Yukonite from the Grotta della Monaca cave, Sant'Agata di Esaro, Italy: characterization and comparison with cotype material from the Daulton mine, Yukon, Canada

Anna Garavelli; Daniela Pinto; Filippo Vurro; Marcello Mellini; Cecilia Viti; Tonci Balic Zunic; Giancarlo Della Ventura

doi:10.3749/canmin.47.1.39

Yukonite from the Grotta della Monaca cave, Sant'Agata di Esaro, Italy: characterization and comparison with cotype material from the Daulton mine, Yukon, Canada

Anna Garavelli, Daniela Pinto, Filippo Vurro, Marcello Mellini, Cecilia Viti, Tonci Balic Zunic, Giancarlo Della Ventura

Geology

12 Citations (Scopus)

Abstract

We report the first Italian occurrence of yukonite, a rare hydratedarsenate of calcium and ferric iron, from Grotta della Monacacave, S. Agata di Esaro, Cosenza, Italy. We have studied samplesof cotype yukonite from the Daulton mine, Yukon, Canada, forcomparison. At Grotta della Monaca, yukonite occurs in compactmasses, dark reddish brown to brownish yellow in color. At theTEM scale, it consists of a chaotic assemblage of small grains(maximum dimension <20 nm) embedded in an amorphous matrix,occasionally admixed with scorodite. SAED patterns of thesegrains consist of weak and diffuse diffraction rings, indicatinglow crystallinity, and preventing any definition of symmetryor lattice parameters. Results of a combination of microanalytical,spectroscopic and thermogravimetric techniques provide chemicalcompositions: Ca_1.76Fe²⁺_0.09Fe³⁺_3.12 [(As_0.81Si_0.10P_0.09)O₄]₃(OH)_3.76·4H₂Ofor yukonite from Grotta della Monaca and Ca_1.76Fe²⁺_0.10Fe³⁺_3.56[(As_0.89Si_0.08P_0.03)O₄]₃(OH)_5.16·3H₂O for yukonite from the Daulton mine,close to the stoichiometry Ca₂Fe₃(AsO₄)₃(OH)₄·4H₂O. Thethermogravimetric data indicate a total H₂O content of ~17 wt%;FTIR data show that most of this occurs as H₂O, but some OHcould be present as well. The FTIR data show, in addition, thepresence of ammonium and organic matter, suggesting that poorlycrystalline organic matter is trapped in the material examined.Both chemical and XRD data point to a close relation with arseniosiderite[Ca₂Fe₃(AsO₄)₃O₂·3H₂O]. Both occur as oxidation productsof As-bearing sulfides and seem to be composed of basicallythe same type of layers; arseniosiderite represents a fullycrystalline substance, whereas yukonite is a semicrystallinematerial with a large variation in composition due to the admixtureof amorphous material.

Original language	English
Journal	Canadian Mineralogist
Volume	47
Issue number	1
Pages (from-to)	39-51
ISSN	0008-4476
DOIs	https://doi.org/10.3749/canmin.47.1.39
Publication status	Published - 2009

Keywords

Faculty of Science
yukonite
southern Italy
Grotta della Monaca
arsenic minerals
TEM investigation

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10.3749/canmin.47.1.39

Cite this

@article{932139f0ea3811deba73000ea68e967b,

title = "Yukonite from the Grotta della Monaca cave, Sant'Agata di Esaro, Italy: characterization and comparison with cotype material from the Daulton mine, Yukon, Canada",

abstract = "We report the first Italian occurrence of yukonite, a rare hydrated arsenate of calcium and ferric iron, from Grotta della Monaca cave, S. Agata di Esaro, Cosenza, Italy. We have studied samples of cotype yukonite from the Daulton mine, Yukon, Canada, for comparison. At Grotta della Monaca, yukonite occurs in compact masses, dark reddish brown to brownish yellow in color. At the TEM scale, it consists of a chaotic assemblage of small grains (maximum dimension <20 nm) embedded in an amorphous matrix, occasionally admixed with scorodite. SAED patterns of these grains consist of weak and diffuse diffraction rings, indicating low crystallinity, and preventing any definition of symmetry or lattice parameters. Results of a combination of microanalytical, spectroscopic and thermogravimetric techniques provide chemical compositions: Ca1.76Fe2+0.09Fe3+3.12 [(As0.81Si0.10P0.09)O4]3(OH)3.76·4H2O for yukonite from Grotta della Monaca and Ca1.76Fe2+0.10Fe3+3.56[(As0.89Si0.08P0.03) O4]3(OH)5.16·3H2O for yukonite from the Daulton mine, close to the stoichiometry Ca2Fe3(AsO4)3(OH)4·4H2O. The thermogravimetric data indicate a total H2O content of ~17 wt%; FTIR data show that most of this occurs as H2O, but some OH could be present as well. The FTIR data show, in addition, the presence of ammonium and organic matter, suggesting that poorly crystalline organic matter is trapped in the material examined. Both chemical and XRD data point to a close relation with arseniosiderite [Ca2Fe3(AsO4)3O2·3H2O]. Both occur as oxidation products of As-bearing sulfides and seem to be composed of basically the same type of layers; arseniosiderite represents a fully crystalline substance, whereas yukonite is a semicrystalline material with a large variation in composition due to the admixture of amorphous material. ",

keywords = "Faculty of Science, yukonite, syd Italien, Grotta della Monaca, arsenik mineraler, TEM unders{\o}gelse, yukonite, southern Italy, Grotta della Monaca, arsenic minerals, TEM investigation",

author = "Anna Garavelli and Daniela Pinto and Filippo Vurro and Marcello Mellini and Cecilia Viti and {Balic Zunic}, Tonci and {Della Ventura}, Giancarlo",

year = "2009",

doi = "10.3749/canmin.47.1.39",

language = "English",

volume = "47",

pages = "39--51",

journal = "Canadian Mineralogist",

issn = "0008-4476",

publisher = "Mineralogical Association of Canada",

number = "1",

}

TY - JOUR

T1 - Yukonite from the Grotta della Monaca cave, Sant'Agata di Esaro, Italy

T2 - characterization and comparison with cotype material from the Daulton mine, Yukon, Canada

AU - Garavelli, Anna

AU - Pinto, Daniela

AU - Vurro, Filippo

AU - Mellini, Marcello

AU - Viti, Cecilia

AU - Balic Zunic, Tonci

AU - Della Ventura, Giancarlo

PY - 2009

Y1 - 2009

N2 - We report the first Italian occurrence of yukonite, a rare hydrated arsenate of calcium and ferric iron, from Grotta della Monaca cave, S. Agata di Esaro, Cosenza, Italy. We have studied samples of cotype yukonite from the Daulton mine, Yukon, Canada, for comparison. At Grotta della Monaca, yukonite occurs in compact masses, dark reddish brown to brownish yellow in color. At the TEM scale, it consists of a chaotic assemblage of small grains (maximum dimension <20 nm) embedded in an amorphous matrix, occasionally admixed with scorodite. SAED patterns of these grains consist of weak and diffuse diffraction rings, indicating low crystallinity, and preventing any definition of symmetry or lattice parameters. Results of a combination of microanalytical, spectroscopic and thermogravimetric techniques provide chemical compositions: Ca1.76Fe2+0.09Fe3+3.12 [(As0.81Si0.10P0.09)O4]3(OH)3.76·4H2O for yukonite from Grotta della Monaca and Ca1.76Fe2+0.10Fe3+3.56[(As0.89Si0.08P0.03) O4]3(OH)5.16·3H2O for yukonite from the Daulton mine, close to the stoichiometry Ca2Fe3(AsO4)3(OH)4·4H2O. The thermogravimetric data indicate a total H2O content of ~17 wt%; FTIR data show that most of this occurs as H2O, but some OH could be present as well. The FTIR data show, in addition, the presence of ammonium and organic matter, suggesting that poorly crystalline organic matter is trapped in the material examined. Both chemical and XRD data point to a close relation with arseniosiderite [Ca2Fe3(AsO4)3O2·3H2O]. Both occur as oxidation products of As-bearing sulfides and seem to be composed of basically the same type of layers; arseniosiderite represents a fully crystalline substance, whereas yukonite is a semicrystalline material with a large variation in composition due to the admixture of amorphous material.

AB - We report the first Italian occurrence of yukonite, a rare hydrated arsenate of calcium and ferric iron, from Grotta della Monaca cave, S. Agata di Esaro, Cosenza, Italy. We have studied samples of cotype yukonite from the Daulton mine, Yukon, Canada, for comparison. At Grotta della Monaca, yukonite occurs in compact masses, dark reddish brown to brownish yellow in color. At the TEM scale, it consists of a chaotic assemblage of small grains (maximum dimension <20 nm) embedded in an amorphous matrix, occasionally admixed with scorodite. SAED patterns of these grains consist of weak and diffuse diffraction rings, indicating low crystallinity, and preventing any definition of symmetry or lattice parameters. Results of a combination of microanalytical, spectroscopic and thermogravimetric techniques provide chemical compositions: Ca1.76Fe2+0.09Fe3+3.12 [(As0.81Si0.10P0.09)O4]3(OH)3.76·4H2O for yukonite from Grotta della Monaca and Ca1.76Fe2+0.10Fe3+3.56[(As0.89Si0.08P0.03) O4]3(OH)5.16·3H2O for yukonite from the Daulton mine, close to the stoichiometry Ca2Fe3(AsO4)3(OH)4·4H2O. The thermogravimetric data indicate a total H2O content of ~17 wt%; FTIR data show that most of this occurs as H2O, but some OH could be present as well. The FTIR data show, in addition, the presence of ammonium and organic matter, suggesting that poorly crystalline organic matter is trapped in the material examined. Both chemical and XRD data point to a close relation with arseniosiderite [Ca2Fe3(AsO4)3O2·3H2O]. Both occur as oxidation products of As-bearing sulfides and seem to be composed of basically the same type of layers; arseniosiderite represents a fully crystalline substance, whereas yukonite is a semicrystalline material with a large variation in composition due to the admixture of amorphous material.

KW - Faculty of Science

KW - yukonite

KW - syd Italien

KW - Grotta della Monaca

KW - arsenik mineraler

KW - TEM undersøgelse

KW - yukonite

KW - southern Italy

KW - Grotta della Monaca

KW - arsenic minerals

KW - TEM investigation

U2 - 10.3749/canmin.47.1.39

DO - 10.3749/canmin.47.1.39

M3 - Journal article

SN - 0008-4476

VL - 47

SP - 39

EP - 51

JO - Canadian Mineralogist

JF - Canadian Mineralogist

IS - 1

ER -