The crystal structure of natural and synthetic holtedahlite

Rømming, Christian; Raade, Gunnar

doi:10.1007/bf01164319

Cited by 19 publications

(27 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Each Al4 octahedron shares a face with one other Al4 octahedron, edges with two other Al4 octahedra, and corners with two Al4 octahedra in the same double-chain, as well as corners with three tetrahedra in the hexagonal channel, one group in the triangular channel, and one Al2 octahedron in a neighboring Al2-Al3 double-chain. This kind of face-sharing double-chain also occurs in the related structures of the minerals holtedahlite (Raade & Mladeck 1979, Rømming & Raade 1989) and satterlyite (Mandarino et al 1978, Kolitsch et al 2002, which have other features in common with the dumortierite structure, as discussed below. The Al2-Al3 double-chain (bottom of Fig.…”

Section: The Dumortierite Structurementioning

confidence: 84%

“…The Satterlyite-Holtedahlite Structure Satterlyite, ideally Fe 12 (OH,O) 6 (PO 3 OH,PO 4 )(PO 4 ) 5 (Mandarino et al 1978, Kolitsch et al 2002, and isostructural holtedahlite, Mg 12 (OH,O) 6 (PO 3 OH,PO 4 ,CO 3 ) (PO 4 ) 5 (Raade & Mladeck 1979, Rømming & Raade 1989) possess a structure, which we will refer to as the satterlyite-holtedahlite structure, based on chains of face-sharing dimers of octahedra like the M H chains in the dumortierite structure (Fig. 12).…”

Section: √2mentioning

confidence: 99%

See 1 more Smart Citation

Structure and Topology of Dumortierite and Dumortierite-Like Materials

Evans

Groat

2012

The Canadian Mineralogist

View full text Add to dashboard Cite

Dumortierite, ca. (Al,)Al 6 (BO 3)Si 3 O 13 (O,OH) 2 , has a complex and unusual crystal structure that is shared by several minerals and an increasing number of synthetic materials, which we group together as dumortierite-like materials (DLMs). Dumortierite has a strongly pseudo-hexagonal orthorhombic structure based on rod-like double-chains of Al octahedra in a framework based on the {6•4•3•4} semi-regular planar tiling. The large hexagonal channels contain chains of face-sharing Al octahedra attached to the framework by rings of SiO 4 tetrahedra. Smaller triangular channels contain planar BO 3 groups, while in other materials the triangular channels are occupied by tetrahedral or pyramidal groups. Holtite and magnesiodumortierite are isostructural with dumortierite, while ellenbergerite, phosphoellenbergerite, ekatite, and the synthetic materials have very similar structures to dumortierite, but with hexagonal symmetry. These minerals and materials differ from one another in the identity of the metal cations occupying the framework and face-sharing chains, and in the tetrahedral, pyramidal, or triangular groups within the hexagonal and triangular channels. We write the following structure-generating function, which describes both topological and stoichiometric properties of DLMs: X(M 2 Φ) 3 (T h Q h 3 q h) 3 (T t Q t 3 q t) where X is the face-sharing hexagonal channel octahedrally coordinated site, M is the framework octahedrally coordinated site, T h and T t are three-to four-coordinate cation sites in the hexagonal and triangular channels, Φ is a four-coordinate anion site, Q h and Q t are three-coordinate basal anion sites, and q h and q t are one-to three-coordinate apical anion sites. We discuss various structural and crystal chemical properties of DLMs, illustrating their commonalities as variations on the theme described by the structure-generating function. We also discuss three closely related structures which involve modifications of different geometrical or topological aspects of the DLM structure: the structure of lyonsite and its synthetic analogues, the structure of satterlyite and holtedahlite, and the structure of the AB polytype of the cancrinite group of feldspathoids.

show abstract

Section: The Dumortierite Structurementioning

confidence: 84%

Section: √2mentioning

confidence: 99%

Structure and Topology of Dumortierite and Dumortierite-Like Materials

Evans

Groat

2012

The Canadian Mineralogist

View full text Add to dashboard Cite

show abstract

“…The C atom may be positioned at the center of one or more of the four faces of a PO 4 tetrahedron as observed in holtedahlite (Rømming and Raade 1989). The very low refi ned occupancy for the P2 site noted above indicates that most of the CO 3 in the structure probably occurs in the vicinity of this site.…”

Section: The Formula Of Meurigitementioning

confidence: 91%

“…Face-sharing octahedral dimers have been previously reported in the structures of fi ve phosphate minerals: trolleite (Moore and Araki 1974), holtedahlite (Rømming and Raade 1989), raadeite (Chopin et al 2001), kidwellite (Kolitsch 2004), and "laubmannite" (Kolitsch 2004). The structures of trolleite, holtedahlite, and raadeite are all dense-packed and bear little resemblance to that of meurigite.…”

Section: Comparisons To Other Structuresmentioning

confidence: 95%

The crystal structure of meurigite

Kampf

Pluth

Chen

2007

American Mineralogist

View full text Add to dashboard Cite

The crystal structure of meurigite, ideally [K(H 2 O) 2.5 ][Fe 8 3+ (PO 4 ) 6 (OH) 7 (H 2 O) 4 ], monoclinic, C2/c, a = 29.018(5), b = 5.1892(6), c = 19.695(3) Å, β = 106.987(1)°, Z = 4, from the Santa Rita mine, New Mexico, has been solved and refi ned to R 1 = 4.69%, wR 2 = 12.6% using 3325 unique [F o > 4σ(F o )] refl ections collected using a Bruker 6000 SMART CCD diffractometer and synchrotron radiation of wavelength 0.41328 Å. The structure of meurigite is a framework consisting of face-sharing octahedral Fe 2 3+ O 9 dimers, which are linked by sharing corners with corner-sharing dimers and isolated Fe 3+ O 6 octahedra to form thick slabs of octahedra parallel to the a-c plane. PO 4 tetrahedra further link octahedra within the slabs and also link slabs to one another perpendicular to the a-c plane. Relatively large channels through the framework along the b axis contain disordered K atoms and H 2 O molecules, which take part in two overlapping arrays. Partial vacancies in the Fe and P sites may account for discrepancies between the empirical and ideal chemical formulas. Packing considerations suggest that the empirical formula should be based on the total number of large ions (K + Na + O = 38.5 per formula unit), which for the chemical analysis provided in the original description yields [(K 0.91 Na 0.03 ) Σ0.94 (H 2 O) 2.56 ] Σ3.50 [(Fe 3+ 7.52 Al 0.17 Cu 0.03 ) Σ7.72 (PO 4 ) 5.48 (CO 3 ) 0.21 (OH) 7.20 (H 2 O) 5.23]. The meurigite structure is related to those of other fi brous ferric phosphates with 5 Å fi ber axes and shows a particularly close relationship with the structure of dufrénite. Crystal chemical evidence suggests that, even if meurigite and phosphofi brite are isostructural, phosphofi brite may qualify as a distinct species based upon its low K content (<0.5 apfu based on a recalculation of the original chemical analysis).

show abstract

“…Il est a`noter que dans ces trois varie´te´s structurales, l'ion Mg> pre´sente des polye`dres de coordination d'une tre`s grande varie´te´: bipyramides trigonales, te´trae`dres monocape´s ou bicape´s, octae`dres. Il en est de meˆme dans les cinq poly-morphes de Mg (PO )OH, ou`Mg est a`la fois hexa-et penta-coordonne´pour quatre d'entre eux, et seulement hexacoordonne´dans la forme de haute pression et basse tempe´rature (holtedahlite" -Mg (PO )OH) (26)(27)(28)(29). Le magne´sium s'adapte donc aise´ment aux distorsions de la charpente structurale provoque´es par la pression et/ou la tempe´rature.…”

Section: Tableau 2 Coordonne´es Atomiques Et Coefficients De De´placeunclassified