The atomic arrangement of the ganophyllite-group modulated layer silicates as determined from the orthorhombic dimorph of tamaite, with the elusive 16.8 Å ganophyllite-group superstructure revealed

Hughes, John M.; Rakovan, John; Bracco, Roberto; Gunter, Mickey E.

doi:10.2138/am-2003-8-915

Cited by 7 publications

(2 citation statements)

References 6 publications

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“…Eggletonite (Table 8) was described as the Na analogue of ganophyllite, and the structure was refined on a subcell . Hughes et al (2003) solved the structure of an orthorhombic dimorph of tamaite (Table 8) and showed that the parent layer of the silicate double-layer sheet is based on the (5.6 2 ) 6 (5.6.7) 4 (6 2 .7) 10 net (Fig. 43).…”

Section: Miscellaneous Complex 3-connected Netsmentioning

confidence: 99%

A structure hierarchy for silicate minerals: sheet silicates

Hawthorne

Uvarova

Sokolova

2018

MinMag

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The structure hierarchy hypothesis states that structures may be ordered hierarchically according to the polymerisation of coordination polyhedra of higher bond-valence. A hierarchical structural classification is developed for sheet-silicate minerals based on the connectedness of the two-dimensional polymerisations of (TO4) tetrahedra, where T = Si4+ plus As5+, Al3+, Fe3+, B3+, Be2+, Zn2+ and Mg2+. Two-dimensional nets and oikodoméic operations are used to generate the silicate (sensu lato) structural units of single-layer, double-layer and higher-layer sheet-silicate minerals, and the interstitial complexes (cation identity, coordination number and ligancy, and the types and amounts of interstitial (H2O) groups) are recorded. Key aspects of the silicate structural unit include: (1) the type of plane net on which the sheet (or parent sheet) is based; (2) the u (up) and d (down) directions of the constituent tetrahedra relative to the plane of the sheet; (3) the planar or folded nature of the sheet; (4) the layer multiplicity of the sheet (single, double or higher); and (5) the details of the oikodoméic operations for multiple-layer sheets. Simple 3-connected plane nets (such as 63, 4.82 and 4.6.12) have the stoichiometry (T2O5)n (Si:O = 1:2.5) and are the basis of most of the common rock-forming sheet-silicate minerals as well as many less-common species. Oikodoméic operations, e.g. insertion of 2- or 4-connected vertices into 3-connected plane nets, formation of double-layer sheet-structures by (topological) reflection or rotation operations, affect the connectedness of the resulting sheets and lead to both positive and negative deviations from Si:O = 1:2.5 stoichiometry. Following description of the structural units in all sheet-silicate minerals, the minerals are arranged into decreasing Si:O ratio from 3.0 to 2.0, an arrangement that reflects their increasing structural connectivity. Considering the silicate component of minerals, the range of composition of the sheet silicates completely overlaps the compositional ranges of framework silicates and most of the chain-ribbon-tube silicates.

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Section: Miscellaneous Complex 3-connected Netsmentioning

confidence: 99%

A structure hierarchy for silicate minerals: sheet silicates

Hawthorne

Uvarova

Sokolova

2018

MinMag

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“…The mineralogical classification of Mn-rich hydrous silicates can be complex and chemical compositions frequently are different from the ideal structural formula. For example, the ganophyllite-like minerals are complex modulated layer silicates (Hughes et al, 2003) with structural formulae like (K, Ca, Na) x Mn 6 (Si 9 Al)O 4 (OH) 4 .nH 2 O (ganophyllite for the K end-member, tamaite for Ca end-member and eggletonite for Na end-member; [Applin, 1958] and [Eman et al, 2009] ). They present various Mn contents ranging from 27.4 wt.% in the Na end-member ( [Peacor et al, 1984] and [Eggleton and Guggenheim, 1986] ) down to 21.8 wt.% in the K end-member.…”

Section: As-rich Mn Oxyhydroxides and Mn Hydrous Silicatesmentioning

confidence: 99%

Fate of arsenic-bearing phases during the suspended transport in a gold mining district (Isle river Basin, France)

Grosbois

Courtin-Nomade

Robin

et al. 2011

Science of The Total Environment

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Arsenic-rich (~140-1520 mg x kg(-1)) suspended particulate matter (SPM) was collected daily with an automatic sampler in the Upper Isle River (France) draining a former gold mining district in order to better understand the fate of arsenic during the suspended transport (particles smaller than 50 μm). Various techniques at a micrometric scale (EPMA, quantitative SEM-EDS with an automated particle counting including classification system and μXRD) were used to directly characterize As-bearing phases. The most frequent ones were aggregates of fine clay particles. Their mineralogy varied with particle sources involved. These aggregates were formed by chlorite-phlogopite-kaolinite assemblages during the high flow and chlorite-illite-montmorillonite during the low flow. Among all the observed As-carriers in SPM, these clay assemblages were the least As-rich (0.10 up to 1.58 wt.% As) and their median As concentrations suggested that they were less concentrated during the high flow than during the low flow. Iron oxyhydroxides were evidenced by μXRD in these clay aggregates, either as micro- to nano-sized particles and/or as coating. (Mn, Fe)oxyhydroxides were also present as discrete particles. Manganese oxides (0.14-1.26 wt.% As) transport significantly more arsenic during the low flow than during the high flow (0.16-0.79 wt.% As). The occurrence of Fe oxyhydroxide particles appeared more complex. During the low flow, observations on banks and in wetlands of freshly precipitated Fe hydroxides (ferrihydrite-type) presented the highest As concentrations (up to 6.5 wt.% As) but they were barely detected in SPM at a microscale. During the high flow, As-rich Fe-oxyhydroxides (0.10-2.80 wt.% As) were more frequent, reflecting mechanical erosion and transport when the surface water level increased. Arsenic transfers from SPM to corresponding aqueous fraction mostly depend on As-carrier stability. This study shows the temporal occurrence of each type of As-bearing phases in SPM, their As concentrations at a particle scale and abundance according to hydrological periods.

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Interlayer deficient micas, stilpnomelane, ganophyllite group and related silicates

Burzo

2007

Phyllosilicates

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The atomic arrangement of the ganophyllite-group modulated layer silicates as determined from the orthorhombic dimorph of tamaite, with the elusive 16.8 Å ganophyllite-group superstructure revealed

Cited by 7 publications

References 6 publications

A structure hierarchy for silicate minerals: sheet silicates

A structure hierarchy for silicate minerals: sheet silicates

Fate of arsenic-bearing phases during the suspended transport in a gold mining district (Isle river Basin, France)

Interlayer deficient micas, stilpnomelane, ganophyllite group and related silicates

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