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Crystal structure of SrMn (sub 2) [Si (sub 2) O (sub 7) ] (OH) (sub 2) .H (sub 2) O, a new mineral of the lawsonite type

Thomas Armbruster, Roland Oberhaensli and Vladimir Bermanec
Crystal structure of SrMn (sub 2) [Si (sub 2) O (sub 7) ] (OH) (sub 2) .H (sub 2) O, a new mineral of the lawsonite type
European Journal of Mineralogy (February 1992) 4 (1): 17-22


A new mineral with this composition occurs as yellow-brown crystals associated with serandite-pectolite in a vein cutting sugilite in fibrous serandite-pectolite from the Wessels mine, Kalahari, South Africa [A.M.73-595]. This new mineral has a 6.255, b 9.034, c 13.397 Angstrom ; space group Cmcm; Z = 4. The structure as determined from single-crystal XRD data (R 0.048) is one of the lawsonite type, with Al completely replaced by Mn (super 3+) and Ca by Sr. [Mn (super 3+) O (sub 6) ] octahedra forming edge- sharing chains a exhibit a Jahn-Teller distortion with four short and two long Mn (super 3+) -O distances; Sr is in eightfold coordination and H (sub 2) O is distorted on a split position. Together with orientite, macfallite, ruizite and okhotskite, the new mineral belongs to a family of structures which have the fundamental building block [Mn (super 3+) (sub 2) (OH) (sub 2) (SiO (sub 4) ) (sub 2) ] and 6 x 9 Angstrom cell dimensions in common. The average of 13 EPMA results gave SiO (sub 2) 28.77, Mn (sub 2) O (sub 3) 37.80, SrO 24.81, (H (sub 2) O 8.62), = 100.00.

ISSN: 0935-1221
Serial Title: European Journal of Mineralogy
Serial Volume: 4
Serial Issue: 1
Title: Crystal structure of SrMn (sub 2) [Si (sub 2) O (sub 7) ] (OH) (sub 2) .H (sub 2) O, a new mineral of the lawsonite type
Affiliation: Johannes Gutenberg Univ., Inst. Geowiss., Mainz, Federal Republic of Germany
Pages: 17-22
Published: 199202
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Federal Republic of Germany
References: 20
Accession Number: 1993-025709
Categories: Mineralogy of silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 3 tables
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United KingdomTwickenhamUKUnited Kingdom. Reference includes data from Geoline, Bundesanstalt fur Geowissenschaften und Rohstoffe, Hanover, Germany
Update Code: 1993
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