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Tveitite-Y and rare-earth enriched fluorite from amazonite pegmatites of western Keivy, Kola Peninsula, Russia; genetic crystal-chemistry of natural Ca, REE-fluorides

, : Tveitite-Y and rare-earth enriched fluorite from amazonite pegmatites of western Keivy, Kola Peninsula, Russia; genetic crystal-chemistry of natural Ca, REE-fluorides. Proceedings of the Russian Mineralogical Society 137.3

Tveitite-(Y) was found at Rovgora, western Keyvy, Kola Peninsula, Russia, in albite-quartz-amazonite pegmatite vein related to alkaline granite. It occurs as pods up to 10 cm. Its grains (up to 4 cm) are composed of parallel micro-intergrowths of two isostructural varieties with composition as follows: Ca(9.5) Na(1.7) Y(5.2) Ln(2.0) ) F(42.6) and Ca(11.4) Na(1.9) Y(4.4) Ln(1.4) F(42.0) . The simplified formula is (Ca,REE, Na)13 (Y,Na)6 F(42) ; space group R-3, a = 17.020, c = 9.679 Aa. Nine fluorite samples containing from 0 to 18 mole % (REE)F3 were examined by electron probe, X-ray diffraction and IR spectroscopy. The crystal structure of natural yttrofluorite has been first studied (R = 1.47 %): Fm3m, a = 5.493 Aa, the structural formula is (Ca(0.82) Y(0.12) Ln(0.06) ) F(2.15) . Earlier-published and new data show that yttrofluorite containing (REE) F3 >20 mole % and REE-rich fluorite with LREE>Y(HREE) are metastable under room conditions. In nature tveitite-(Y) is a product of solid-state transformation of metastable yttrofluorite with (REE) F3 >20 mole %, which can also break down to varieties of tveitite-(Y) with different compositions of tveitite-(Y) + stable yttrofluorite. For the formation of tveitite-(Y), enrichment of the system by not only Y but also light and heavy lanthanides is presumably necessary. LREE and HREE seem stabilizing admixtures, which order to different types of Ca-dominant sites in the structure. Tveitite-(Y) and yttrofluorite are geochemical indicators for media not only enriched by Y, Ln and F but also depleted by Na, Ca, CO2 and P.


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Netea, Mihai G., 2003: Toll-like receptors in defense to Candidiasis and Aspergillosis. Toll-like receptors (TLRs) have been recently described as the most important class of pattern-recognition receptors in mammals. Initially described in Drosophilla for mediating antifungal defense to Aspergillus fumigatus, recent studies identifie...

Augur C.; Y.L.; Dervill A.; Albersheim P., 1991: A new bioactive xyloglucan undecasaccharide and confirmation by chemical synthesis of the structure of a previously characterized bioactive nonasaccharide. Journal of Cellular Biochemistry Supplement (15 PART A): 143

Abreu, M.S.; Giacomini, A.Cristina.V.; Gusso, D.; Koakoski, G.; Oliveira, T.A.; Marqueze, A.; Barreto, R.Egydio.; Barcellos, L.J.G., 2016: Behavioral responses of zebrafish depend on the type of threatening chemical cues. Journal of Comparative Physiology. A, Neuroethology, Sensory, Neural, and Behavioral Physiology 202(12): 895-901

Hargadon, K.Michael., 2015: Whole Genome Expression Microarray Analysis of Highly Versus Poorly Tumorigenic Murine Melanoma Cell Lines Provides Insights into Factors That Regulate Tumor Growth, Metastasis, and Immunogenicity. Frontiers in Immunology 6: 452-452

Pissas, M.; Lee, S.; Yamamoto, A.; Tajima, S., 2002: Peak effect in single crystal MgB(2) superconductor for H axially c-axis. We have studied the phase diagram of the MgB(2) superconductor using a single crystal for the H parallel c-axis. For the first time we report the existence of peak effect in the screening current in the MgB(2) for the H parallel c-axis. In the mag...

Gist, Y.J., 1993: Aging trends--Fiji. An analysis of recent demographic trends in Fiji is presented using data from the International Data Base on Aging at the U.S. Bureau of the Census. The focus is on the aging of the population and its consequences. The author discusses such issues...

Khalidova, K. R.; Tukhvatullina, Z.G.; Khakberdyyeva, D.M., 2007: Kaposi'sarcoma: contemporary data on the etiology and pathogenesis. The article reviewed literature data on the role of retroviruses in the development of Kaposi's sarcoma. It was found that virus HHV-8 was the main etiological factor in the development of the disease. Many investigations indicated that the o...

Turner J.E.; Callen J.P., 1981: Aggressive behavior of squamous cell carcinoma in a patient with preceding lymphocytic lymphoma. Actinically induced squamous cell carcinomas of the skin (SCC) are generally considered nonaggressive and are usually curable tumors. In patients with lymphoma or leukemia these tumors may behave in an extremely aggressive manner. A case is report...

Kulkarni, S.; Ballal, A.; Apte, S.Kumar., 2014: Bioprecipitation of uranium from alkaline waste solutions using recombinant Deinococcus radiodurans. Bioremediation of uranium (U) from alkaline waste solutions remains inadequately explored. We engineered the phoK gene (encoding a novel alkaline phosphatase, PhoK) from Sphingomonas sp. for overexpression in the radioresistant bacterium Deinococc...

Lecher, P., 1967: Cytogenetique de l'hybridisation experimentale et naturelle chez l'isopode Jaera (albifrons) syei Bocquet. Archives de Zoologie Experimentale et Generale, 108: 633-698