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Showing 1 to 20 of 29 for “"tourmaline"”.
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An Overview of Tourmaline Mineralogy from Gem Tourmaline Producing Pegmatite Districts in Africa
Suites of gem-quality faceted tourmaline, slices and fragments from Nigeria Namibia, Mali, Tanzania, Congo and Mozambique were quantitatively analyzed to determine mineralogy and minor elementChemistry. The specimens range in color from colorless to pink, red, yellowish-brown, green, bluish-gray, …
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The Chemical and Physical Properties of Tourmaline
The decomposition temperature of schorl was found to be 880 ± 10°C using X-ray and optical methods. The main crystalline product in decomposed schorl and dravite was found to be a boron containing mullrte, the composition of this phase was found to become closer to that of mullite (3Al203.2Si02) as …
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Oxygen and hydrogen isotopic analysis of tourmaline by secondary ion mass spectrometry
… bias (IMB). For certain mineral groups (e.g. tourmalines), there are large variations in major element composition between species. This study uses three of these tourmaline species (schorl, dravite, and elbaite) to construct calibration curves to correct for IMB during SIMS analysis of O and …
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A Turmalina Paraíba e seus cenários.
This paper discusses the Paraiba Tourmaline, discovered in the mid-1980s in state of Paraíba. Therefore, surveys were conducted in both books, the Internet, and conducting interviews. Despite the discovery of new mines, this still remains a rare type of tourmaline, which, among other reasons, …
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Lithium, Beryllium and Boron in High-Pressure Metamorphic Rocks from Syros (Greece)
… of B is controlled by the occurrence of tourmaline. Tur-bearing samples display very high B/Be ratios, while Tur-free samples show low B concentrations and B/Be ratios. These results demonstrate that Li is probably a good tool for tracing metasomatic enrichment processes, while B is …
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Gold and Base Metal Mineralization, Hydrothermal Alteration and Vein Paragenesis in the Spring Valley Deposit, Pershing County, Nevada
… of crosscutting quartz-carbonate ± pyrite ± tourmaline ± sphalerite ± galena veins of clear mesozonal origin associated with weakly to strongly pervasive quartz-sericite-pyrite-carbonate ± tourmaline alteration. Initial classification as a porphyry gold system is thus disproved, and alternate …
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Intensive parameters of a sulfide and aluminosilicate-bearing granite, Hancock County, Maine
… 2) volatile-rich phases such as muscovite, tourmaline, apatite, and chlorite, and 3) high-temperature anhydrous phases such as andalusite and fibrolite. Feldspars have been partially altered to muscovite, and biotite has partially altered to chlorite. Sulfides and tourmaline appear to have …
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Magmatism, Deformation And Mesothermal Metasomatism: Interpretation Of Aluminosilicate Mineral Assemblages In The Cargo Muchacho Mountains, Southeastern California
… Zone, with quartz-muscovite-biotite-magnetite-tourmaline-apatite, and (c) the Kyanite Zone, with quartz-kyanite-muscovite-magnetite-rutile-tourmaline-apatite (with or without andalusite, pyrophyllite, staurolite, lazulite, and specularite) occur in the Kyanite Zone.;The host rocks are find …
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Buffalo Canyon: An Oligocene Greisen-Like Intrusion-Related Gold Deposit in the Union Mining District, Nye County, Nevada
… rocks are variably altered to muscovite-tourmaline or propylitic assemblages. Base-metal sulfide mineralization occurs as veins and replacements, both of which are associated with tourmaline as a dominant gangue mineral. Base-metal sulfide mineralization has a Ag-Pb-Zn-Sb-As-(Au-Bi-Cu-Mo) …
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The Lithology of Herman and Campbell Beach of Glacial Lake Agassiz in the Area of Larimore and Arvilla, North Dakota
… are: magnetite, ilmenite, biotite, amphibole, tourmaline, and hyalophane.</p>
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The Auborus Formation of the Bethanie district, South West Africa
… clinozoisite, mica, monazite, zircon and tourmaline. Zircon has been classified on colour, roundness, inclusions and zoning; tourmaline on colour, roundness and inclusions. Bedding in the sands tone is from thin to laminated. The commonest sedimentary structures are cross-beds, mud cracks …
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Mineralogy and Geochemistry of the Dumper Dew Pegmatite, Oxford County, Maine
… beryl, spodumene, triphylite-lithiophilite, tourmaline, cassiterite, and columbite-tantalite were attained via instrumentation assay. These trends illustrate an enhanced degree of magmatic differentiation relative to other pegmatites in the area.
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Heavy minerals of the Cretaceous Hell Creek and Paleocene Ludlow Formations of Slope and Bowman counties, North Dakota
… The heavy minerals include zircon, rutile, tourmaline, garnet, ilmenite, spinel, apatite, epidote, sphene, pyroxene, dolomite, biotite, andalusite, pyrite, monazite, and barite. Most of the heavy minerals have angular shapes, indicating one cycle of erosion and deposition. </p><p> The heavy …
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Piezoelectric response of bone and tendon subjected to inhomogeneous stress
… although the piezoelectric minerals quartz and tourmaline do. This thesis shows that an adequate, extended theory of piezoelectricity can be developed by including in addition to the usual independent variable, stress, a new independent variable, the gradient of stress. The extended theory …
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Petrogenesis of a migmatite, Penobscot County, Maine: ultrametamorphism or intrusion?
… included in biotite or hornblende), or S-type (tourmaline and red-brown biotite). They are conformable with melanosome (Bucksport) layering, and vary in outcrop from 7-88% areally, and in composition from tonalite to alkali granite. Igneous textures in leucosomes argue against a solid-state …
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Petrogenesis and geochemistry of kyanite-bearing pegmatites in the Buncombe Pegmatite District, North Carolina
… and kyanite, as well as apatite, muscovite, tourmaline, and microscopic primary sillimanite. Potassium feldspar is notably absent. One site, the Thomas Mine, was examined in detail in order to determine the mode of occurrence for these rocks. Excavation revealed pegmatite with two texturally …
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Role of Li and B bearing fluids in crystallization and alteration of granitic pegmatites, San Diego, California
… minerals including euhedral quartz, elbaite tourmaline, and spodumene. Feldspars in pockets are usually altered to kaolinite. This study investigates the role that fluid-soluble elements, Li, B, Cl, and F, have in controlling the mineralogy of pegmatites and subsolidus alteration includes two …
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Sedimentary Petrology of the Hartshorne Formation, Southeastern Arkoma Basin, Arkansas
… addition to accessory minerals including zircon, tourmaline and muscovite. Metamorphic rock fragments composed of phyllite dominate the lithic components, schist fragments occur but are rare.</p> <p>The uplands north of the Arkoma basin are uniformly composed of sandstone composed of quartzarenite …
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Petrogenesis of the Spruce Pine pegmatites, North Carolina
… magmatic source. K-feldspar, garnet, beryl and tourmaline also have similar regional trends. Although the chemical core of the area revealed by the mineral chemistry does not correspond to an exposure of granodiorite, it may correspond to the core of a larger plutonic body that has not been …
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The geology and geochemistry of a Robinson Creek gold ocurrence, north of Amisk Lake, Saskatchewan
… muscovite (sericite), pyrite and locally tourmaline. Carbonate alteration (ankerite), predates the introduction of the gold-bearing quartz veins in the sheared mafic volcanics. Metasomatic alteration of the mafic rocks associated with gold mineralization is typified by an enrichment in Rb, …
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