Emerald-bearing deposits are structurally controlled by the intersection of two fault systems. At the intersection, intense fracturing affected by sodium and carbonate metasomatism host the emerald mineralization. Sampling of stream sediments for their sodium content might be a useful exploration tool to locate new deposits.

Die Smaragdlagerstätten Kolumbiens [The Colombian Emerald Deposits], J. Hintze, Der Aufschluss, Vol. 30, No. 3, pp. 83-92, (1979). Article not seen.

“Emerald and Other Beryls”, J. Sinkankas, Chilton Book Company, Radnor, Pennsylvania, 665 pp., (1981). This book presents detailed information on all aspects of the varieties of beryl.

Emeralds of Colombia, P.C. Keller, Gems & Gemology, Vol. 17, No. 2, pp. 80-92, (1981). This article reviews the history, geologic setting, and mining of emeralds in the country.

The Oil Treatment of Emeralds in Bogota, Colombia, R. Ringsrud, Gems & Gemology, Vol. 19, No. 3, pp. 149-156, (1983). A description is given for the clarity treatment of emeralds using oil forced into surface-reaching fractures.

Die Kolumbianischen Smaragdlagerstätten Muzo und Chivor [The Colombian Emerald Deposits Muzo and Chivor], W. Schäfer, Lapis, Vol. 9, No. 4, pp. 9-23, (1984). Article not seen.

The Coscuez Mine: A Major Source of Colombian Emeralds, R. Ringsrud, Gems & Gemology, Vol. 22, No. 2, pp. 67-79, (1986). A description is given of one of the major emerald mines is presented.

Emeralds from Somondoco, Columbia: Chemical Composition, Fluid Inclusions and Origin, A. Kozlowski, P. Metz, and H.A.E. Jaramillo, Neues Jahrbuch für Mineralogie Abhandlungen, Vol. 159, pp. 23-49, (1988). The authors discuss chemical composition and fluid inclusion data that provide information on the geographic origin of emeralds.

Muzo Emerald, R. Ringsrud, Lapidary Journal, Vol. 41, No.10, pp. 27-34, (1988). The Muzo mine and its history are discussed.

Emerald and Gold Treasures of the Spanish Galleon Nuestra Señora de Atocha, R.E. Kane, R.C. Kammerling, R. Moldes, J.I. Koivula, S.F. McClure and C.R. Smith, Gems & Gemology, Vol. 25, No. 4, pp. 196-206, (1989). In September 1622, while returning to Spain from Havana, the Atocha and several other ships carrying gold, silver, emeralds, jewelry and other goods from the New World sank off of the Florida Keys during a violent storm. Treasures from two shipwrecks were recovered by divers between 1971 and 1985. The emeralds displayed typical features of gem material from Colombia, and in some instances, evidence that they had been submerged for long periods in seawater.

Hydrothermal Gem Deposits: The Emerald Deposits of Colombia, P.C. Keller, “Gemstones and Their Origins”, Springer, pp. 39-55, (1990). This book contains a chapter on the Colombian emerald mines.

A Gemmological Review of Colombian Emeralds, J.I. Koivula and R.C. Kammerling, South African Gemmologist, Vol. 4, No. 1, pp. 5-12, (1990). The authors summarize the key gemological properties of this material.

The Timeless Mystique of Emeralds, F. Ward, National Geographic Magazine, Vol. 7, pp. 38-69, (1990). Article not seen.

Les Gisements d’Émeraude de la Cordillère Orientale de la Colombie: Novuelles Données Métallogéniques [The Emerald Deposits of the Eastern Cordillera of Colombia: New Metallogenic Data], G. Giuliani, C.T. Rodriguez, and F. Rueda, Mineralium Deposita, Vol. 25, No. 2, pp. 105-111, (1990). Emeralds occur along with other minerals in calcite veins which fill fractures in hydrothermally altered shales. The source of the beryllium needed for emerald formation is somewhat uncertain.

Emeralds from Colombia, G. Bosshart, Journal of Gemmology, Vol. 22, No. 6, pp. 355-361, No. 7, pp. 409-425, and No. 8, pp. 500-503, (1991). The author reviews the gemological properties, treatment methods, and means of identification of Colombian emeralds.

The Chemical Properties of Colombian Emeralds, D. Schwarz, Journal of Gemmology, Vol. 23, No. 4, pp. 225-233, (1992). Chemical composition data on ninety emeralds are analyzed and discussed in this article.

Connoisseur's Choice: Beryl, Variety Emerald - Chivor Mine, Chivor, Colombia, Robert B. Cook, Rocks & Minerals, Vol. 68, No. 5, pp. 332-334 , (1993). This is a brief discussion of emeralds from Colombia.

Chemical Composition of Fluid Inclusions in Colombian Emerald Deposits, G. Giuliani, A. Cheilletz, J. Dubessy, and C.T. Rodriguez, Proceedings of the Eighth Quadrennial IAGOD Symposium, pp. 159-168, (1993). The emerald deposits are related to a hydrothermal alteration process with black sedimentary shales which generated the necessary components for emerald formation. Fluid inclusions studies indicate that complex saline palaeofluids were also involved. The authors suggest that the saline component of these fluids may have originated in evaporitic salt layers within the sequence of sediments.

“Emeralds”, F. Ward, Gem Book Publishers, Bethseda, Maryland, 64 pp. (1993). This booklet contains general information on emeralds.

Time-Pressure and Temperature Constraints on the Formation of Colombian Emeralds: An 40Ar/39Ar Laser Microprobe and Fluid Inclusion Study, A. Cheilletz, G. Féraud, G. Giuliani, and C.T. Rodriguez, Economic Geology, Vol. 89, No. 2, pp. 361-380, (1994). The authors discuss the origin of the emerald deposits based on information obtained from age dating and fluid inclusion studies. The emeralds formed by hydrothermal alteration of certain layers within the black shale sediments.

Formation of the Muzo Hydrothermal Emerald Deposit in Colombia, T.L. Ottaway, F.J. Wicks, L.T. Bryndzia, T.K. Kyser, and E.T.C. Spooner, Nature, Vol. 369, No. 6481, pp. 552-554, (1994). A geologic model is presented for the hydrothermal alteration of black shales to produce the needed conditions for emerald formation.

An Evaporitic Origin of the Parent Brines of Colombian Emeralds: Fluid Inclusion and Sulphur Isotope Evidence, G. Giuliani, A. Cheilletz, C. Arboleda, V. Carrillo, F. Rueda, and J.H. Baker, European Journal of Mineralogy, Vol. 7, No. 1, pp. 151-165, (1995). Chemical data from fluids inclusions are consistent with an evaporitic sedimentary environment of formation. The Colombian deposits are unique in the world – they represent emerald mineralization at temperatures of about 300 degrees Centigrade that are produced by a thermochemical reaction of brines with organic-rich shale strata.

The Genesis of Colombian Emeralds: A Restatement, A. Cheilletz and G. Giuliani, Mineralium Deposita, Vol. 31, No. 5, pp. 359-364, (1996). The authors present further evidence for the geologic conditions of emerald formation.

Mineralogical Significance of Fluids in Channels of Colombian Emeralds: A Mass-Spectrometric Study, J.L. Zimmermann, G. Giuliani, A. Cheilletz and C. Arboleda, International Geology Review, Vol. 39, No. 5, pp. 425-437, (1997). Fluid inclusion data indicate the existence of differences in fluid composition for emeralds from the eastern and western deposits of Colombia.

Smaragde, das “Grüne Feuer” aus Kolumbien [Emeralds, the “Green Fire” from Colombia], F. Schindler, Lapis Magazine, Vol. 23, No. 10, pp. 13-18, (1998). This brief article describes a visit to the emerald mines.

Oxygen Isotope Systematics of Emerald: Relevance for its Origin and Geological Significance, G. Giuliani, C. France-Lanord, P. Coget, D. Schwarz, A. Cheilletz, Y. Branquet, D. Giard, A. Martin-Izard, P. Alexandrov, D.H. Piat, Mineralium Deposita, Vol. 33, No. 5, pp. 513-519, (1998). The authors present oxygen isotope data on emeralds from 62 world occurrences to show the usefulness of this analytical technique to determine emerald origin and host-rock environment.

Emeralds in the Eastern Cordillera of Colombia: Two Tectonic Settings for One Mineralization, Y. Branquet, B. Laumonier, A. Cheilletz, and G. Giuliani, Geology, Vol. 27, No. 7, pp. 597-600, (1999). The authors contrast the different geologic setting of the eastern and western groups of emerald deposits, and they suggest guidelines for prospecting for new deposits in the region.

Colombian Emerald Reserves Inferred from Leached Beryllium of their Host Black Shale, G. Giuliani, D. Bouries, J. Massot, and L. Siame, Exploration and Mining Geology, Vol. 8, No. 1/2, pp. 109-116, (1999). A method for locating emerald mineralization based on the beryllium content of the black shales is presented.

Emerald Mineralization in Colombia: Fluid Chemistry and the Role of Brine Mixing, D.A. Banks, G. Giuliani, B.W.D. Yardley, and A. Cheilletz, Mineralium Deposita, Vol. 35, No. 8, pp. 699-713, (2000). Differences in chemical data from fluid inclusions in emeralds from the two groups of deposits are discussed.

Sulfate Reduction by Organic Matter in Colombian Emerald Deposits: Chemical and Stable Isotope (C, H, O) Evidence, G. Giuliani, C. France-Lanord, A. Cheilletz, P. Coget, and Y. Branquet, Economic Geology, Vol. 95, No. 5, pp. 1129-1153, (2000). The authors discuss the idea that organic matter may have played a role in emerald formation in the Colombian deposits.

Oxygen Isotopes and Emerald Trade Routes since Antiquity, G. Giuliani, M. Chaussidon, H-J. Schubnel, D.H. Piat, C. Rollion-Bard, C. France-Lanord, D. Giard, D. de Narvaez, and B. Rondeau, Science, Vol. 287, No. 5453, pp. 631-633, (2000). Chemical data for oxygen isotopes obtained from historical emerald artifacts reveal the material originated from deposits in present-day Egypt, Pakistan and Austria, but since the 16th century, Colombian emeralds have dominated the international emerald trade.

Les Émeraudes de Gachalá, Colombie: Historique, Genèse et Découvertes Paléontologiques [The Emeralds of Gachalá, Colombia: History, Genesis and Paleontological Discoveries], P. Vuillet, G. Giuliani, J-C. Fischer, and P-J. Chiappero, Le Règne Minérale, No. 46 (July/August), pp. 5-18, (2002). In the Gachalá area, underground mining has uncovered fossil gastropod shells that have been replaced by emerald mineralization.

Minerals of the Andes: Emeralds, Gold and Silver from the Sky, T.C. Wallace and M.K. Hall-Wallace, Rocks & Minerals, Vol. 78, No. 1, pp. 12-38, (2003). A review of Andean mineral and gem localities is presented.

Emerald Deposits and Occurrences: A Review, L.A. Groat, G. Giuliani, D.D. Marshall, and D. Turner, Ore Geology Reviews, Vol. 34, No. 1/2, pp. 87-112, (2008). This article reviews the geologic settings of the various types of world-wide emerald deposits. Studies of individual deposits show that in most cases a combination of geologic mechanisms (magmatic, hydrothermal, and metamorphic) were needed to bring beryllium into contact with the chromophores chromium or vanadium in order for emerald mineralization to take place.

Peñas Blancas: An Historic Colombian Emerald Mine, R. Ringsrud and E. Boehm, Journal of Gemmology, Vol. 33, No. 7/8, pp. 187-199, (2013). The authors present a description of this historic mine.

The History of Emerald Mining in Colombia: An Examination of Spanish-Language Sources, B. Brazeal, Extractive Industries and Society, Vol. 1, No. 2, pp. 273-283, (2014). This article presents a review of literature sources on the history of emerald mining and trading in Colombia from colonial to modern times.

Colombian Trapiche Emeralds: Recent Advances in Understanding Their Formation, I. Pignatelli, G. Giuliani, D. Ohnenstetter, G. Agrosi, S. Mathieu, C. Morlot and Y. Branquet, Gems & Gemology, Vol. 51, No, 3, pp. 222-259, (2015). A detailed description is given on the structure and origin of trapiche emeralds.

The Emerald Mines of Colombia, T.P. Moore and W.E. Wilson, Mineralogical Record, Vol. 47, No. 1, pp. 5-68, (2016). The authors present a detailed review of the history, geological setting and mineralogy of the Colombian emerald deposits. The article includes photographs of many attractive emerald mineral specimens.

Classification Géologique des Gisements d’Émeraude [Geological Classification of Emerald Deposits], G. Giuliani, Y. Branquet, A.E. Fallick, L.A. Groat, and D. Marshall, Revue de Gemmologie a.f.g., No. 196, pp. 12-20, (2016). A review is presented of the various types of emerald deposits in terms of their geological setting and formation.

In Rainier’s Footsteps: Journey to the Chivor Emerald Mine, R. Weldon, J.G. Ortiz, and T. Ottaway, Gems & Gemology, Vol. 52, No. 2, pp. 168-187, (2016). The authors retrace the steps of Peter Rainier, an engineer who in 1926 re-established operations to recover emeralds at the Chivor mine.

Dr. James Shigley is a distinguished research fellow at the Gemological Institute of America in Carlsbad, California.