Crystal-structure refinement of a Zn-rich kupletskite from Mont Saint-Hilaire, Quebec, with contributions to the geochemistry of zinc in peralkaline environments

Piilonen, Paula C.; Pekov, Igor V.; Back, Malcolm E.; Steede, T.; Gault, Robert A.

doi:10.1180/0026461067050350

Cited by 11 publications

(3 citation statements)

References 21 publications

(18 reference statements)

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“…There are four octahedrally coordinated M -sites ( M 1– M 4) that are occupied dominantly by Fe 2+ ( astrophyllite group ) and Mn 2+ ( kupletskite group ) although minor amounts of other cations (e.g. Zn 2+ ; Piilonen et al ., 2003 a , b , 2006) can be incorporated. The resulting octahedra share edges to form a continuous sheet, called the O-sheet (Fig.…”

Section: Tr3tr Classmentioning

confidence: 99%

A structure hierarchy for silicate minerals: chain, ribbon, and tube silicates

Day

Hawthorne

2020

MinMag

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A structure hierarchy is developed for chain-, ribbon- and tube-silicate based on the connectedness of one-dimensional polymerisations of (TO4)n− tetrahedra, where T = Si4+ plus P5+, V5+, As5+, Al3+, Fe3+, B3+, Be2+, Zn2+ and Mg2+. Such polymerisations are described by a geometrical repeat unit (with ng tetrahedra) and a topological repeat unit (or graph) (with nt vertices). The connectivity of the tetrahedra (vertices) in the geometrical (topological) repeat units is denoted by the expression cTr (cVr) where c is the connectivity (degree) of the tetrahedron (vertex) and r is the number of tetrahedra (vertices) of connectivity (degree) c in the repeat unit. Thus cTr = 1Tr12Tr23Tr34Tr4 (cVr = 1Vr12Vr23Vr34Vr4) represents all possible connectivities (degrees) of tetrahedra (vertices) in the geometrical (topological) repeat units of such one-dimensional polymerisations. We may generate all possible cTr (cVr) expressions for chains (graphs) with tetrahedron (vertex) connectivities (degrees) c = 1 to 4 where r = 1 to n by sequentially increasing the values of c and r, and by ranking them accordingly. The silicate (sensu lato) units of chain-, ribbon- and tube-silicate minerals are identified and associated with the relevant cTr (cVr) symbols. Following description and association with the relevant cTr (cVr) symbols of the silicate units in all chain-, ribbon- and tube-silicate minerals, the minerals are arranged into decreasing O:T ratio from 3.0 to 2.5, an arrangement that reflects their increasing structural connectivity. Considering only the silicate component, the compositional range of the chain-, ribbon- and tube-silicate minerals strongly overlaps that of the sheet-silicate minerals. Of the chain-, ribbon- and tube-silicates and sheet silicates with the same O:T ratio, some have the same cVr symbols (vertex connectivities) but the tetrahedra link to each other in different ways and are topologically different. The abundance of chain-, ribbon- and tube-silicate minerals decreases as O:T decreases from 3.0 to 2.5 whereas the abundance of sheet-silicate minerals increases from O:T = 3.0 to 2.5 and decreases again to O:T = 2.0. Some of the chain-, ribbon- and tube-silicate minerals have more than one distinct silicate unit: (1) vinogradovite, revdite, lintisite (punkaruaivite) and charoite have mixed chains, ribbons and/or tubes; (2) veblenite, yuksporite, miserite and okenite have clusters or sheets in addition to chains, ribbons and tubes. It is apparent that some chain-ribbon-tube topologies are favoured over others as of the ~450 inosilicate minerals, ~375 correspond to only four topologically unique graphs, the other ~75 minerals correspond to ~46 topologically unique graphs.

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Section: Tr3tr Classmentioning

confidence: 99%

A structure hierarchy for silicate minerals: chain, ribbon, and tube silicates

Day

Hawthorne

2020

MinMag

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“…In the astrophyllite-supergroup minerals, the dominant cations at the M sites are mainly Fe 2+ and Mn 2+ (Table 2). Other dominant M cations are rare: Mg at the M(4) site and Na at the M(1) site in lobanovite, and Zn at the M(4) site in kupletskite-(Cs) and Zn-rich astrophyllite (Piilonen et al, 2006). In the H sheet, there are four T sites, mainly occupied by Si with minor Al (Piilonen et al, 2003a,b).…”

Section: Cation Sitesmentioning

confidence: 99%

The astrophyllite supergroup: nomenclature and classification

et al. 2017

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Here we report a nomenclature and classification for the astrophyllite-supergroup minerals. The HOH block is the main structural unit in all astrophyllite-supergroup structures; it consists of three H–O–H sheets where the T4O12 astrophyllite ribbons occur in the H sheets. In each structure, HOH blocks alternate with I (Intermediate) blocks along [001]. The twelve minerals of the astrophyllite supergroup are divided into three groups based on (1) the type of self-linkage of HOH blocks, i.e. (a) HOH blocks link directly where they share common vertices of D octahedra, or (b) HOH blocks do not link directly; and (2) the dominant cation of the O sheet (the C group: C7 apfu). In the astrophyllite group (HOH blocks connect via D– XDP–D bridges, Fe2+ is dominant at C7), there are six minerals: astrophyllite, niobophyllite, zircophyllite, tarbagataite, nalivkinite and bulgakite. In the kupletskite group (HOH blocks connect via D–XDP–D bridges, Mn2+ is dominant at C7), there are three minerals: kupletskite, niobokupletskite and kupletskite-(Cs). In the devitoite group (HOH blocks do not connect via D–XDP–D bridges), there are three minerals: devitoite, sveinbergeite and lobanovite. The general formula for the astrophyllite-supergroup minerals is of the form A2pBrC7D2(T4O12)2IXD2OXA4OXDnPWA2, where C [cations at the M(1–4) sites in the O sheet] = Fe2+, Mn, Na, Mg, Zn, Fe3+, Ca, Zr, Li; D (cations in the H sheets) = [6,5]Ti, Nb, Zr, Sn4+ , [5]Fe3+, Mg, Al; T = Si, minor Al; A2pBrIWA2 (I block) where p = 1,2; r = 1,2; A = K, Cs, Ba, H2O, Li, Rb, Pb2+, Na,□; B = Na, Ca, Ba, H2O,□; I represents the composition of the central part of the I block, excluding peripheral layers of the form A2pBrWA2, e.g. (PO4)2(CO3) (devitoite); XDO = O; XAO = OH, F; XDP = F, O, OH, H2O,□, where n = 0, 1, 2 for (XDP)n; WA = H2O,□.

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“…One may note that in a Zn-rich variety of another layered titanosilicate, kupletskite, zinc occupies the sites together with prevailing Mn 2þ (Piilonen et al, 2006). Unlike epistolite-group minerals, in this case zinc is a primary component involved during the crystallization of kupletskite in a relatively high-temperature peralkaline pegmatite system.…”

Section: Atommentioning

confidence: 99%

Crystal chemistry of cation-exchanged forms of epistolite-group minerals. Part II. Vigrishinite and Zn-exchanged murmanite

Lykova¹,

Pekov²,

Zubkova³

et al. 2015

ejm

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The crystal structure of vigrishinite, an epistolite-group heterophyllosilicate with essential Zn, has been reinvestigated; the ideal end-member formula is revised to Zn 2 Ti 4-x (Si 2 O 7) 2 O 2 (OH,F,O) 2 (H 2 O,OH,&) 4 with x,1. Structure models of Zn-exchanged forms of murmanite after 5 and 24 hour experiments with 1N ZnSO 4 solution at 90 C have been obtained from single-crystal X-ray diffraction data. The structural formulae are [B1] Ca 0.04 {Na 1.22 (Ti 1.19 Mn 0.60 Nb 0.21)}{ [A1,A2] Zn 1.03 (Ti 1.64 Nb 0.36)[Si 2 O 7 ] 2 }O 2 (O,OH) 2 (H 2 O) 4 for vigrishinite and {Na 1.14 (Ti 1.45 Mn 0.50 Nb 0.05)}{ [A1] Ca 0.77 [A2] Zn 0.13 (Ti 1.85 Nb 0.15)[Si 2 O 7 ] 2 }O 2 (OH,O) 2 (H 2 O) 4 and [B1] Zn 0.15 [B2] Ca 0.18 {Na 1.06 (Ti 1.32 Mn 0.60 Nb 0.08)}{ [A1] Zn 0.70 [A2] Ca 0.12 (Ti 1.74 Nb 0.26)[Si 2 O 7 ] 2 }O 2 (OH,O) 2 (H 2 O) 4 for the 5 and 24 hour Zn-exchanged forms of murmanite, respectively (braces give successively the contents of the octahedral O and heteropolyhedral H sheets). The triclinic (PÀ1) unit-cell parameters are respectively:

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Crystal-structure refinement of a Zn-rich kupletskite from Mont Saint-Hilaire, Quebec, with contributions to the geochemistry of zinc in peralkaline environments

Cited by 11 publications

References 21 publications

A structure hierarchy for silicate minerals: chain, ribbon, and tube silicates

A structure hierarchy for silicate minerals: chain, ribbon, and tube silicates

The astrophyllite supergroup: nomenclature and classification

Crystal chemistry of cation-exchanged forms of epistolite-group minerals. Part II. Vigrishinite and Zn-exchanged murmanite

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