 | | Journal (article/letter/editorial) | | combeite- and götzenite-bearing nephelinite at Nyiragongo, Virunga Volcanic Province in the East African...a c t The lavas and pyroclastic rocks of Nyiragongo volcano (East African Rift) range in composition...combeite nephelinite. In peralkaline nephelinites at Nyiragongo, titanium is hosted in mineral assemblages with...(replacing melilite phenocrysts), recrystallized nepheline + kalsilite phenocryst aggregates and a range...including delhayelite. The compositions of coexisting nepheline and kalsilite in phenocryst aggregates and groundmass |  | | Journal (article/letter/editorial) | | Kalsilite in the lavas of Mt. Nyiragongo (Belgian Congo) by TH. G. S AH AM A University of Helsinki,...nephelinite lavas of the volcano Mt. Nyiragongo in the eastern Belgian Congo contains kalsilite as one...feldspathoid of the rock but is accompanied by nepheline, abundant melilite, and, sometimes, by small to...are lacking. Kalsilite occurs both as complex nepheline-kalsilite phenocrysts in which these phases are... as grains separate from those of nepheline. The complex nepheline-kalsilite phenocrysts exhibit a continuous |  | | Journal (article/letter/editorial) | | Kalsilite in the lavas of Mt. Nyiragongo (Belgian Congo) by TH. G. S AH AM A University of Helsinki,...nephelinite lavas of the volcano Mt. Nyiragongo in the eastern Belgian Congo contains kalsilite as one...feldspathoid of the rock but is accompanied by nepheline, abundant melilite, and, sometimes, by small to...are lacking. Kalsilite occurs both as complex nepheline-kalsilite phenocrysts in which these phases are... as grains separate from those of nepheline. The complex nepheline-kalsilite phenocrysts exhibit a continuous |  | | Report (issue) | | 1.2 Crystal Data: Hexagonal. Point Group: 6: nepheline and kalsilite. Physical Properties: Extremely...501(2) Z = n.d. X-ray Powder Pattern: Kabfumu volcanic °ow, Congo. 3.076 (100), 3.050 (95), 2.558 (45)...In lava. Association: Nepheline, kalsilite. Distribution: From the Kabfumu volcanic °ow, between the...the Mt. Mikeno and Mt. Nyiragongo volcanos, Kivu Province, Congo (Zaire). Name: For the length of the...Trikalsilite: its structural relationships with nepheline and tetrakalsilite. Neues Jahrb. Mineral., Monatsh |  | | Journal (article/letter/editorial) | | Aufs~itze Mineralogical composition of the Nyiragongo rod, s By TrL G. SArr~MA,Helsinki *) With 8 figures...figures and 2 tables Dedicated to Professor Dr. A. RITTMANNon the oeeasion of his 75. birthday Zusammenfassung...Gesteinsanalysen auf die Laven des Nyiragongo-Vulkans in Nord Kivu, Republik Congo (Kinsasha). In dem hetr. vulkanischen...Basanitgruppe (m~il3ig unters~ttigt) und das Nyiragongo-Gebiet mit Gesteinen der Leuzitit-NephelinitMelilitithgruppe...Entstehung des hauptsiichlich melilitithischen Nyiragongo-Magmas mSglicherweise mit karbonatischen Anteilen |  | | Journal (article/letter/editorial) | | avaiiable from a lava flow at Kabfumu, Nyiragongo area in North Kivu, Belgian Congo, which has been studied...kalsilite occurs as the dominant phase in a kalsilite-nepheline microperthite of a texture similar to that describedby...sharp reflections expected for kalsilite and nepheline. The diffuse reflections originate from the kalsilite...photographs obtained for several crystals from the Kabfumu lava revealed variations in the intensity of the...order, thus showing that the kalsilite of the Kabfumu Iava has not reached equilibrium. * Present address |  | | Journal (article/letter/editorial) | | melilite and nepheline (melilite nephelinites) from the Nyiragongo volcano of the Congo and a group rich...(the melilite nephelinite of the lava lake of Nyiragongo) through the Cameroons etindite (clinopyroxene...includes a number of lavas of the Nyiragongo Crater area of the Congo and an etindite from the Cameroons...nephelinites which hold phenocrysts of melilite and nepheline, one also carrying leucite (VM 220) and another...consisting of a core of perthitic nepheline-kalsilite surrounded by a nepheline margin (FEAE 83). The lava of |  | | Journal (article/letter/editorial) | | and the nepheline-kalsilite series would suggest existence of similar phenomena also in nepheline, such...necessarily fail in the case of nepheline. The hexagonal symmetry of nepheline, from which no deviation is...crystallographic axes. The ways of attack on studying nepheline must be different from those used for the feldspars...microscope heating stage. Two optical types of nepheline were distinguished on the basis of the absolute...temperature and a highJy positive optical A-value. The nepheline specimens studied represent optically a continuous |  | | Journal (article/letter/editorial) | | ratios (average = 0-707) than the melilite- and nepheline-bearing varieties (average = 0-705). Samples of...also for lava flows from one extensively sampled volcano. Hypotheses involving simple fractional crystallization...Birunga area at the junction of the Congo, south-west Uganda, and north-west Rwanda (see Fig. 1). The Birunga...Nyamlagira (Nyamuragira) and Nyiragongo in the Virunga province of the Congo. Most of the volcanoes in the...than olivine leucitite and has a glassy base. Nepheline-bearing varieties also are found. (2) Leucitite-Nephelinite |  | | Journal (article/letter/editorial) | | and andremeyerite-bearing nephelinite from Nyiragongo volcano, East African Rift Tom Andersen a,⁎, Marlina...peralkaline leucite nephelinite from the active volcano Nyiragongo in the Virunga province of the East African...mineral. Low-variance mineral assemblages in Nyiragongo nephelinite define a cooling trend from eruptive...East African Rift (Shombole, Oldoinyo Lengai, Nyiragongo). A number of rare minerals that are characteristic...nephelinite from Nyiragongo in the Virunga volcanic province, Democratic Republic of Congo, including götzenite |  | Chakrabarti, Ramananda, Basu, Asish R., Santo, Alba P., Tedesco, Dario, Vaselli, Orlando (2009) Isotopic and geochemical evidence for a heterogeneous mantle plume origin of the Virunga volcanics, Western rift, East African Rift system. Chemical Geology, 259 (3) 273-289 doi:10.1016/j.chemgeo.2008.11.010 | Journal (article/letter/editorial) | | active Virunga volcanoes, Nyiragongo and Nyamuragira, are 15 km apart. Nyiragongo shows unusual compositions...major, trace elements and Nd–Sr–Pb isotopes in Nyiragongo and Nyamuragira lavas including samples from...from 2002, 2003 and 2004 eruptions. The youngest Nyiragongo lavas are ultrapotassic, ultrasodic and have...basanites and tephrites, distinct from the foiditic Nyiragongo lavas. Both volcanic products show enrichment...Dy/Yb suggests residual garnet in the source(s). Nyiragongo and Nyamuragira lavas show high Nb/U similar |  | | Journal (article/letter/editorial) | | from rocks where it is closely associated with nepheline. An analysis of one of the ncphelines is also...very slight. Accordingly, for determining the nepheline composition in petrographic rock description,...change in the ratio of potassium to sodium in nepheline is accompanied b y a considerable change in the...cent, I(X) K / ( K - ' - N a + C a ) . As in nepheline, powder diffraction data. m a y be used for determining...and Hey, 1942 ; Sahama, 1954), and Nyiragongo area in the Belgian Congo (Sahama, 1953). The last-mentioned |  | | Journal (article/letter/editorial) | | kalsilite from volcanic and metamorphic rocks (Mount Nyiragongo, Z,aire; Alban Hills, Italy; Kerala, southern...superstructuredevelopsmay be - 500 "C. Natural nepheline exsolvedfrom kalsilite displays merohedral twinning...Carpenter(1989) of compositions at the Ks-rich end of the nepheline-kal- found that the transition occurs by means...con- from crystalstaken from a lava from Mount Nyiragongo, sequence. SyntheticKAlSiOnhasP6rmc symmetryat...solution. Finally, kalsilite crystalsproduced from nepheline by ion exchangein molten KCI can give diffraction |  | | Journal (article/letter/editorial) | | of kalsilite-nepheline microperthite, the lava from Kabfumu, North Kivu in Belgian Congo, contains parallel...growths of a new mineral, tri-kalsilite, and nepheline. After heating to 1000o C. for two hours, one...slightly difiuse reflections revealed the presenceof nepheline in parallel association.Tri-kalsilite is hexagonal...probably P63. Along with d-kalsilite (@5.15 A), nepheline (a l0 A) and tetra-kalsilite (a 20 A;, tri-kutsilite...high-tridymite (@5.0 A;. fne structures of kalsilite and nepheline have been shown to be based on a tridymite-type |  | | Journal (article/letter/editorial) | | Ion Exchange Between Tectosilicates with the Nepheline-Kalsilite Framework and Molten MNO3 or MCI (M--Li...June 5, 1993 Abstract. Natural nepheline, a synthetic Na-rich nepheline, and synthetic kalsilite were...Two new compounds were obtained: Li-exchanged nepheline with a formula near (Li,Ko.3,D)Li~[A13(A1,Si)Si~O16]...1(6) c=822.9(5) pm 7= 119.15 ~ and Ag-exchanged nepheline with a formula near (K,Na, D)Ag3[At3(A1,Si)Si40~6]...as an intermediate composition which has the nepheline structure and is miscible with the sodian end |  | | Journal (volume) | | Kirjeenvaihtajajäsenet Barth , Tom F. W ., Prof. Cloos, Ernst, Dr. von Eckermann, Harry, Prof. Flint, Richard, F ....F . J ., Prof. Ramdohr, Paul, Prof. Dr. Sander, Bruno, Prof. Dr. Szadeczky-Kardoss, Elemer, Prof. Vendl...Vendl, A., Prof. Wojno, Tadeusz, Prof. Öpik, Ar., Dr. MEMBERSHIP LIST H onorary Members Rakuunantie...0 218. Ulkomaiset jäsenet Adamson, Olge J., Fil. Dr. Armstrong, Herbert S., Prof. Barbour, George B.... Geolog Bem, Hansjürgen, Mag. Blake, Weston Jr., Dr. Bloomfield, Keith, M. Sc. Brognon, Georges, Inge |  | | Journal (volume) | | Kirjeenvaihtajajäsenet Barth , Tom F. W ., Prof. Cloos, Ernst, Dr. von Eckermann, Harry, Prof. Flint, Richard, F ....F . J ., Prof. Ramdohr, Paul, Prof. Dr. Sander, Bruno, Prof. Dr. Szadeczky-Kardoss, Elemer, Prof. Vendl...Vendl, A., Prof. Wojno, Tadeusz, Prof. Öpik, Ar., Dr. MEMBERSHIP LIST H onorary Members Rakuunantie...0 218. Ulkomaiset jäsenet Adamson, Olge J., Fil. Dr. Armstrong, Herbert S., Prof. Barbour, George B.... Geolog Bem, Hansjürgen, Mag. Blake, Weston Jr., Dr. Bloomfield, Keith, M. Sc. Brognon, Georges, Inge |  | | Journal (volume) | | gongo (Eastern Congo) 8. TH. G. SAHAMA, Contact Microradiographic Distinction between Nepheline and Kalsilite...Philippines Ojakangas, Richard, M. A., USA Dudek, Arnost, Dr., Czecho-Slovakia Clark, Alan, B. Sc., Great Britain...malmiesiintymistii. 40 Bulletin de la Commission g6ologiquc dr? Finlande N:o 196. Veikko Okko: Geologi-lehden ilmestymisen.... Lougee: Glacial Shoreline History in Eastern North America. A. Von Volborth: Vayryneniitistä. H. Stigzelius:...areas of molasse in Finland. Beginning from the north, the Kumpu formation has been thought to be a molasse |  | | Journal (volume) | | gongo (Eastern Congo) 8. TH. G. SAHAMA, Contact Microradiographic Distinction between Nepheline and Kalsilite...Philippines Ojakangas, Richard, M. A., USA Dudek, Arnost, Dr., Czecho-Slovakia Clark, Alan, B. Sc., Great Britain...malmiesiintymistii. 40 Bulletin de la Commission g6ologiquc dr? Finlande N:o 196. Veikko Okko: Geologi-lehden ilmestymisen.... Lougee: Glacial Shoreline History in Eastern North America. A. Von Volborth: Vayryneniitistä. H. Stigzelius:...areas of molasse in Finland. Beginning from the north, the Kumpu formation has been thought to be a molasse |  | | Journal (article/letter/editorial) | | existing MELTS software package. The model for nepheline is formulated for the simplifying assumptions...cation and the three small cation sites in the nepheline structure at high temperatures, an average dT.../kbar for the reaction nepheline kalsilite tetrakalsilite (K-rich nepheline) over the temperature...ordered components in nepheline, and large positive Gibbs energies for the nepheline reciprocal reactions...O6 (3=2 H2 OAlSi2 O6 K(1=2 : Introduction Nepheline, leucite, and kalsilite are the three most common |  | | Journal (article/letter/editorial) | | much to clarify phase relations in the system nepheline-kalsilite and polymorphism in KAlSiOr. These studies...kalsilite-nephelinemicroperthite from Kabfumu, (Beigian) congo showed six additional diffuse reflectionsindicating...287-288. Surrn, J. V. e.NnTurrr,n, O. F., 1957,The nepheline-kalsilite system: I. X-ray data for the crystalline...'l'urrr.r:, 'fhe O. F. enn Surrn, J. V., 1958, nepheline-kalsilite system: IL Phase relations: Amer. Jour |  | | Book (volume) | | felspars we have been particularly fortunate in having Dr W. S. MacKenzie close at hand and are most grateful...Tridymite, Cristobalite . . . . .179 NEPHELINE GROUP.231 Nepheline, Kalsilite ....... 231 PETALITE.271...nomenclatures we have been guided princip¬ ally by Dr. W. S. MacKenzie, whose assistance is gratefully...Sodium-rich orthoclase cryptoperthite, ijolite-nepheline-syenite, Sinkwa, Mogok, Burma (Tilley, 1954)....analyses. ...U1“’ 1>0rway 2. M““^Perthite- nepheline-syenite, Fukushin-zan district, Korea (Yoshizawa |  | | Journal (volume) | | Dietrich about ten years ago when Dr. William F. Foshag and Dr. George Switzer were kindly helping...locality ptygmatic features, was sent to the museum by Dr. J. J. Sederholm. The only location given was »southern...Bl'acksburg, Virginia, U.S. A . 1believe that most of Dr. Marmo's points are covered sufficiently in the original...described specimen was not, in my opinion, sent by Dr. Sederholrn to illustrate ptygmatic features. The...nephelinite lava. Mt. Kyiragongo (specimen VM 611), Congo. Magnificiltion 200 x. nating higher and weaker |  | | Journal (volume) | | Dietrich about ten years ago when Dr. William F. Foshag and Dr. George Switzer were kindly helping...locality ptygmatic features, was sent to the museum by Dr. J. J. Sederholm. The only location given was »southern...Bl'acksburg, Virginia, U.S. A . 1believe that most of Dr. Marmo's points are covered sufficiently in the original...described specimen was not, in my opinion, sent by Dr. Sederholrn to illustrate ptygmatic features. The...nephelinite lava. Mt. Kyiragongo (specimen VM 611), Congo. Magnificiltion 200 x. nating higher and weaker |  | | Book (edition) | | This book is respectfully dedicated to the memory of Dr. John Sinkankas for his kind initiative and support...by Strunz (1996). Thanks to the kind permission of Dr. E. Nagele from the E. Schweizerbart'sche Verlagsbuchhandlung...(mountains), R. (river), Is. (island), Vole. (volcano), Penin. (peninsula), St. (Saint), Ste. (Sainte)...arisen with localities in Congo-Zaire: the country, named Democratic Republic of Congo since 1960, was changed...The former Kivu province is now divided to three regions: INTRODUCTION Nord-Kivu, Sud-Kivu, and Maniema |
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