Skip to Main Content
Skip Nav Destination
GEOREF RECORD

Structural study of magnesioaxinite and its crystal-chemical relations with axinite-group minerals

Giovanni B. Andreozzi, Sergio Lucchesi and Giorgio Graziani
Structural study of magnesioaxinite and its crystal-chemical relations with axinite-group minerals
European Journal of Mineralogy (December 2000) 12 (6): 1185-1194

Abstract

The magnesium end-member of the axinite mineral group was studied by single-crystal X-ray diffraction and refined in the P1 space group (R = 2.2%). Cell parameters are a = 7.1381(3) Aa, b = 9.1626(4) Aa, c = 8.9421(4) Aa, alpha = 91.903(4) degrees , beta = 98.105(3) degrees , gamma = 77.468(4) degrees , V = 565.21(4) Aa (super 3) . Magnesioaxinite is isostructural with (Mn, Fe)-axinites, but shows structural features which may account for the compositional gap observed between magnesioaxinite and manganaxinite. Electron and ion microprobe analyses and refined site occupancies gave the following crystal chemical formula: (super [6]) [Ca (sub 2.00) (Ca (sub 1.95) Mn (sub 0.03) )(Mg (sub 1.92) Mn (sub 0.04) V (sub 0.03) Cr (sub 0.01) )Al (sub 2.00) Al (sub 2.00) ] (super [4]) [B (sub 2.01) Si (sub 8.02) O (sub 30) ](OH (sub 1.9) O (sub 0.1) ), very close to the ideal Mg end-member. The octahedron occupied by Mg ({Mg-O} = 2.17 Aa) is distorted and closely connected with both tetrahedral and octahedral structure components. Its modification (when Mg substitutes for Fe (super 2+) and Mn) causes lattice deformations and also influences T-O-T angles and geometry of octahedral sheets.


ISSN: 0935-1221
Serial Title: European Journal of Mineralogy
Serial Volume: 12
Serial Issue: 6
Title: Structural study of magnesioaxinite and its crystal-chemical relations with axinite-group minerals
Affiliation: Universita di Roma "La Sapienza", Dipartimento di Scienze della Terra, Rome, Italy
Pages: 1185-1194
Published: 200012
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Federal Republic of Germany
References: 22
Accession Number: 2001-040132
Categories: Mineralogy of silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 5 tables
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 200112
Close Modal

or Create an Account

Close Modal
Close Modal