1 / 51

" T our ma l in es; Mother Natures Rainbow "

" T our ma l in es; Mother Natures Rainbow ". Tourmaline, from the Singhalese tourmali, meaning mixed stone. It is widespread in metamorphic, igneous and sedimentary rocks. 5 Subgroups and 13 members : Alkali-Deficient Tourmaline subgroup : Foitite, Magnesiofoitite, Rossmanite

rad
Download Presentation

" T our ma l in es; Mother Natures Rainbow "

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. " Tourmalines; Mother Natures Rainbow " Tourmaline, from the Singhalese tourmali, meaning mixed stone. It is widespread in metamorphic, igneous and sedimentary rocks. 5 Subgroups and 13 members : Alkali-Deficient Tourmaline subgroup: Foitite, Magnesiofoitite, Rossmanite Calcic Tourmaline subgroup: Liddicoatite, Uvite, Feruvite Ferric Tourmaline subgroup: Buergerite, Povondraite Lithian Tourmaline subgroup: Olenite, Elbaite Sodic Tourmaline subgroup: Dravite, Schorl, Chromdravite The general formula for tourmaline is: WX3Y6(BO3)3Si6O18(O,OH,F)4 where: W = Ca, K, NaX = Al, Fe2+, Li, Mn2+Y = Al, Cr3+, Fe3+

  2. TOURMALINE ACHROITE, RUBELLITE, INDICOLITE, VERDELITE, AND WATERMELON • Gem variety falls under the subgroup of tourmalines • known as ELBITE[Na(Li, Al)3 Al6(BO3)3Si6O18(OH)4]. • Gem Elbaite is, however, nearly restricted to pegmatites. Literally thousands of tourmaline-bearing pegmatites are known; only a few hundred apparently contain gem quality material in mineable quantities. • The principle commercial source is Brazil. Important other sources are the U.S. (Maine and S. California), U.S.S.R., Sri Lanka, Burma, Madagascar, Tanzania, and Afghanistan. http://www.cigem.ca/414.html#SCRL4

  3. BRAZIL Paraiba State • Largest producer of gem tourmaline. All colors. Most mines in the State ofMinas Gerias; the most prolific and famous pegmatite mines are Cruzeiro, Galconda, Virgem da Lapa and Jonas (Itatiaia). • Some of the finest red ("Cranberry") tourmaline was discovered at the Jonas mine in 1978. • Recently discovered deposit in the State of Paraibahas yielded unusually vivid purples,blues and greens. Chromophore in some of these is copper, and most contain a fairly high gold content. These are some of the most expensive tourmalines on the market, commanding prices that were previously unheard of for tourmaline Minas Gerais State

  4. A very rare combination, elbaite tourmaline on sceptered quartz. From Minas Gerais, Brazil.

  5. A huge green tourmaline with basal termination from one of the most prolific mines in the world, the Cruzeiro Mine, Minas Gerais, Brazil. Size 5x5x3-1/2 inches. Evaluation on a custom-made base worth $12,500!

  6. Arríba, Paraíba • tantalizing blue and blue-green tourmalines from Paraíba (discovered in 1989), Brazil. • rare tourmalines, known mineralo- gically as "cuprian elbaites," Mining Paraíba tourmaline is difficult, accomplished mostly by hand with wedges, sledge hammers and occasionally dynamite, though the latter is discouraged because it can damage the crystals.

  7. The famous Jonas Mine in Minas Gerais, Brazil also produced a few nice gemmy watermelon elbaites in addition to the cranberry xls.

  8. A doubly-terminated cranberry rubellite xl from the famous Jonas Mine, Itatiaia, Minas Gerais, Brazil. Note the doubly-terminated attached quartz xl.

  9. Black dravite tourmaline crystal from Brumado,Bahia, Brazil. This larger xl grew from multiple seed xls, each being doubly- terminated.

  10. UNITED STATES • SOUTHERN CALIFORNIA • Pala District,San Diego County. • Bicolored crystals common; fine pinks. • Mined extensively from 1900-1912; pinks and reds favored by Chinese for carvings and other ornamental uses. Market all but evaporated with the collapse of the Manchu dynasty in 1912. • MAINE • Some mines have recently reopened and are being worked on a fairly large scale. • Near Newry (1970's) and Paris (since mid 1800's) Newry deposit noted for watermelon, red and apple-green crystals; blues usually too dark to cut. • Some very large crystals ("tourmaline logs") discovered as well; highly prized as mineral specimens.

  11. China’s Dowager Empress was wild about San Diego’s tourmalines. Her love of this gem triggered the California boom in the early 1900s. http://www.palagems.com/california_gem_mining.htm

  12. The Himalaya Mine is located a few miles northwest of Mesa Grande, San DiegoCounty, California. The Himalaya Mine is a world famous locality but was not open to collectors. The current "owners" apparently are letting people up to collect for a fee or investment. The Himalaya Mine is famous for the beautiful elbaite, rubellite and verdelite tourmaline gemstones and associated combinations which have been mined there for many years. Other minerals found at the mine include spessartite garnet, bladed albite clusters, etched feldspar crystals, stibiotantalite,topaz, morganite beryl, smoky quartz, clear quartz, lepidolite balls and clusters, and combinations of these minerals.

  13. The Himalaya Mine, California’s biggest producer of tourmaline, ca. 1900.

  14. Bi-colored tourmaline with attached lepidolite mica from the Himalaya mine. John Sinkankas, examines tailings from the Himalaya Mine for tourmaline specimens.

  15. Searching for tourmaline-bearing pegmatite at the Tourmaline Queen mine, ca. 1975. http://www.palagems.com/tourmaline_queen.htm

  16. The Tourmaline Queen Mine located in Pala, San Diego County, California, has always inspired mineral collectors, high graders and geologists. It was originally claimed by Frank Salmons and Associates in March, 1903. Exploratory work yielded some 80 pounds of gem tourmaline. The Queen immediately became the leading producer of tourmaline in the Pala district during the period 1904 through 1914. With the collapse of the major Chinese market for tourmaline, due to the 1911 overthrow of the Imperial government, the mines soon became uneconomical. From about 1914 to 1971, the Queen was worked intermittently by high graders, with limited success.

  17. The main adit at the Tourmaline Queen mine, circa 1972

  18. A view of the tunnel walls looking down the main adit.

  19. Drilling is essential. Here, John McLean and José Montes use a pneumatic jack leg, used to support the drill during drilling. A clay pocket exposed in the pegmatite.

  20. A tourmaline crystal coated with clay in a just-exposed pocket.

  21. Another fine "blue cap" on quartz specimen from the find at the Tourmaline Queen in the early 70's.

  22. Tourmaline in quartz. Crystals are 2.5 x 3 inches; overall size is 9 x 5 inches.

  23. Tourmaline and cleavelandite whichmeasures approx. 5 x 2.5 inches. An unusual pair of tourmaline crystals;the individual crystals are approx. 2.5 x 5 inches each. This tourmaline group measures approximately 5 x 3.5 inches.

  24. The "Candelabra” one of the most beautiful tourmaline specimens ever discovered from the Tourmaline Queen Mine, Pala, CALIFORNIA.

  25. The Blue-Berry Mine, Poland, Maine, USA. http://members.aol.com/Gemelbaite/BerryGemMine3.html

  26. WATERMELON TOURMALINE, NEWRY, MAINE http://www.rockhounds.com/rockgem/articles/pegmatites.html 7.80 carats, US$ 3,000

  27. http://www.dunton.org/archive/DuntonMine/dunton_mine.gif

  28. In 1972, the Dutton Mine in Newry, Maine established itself as one of the largest finds on record ever and for a brief period of time, became a world-source of superior quality red and green tourmaline.

  29. MOUNT MICA TOURMALINE MINE, MAINE http://www.megalink.net/~mtmica/History_/history_.html Discovered in 1820

  30. Mining Today at Mount Mica

  31. Probing the gem bearing zone

  32. AFGHANISTAN Tourmaline from Nuristan, Kumar Province, Afghanistan is found in many colors and shades.

  33. 16 Very Large, Green Tourmaline Crystals

  34. Green Tourmaline Crystals

  35. Pink tourmaline crystals grown in quartz crystals (2 1/2" X 1 1/2"). Found in Nuristan, Afghanistan. Priced at $160.00.

  36. This small tourmaline crystal lot weighs 320ct. White and Light Pink Tourmaline

  37. This beautiful 9.66 carat Tourmaline from Nuristan, Afghanistan. It is priced at $590.00 per carat. Pink Tourmaline Necklace

  38. NIGERIA A brand new deposit of red tourmaline from Nigeria. This stone will probably be the hot new material at the Tucson Gem Show in `99. Expect to see large quantities of this gem in all price ranges and qualities at the show. Approximately 1/3 of the deposit went to Germany, 1/3 to Bangkok and 1/3 to the United States. What is unusual about this material is that it is clean and not irradiated.

  39. In the summer of 1998 a new tourmaline deposit was discovered in a farming area 25 miles from the city of Ibadan, Nigeria, near the border with Benin. Gem dealers have noted that this is one of the finest discoveries of tourmaline in many years. The deposit is alluvial in nature, many of the tourmaline crystals have a frosted skin resulting from natural abrasion and weathering. Other crystals have sharp terminations indicating that they have not traveled far from their original source. The crystals were found under a relatively shallow overburden of soil (about six feet), and the deposit stretched for about 1000 meters. A flood of miners rapidly moved into the area and removed over 1,000 kilograms of fine tourmaline. Because this source is largely worked out, the depressed price of these fine tourmalines is not likely to persist. Tourmaline deposit near Ibadan, Nigeria

  40. The worn tourmaline crystals show very good clarity and range in color from pale pink, to raspberry pink, to orangish pink, to burgundy red. Some of the crystals show distinct color zoning. The fashionable colors, combined with the remarkable clarity and size of the rough gem material, have made this tourmaline a hit with gemstone dealers and the public. Because of the large supply of material, average prices for faceted stones at the 1998 Tucson gem and mineral shows were as low as $60 to $100 per carat.

  41. Bright Emerald Cut, 3.83 ct., 11.0 x 7.5 x 6.7 mm, VS, $287.25 Curved Triangular Brilliant Cut, 5.66 ct., VVS, 12.5 x 12.5 x 7.5 mm, $311.30

  42. Tourmaline Gem Mines of the Malkhany Region of the Buryat Republic, CIR (Siberia) http://www.mtlilygems.com/mineinfo/mulkinfo.html Standing on top of the Moss pegmatite looking over the Taiga of the Malkhany Region of Siberia

  43. Malkhany pegmatites were discovered only recently. During the 1970's Russian geologists exploring the region for sources of rare earth metals discovered these gem pegmatites. • The pegmatite consists of a rather large lenticular body approximately 300 meters in diameter and nearly 50 meters in thickness. This pegmatite contains many gem pockets lined with fine pink to red tourmaline crystals. • These pockets range in size from 0.5 to 2 meters in diameter.

  44. The heart of the Moss Mine pegmatite. The bulldozer is removing some of the barren pegmatite boulders. The pegmatite body is being worked as a 20 meter thick bench, drilling and blasting only small areas at a time. The unworked portion extends into the hill to the right. In the lower right, amongst the pry bars and drill steel, have been found many pockets containing beautiful pink tourmaline crystals.

  45. The miners overlooking some of their finds. Valeri, far right, is a trained geologist, Misha, on the far left, was a Russian military helicopter pilot.

  46. A 2.2 carats pink tourmaline (Curved triangular brilliant cut) from the Moss Mine set in an 18kt gold slider with diamond accent stones. Tourmaline crystals from one of the Moss Mine gem pockets. As is the case for many pegmatites, only 5 to 10 percent of the material is suitable for faceting.

More Related