Skip to Main Content
Skip Nav Destination
GEOREF RECORD

Argesite, (NH (sub 4) ) (sub 7) Bi (sub 3) Cl (sub 16) , a new mineral from La Fossa Crater, Vulcano, Aeolian Islands, Italy; a first example of the [Bi (sub 2) Cl (sub 10) ] (super 4-) anion

Francesco Demartin, Italo Campostrini, Carlo Castellano and Carlo Maria Gramaccioli
Argesite, (NH (sub 4) ) (sub 7) Bi (sub 3) Cl (sub 16) , a new mineral from La Fossa Crater, Vulcano, Aeolian Islands, Italy; a first example of the [Bi (sub 2) Cl (sub 10) ] (super 4-) anion
American Mineralogist (August 2012) 97 (8-9): 1446-1451

Abstract

The new mineral argesite, ammonium bismuth chloride (NH (sub 4) ) (sub 7) Bi (sub 3) Cl (sub 16) , was found in a medium-temperature (approximately 250 degrees C) active fumarole at La Fossa crater, Vulcano, Aeolian Islands, Sicily, Italy. The mineral occurs on a pyroclastic breccia as pale-yellow crystals up to 0.15 mm in length, in association with bismuthinite, adranosite, brontesite, demicheleite-(Br), demicheleite-(Cl), and panichiite. Argesite is trigonal, space group: R3c (no. 167) with Z = 18; the unit-cell parameters are (single-crystal data): a = 13.093(1), c = 102.682(1) Aa, and V = 15245(2) Aa (super 3) . The six strongest reflections in the X-ray powder diffraction pattern are: [d (sub obs) (Aa) (I) (hkl)] 3.164 (100) (0 3 18), 3.808 (44) (2 2 20), 2.742 (78) (2 4 21), 6.14 (16) (1 2 6), 1.906 (16) (0 0 54), 1.686 (13) (5 6 34). The mineral is uniaxial (-), with omega = 1.731(2), epsilon = 1.725(2) (589 nm). The IR spectrum shows absorptions at 3188(vs), 3060(s), and 1397(vs) cm (super -1) , in agreement with the presence of the ammonium ion. Chemical analyses obtained by EDS electron microprobe gave (average wt%) Bi 42.26, Cl 32.57, Br 13.06, I 0.95, K 2.46, Tl 0.88, NH (sub 4) 7.82 (by difference) total 100.00, corresponding to the empirical formula: [(NH (sub 4) ) (sub 6.29) K (sub 0.91) Tl (sub 0.06) ] (sub Sigma 7.26) Bi (sub 2.93) (Cl (sub 13.33) Br (sub 2. 37) I (sub 0.11) ) (sub Sigma 15.81) . The measured density is 2.88(1) g/cm (super 3) . The structure was refined, using single-crystal diffraction data, to a final R = 0.0345 for 1289 independent observed reflections [I > 2sigma (I)]. It contains Bi (sub 2) Cl (sub 10) (super 4-) and BiCl (sub 6) (super 3-) anions where the Bi atoms are octahedrally coordinated, and NH (sub 4) (super +) cations are partially replaced by K (super +) and Tl (super +) ions.


ISSN: 0003-004X
EISSN: 1945-3027
Coden: AMMIAY
Serial Title: American Mineralogist
Serial Volume: 97
Serial Issue: 8-9
Title: Argesite, (NH (sub 4) ) (sub 7) Bi (sub 3) Cl (sub 16) , a new mineral from La Fossa Crater, Vulcano, Aeolian Islands, Italy; a first example of the [Bi (sub 2) Cl (sub 10) ] (super 4-) anion
Affiliation: Universita di Milano, Dipartimento di Chimica Strutturale e Stereochimica Inorganica, Milan, Italy
Pages: 1446-1451
Published: 201208
Text Language: English
Publisher: Mineralogical Society of America, Washington, DC, United States
References: 24
Accession Number: 2012-079912
Categories: Mineralogy of non-silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 5 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: 201242
Close Modal

or Create an Account

Close Modal
Close Modal