No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Crystal structures and isotypism of the iron(III) arsenate kamarizaite and the iron(III) phosphate tinticite
Abstract
The crystal structures of the secondary ferric iron minerals kamarizaite, Fe33+(AsO4)2(OH)3 · 3H2O, and tinticite, Fe33+(PO4)2(OH)3 · 3H2O, for which highly contradictory data on crystal symmetry were reported, were studied by a combination of single-crystal X-ray diffraction and Rietveld refinement (supplemented by chemical analyses and thermogravimetry), using type material of both species and additional samples from several other localities, including the type localities. The previously unknown crystal structure of kamarizaite was determined from single-crystal intensity data (MoKα, 293 K, R(F) = 2.91 %; all H atoms detected) using a sample from the Le Mazet vein, Échassières, Auvergne, France. The mineral is triclinic, space group P1 (no. 2), with a = 7.671(2), b = 8.040(2), c = 10.180(2) Å, α = 68.31(3), β = 75.35(3), γ = 63.52(3)°, V = 519.3(2) AR3, Z = 2. Rietveld analyses of fine-grained kamarizaite collected underground at two different spots in Lavrion, Greece (Hilarion and Jean Baptiste areas) confirmed the structure model. Rietveld analyses of fine-grained tinticite from Tintic, Utah (USA), Bruguers (Spain) and Weckersdorf (Germany) demonstrate that kamarizaite and tinticite are triclinic and isotypic. A previously published structure model for tinticite, as well as the originally reported orthorhombic symmetry for kamarizaite, are shown to be incorrect. Refined unit-cell parameters of acotype tinticite specimen from Tintic are: a = 7.647(1), b = 7.958(1), c = 9.987(1) Å, α = 67.90(1), β = 76.10(1), γ = 64.10(1)°, V = 504.4(2) Å. Bruguers and Weckersdorf tinticite have very similar parameters. The common atomic arrangement is characterised by three unique, octahedrally coordinated Fe sites (on which Fe may be partially replaced by minor Al), two unique tetrahedrally coordinated T (As or P) sites, eight O, three Oh, three Ow and nine H sites. The topology features zig-zag chains along [110] of dimers built of two edge-sharing FeO6 octahedra corner-linked by a third FeO6 octahedron. The chains are corner-linked by the TO4 tetrahedra thus establishing a mixed octahedral-tetrahedral framework with a T:Fe ratio of 0.67, a pronounced layered arrangement parallel to (001) and narrow channels along [010]. Medium-strong to weak hydrogen-bonds provide additional strengthening of the structure. The topology is closely related to that of the recently described, triclinic aluminium phosphate afmite.
... The samples consist of aggregates (up to 1.5 cm in diameter, Fig. 1a) of fine-grained kamarizaite (platy crystals 1-2 m large, but <0.2 m thick; Fig. 1b, c) embedded in a heterogeneous matrix of fine-grained jarosite [KFe 3 (SO 4 ) 2 (OH) 6 ], scorodite, and iron oxides. The crystallography of these and other kamarizaite samples from Lavrion was described in detail by Kolitsch et al. (2016). In the vicinity of the kamarizaitebearing sites, somewhat larger crystals of scorodite grow on quartz relics in the gossan. ...
... For kamarizaite, the chemical composition was determined by electron microprobe, and is listed in Table 2. The only metal in any substantial concentration was Fe. Kolitsch et al. (2016) also reported minor Al in their kamarizaite samples and samples of related minerals. In our case, the Fe/(Fe+Al) ratio was always greater than 99.4%. ...
... Our results are in broad agreement with the TG data for type kamarizaite by Chukanov et al. (2010) who observed, using a heating rate of 4°C/min, complete dehydration and dehydroxylation in vacuum in the 110-420°C temperature range, with a weight loss of 15.3(1)%. The TG measurements of Kolitsch et al. (2016), conducted in N 2 and using a heating rate of 5°C/min, were also similar. They revealed a one-step weight loss of 14.6 wt% in the 99-500 °C range for kamarizaite; in very good agreement with the calculated value of 14.73 wt%. ...
Thermodynamic properties of mansfieldite (AlAsO4·2H2O), angelellite (Fe4(AsO4)2O3), and kamarizaite (Fe3(AsO4)2(OH)3·3H2O) - Juraj Majzlan, Ulla Gro Nielsen, Edgar Dachs, Artur Benisek, Petr Drahota, Uwe Kolitsch, Julia Herrmann, Ralph Bolanz, Martin Števko
... L'any 2004 es publica un article on es descriu la tinticita d'una altra mina japonesa (mina Shunomata) on s'indica, com ja havia proposat el seu col·lega japonès, una estructura de tipus ortoròmbic (Suo et al., 2004) . Repetint els estudis de Chukanov et al. (2010), amb exemplars ben cristal·litzats de kamarizaïta (un hidroxilarsenat hidratat de ferro, anàleg composicionalment i isoestructural de la tinticita) procedents del filó de Le Mazet (Échassieres, Allier, França), Kolitsch et al. (2016) van poder afinar comparativament els resultats obtinguts de les difraccions de tinticita i es van poder realitzar mesures de difracció monocristall que van permetre determinar més acuradament la seva estructura. D'aquest treball comparatiu entre kamarizaïta i tinticita es va despendre que són espècies isoestructurals que pertanyen al sistema triclínic. ...
... Cal dir, a tall de curiositat, que els exemplars de tinticita de Bruguers que Uwe Kolitsch va utilitzar per als seus estudis (Kolitsch et al., 2016) van ser aportats per en Carles Rubio, membre del Grup Mineralògic Català. ...
Les Ferreres range (Gavà, Barcelona, Catalonia) has seen several cultures and empires pass through the millennia. Since the Neolithic, its entrails have been mined in search of the men they hide. In the Neolithic period, variscite was the mineral that moved the miners to open galleries and trenches. Later, those who knew the secret of iron production opened up the earth looking for minerals such as goethite, iron ochres (limonite) or hematite. Behind them, the Roman Empire continued the extraction of precious minerals. And in the Middle Ages and the modern age, the iron of these regions continued to be appreciated. Until the sixties of the 20th century, the mines worked when the price of the ore allowed it.
But in addition to this rich mining heritage, this mountain range and its mines and outcrops have provided numerous mineral species, some appreciated by mineralogists from all over the world... They have also expanded our mineralogical heritage.
In this book you are holding in your hands you will find a collection of mining history and a description of this exceptional mineralogy. It is the result of the research carried out by the Grup Mineralògic Català in recent years, with the collaboration of Geociències Barcelona (GEO3BCN-CSIC), the Museu de Ciències NAturals de Barcelona and the support of the Universitat de Barcelona.
Sharing experiences with the people of the region, historical research, field work and scientific curiosity have been the engines that have pushed us to carry out this work.