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Lucabindiite, (K,NH (sub 4) )As (sub 4) O (sub 6) (Cl,Br), a new fumarole mineral from the "La Fossa" crater at Vulcano, Aeolian Islands, Italy

Anna Garavelli, Donatella Mitolo, Daniela Pinto and Filippo Vurro
Lucabindiite, (K,NH (sub 4) )As (sub 4) O (sub 6) (Cl,Br), a new fumarole mineral from the "La Fossa" crater at Vulcano, Aeolian Islands, Italy
American Mineralogist (February 2013) 98 (2-3): 470-477

Abstract

Lucabindiite, ideally (K,NH (sub 4) )As (sub 4) O (sub 6) (Cl,Br), is a new mineral found as a medium-temperature fumarole encrustation (T = 170 degrees C) at "La Fossa" crater of Vulcano, Aeolian Islands, Italy. The mineral deposited as aggregates of micrometer-sized hexagonal and platy crystals on the surface of the pyroclastic breccia in association with arsenolite, sal ammoniac, sulfur, and amorphous arsenic-rich sulfurite. The new mineral is colorless to white, transparent, non-fluorescent, has a vitreous luster and a white streak. The calculated density is 3.68 g/cm (super 3) . Lucabindiite is hexagonal, space group P6/mmm, with a = 5.2386(7) Aa, c = 9.014(2) Aa, V = 214.23(7) Aa (super 3) , and Z = 1. The eight strongest reflections in the X-ray powder-diffraction data [d in Aa (I) (hkl)] are: 3.20 (100) (102), 2.62 (67) (110), 4.51 (52) (002), 4.54 (30) (100), 1.97 (28) (113), 1.49 (21) (115), 1.60 (21) (212), 2.26 (19) (112). Lucabindiite's average chemical composition is (wt%): K (sub 2) O 5.14, As (sub 2) O (sub 3) 84.71, Cl 3.63, Br 6.92, F 0.77, (NH (sub 4) ) (sub 2) O 2.73, O=F,Cl,Br -1.84, total 102.06. The empirical chemical formula, calculated on the basis of 7 anions pfu, is [K (sub 0.51) (NH (sub 4) ) (sub 0.49) ] (sub Sigma 1.00) As (sub 4.00) O (sub 5.93) (Cl (sub 0.48) Br (sub 0.40) F (sub 0.19) ) (sub Sigma 1.07) . According to chemical analyses and X-ray data, lucabindiite is the natural analog of synthetic phases with general formula MAs (sub 4) O (sub 6) X where M = K, NH (sub 4) and x = Cl, Br, I. The crystal structure is characterized by neutral As (sub 2) O (sub 3) sheets arranged parallel to (001). The As atoms of two neighboring sheets point at each other and the sheets are separated by interlayer M (=K, NH (sub 4) ) and x (=Cl, Br, F) atoms. The name is in honor of Luca Bindi (b. 1971), Professor of Mineralogy and former Head of the Division of Mineralogy of the Natural History Museum of the University of Florence. Both the mineral and the mineral name have been approved by the IMA-CNMNC Commission (IMA 2011-010).


ISSN: 0003-004X
EISSN: 1945-3027
Coden: AMMIAY
Serial Title: American Mineralogist
Serial Volume: 98
Serial Issue: 2-3
Title: Lucabindiite, (K,NH (sub 4) )As (sub 4) O (sub 6) (Cl,Br), a new fumarole mineral from the "La Fossa" crater at Vulcano, Aeolian Islands, Italy
Affiliation: Universita di Bari, Dipartimento di Scienze della Terra e Geoambientali, Bari, Italy
Pages: 470-477
Published: 201302
Text Language: English
Publisher: Mineralogical Society of America, Washington, DC, United States
References: 49
Accession Number: 2013-025195
Categories: Mineralogy of non-silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 7 tables
N38°19'60" - N38°25'00", E14°52'00" - E15°00'00"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, copyright, Mineralogical Society of America. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201316
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