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The crystal structure of flamite and its relation to Ca (sub 2) SiO (sub 4) polymorphs and nagelschmidtite

Frank Gfeller, Remo Widmer, Biljana Kruger, Evgeny V. Galuskin, Irina O. Galuskina and Thomas Armbruster
The crystal structure of flamite and its relation to Ca (sub 2) SiO (sub 4) polymorphs and nagelschmidtite
European Journal of Mineralogy (July 2015) 27 (6): 755-769

Abstract

The recently accepted new mineral flamite IMA No. 2013-122, (Ca,Na,K) (sub 2) (Si,P)O (sub 4) , found in the pyrometamorphic rocks of the Hatrurim Formation, Israel, was reported to crystallize in the hexagonal space group P6 (sub 3) with unit-cell parameters a = 43.3726(18), c = 6.8270(4) Aa. A careful re-examination of single crystals from the type locality and holotype material, however, shows that flamite is better described by the formula Ca (sub 8-x) (Na,K) (sub x) (SiO (sub 4) ) (sub 4-x) (PO (sub 4) ) (sub x) and that it crystallizes in the space group Pnm2 (sub 1) , a = 9.3845(6), b = 21.7310(14), c = 6.8346(4)Aa, V = 1393.81(15)Aa (super 3) , Z = 4 and is isostructural with the known synthetic P-doped clinker phase Ca (sub 15) (SiO (sub 4) ) (sub 6) (PO (sub 4) ) (sub 2) . The structure is a derivative of the hexagonal high-temperature variety of dicalcium-silicate, alpha -C (sub 2) S, and is characterized by a cyclic triplet of individuals rotated 120 degrees around C: , interpreted as symplectite-like transformation "twinning" derived from alpha -C (sub 2) S. The composition of intergrown flamite lamellae is chemically variable concerning the degree of Na, K and P substitution. We present the structure of flamite and discuss its close relationship to nagelschmidtite, Ca (sub 7) (SiO (sub 4) ) (sub 2) (PO (sub 4) ) (sub 2) , and the high-temperature polymorphs of C (sub 2) S.


ISSN: 0935-1221
EISSN: 1617-4011
Serial Title: European Journal of Mineralogy
Serial Volume: 27
Serial Issue: 6
Title: The crystal structure of flamite and its relation to Ca (sub 2) SiO (sub 4) polymorphs and nagelschmidtite
Affiliation: University of Bern, Institute of Geological Sciences, Bern, Switzerland
Pages: 755-769
Published: 20150723
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Germany
References: 24
Accession Number: 2015-082165
Categories: Mineralogy of silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 5 tables
N29°30'00" - N33°30'00", E34°19'60" - E35°30'00"
Secondary Affiliation: University of Silesia, POL, Poland
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: 201535
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