Emerald The Most Valuable Beryl; the Most Precious Gemstone -----------extraLapis English No.2 ----------- with Contributions by Christa Behmenburg, Lawrence Conklin, Gaston Giuliani, Maximilian Glas, Patricia & Michael Gray, Gunter Grundrnann, Rupert Hochleitner, Jan Kanis, Lore Kiefert, Karl Schrnetzer, Dietmar Schwarz, Zak Swartz, Marc Wilson, Michael Wise and Marisa Zachovay Translation by Alfredo Petrov and Gunther Neumeier Photos and Diagrams by Roberto Appiani, Marcus Budil, Helmut Burger, Warren Dobson, Gilson Archive, Gaston Giuliani, Maximilian Glas, Konrad Gotz, Gunter Grundmann, Henry Hanni, Tino Harnrnid, Rupert Hochleitner, Jan Kanis, Fotodesign Lichtblick, Hwa Ja Nier, Fotostudio Otto, Eckehard Petsch, Harold & Erica van Pelt, Federico Pezzotta, Jeff Scovil, Karl Schmetzer, Dietmar Schwarz, John Sinkankas, Franco Valoti, Stefan Weiss and Debra Wilson Valued Since Prehistoric Times as the Most Precious of Gemstones: Emerald Whether from ancient India, Greece, Rome or Colombia, emeralds have alwavs been a highly prized gemstone, This postcard depicts pre-Columbian emeralds from the Calima culture circa 1,000 to 1,500 AD. The largest stone weighs 37 carats. Stones from the Ronald Ringsrud collection, Saratoga, California; photo Tino Hammid IN COLLABORATION WITH LAPIS MAGAZINE, CHRISTIAN WEISE VERLAG, GERMANY AND LAPIS INTERNATIONAL, USA The Origin of Emerald... by As a beryl, emerald is composed primarily of the While aquamarine and other pegmatite minerals Dietmar Schwarz, abundant elements silicon, aluminum and oxy­ develop in relatively calm environments which Gaston Giuliani, gen. The fourth primary component, beryllium, allow for continuous crystal growth without Gunter is rare in the Earth's upper crust (1.5 ppm); thus, strong perturbations, emeralds are formed in Grundmann beryl is not a common mineral. Beryllium, as a geologic environments characterized by abrupt and rule, comes from rocks of the continental crust. changes and mechanical stress. Maximilian Glas Its sources include pegmatites, aluminum and sil­ Smaller crystals with considerable internal de­ icon-rich magmas, clayston~s and black shales fects such as fissures, fractures or foreign solid with their metamorphic equivalents, such as or­ inclusions are consequences of forming in a per­ thogneisses and mica schists. turbed mineralogical-geologic environment, and The elements that give emerald its color, chromi­ partially healed or unhealed fissures and fractures um and vanadium, are less rare than beryllium in are quite common. Understandably, the presence the Earth's upper crust (185 and 230 ppm respec­ of such defects lower a crystal's mechanical resis­ tively). They are concentrated in dunites, tance. Unable to withstand the stress of river peridotites and basalts of the oceanic crust and transport, emerald is rarely found in secondary Earth's upper mantle. Concentrations of chromi­ deposits. um and vanadium sufficient to form emerald can also occur in sedimentary rocks, particularly black shales. Ages of Emerald Mineralizations With beryllium concentrated in the Earth's Emerald deposits are known from five continents, continental crust and chromium and vanadium with South America having been by far the most concentrated below in the upper mantle, unusual important emerald producer for many years. geologic and geochemical conditions are required Emeralds formed during almost every geologic for chromium and/or vanadium to encounter epoch. The most intense emerald formation beryllium. Though there are a few deposits in occurred during continental collisions, which which the circulation processes inside one geo­ gave rise to large mountain complexes, extended logical unit are sufficient for emerald formation fault zones, regional metamorphic overprints and (e.g., the black shales of Colombia), but in gener­ eventually to further uplift and erosion. All of al the source rocks must first be brought together these events favor the formation of emerald de­ and then channels must be opened to permit the posits. Emerald can, therefore, take its place circulation of fluids and the mobilization of among the oldest gemstones in the Earth's crust: elements. • 2.97 billion years: the Gravelotte emerald deposits of Transvaal in the Archean of South Formation of the Deposits Africa formed. Disparate bodies can be brought together through • 2.6 billion years: the emerald deposits in the actions of plate tectonics. The resulting folds Poona, Australia and Sandawana, Zimbabwe and faults mobilize fluids that move along the formed during the last rock forming processes. newly created fractures. As they move, these flu­ • 2 billion years: the Brazilian emeralds of ids can then dissolve and transport the Camafba and Socot6 in the state of Bahia elements necessary for emerald formation. formed during the early Proterozoic. Once the necessary elements have been brought • 500 million years: the Brazilian deposits in Mi­ together, emeralds can crystallize in diverse geo­ nas Gerais (Belmont Mine, Capoeirana, Piteiras) logic environments: as a rock-forming mineral in and the enormous deposit of Santa Terezinha in schists and gneisses or as isolated crystal pockets Goias both formed in the Paleozoic (510 and in geologic structures such as veins along fracture 520 million years ago respectively). In Africa, zones, faults, breccias, lenticular vugs, druses, the emerald occurrences of Mananjari and miarolitic cavities or quartz lenses. Ianapera formed 490 million years ago. 18 siderite-caIci te-quartz rocks: counrry ASIA rock is carbonate-bearing metapelite Emeralds and graphite schist Sim: Gujarkili, Chabargh, Makhad, PAKISTAN • Mohmand Region 2 Alpurai, Malam, Bar Kotkai, 3azarkot. of the Gandao 100 workings in a 1 km area also Khazana (Sharnozai Region) on the NW slopes of Tora-Tigga Mt. discovered early 1990's SE of Tora-Tigga viIlage. Mohmand Incl: Actinolite, Fuchsite, chrornite, Region. 43 krn NW of Peshawar, NW chromium-dravite. enstatite, plagioclase, World Pakistan tourmaline, gersdorffite. magnesite, Notes on known emerald occurrences Finds: No commercial significance dolomite, pyrrhotite, chlorite and quartz by Giinter Grundmann from the Beryl: Green beryl, colored (at least in Ref: Arifet al (J996) Technische Universitat, Miinchen. Gandao) by vanadium (up to 0.7%) and Gaston Giuliani and chromium (up toO.l%) PAKISTAN • Bajaur Region from the Institut de Recherche pour Geo: Countless quartz veins and lens­ Barang-Turghao (Mor-Darra) 80 km Ie Developpement et CRPG/CNRS, es in an alternating greenschist­ Nancy dolomite layers with mobilization of N of Peshawar In the Bajaur region beryllium from nearby beryl-bearing Finds: No commercial significance Abbreviations: pegmatites Beryl: Colored by chromium and iron Geo: Contact metasomatism between Sim: Similar or other deposits Mat: Quartz veins and lenses In dolomite rock ultrabasic and quartz-feldspar rocks Finds: Quality of emerald Sim: Nawe Kill (Nawe Dand), Mat: Quartz-calcite-feldspar veins in specimens and significant Finds Tsapari, Bucha, Pranghar, Khanori Kot talc schist at contact with amphibole­ Beryl: Type ot beryl or emerald and and Zankhae chlorite-talc schist and talc-carbonate the chromophorous elements lncl: Quartz, dolomite, rrernolite, talc, rocks (as weight % of the oxides Cr20:;, chlorite, epidote and phlogopite Sim: Arnankor. Maimoln. Nawe Dand: V20:; and FeO) Ref: For Pakistan, AFghanistan and south of Nawe Dand village, 40 krn N Geo: Geology and origin India: Kazrni and Snee (1989) of Peshawar, Bajaur region Mat: Matrix or host rock Incl: Quartz, plagioclase, calcite, Incl: Solid inclusions (fluid inclusions PAKISTAN • Swat District phlogopite. talc, chlorite, actinolite are not noted) Mingora Mine. in the Swat River Val­ Ref: References or recommended ley, 200 km NE of Peshawar. Largest PAKISTAN • Gilgit Division reading for further information deposit in Pakistan: discovered in Khaltaro deposits: known as Ravjud on a deposit 1958. Five mines, Mine I (Farooq near Khalraro, Haramosh Range, Mine). Mine 2. Mine ], lslarnia 70 km E of Gilgit, northern Pakistan: Trench, Carrel's Trench. spreading discovered 1985, rugged terrain at SSW to NNE over I km 4, I00 m in the Nanga Parbat­ Finds: Richest deposit in Pakistan Haramosh massif with the best quality finds. Emeralds Finds: Inclusion-rich and Fractured easily detach From matrix: matrix emeralds, rarely gem quality: rough specimens rare: crystals I to 2 em, stones I to 3 cm diameter rarely up to 10 em Beryl: Colored pale to medium green Beryl: Colored by chromium and iron: by chromium and iron color always inhomogeneous, often Geo: The only deposit in Pakistan sharply zoned; high magnesium with contact metasomatism between contents (up to 3<!r 'vIgO) amphibolite and crosscutting fluorine­ Geo: Sporadic emerald mineralization rich pegrnaritic hydrothermal vein sys­ in talc-carbonate schist related to Fault tem, situated near the northern border zones in the Charbagh greenschist of the lndian tectonic plate zone or Mingora ophiolite zone; Mat: Medium- to coarse-grained beryllium introduced by hydrothermal biotite-muscovite-aIbite-quartz­ fluids of magmatic or regional meta­ tourmaline-Fluorite zones in miarolitic morphic origin pegmatite Mat: Magnesite-talc-quam schist. Incl: Quartz. biotite, white mica, talc-chlorite-dolomite schist and chlo­ plagioclase, tourmaline, fluorite rite schist, quartz lenses, magnesite- Ref: Lams et al (1996) 24 The World of Emeralds in 2002 AFGHANISTAN • Konar Province known already in Pliny's time as the quartz