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Titolo:
ARTROEITE, PBALF3(OH)(2), A NEW MINERAL FROM THE GRAND REEF MINE, GRAHAM COUNTY, ARIZONA - DESCRIPTION AND CRYSTAL-STRUCTURE
Autore:
KAMPF AR; FOORD EE;
Indirizzi:
NAT HIST MUSEUM LOS ANGELES,MINERAL SECT,900 EXPOSIT BLVD LOS ANGELESCA 90007 US GEOL SURVEY LAKEWOOD CO 80225
Titolo Testata:
The American mineralogist
fascicolo: 1-2, volume: 80, anno: 1995,
pagine: 179 - 183
SICI:
0003-004X(1995)80:1-2<179:APANMF>2.0.ZU;2-6
Fonte:
ISI
Lingua:
ENG
Soggetto:
BOND-VALENCE PARAMETERS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
8
Recensione:
Indirizzi per estratti:
Citazione:
A.R. Kampf e E.E. Foord, "ARTROEITE, PBALF3(OH)(2), A NEW MINERAL FROM THE GRAND REEF MINE, GRAHAM COUNTY, ARIZONA - DESCRIPTION AND CRYSTAL-STRUCTURE", The American mineralogist, 80(1-2), 1995, pp. 179-183

Abstract

Artroeite, PbAlF3(OH)(2), space group P ($) over bar 1, a = 6.270(2),b = 6.821(3), c = 5.057(2) Angstrom, alpha = 90.68(2), beta = 107.69(2), gamma = 104.46(2)degrees, V = 198.6(2) Angstrom(3), Z = 2, is a new mineral from the Grand Reef mine, near Klondyke, Graham County, Arizona. It occurs as colorless bladed crystals associated with quartz, fluorite, galena, anglesite, and an as yet undescribed mineral of composition PbCa2Al(F,OH)(9). Artroeite has a Mohs hardness of about 2.5, a measured density of 5.36(2) g/cm(3), and a calculated density of 5.47 g/cm(3). It exhibits a perfect {100} cleavage and a good {010} cleavage. Optically it is biaxial (-) with alpha = 1.629(1), beta = 1.682(2),and gamma = 1.691(2). Dispersion is strong, r > v. The six strongest powder diffraction lines are [d(I,hkl)] 4.42(100)(($) over bar 101), 3.221(40)(101), 2.595(70)(1 ($) over bar 21,021), 2.190(65) (201,012,030), 2.030(50)(022), 2.015(40)(($) over bar 230) Angstrom. The structure was solved by direct methods and refined to R = 0.022 using X-ray diffractometer data (1096 independent reflections). In the structure, edge-sharing dimers of AlF3(OH)(3) octahedra link together by bonds to Pb atoms to form approximately close-packed layers parallel to (10 ($) over bar 1). The layers are linked to one another by one Pb-F bond andtwo II bonds per formula unit. Pb is coordinated to 6 F and 3 O atoms. Three F ligands are associated with the same Al octahedral face and correspond to much longer bonds. It is probable that the lone pair electrons are situated on that side of the Pb atom. The structure is compared with those of acuminite and tikhonenkovite.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 21/10/19 alle ore 04:39:34