Crystal chemistry of double-ring silicates: structure of roedderite at 100 and 300 K

Armbruster, Thomas

doi:10.1127/ejm/1/5/0715

Cited by 23 publications

(34 citation statements)

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“…In accordance with Armbruster & Oberhänsli (1988), the a and c parameters of sogdianite increase as both the common edge between the T(2) tetrahedron and the A octahedron and the C-O bond length become longer: a = 10.1240(3), c = 14.3198(5) Å, V = 1271.1(1) Å 3 for end-member sogdianite versus a = 10.053(1), c = 14.211(2) Å, V = 1243.8(4) Å 3 for sogdianite (Cooper et al 1999).…”

Section: On the Isomorphous Series Sugilite-sogdianitementioning

confidence: 94%

THE CRYSTAL CHEMISTRY OF Li-BEARING MINERALS WITH THE MILARITE-TYPE STRUCTURE: THE CRYSTAL STRUCTURE OF END-MEMBER SOGDIANITE

Sokolova

Hawthorne

Pautov

2000

The Canadian Mineralogist

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The crystal structure of end-member sogdianite from the Dara-i-Pioz alkaline massif, northern Tajikistan, a 10.1240(3), c 14.3198(5) Å, V 1271.1(1) Å 3 , space group P6/mcc, Z = 2, has been refined to an R index of 2.0% using 576 observed (|F o | > 4F) reflections collected with single-crystal diffractometer with MoK␣ X-radiation. Electron-microprobe analysis gives a composition (Zr 1.98 Hf 002 ) ⌺2.00 (K 0.99 Na 0.01 ) ⌺1.00 Li 2.97 Si 12.01 O 30 . The sogdianite end-member has the typical structure of the double-ring silicates of the milarite structure-type: the A octahedron and T(2) tetrahedron are completely occupied by Zr and Li, and tetravalent Zr at the A site induces the lack of Na at the B site.

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Section: On the Isomorphous Series Sugilite-sogdianitementioning

confidence: 94%

THE CRYSTAL CHEMISTRY OF Li-BEARING MINERALS WITH THE MILARITE-TYPE STRUCTURE: THE CRYSTAL STRUCTURE OF END-MEMBER SOGDIANITE

Sokolova

Hawthorne

Pautov

2000

The Canadian Mineralogist

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“…The issue of what affects the relative chemical stabilities of specific bond topologies is one that challenges our understanding of structure stability and deserves serious consideration in the future. Pautov and Agakhanov (1997); (5) White et al (1973), Armbruster and Oberhänsli (1988b); (6) Velde et al (1989); (7) Semenov et al (1975), Ferraris et al (1999); (8) Pautov et al (1996), Sokolova and Pautov (1995); (9) Abraham et al Grice et al (1987); (18) Fuchs et al (1966), Hentschel et al (1980), Armbruster (1989); (19) Pautov et al (1998), Sokolova et al (1999); (20) Dusmatov et al (1968), Cooper et al (1999), Sokolova et al (2000); (21) Murakami et al (1976), Kato et al (1976); (22) Postl et al (2004); (23) Bunch and Fuchs (1969). a Omitting (H 2 O) in the channels.…”

Section: Discussionmentioning

confidence: 96%

Agakhanovite-(Y), ideally (YCa) 2KBe3Si12O30, a new milarite-group mineral from the Heftetjern pegmatite, Tordal, Southern Norway: Description and crystal structure

Hawthorne

Abdu

Ball

et al. 2014

American Mineralogist

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Agakhanovite-(Y), ideally (YCa)o 2 KBe 3 Si 12 O 30 , is a new milarite-group mineral from the Heftetjern pegmatite, Tørdal, southern Norway. Crystals are prismatic along [001], and show the forms {100} and {100}. Agakhanovite-(Y) is colorless with a white streak and a vitreous luster, and does not fluoresce under ultraviolet light. There is no cleavage or parting, and no twinning was observed. Mohs hardness is 6, and agakhanovite-(Y) is brittle with a conchoidal fracture. The calculated density is 2.672 g/cm 3 . Optical properties were measured with the Bloss spindle stage for the wavelength 590 nm using a gel filter. Agakhanovite-(Y) is uniaxial (-) with indices of refraction w = 1.567, e = 1.564, both ±0.002; the calculated birefringence is 0.003 and it is non-pleochroic. Agakhanovite-(Y) is hexagonal, space group P6/mcc, a = 10.3476(2), c = 13.7610(3) Å, V = 1276.02(9) Å 3 , Z = 2, c:a = 1.330. The seven strongest lines in the X-ray powder-diffraction pattern are as follows: d (Å), I, (hkl): 2.865, 100, (124); 3.287, 96, (131); 4.134, 84, (122); 6.877, 56, (002); 2.986, 43, (030); 4.479, 38, (020); 2.728, 36, (024). Chemical analysis by electron microprobe gave SiO 2 69.56, Al 2 O 3 0.35, Y 2 O 3 9.69, Yb 2 O 3 0.15, FeO 0.02 CaO 5.75, Na 2 O 0.07, K 2 O 4.52, BeO(calc) 7.06, H 2 O(calc) 1.74, sum 98.91 wt%. The H 2 O content was determined by crystal-structure analysis. On the basis of 30 anions, the empirical formula is (Y 0.89 Yb 0.01 Ca 1.06 ) S1.96 (H 2 O) 0.92 Na 0.02 K 1.00 (Be 2.93 Al 0.07 ) S3.00 Si 12.02 O 30 . The crystal structure of agakhanovite-(Y) was refined to an R 1 index of 1.9% based on 660 unique observed reflections collected on a three-circle rotating-anode (MoKa X-radiation) diffractometer equipped with multilayer optics and an APEX-II detector. In the end-member structure of agakhanovite-(Y), the A site is occupied equally by Y and Ca, and the B site is vacant; agakhanovite-(Y) is the Y-analog of oftedalite: ScCao 2 KBe 3 Si 12 O 30 , and the Y-Ca-Be analog of klöchite, (Fe 2+ Fe 3+ )o 2 KZn 3 Si 12 O 30 .

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“…; [12]C = K, Na, Ca, Ba; [lSlD = I--], ? ; t41T2 = A1, Be, Fe 2+, Fe 3+, Li, Mg; [41T1 = Si, A1), which crystallize in the P6/ mcc, P62c and, probably, Acam, Aba2 space groups (Armbruster, 1989;Fleischer and Mandarino, 1991). Each T1 tetrahedron shares three corners with adjacent T1 tetrahedra to form six-membered double rings that are linked each other, laterally and vertically, by sharing the fourth corner with an A octahedron and a 72 tetrahedron.…”

Section: C[is]d[4]t2314]t112030 (Wherementioning

confidence: 99%

“…Furthermore, in roedderite, the B site splits into two different B positions: B1, preferentially occupied by Na, and B2, which is either empty or contains only small amounts of Na; this reduces the symmetry from P6/mcc to P62c (Armbruster, 1989). The occurrences and the conditions of crystallization of natural and synthetic minerals of the osumilite group have been summarized by Hawthorne et al (1991).…”

Section: C[is]d[4]t2314]t112030 (Wherementioning

confidence: 99%

The roedderite-chayesite series from Spanish lamproites: crystal-chemical characterization

Alietti

Brigatti²,

Capedri³

et al. 1994

Mineral. mag.

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Members of the roedderite-chayesite series in lamproites from Cancarix (SE Spain), crystallized from late magmatic residua under low PH20, high temperature (~ l l00~ oxidizing conditions. They exhibit the following main chemical variations: 0.14 ~< Na ~< 0.62 atoms per formula unit ( The 12-coordinated C site, located between two double rings of T1 tetrahedra, is occupied mainly by K and subordinately by Na. Furthermore, Na occupies the partially empty nine-fold coordinated B site which occurs both in the ideal (z = 0) and in a split-atom position along the c direction.

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Crystal chemistry of double-ring silicates: structure of roedderite at 100 and 300 K

Cited by 23 publications

References 0 publications

THE CRYSTAL CHEMISTRY OF Li-BEARING MINERALS WITH THE MILARITE-TYPE STRUCTURE: THE CRYSTAL STRUCTURE OF END-MEMBER SOGDIANITE

THE CRYSTAL CHEMISTRY OF Li-BEARING MINERALS WITH THE MILARITE-TYPE STRUCTURE: THE CRYSTAL STRUCTURE OF END-MEMBER SOGDIANITE

Agakhanovite-(Y), ideally (YCa) 2KBe3Si12O30, a new milarite-group mineral from the Heftetjern pegmatite, Tordal, Southern Norway: Description and crystal structure

The roedderite-chayesite series from Spanish lamproites: crystal-chemical characterization

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