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Stefanweissite, (Ca,REE) (sub 2) Zr (sub 2) (Nb,Ti)(Ti,Nb) (sub 2) Fe (super 2+) O (sub 14) , a new zirconolite-related mineral from the Eifel paleovolcanic region, Germany

Nikita V. Chukanov, Natalia V. Zubkova, Igor V. Pekov, Marina F. Vigasina, Yury S. Polekhovsky, Bernd Ternes, Willi Schueller, Sergey N. Britvin and Dmitry Yu. Pushcharovsky
Stefanweissite, (Ca,REE) (sub 2) Zr (sub 2) (Nb,Ti)(Ti,Nb) (sub 2) Fe (super 2+) O (sub 14) , a new zirconolite-related mineral from the Eifel paleovolcanic region, Germany
Mineralogical Magazine (August 2019) 83 (4): 607-614

Abstract

The new mineral stefanweissite, IMA2018-020, was discovered in sanidinite volcanic ejecta from the Laach Lake (Laacher See) paleovolcano, Eifel region, Rhineland-Palatinate, Germany. Associated minerals are sanidine, nosean, biotite, augite, titanite, ferriallanite-(La), magnetite, baddeleyite and a pyrochlore-group mineral. Stefanweissite is brown and reddish-brown, with adamantine lustre; the streak is light brown to yellow. It forms long-prismatic crystals up to 0.03 mmX0.07 mmX1.0 mm and acicular crystals up to 2 mm long and 0.02 mm thick typically combined in radiated aggregates in cavities in sanidinite. D (sub calc.) =5.254 g/cm (super 3) . The mean refractive index calculated from the Gladstone-Dale equation is 2.260. The Raman spectrum shows the absence of hydrogen-bearing groups. The chemical composition is (electron microprobe, wt.%): CaO 7.63, MnO 2.51, FeO 7.86, Al (sub 2) O (sub 3) 0.25, La (sub 2) O (sub 3) 2.28, Ce (sub 2) O (sub 3) 6.54, Pr (sub 2) O (sub 3) 1.01, Nd (sub 2) O (sub 3) 1.59, ThO (sub 2) 3.71, UO (sub 2) 1.09, TiO (sub 2) 17.32, ZrO (sub 2) 28.03, HfO (sub 2) 0.91, Nb (sub 2) O (sub 5) 19.96, total 99.69. The empirical formula based on 14 O atoms per formula unit is Ca (sub 1.13) (Ce (sub 0.33) La (sub 0.12) Nd (sub 0.08) Pr (sub 0.05) ) (sub Sigma 0.58) Th (sub 0.12) U (sub 0.03) Mn (sub 0.29) Fe (sub 0.91) Al (sub 0.04) Zr (sub 1.89) Hf (sub 0.04) Ti (sub 1.80) Nb (sub 1.19) O (sub 14) . The simplified formula is (Ca,REE) (sub 2) Zr (sub 2) (Nb,Ti)(Ti,Nb) (sub 2) Fe (super 2+) O (sub 14) . Stefanweissite is orthorhombic, with space group Cmca. The unit-cell parameters are: a=7.2896(4) Aa, b=14.1435(5) Aa, c=10.1713(4) Aa and V=1048.68(7) Aa (super 3) . The crystal structure was solved using single-crystal X-ray diffraction data. Stefanweissite is an analogue of zirconolite-3O with Nb dominant over Ti in one of two octahedral sites. The strongest lines of the powder X-ray diffraction pattern [d, Aa (I, %)(hkl)] are: 2.983(100)(202), 2.897(71)(042), 1.828(38)(154,400,333), 1.793(25)(244), 1.767(16)(080), 1.517(10)(282), 1.187(19)(483,1.11.3,602). Type material is deposited in the collections of the Fersman Mineralogical Museum of the Russian Academy of Sciences, Moscow, Russia, with the registration number 5191/1.


ISSN: 0026-461X
EISSN: 1471-8022
Serial Title: Mineralogical Magazine
Serial Volume: 83
Serial Issue: 4
Title: Stefanweissite, (Ca,REE) (sub 2) Zr (sub 2) (Nb,Ti)(Ti,Nb) (sub 2) Fe (super 2+) O (sub 14) , a new zirconolite-related mineral from the Eifel paleovolcanic region, Germany
Affiliation: Russian Academy of Sciences, Institute of Chemical Physics, Chernogolovka, Russian Federation
Pages: 607-614
Published: 201908
Text Language: English
Publisher: Mineralogical Society, London, United Kingdom
References: 32
Accession Number: 2020-006675
Categories: Mineralogy of non-silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 7 tables
N50°00'00" - N50°30'00", E06°19'60" - E07°19'60"
Secondary Affiliation: Moscow State University, RUS, Russian FederationRussian Academy of Sciences, Vernadskiy Institute of Geochemistry and Analytical Chemistry, RUS, Russian FederationSt. Petersburg State University, RUS, Russian FederationRussian Academy of Sciences, Kola Science Centre, RUS, Russian Federation
Country of Publication: United Kingdom
Secondary Affiliation: GeoRef, Copyright 2020, American Geosciences Institute. Abstract, Copyright, Mineralogical Society of Great Britain and Ireland. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 202006
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