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Grenmarite, a new member of the goetzenite-seidozerite-rosenbuschite group from the Langesundsfjord district, Norway; definition and crystal structure

Marco Bellezza, Marco Franzini, Alf O. Larsen, Stefano Merlino and Natale Perchiazzi
Grenmarite, a new member of the goetzenite-seidozerite-rosenbuschite group from the Langesundsfjord district, Norway; definition and crystal structure
European Journal of Mineralogy (December 2004) 16 (6): 971-978

Abstract

Grenmarite, a new mineral of the gotzenite-seidozerite-rosenbuschite group, was found in a syenite pegmatite at the eastern side of the island Vesle Aroya in the Langesundsfjord district, Norway. Grenmarite, ideally (Zr,Mn) (sub 2) (Zr,Ti)(Mn,Na)(Na,Ca) (sub 4) (Si (sub 2) O (sub 72) (O,F) (sub 4) , is the Zr-analogue of seidozerite. It is monoclinic with space group P2/c, Z = 2, a = 5.608(1), b = 7.139(1), c = 18.575(5) Aa, beta = 102.60(2) degrees and V = 725.72(3) Aa (super 3) . It occurs as yellowish brown, semi-parallel aggregates of elongated, flattened crystals up to 1 cm in length. The mineral is translucent, with vitreous lustre, good {001} cleavage and uneven fracture. Mohs' hardness is 41/2; the measured density is 3.49(1) g/cm (super 3) . The strongest five X-ray diffraction lines of the powder pattern [d in Aa (1)] are: 2.898(100), 3.027(68), 2.613(26), 2.459(24), 1.853(24). An average of fifteen electron microprobe analyses of grenmarite gave SiO (sub 2) 29.85, TiO (sub 2) 4.51, CaO 1.84, MnO 8.25, FeO 2.01, Na (sub 2) O 15.43, Y (sub 2) O (sub 3) 0.22, Ce (sub 2) O (sub 3) 0.01, ZrO (sub 2) 31.63, Nb (sub 2) O (sub 5) 0.06, F 5.24, O identical with F 2.21, total 96.84 wt.%. The empirical formula, based on 4 Si atoms, is (Zr (sub 1.52) Mn (sub 0.46) Y (sub 0.02) ) (sub Sigma 2.00) Zr (sub 0.55) Ti (sub 0.45) ) (sub Sigma 1.00) (Mn (sub 0.48) Na (sub 0.29) Fe (sub 0.23) ) (sub Sigma 1.00) (Na (sub 3.72) Ca (sub 0.26) ) (sub Sigma 3.98) Si (sub 4) O (sub 15.40) F (sub 2.22) . Grenmarite is isostructural with seidozerite: its structure can be described as built up with three distinct modules connected through corner-sharing: an "octahedral" layer, an "octahedral" ribbon, and disilicate groups. The crystal structure has been refined to a final R of 0.043. The crystal chemical formula resulting from the structural refinement is: (Zr (sub 1.76) Mn (sub 0.24) ) (sub Sigma 2.00) (Zr (sub 0.54) Ti (sub 0.46) ) (sub Sigma 1.00) (Mn (sub 0.76) Na (sub 0.24) ) (sub Sigma 1.00) (Na (sub 3.32) Ca (sub 0.38) Mn (sub 0.30) ) (sub Sigma 4.00) (Si (sub 2) O (sub 7) ) (sub 2) O (sub 1.96) F (sub 2.04) .


ISSN: 0935-1221
EISSN: 1617-4011
Serial Title: European Journal of Mineralogy
Serial Volume: 16
Serial Issue: 6
Title: Grenmarite, a new member of the goetzenite-seidozerite-rosenbuschite group from the Langesundsfjord district, Norway; definition and crystal structure
Affiliation: Universita di Pisa, Dipartimento di Scienze della Terra, Pisa, Italy
Pages: 971-978
Published: 200412
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Federal Republic of Germany
References: 20
Accession Number: 2005-023467
Categories: Mineralogy of silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 9 tables
N59°00'00" - N59°07'60", E09°37'60" - E09°54'00"
Secondary Affiliation: Norsk Hydro, NOR, Norway
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 200512
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