Artículo
Bismutotantalite from northwestern Argentina: Description and crystal structure
Galliski, Miguel Angel
; Marquez Zavalia, Maria Florencia
; Cooper, Mark A.; Cerný, Petr; Hawthorne, Frank C.
Fecha de publicación:
02/2001
Editorial:
Mineralogical Association of Canada
Revista:
Canadian Mineralogist
ISSN:
0008-4476
Idioma:
Inglés
Tipo de recurso:
Artículo publicado
Clasificación temática:
Resumen
Bismutotantalite occurs in albite-rich cores of the La Elvirita granitic pegmatites, northwestern Argentina, associated mainly with bismuth, bismuthinite, ferrotapiolite, manganotantalite, microlite, uranmicrolite, bismutomicrolite, hafnian zircon and montebrasite. A fresh, cm-sized crystal, dark grey with a greasy luster and D = 8.809 g/cm3, was examined. In reflected light, it is grey with very weak bireflectance; two phases can be distinguished. Electron-microprobe analysis gives the host bismutotantalite [Bi] as [Bi,Sb], (Bi0.68Sb0.32)(Ta0.89Nb0.11)O4, is enriched in Sb. Least-squares refinement of X-ray powder-diffraction data of [Bi] gave a 4.968(1), b 11.796(3), c 5.646(1) Å, V = 330.85(9) Å3. The crystal structures of [Bi] and [Bi,Sb] were refined to R indices of 1.9 and 2.4%, based on 387 and 377 observed (4σ) reflections, respectively, measured with MoKα X-radiation. Both phases are orthorhombic, space group Pcnn. Z = 4; [Bi] has a 4.9652(4), b 11.7831(16), c 5.6462(5) Å. V 330.32(6) Å3, and [Bi,Sb] has a 4.9471(4), b 11.7878(7), c 5.6048(3) Å, V 326.83(4) Å3. These results show that the centrosymmetric structure of bismutotantalite can accommodate up to ∼40% Sb3+ substituting for Bi3+ without changing to the Pc21n structure of stibiotantalite.
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Articulos(IANIGLA)
Articulos de INST. ARG. DE NIVOLOGIA, GLACIOLOGIA Y CS. AMBIENT
Articulos de INST. ARG. DE NIVOLOGIA, GLACIOLOGIA Y CS. AMBIENT
Citación
Galliski, Miguel Angel; Marquez Zavalia, Maria Florencia; Cooper, Mark A.; Cerný, Petr; Hawthorne, Frank C.; Bismutotantalite from northwestern Argentina: Description and crystal structure; Mineralogical Association of Canada; Canadian Mineralogist; 39; 1; 2-2001; 103-110
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