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GEOREF RECORD

Pumpellyite-(Al), a new mineral from Bertrix, Belgian Ardennes

Frederic Hatert, Marco Pasero, Natale Perchiazzi and Thomas Theye
Pumpellyite-(Al), a new mineral from Bertrix, Belgian Ardennes
European Journal of Mineralogy (March 2007) 19 (2): 247-253

Abstract

Pumpellyite-(Al), ideally Ca (sub 2) (Al,Fe (super 2+) ,Mg)Al (sub 2) (SiO (sub 4) ) (Si (sub 2) O (sub 7) ) (OH,O) (sub 2) .H (sub 2) O, is a newly approved mineral species from Bertrix, Ardennes mountains, Belgium. It occurs as radiating fibrous aggregates reaching 5 mm in diameter, constituted by acicular crystals associated with calcite, K-feldspar and chlorite. Pumpellyite-(Al) is transparent to translucent and exhibits an emerald-green to white colour, sometimes with bluish tinges. The lustre is vitreous and the streak is colourless. The mineral is non-fluorescent, brittle, and shows a perfect {100} cleavage. The estimated Mohs hardness is 5 1/2, and the calculated density is 3.24 g/cm (super 3) . Pumpellyite-(Al) is biaxial positive, alpha = 1.678(2), beta = 1.680(2), gamma = 1.691(1) (lambda = 590 nm), colourless in thin section, 2V = 46 degrees , Y = b, no dispersion. Electron-microprobe analyses gave SiO (sub 2) 37.52, Al (sub 2) O (sub 3) 25.63, MgO 1.99, FeO 4.97, MnO 0.11, CaO 23.21, BaO 0.01, Na (sub 2) O 0.03, K (sub 2) O 0.02, H (sub 2) O (sub calc) . 6.71, total 100.20 wt. %. The resulting empirical formula, calculated on the basis of 8 cations, is (Ca (sub 1.99) Na (sub 0.01) ) (sub Sigma 2.00) (Al (sub 0.42) Fe (super 2+) (sub 0.33) Mg (sub 0.24) Mn (sub 0.01) ) (sub Sigma 1.00) Al (sub 2.00) (SiO (sub 4) ) (Si (sub 2) O (sub 7) ) (OH) (sub 2.42) 0.58H (sub 2) O. The simplified formula is Ca (sub 2) AlAl (sub 2) (SiO (sub 4) ) (Si (sub 2) O (sub 7) ) (OH) (sub 3) , which requires SiO (sub 2) 38.16, Al (sub 2) O (sub 3) 32.38, CaO 23.74, H (sub 2) O 5.72, Total 100.00 wt. %. The unit-cell parameters, refined from X-ray powder diffraction data, are: a = 8.818(2), b = 5.898(2), c = 19.126(6) Aa, beta = 97.26(3) degrees , V = 986.7(4) Aa (super 3) , space group A2/m. The eight strongest lines in the powder pattern [d-values(in Aa)(I)(hkl)] are: 4.371(65)(200), 3.787(80)(202), 3.040(70)(204), 2.912(95)(300), 2.895(100)(302), 2.731(40)(206), 2.630(35)(311), 2.191(45)(402). Pumpellyite-(Al) belongs to the pumpellyite group, and corresponds to the Al-rich compositions where the M1 and M2 sites contain Al as predominant cation. The crystal structure of pumpellyite-(Al) has been refined by the Rietveld method, based on an X-ray powder diffraction pattern, to R (sub Bragg) = 7.09%. The infrared spectrum is similar to those of minerals of the pumpellyite group. The mineral species and name were approved by the Commission on New Minerals and Mineral Names, IMA (no. 2005-016).


ISSN: 0935-1221
EISSN: 1617-4011
Serial Title: European Journal of Mineralogy
Serial Volume: 19
Serial Issue: 2
Title: Pumpellyite-(Al), a new mineral from Bertrix, Belgian Ardennes
Affiliation: Universite de Liege, Departement de Geologie, Liege, Belgium
Pages: 247-253
Published: 200703
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Federal Republic of Germany
References: 29
Accession Number: 2007-045079
Categories: Mineralogy of silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 5 tables
N49°51'00" - N49°51'00", E05°15'00" - E05°15'00"
Secondary Affiliation: Universita di Pisa, ITA, ItalyUniversitaet Stuttgart, DEU, Federal Republic of Germany
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, copyright, Schweizerbart'sche Verlagsbuchhandlung. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 200724
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