Crystal-chemistry and cation ordering in the system diopside-jadeite: A detailed study by crystal structure refinement

1983 ◽  
Vol 83 (3-4) ◽  
pp. 247-258 ◽  
Author(s):  
Giuseppe Rossi ◽  
David C. Smith ◽  
Luciano Ungaretti ◽  
M. Chiara Domeneghetti
Keyword(s):  
Crystal Structure ◽  
Crystal Chemistry ◽  
Structure Refinement ◽  
Cation Ordering ◽  
Crystal Structure Refinement

scholarly journals Crystal structure refinement and crystal chemistry of parasymplesite and vivianite

2021 ◽  
Vol 116 (4) ◽  
pp. 183-192
Author(s):  
Hidetomo HONGU ◽  
Akira YOSHIASA ◽  
Ginga KITAHARA ◽  
Yumiko MIYANO ◽  
Karin HAN ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Crystal Chemistry ◽  
Structure Refinement ◽  
Crystal Structure Refinement

Fluoronyböite from Jianchang (Su-Lu, China) and nyböite from Nybö (Nordfjord, Norway): a petrological and crystal-chemical comparison of these two high-pressure amphiboles

2003 ◽  
Vol 67 (4) ◽  
pp. 769-782 ◽  
Author(s):  
R. Oberti ◽  
M. Boiocchi ◽  
D. C. Smith
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
Structure Refinement ◽  
New Mineral ◽  
Cation Ordering ◽  
Crystal Chemical ◽  
Crystal Structure Refinement ◽  
Mineral Data

AbstractFluoronyböite, ideally NaNa2(Al2Mg3)(Si7Al)O22F2, has been found in the Jianchang eclogite pod, Su-Lu coesite-eclogite province, China. It has been approved as a new mineral by the IMA. Single-crystal structure refinement and electron microprobe analysis were used for characterization: C2/m, with a = 9.666(4), b = 17.799(6), c = 5.311(2) Å, β = 104.10(3)º, V = 886.2(8) Å3, Z = 2, formula: A(Na0.78K0.06)Σ0.84B(Na1.53Ca0.47)Σ2.00C(Fe2+0.89Mg2.55Mn0.01Zn0.01Fe3+0.32Al1.21Ti0.01)Σ5.00T(Si7.14Al0.86)Σ8.00O22X(OH0.84F1.16)Σ2.00.Fluoronyböite formed during UHPM conditions, and is preserved in the retrograded kyanite-bearing eclogite sample DJ102 together with clinopyroxene (Jd70Ae20Di10), garnet (Alm60Prp21Grs17Sps02), and rutile. Lower-pressure minerals are also present (fluoro-alumino-magnesiotaramite, apatite, paragonite), and symplectitic rims were also developed around clinopyroxene crystals. Cation ordering and the structural and physical properties of fluoronyböite are reported and discussed with reference to those of F-free nyböite from the type locality at Nyböin Norway, for which some as yet unpublished mineral data are also reported. Relations between composition and petrogenetic conditions of these rare high-pressure amphiboles are discussed.

Aschamalmite (Pb6Bi2S9): crystal structure and ordering scheme for Pb and Bi atoms)

2009 ◽  
Vol 73 (1) ◽  
pp. 83-94 ◽  
Author(s):  
A. M. Callegari ◽  
M. Boiocchi
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Monoclinic Phase ◽  
Structure Refinement ◽  
Single Crystal Structure ◽  
Mirror Plane ◽  
Cation Ordering ◽  
Crystal Structure Refinement ◽  
Unit Cells ◽  
Probable Site

The first single-crystal structure refinement of aschamalmite (Pb6Bi2S9) from Susa Valley (Piedmont, Italy) is reported. The mineral is monoclinic, C2/m, a = 13.719(1) Å, b = 4.132(1) Å, c = 31.419(3) Å, β = 90.94(1)º, V = 1 780.8(4) A ˚3, Z = 4. The Pb6Bi2S9 compound crystallizes also in an orthorhombic form as heyrovskyite (Cmcm) and our study is focused on understanding the reason leading to a change in symmetry. The aschamalmite structure forms because of ordering between Pb and Bi on the margins of the two octahedral layers that are symmetrically equivalent in heyrovskyite. The two alternate set of octahedral slabs are not related by a crystallographic mirror plane and the symmetry decreases to monoclinic. The cation ordering couples opposite sequences of Pb and Bi octahedra at the margins of slabs. In particular,the succession [Me4A]Bi-[Me5A]Pb-[Me4A]Bi-[Me5A]Pb faced to the series [Me4B]Pb- [Me5B]Bi-[Me4B]Pb-[Me5B]Bi occurs in about 70% of the unit-cells of the crystal,while the contrary sequence ([Me4A]Pb-[Me5A]Bi-[Me4A]Pb-[Me5A]Bi faced to [Me4B]Bi-[Me5B]Pb-[Me4B]Bi-[Me5B]Pb) occurs in the remaining unit-cells. The marginal octahedra have ideal populations (a.p.f.u.): [Me4A]1.40Bi+0.60Pb, [Me4B]1.40Pb+0.60Bi, [Me5A]1.40Pb+0.60Bi, [Me5B]1.40Bi+0.60Pb,in agreement with our structurerefinement results.The probable site populations for pure heyrovskyite have been proposed,as well as the reasons that prevent the formation of a completely ordered monoclinic phase.

scholarly journals Asbecasite: crystal structure refinement and crystal chemistry

1993 ◽  
Vol 57 (387) ◽  
pp. 315-322 ◽  
Author(s):  
Michele Sacerdoti ◽  
Gian Carlo Parodi ◽  
Annibale Mottana ◽  
Adriana Maras ◽  
Giancarlo Della Ventura
Keyword(s):  
Crystal Structure ◽  
Crystal Chemistry ◽  
Structure Determination ◽  
Electron Microprobe ◽  
Structure Refinement ◽  
Volcanic Complex ◽  
Crystal Chemical ◽  
Crystal Structure Refinement ◽  
Roman Potassic Province ◽  
Original Crystal

AbstractThe crystal structure of antimonian asbecasite in an ejectum of hypabyssal origin occurring at Tre Croci near Vetralla, Vico volcanic complex, Roman potassic province, Latium, Italy, has been refined to R = 0.042, and is compared to the original crystal structure determination carried out on the Sb-free asbecasite of hydrothermal metamorphic origin from the type-locality, Cherbandung in Binna valley, Monte Leone nappe, Switzerland. New electron microprobe analyses of samples from both localities demonstrate crystal-chemical features that permit distinction between asbecasites from the two occurrences, so far the only known localities for this mineral.

Iron in kornerupine; a57Fe Moessbauer spectroscopic study and comparison with single-crystal structure refinement

1999 ◽  
Vol 84 (4) ◽  
pp. 536-549 ◽  
Author(s):  
Edward S. Grew ◽  
Guenther J. Redhammer ◽  
Georg Amthauer ◽  
Mark A. Cooper ◽  
Frank C. Hawthorne ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Spectroscopic Study ◽  
Structure Refinement ◽  
Single Crystal Structure ◽  
Crystal Structure Refinement
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