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GEOREF RECORD

Vicanite-(Ce); a new Ca-Th-REE borosilicate from the Vico volcanic district (Latium, Italy)

Adriana Maras, Gian Carlo Parodi, Giancarlo Della Ventura and Daniel Ohnenstetter
Vicanite-(Ce); a new Ca-Th-REE borosilicate from the Vico volcanic district (Latium, Italy)
European Journal of Mineralogy (April 1995) 7 (2): 439-446

Abstract

Vicanite-(Ce), ideally (Ca,REE,Th) (sub 15) As (super 5+) (As (super 3+ ) (sub 0.5 ) Na (sub 0.5) )Fe (super 3+) Si (sub 6) B (sub 4) O (sub 40) F (sub 7) , was found in a volcanic ejectum collected from a pyroclastic formation of the Vico volcanic complex at Tre Croci, Vetralla (N of Rome). It occurs in small miarolitic cavities in association with zircon, thorite, thorian uraninite, betafite, thorian hellandite, titanite, antimonian asbecasite, apatite, stillwellite-(Ce), etc., in a host rock of sanidine, plagioclase, clinopyroxene amd minor magnetite and clinoamphibole. Vicanite-(Ce) forms euhedral crystals up to 0.3 mm and is yellowish green, with epsilon 1.722, Omega 1.757. EPMA gave SiO (sub 2) 13.82, TiO (sub 2) 0.14, Al (sub 2) O (sub 3) 0.16, P (sub 2) O (sub 5) 0.38, As (sub 2) O (sub 3) 4.49, Fe (sub 2) O (sub 3) 1.66, CaO 17.07, Na (sub 2) O 0.14, ThO (sub 2) 18.24, UO (sub 2) 1.96, RE (sub 2) O (sub 3) 30.98, B (sub 2) O (sub 3 (calc)) 5.27, F 7.50, less F = O 3.16, = 98.65 (with the RE (sub 2) O (sub 3) = La (sub 2) O (sub 3) 12.01, Ce (sub 2) O (sub 3) 14.41, Pr (sub 2) O (sub 3) 2.77, Nd (sub 2) O (sub 3) 1.79). Indexed XRD powder data are tabulated; strongest lines 2.993(100), 2.950(70), 7.70(50), 4.42(50), 3.13(50), 2.698(50), 1.839(50), 1.802(50) Aa; a 10.795, c 27.336 Aa: space group R3m, Z = 3. The main feature of the structure is the presence of a new polyanion(Si (sub 3) B (sub 3) O (sub 18) ) (super 15-) . The cell dimensions are very close to those of okanoganite-(Ce), but the REE chemistry is different.


ISSN: 0935-1221
Serial Title: European Journal of Mineralogy
Serial Volume: 7
Serial Issue: 2
Title: Vicanite-(Ce); a new Ca-Th-REE borosilicate from the Vico volcanic district (Latium, Italy)
Affiliation: Universita di Roma "La Sapienza", Dipartimento di Scienze della Terra, Roma, Italy
Pages: 439-446
Published: 199504
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Federal Republic of Germany
References: 26
Accession Number: 1995-027345
Categories: Mineralogy of silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 3 tables
Secondary Affiliation: Museum National d'Histoire Naturelle, FRA, FranceCRSCM-CNRS, FRA, France
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United KingdomTwickenhamUKUnited Kingdom
Update Code: 199510
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