The mineral description is provided for ferro-tschermakite, ideally A☐BCa2C()T(Si6Al2)O22W(OH)2. The type specimen has been found in the dump of the Bâtiment et Granit de Ploumanac'h northern granite quarry, La Clarté, Perros-Guirec, Ploumanac'h granitic complex, Brittany, France. The empirical formula derived from electron microprobe analysis and single-crystal structure refinement is: A()Σ=0.37B()Σ=2.00C()Σ=5.00T(Si6.15Al1.85)Σ=8.00O22W(OH1.94F0.06)Σ=2.00. Ferro-tschermakite is biaxial (–), with α = 1.666(2), β = 1.680(2), γ = 1.690(2) and 2V (meas.) = 84(1)°, 2V (calc.) = 79.8. The dispersion is medium (r > v), and the orientation is: X ^ a = 9.5° (in β acute), Y || b, Z ^ c = 24.3° (in β obtuse). The unit-cell parameters are a = 9.7598(6), b = 18.0220(11), c = 5.3299(3) Å, β = 104.826(1)°, V = 906.27 (9) Å3, Z = 2, space group C2/m. The strongest ten reflections in the X-ray powder pattern obtained from single-crystal data [d values (in Å), I, (h k l)] are: 8.359, 100, (1 1 0); 2.708, 84, (1 5 1); 3.098, 55, (3 1 0); 2.552, 43, ( 0 2); 2.595, 41, (0 6 1); 2.330, 33, ( 5 1); 2.159, 27, (2 6 1); 2.936, 27, (2 2 1); 3.338, 27, (1 3 1); 2.012, 24, ( 0 2; 3 5 1).
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Research Article|
January 01, 2018
Ferro-tschermakite from the Ploumanac'h granitic complex, Brittany, France: mineral description
Roberta Oberti;
1
CNR-Istituto di Geoscienze e Georisorse, Sede secondaria di Pavia
, via Ferrata 1, 27100Pavia, Italy
*
Corresponding author, e-mail: oberti@crystal.unipv.it
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Massimo Boiocchi;
Massimo Boiocchi
2
Centro Grandi Strumenti, Università di Pavia
, via Bassi 21, 27100Pavia, Italy
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Frank C. Hawthorne;
Frank C. Hawthorne
3
Department of Geological Sciences, University of Manitoba
, Winnipeg, ManitobaR3T 2N2, Canada
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Marco E. Ciriotti
Marco E. Ciriotti
4
Associazione Micromineralogica Italiana
, via San Pietro 55, 10073Devesi-Cirié, Italy
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1
CNR-Istituto di Geoscienze e Georisorse, Sede secondaria di Pavia
, via Ferrata 1, 27100Pavia, Italy
Massimo Boiocchi
2
Centro Grandi Strumenti, Università di Pavia
, via Bassi 21, 27100Pavia, Italy
Frank C. Hawthorne
3
Department of Geological Sciences, University of Manitoba
, Winnipeg, ManitobaR3T 2N2, Canada
Marco E. Ciriotti
4
Associazione Micromineralogica Italiana
, via San Pietro 55, 10073Devesi-Cirié, Italy
*
Corresponding author, e-mail: oberti@crystal.unipv.it
Publisher: Deutsche Mineralogische Gesellschaft, Sociedad Española de Mineralogia, Societá Italiana di Mineralogia e Petrologia, Société Francaise de Minéralogie
Received:
09 May 2017
Revision Received:
18 Aug 2017
Accepted:
30 Aug 2017
First Online:
12 Jun 2018
Online Issn: 1617-4011
Print Issn: 0935-1221
© 2018 E. Schweizerbart'sche Verlagsbuchhandlung, D-70176 Stuttgart
European Journal of Mineralogy (2018) 30 (1): 171–176.
Article history
Received:
09 May 2017
Revision Received:
18 Aug 2017
Accepted:
30 Aug 2017
First Online:
12 Jun 2018
Citation
Roberta Oberti, Massimo Boiocchi, Frank C. Hawthorne, Marco E. Ciriotti; Ferro-tschermakite from the Ploumanac'h granitic complex, Brittany, France: mineral description. European Journal of Mineralogy 2018;; 30 (1): 171–176. doi: https://doi.org/10.1127/ejm/2018/0030-2700
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Index Terms/Descriptors
- amphibole group
- Brittany
- cell dimensions
- chain silicates
- chemical composition
- clinoamphibole
- crystal chemistry
- crystal structure
- electron probe data
- Europe
- formula
- France
- granites
- igneous rocks
- mineral data
- optical properties
- physical properties
- plutonic rocks
- quarries
- refinement
- silicates
- space groups
- tschermakite
- type localities
- type specimens
- Western Europe
- X-ray diffraction data
- Perros-Guirec France
- Ploumanac'h Complex
- ferro-tschermakite
- La Clarte France
Latitude & Longitude
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