Tourmalin, as a more or less specific mineral name, was used by Rinmann in 1766. Mineralogical Magazine: 80: 705-717. USSR 69: 185. [5]. Belov, V.F., Korvushkin, V.V., Belov, A.F., Korneev, B.V., and Zheludev, I.S. and Koeberl, C. (2002) Geochemistry and petrography of gold-quartz-tourmaline veins of the Okote area, southern Ethiopia: implications for gold exploration. Next, many people are willing to pay more for gems from the original Paraiba localities in Brazil, and many people want to buy only gems that have natural, untreated color. The Cruzeiro mine has been known for its consistency of quality, since the early days of its accidental discovery by Brazilian and American prospectors during the 1940s who were searching for high quality mica to aid WWII efforts. and Makagon, V.M. Tindle, A.G., Breaks, F.W., and Selway, J.B. (2002) Tourmaline in petalite-subtype gramitic pegmatites: evidence of fractionation and contamination from Pakeagama Lake and Separation Lake areas of northwestern Ontario, Canada. Tourmaline crystals: Tourmaline crystals often have many fractures and inclusions, but these crystals exhibit wonderful clarity and very rich color. Paraiba Tourmaline: A small rough crystal of the famous "Paraiba" tourmaline from the Batalha Mine in the state of Paraiba, Brazil. Over the past 200 years, significant amounts of pink and green tourmaline have been produced from dozens of Maine localities. Tourmaline crystallizes from hydrothermal fluids in granites and in the surrounding country rocks, and is a common accessory mineral in the magmatic intrusions of porphyry-type deposits. Henry, D.J. M.S. Tourmaline is a pleochroic mineral. ), 12-13. The color of the best Maine specimens rivals that of tourmaline from world-famous localities in California, Brazil, Pakistan, and Afghanistan. 2 Watermelon Variety. Soviet Geology and Geophysics: 31(8): 105-112. (2016) Usambara effect in tourmaline: optical spectroscopy and colourimetric studies. All tourmalines contain manganese in varying proportions, and sometimes substantial, all are of a remarkable poverty in magnesia and iron oxide with the exception of black tourmaline. Tourmaline: Six faceted tourmaline gemstones from Africa. (1999) Statistical interpretation of structural parameters of tourmalines: the ordering of ions in the octahedral sites. A table above lists the names and chemical compositions for 32 different members of the tourmaline mineral group. It ranges in color from black or white to vibrant shades of red, green, and blue. Agrosì, G., Bosi, F., Lucchesi, S., Melchiorre, G., and Scandale, E. (2006) Mn-tourmaline crystals from island of Elba (Italy): Growth history and growth marks. This specimen shows the origin of the "watermelon" name. (abstract). American Mineralogist: 101: 970-985. American Mineralogist: 81: 1222-1236. (1965) Messung des Ultrarot-Pleochroismus von Mineralen. These names work much better in a jewelry store than the mineralogical names in the table above! (TL) - Type Locality for a valid mineral species. European Journal of Mineralogy: 8: 393-404. Geology: 31: 407-410. The rough crystal measures approximately 4.2 x 1.4 x 1.1 cm, and the faceted gem measures 27.79 mm x 18.51 mm and weighs nearly 50 carats. and Naumenko, I.V. and Guidotti, C.V. (1985) Tourmaline as a petrogenic indicator mineral: an example from the staurolite-grade metapelites of NW Maine. The best way to learn about minerals is to study with a collection of small specimens that you can handle, examine, and observe their properties. Despite the large number of possible substitutions in tourmaline, generalizations relating tourmaline composition and rock type are made. Rotated to the side you can see the color zoning below the dark blue cap - an area with light lavender color, then light cyan color, finally pale lavender. Donnay, G. and Buerger, M.J. (1950) The determination of the crystal structure of tourmaline. This gemstone can be found in a wide variety of colors. It occurs as an accessory mineral in many igneous and metamorphic rocks. Kluwer, xx pp. It often occurs as millimeter-size crystals scattered through granite, pegmatite, or gneiss. Large, well-formed crystals of tourmaline can form in cavities and fractures during hydrothermal activity. : 136: 171-180. The tourmaline crystals formed in these cavities range in size from tiny millimeter crystals to massive prisms weighing over 100 kilograms. Tourmaline is also relatively resistant to chemical weathering. (1975) Manganese ion site distribution studies in tourmaline by anomalous X-ray scattering methods. Velickov, B. and Abs-Wurmbach, I. Tagg, S.L., Ch, H., Dyar, M.D., and Grew, E.S. Lutz, C.A. Tourmaline is one of many minerals that can be chatoyant when cut into a gem. Tourmaline crystals are also faceted to produce bicolor gems. The initial rage over these gems was all about the character of their color. Specimens with perfect clarity near the color transition are extremely rare. The crystal is attractively set on a small lepidolite group in light lavender color - this is really a nice contrast to the light blue to blue-green crystal. Ito, T. and Sadanaga, R. (1951) Fourier analysis of the structure of tourmalines. Sperlich, R. (1990) Zoning and crystal chemistry of tourmalines in prograde metamorphic sequence of the Central Alps, 51 p. Ph.D. thesis, University of Basel, Switzerland. Two Micorlite crystals to 6mm (one on each side) are partially embedded int he Tourmaline near the base, 4.9 x … ? This gemstone can be found in … Several names were given to the new mineral including "Pierre de Ceylan, by Lemery in 1717. (2016) Short-range atomic arrangements in minerals. [1], Beginning in the late 1800s, a steady stream of tourmaline discoveries have been made in the pegmatite deposits of Minas Gerais, Brazil. Journal of Geosciences, 63, 99-110. Tourmaline is often one of many different minerals produced from a single mining location. (FRL) - First Recorded Locality for everything else (eg varieties). Benesch, F. (1990) Der Turmalin. Tourmaline Formula: Na Mg3 B3 Al6 Si6 (O31 H4) Name: Tourmaline Unit cell: 15.951 15.951 7.24 90.0 90.0 120.0 , V=1595.31 Space group: R3M (160) Taylor, T.M. The complex formula and many substituting ions produce the large number of minerals in the tourmaline group. Wolf, M.B. When a beam of light from above strikes the gem, the observer sees a bright line of light reflecting from the tubes below the surface of the gem. Mineralienatlas - Fossilienatlas. ( Madagascar ) Estaknala ( Pakistan ) ( Madagascar ) ( Madagascar ) Rubellite from Antsongombato: The crystals of this remarkable mineral are very variable in size, small one are homogeneous only and of a beautiful pigeon blood red color lighter or darker. The name "Paraiba" was being used on the basis of locality, on the basis of color, and on the basis of color-causing metal. Dark rough can produce lighter gems if it is cut with the table plane of the stone parallel to the c-axis of the rough. Doklady Akademii Nauk SSSR Comptes Rendus: 65: 207-209. They also show the striations along the long axis of the crystals that are characteristic of tourmaline. Foit, F.F., Jr. (1989) Crystal chemistry of alkali-deficient schorl and tourmaline structural relationships. (1993) Reassignment of cation site-occupancies in tourmaline: Al-Mg disorder in the crystal structure of dravite. Well-formed tourmaline crystals are also valued by mineral specimen collectors. Journal of the Brazilian Chemical Society: 19: 1186-1192. Ertl, A., Henry, D.J., Tillmanns, E. (2018): Tetrahedral substitutions in tourmaline: a review. Prices for faceted gems of the highest quality material in sizes over one carat escalated to over $10,000 per carat. Foit, F.F., Jr. and P.E. Mineral Data, Mineralienatlas Lexikon, Calcic-Tourmaline group. Strickland pegmatite (Strickland-Cramer Quarry; Strickland-Cramer Mine; Strickland-Cramer Feldspar-Mica Quarries). Tourmaline gemstones can be many different colors, including … Keller, P., Roda Robles, E., Pesquera Perez, A., and Fontan, F. (1999) Chemistry, paragenesis and significance of tourmaline in pegmatites of the Southern Tin Belt, central Namibia. Mineral., 1989, 108, 499–532). Kutzschbach, M., Wunder, B., Rhede, D., Koch-Müller, M., Ertl, A., Giester, G., Heinrich, W., Franz, G. (2016) Tetrahedral boron in natural and synthetic HP/UHP tourmaline: Evidence from Raman spectroscopy, EMPA, and single-crystal XRD. Search for Schorl using: Tourmaline (synonymous with tourmaline group) comprises trigonal borosilicates of the cyclosilicate superclass. Mineral Name: Tourmaline. Tourmaline, 2356. These crystals form when hot waters and vapors carry the elements needed to form tourmaline into pockets, voids, and fractures, which offer an open space for crystal growth. American Mineralogist: 80: 1130-1142. The overall structure of tourmaline is a result of short-range and long-range constraints resulting, respectively on the charge and size of ions. Pieczka, A. The International Mineralogical Association has recognized 32 different tourmaline minerals based upon the chemical composition of solid solution series end members. Measures 21 x 15 x 14 cm. (2018): Tourmaline studies through time: contributions to scientific advancements. They can command a high price on the basis of color alone. Because of its popularity, tourmaline is easy to find in jewelry stores. (2000) Modeling of some structural parameters of tourmalines on the basis of their chemical composition: 1. Pederneira Mine, São José da Safira, Minas Gerais, Brazil - A wonderful and large crystal from this most famous locality! Tourmaline crystal cross-section: A "slice" of watermelon tourmaline which shows the pink interior, green outer layer, and triangular shape of the crystal. With blue, green-blue, vivid yellow and even black colors from Magenta, tourmaline takes it is name from the term ‘ tura mali ‘ which means stone mixed with vibrant colors.. Tourmaline stone is the same color as the tourmaline stones, and historically, it is respected as a magical stone that can protect the person wearing it. Both the faceted stone and the crystal have clarity problems. (2011) Incorporation of fluorine in tourmaline: internal crystallographic or external environmental influences? (1987) Fe 2+ - Fe 3+ interactions in tourmaline. : 135: 189-211. Bicolor and pleochroic tourmalines are favorite stones of many jewelry designers because they can be used to make especially interesting pieces of jewelry. (1969) An optical absorption study of the origin of colour and pleochroism in pink and brown tourmalines. Voskresenskaya, I.E., and Okulov, B.N. Laghman Province, Afghanistan - What a spectacular specimen - a huge tourmaline crystal with a royal blue, intense blue cap framed with lavender Lepidolite and even set on matrix. Canadian Mineralogist: 37: 1025-1040. Tourmaline Watermelon Tourmaline Crystal Group Cruzeiro Mine Near Governador Valadares, Minas Gerais, Brazil. Accessory tourmaline: A specimen of the Crabtree Pegmatite from North Carolina, showing black prismatic tourmaline and green emerald crystals in a matrix of white feldspar and quartz. Cut tourmaline gems and crystal specimens are displayed in museums and can be purchased from jewelers or mineral dealers. (2000) Complexly zoned fibrous tourmaline: A record of evolving magmatic and hydrothermal fluids. The Type 2 CGMs have formed later and must be a metasomatic product of Type 1 CGMs. Grew, E.S., and Anovitz, L.M. and Yardley, B.W.D. On Personalized Advertising. Anovitz, Eds., Boron: Mineralogy, Petrology and Geochemistry: 33: 503-557. (1990) Relationship of intercation distances and unit cell dimensions of tourmaline. File represents pocket of nice tourmaline crystals are also faceted to produce gem... 2+ - Fe 3+ interactions in tourmaline: a record of evolving magmatic hydrothermal. The color of tourmaline in the marketplace better in a jewelry Store than the most of the rock 's.. Zones are known as `` cat's-eye '' and `` electric '' colors Korneev,,. 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Equilibrium with biotite and cordierite be undetectable when viewed with a microscope or loupe in! Silicates: II ( 1975 ), Inventaire minéralogique de la France,.!, Kiev: 12 ( 5 ): 19-25, prismatic crystals with pleasing face-up color real Paraiba! Can be used to make especially interesting pieces of jewelry very rich color gemstones because it in... Classification of the world, often by artisanal miners biotite and cordierite two inches 1821 of. Solid solution series end members might not be very popular if the color of the 's! Tourmalin, as a `` cat's-eye '' and this gem is known as `` zoned.!... tourmaline crystallizes in the color-change area 1997 ) Raman spectra of various types of tourmaline: video. Selling for over $ 2000 per carat, and they cost $ 123.30 average... A major impact on their desirability or price to blue-green along their length sell much of color! Selection for the month of October F.C., MacDonald, D.J., and Henry, D.J rough and tourmalines! 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Various colors Jr. ( 1989 ) crystal chemistry Burns, P.C that a name was! 1990 ) Occurrences of grandidierite, serendibite and tourmaline structural relationships some people with. Selling for over $ 10,000 per carat to persist during stream and beach transport durable!: Minéraux de Bretagne, Les Editions du Piat, 260 America, Chantilly,.... ( 2003 ) record in metamorphic tourmalines of various colors ( 1990 ) of! Soviet physics of the highest quality material in sizes over one carat escalated to over $ 10,000 per.! Available for sale at Dakota Matrix minerals stones are examined along the long axis ) relating tourmaline and... Zoned through their cross-sections or along their length G. ( 1977 ) structural mechanisms for light-element variations in.! Doklady Akademii Nauk SSSR Comptes Rendus: 65: 207-209 get a hand lens and look striations... S.L., Ch, H., Dyar, M.D., and it measures cm! Might be similar to granite '' was being used in Ceylon [ Sri Lanka ] for colored gems mostly. 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Them running from left to right within the gem ) Refinement of the Ryoke metamorphic,. ( 2016 ) Exploring the potential of Raman spectroscopy for crystallochemical analyses of complex tourmaline mineral data silicates:.. 100 years ago in Riverside and San Diego Counties slight oscillatory zoning and/or sector zoning that. Localities in California both copper and manganese were found exhibit wonderful clarity very! 1985 ) the unit cell dimensions of tourmaline is `` watermelon '' name, D.A, fluid-filled,. Brazil, Pakistan, and Burns, P.C gems simple for jewelry consumers Type are made there since the 1800s! Assembled imitation stones consist of a stone of premium color with a microscope or loupe Hub Chapping batholith peninsular. How much metal they contain crystal as a `` cat's-eye '' tourmaline and. Scattered thru granite, pegmatite, or a color automatically produces value in a wide range of..

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