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Fluoro-tremolite from the Limecrest-Southdown Quarry, Sparta, New Jersey, USA; crystal chemistry of a newly approved end-member of the amphibole supergroup

Roberta Oberti, Fernando Camara, Fabio Bellatreccia, Francesco Radica, Antonio Gianfagna and Massimo Boiocchi
Fluoro-tremolite from the Limecrest-Southdown Quarry, Sparta, New Jersey, USA; crystal chemistry of a newly approved end-member of the amphibole supergroup
Mineralogical Magazine (February 2018) 82 (1): 145-157

Abstract

During systematic characterization of amphiboles that still lack a complete mineral description, fluoro-tremolite was identified in a specimen from the Limecrest-Southdown quarry, Sparta, New Jersey, USA, which was provided by the Franklin Mineral Museum. The ideal formula of fluoro-tremolite is (super A) (super B) Ca (sub 2) (super C) Mg (sub 5) (super T) Si (sub 8) O (sub 22) (super W) F (sub 2) and the empirical formula derived for the holotype specimen, based on the results of electron-microprobe analysis and single-crystal structure refinement, is (super A) (Na (sub 0.28) K (sub 0.02) ) (sub Sigma 0.30) (super B) (Ca (sub 1.99) Na (sub 0.01) ) (sub Sigma 2.00) (super C) (Mg (sub 4.70) Fe (sub 0.28) (super 2+) Zn (sub 0.01) Ti (sub 0.01) (super 4+) ) (sub Sigma 5.00) (super T) (Si (sub 7.68) Al (sub 0.32) ) (sub Sigma 8.00) O (sub 22) (super W) (F (sub 1.16) OH (sub 0.84) ) (sub Sigma 2.00 ) . The unit-cell dimensions in space group C2/m are a = 9.846(2), b = 18.050(3), c = 5.2769(14) Aa, beta = 104.80(2) degrees and V = 906.7 (3) Aa (super 3) and Z = 2; the a:b:c ratio is 0.545:1:0.292. Fluoro-tremolite is biaxial (+), with alpha = 1.5987(5), beta = 1.6102(5), gamma = 1.6257(5), 2V(meas.) = 85(1) degrees and 2V(calc.) = 82 degrees . The strongest ten reflections in the powder X-ray pattern [d values (in Aa), I, (hkl)] are: 2.706, 100, (151); 3.126, 67, (310); 2.531, 59, (202); 3.381, 57, (131); 2.940, 43, (151, 221); 3.276, 37, (240); 2.337, 36, (351); 2.592, 35, (061); 2.731, 34, (331); 2.163, 34, (261). Both the mineral and the mineral name have been approved by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association (IMA2016-018); the holotype has been deposited at the Franklin Mineral Museum (32 Evans Street, Franklin, 07416 New Jersey, US), under the catalogue number 7710. Comparison with new data on tremolite and synthetic fluoro-tremolite provides a more sound crystal-chemical model of the end-member compositions and their solid-solution.


ISSN: 0026-461X
EISSN: 1471-8022
Coden: MNLMBB
Serial Title: Mineralogical Magazine
Serial Volume: 82
Serial Issue: 1
Title: Fluoro-tremolite from the Limecrest-Southdown Quarry, Sparta, New Jersey, USA; crystal chemistry of a newly approved end-member of the amphibole supergroup
Affiliation: CNR, Istituto di Geoscienze e Georisorse, Italy
Pages: 145-157
Published: 201802
Text Language: English
Publisher: Mineralogical Society, London, United Kingdom
References: 29
Accession Number: 2018-054146
Categories: Mineralogy of silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 7 tables
N40°52'60" - N41°22'60", W74°58'60" - W74°22'60"
Secondary Affiliation: Universita degli Studi di Milano, ITA, ItalyUniversita Roma Tre, ITA, ItalyUniversity of Camerino, ITA, ItalyUniversita di Roma "La Sapienza", ITA, ItalyUniversita di Pavia, ITA, Italy
Country of Publication: United Kingdom
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute. Abstract, Copyright, Mineralogical Society of Great Britain and Ireland. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201813
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