Anisotropic garnet from the Yamansu ore deposit, Xinjiang, China

Kobayashi, Shôichi; Miyawaki, Ritsuro; Momma, Koichi; Fujisawa, Akiko; Kaneda, Hiroaki

doi:10.2465/jmps.120927

Cited by 7 publications

(9 citation statements)

References 12 publications

(19 reference statements)

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“…The extinction rule for the body-centered lattice (hkl: h + k + l = 2n) was applied for the reflection data collection. Although the space group setting I 1 is irregular for the triclinic symmetry, the setting was selected for ease of comparison of our refined crystal structures with the results of previous studies (e.g., Takéuchi et al, 1982;Allen and Buseck, 1988;Kingma and Downs, 1989;Wildner and Andrut, 2001;Frank-Kamenetskaya et al, 2007;Kobayashi et al, 2013). In addition, as the sample of the {211} c sector was too small in size to perform experiments in our laboratory, the SC-XRD experiments were conducted using synchrotron radiation (λ = 0.7122 Å) at the beam line BL-10A, Photon Factory, KEK, Japan.…”

Section: Single-crystal X-ray Diffraction Experimentsmentioning

confidence: 99%

“…ΔY 11-14 and ΔY 21-24 denote the maximum differences in occupancies within the Y1 and Y2 groups, respectively. Refereces are as follows: (1) This study, (2) Takéuchi et al (1982), (3) Kingma and Downs (1989), (4) Frank-Kamenetskaya et al (2007), (5) Kobayashi et al (2013), (6) Wildner and Andrut (2001).…”

Section: Acknowledgementsmentioning

confidence: 99%

“…Birefringent garnet, which does not possess isometric symmetry, is commonly found in natural samples of the ugrandite series garnet, uvarovite (Ca 3 Cr 2 Si 3 O 12 ) -grossular (Ca 3 Al 2 Si 3 O 12 ) -andradite (Ca 3 Fe 2 Si 3 O 12 ) (e.g., Ingerson and Barksdale, 1943;Lessing and Standish, 1973;Takéuchi et al, 1982;Akizuki, 1984;Rossman and Aines, 1986;Allen and Buseck, 1988;Kingma and Downs, 1989;Griffen et al, 1992;Wildner and Andrut, 2001;Frank-Kamenetskaya et al, 2007;Kobayashi et al, 2013). The birefringent garnet shows clear sectoral structure and twinning under cross-polarized microscopic observations.…”

Section: Introductionmentioning

confidence: 99%

“…As discussed by Akizuki (1984), when cation ordering in birefringent garnet is produced by something kinetic effects during crystal growth, the {110} c and {211} c growth sectors are expected to have different degrees of cation ordering in their crystal structures. Several structural refinements have been performed on birefringent garnet samples with various chemical compositions in ugrandite solid solution (Allen and Buseck, 1988;Kingma and Downs, 1989;Wildner and Andrut, 2001;Frank-Kamenetskaya et al, 2007;Kobayashi et al, 2013); however, most of these studies did not consider the growth sectors with the exception of examined crystals, except for Frank-Kamenetskaya et al (2007).…”

Section: Introductionmentioning

confidence: 99%

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Cation ordering of {110} and {211} sectors in grandite garnet from Mali

Nakamura

Kuribayashi

Nagase

2016

Journal of Mineralogical and Petrological Sciences

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The cation ordering of the {110} c and {211} c growth sectors in birefringent garnet from Kayas, Mali was investigated by means of single-crystal X-ray diffraction (SC-XRD) 3d were observed, and crystal structure models for both the {110} c and {211} c sectors should have triclinic symmetry with the space group I 1. The unit-cell parameters of both growth sectors were a = 11.9739(13), b = 11.9742(14), c = 11.9737(13) Å, α = 90.001(9), β = 90.098(9) and γ = 90.014 (10)°for the {110} c sector; a = 11.952(6), b = 11.952(6), c = 11.957(6) Å, α = 90.06(4), β = 90.01(4) and γ = 89.94(4)°for the {211} c sector. Structure refinements for I 1 models of both sectors were convergent with R1 = 3.02 and 3.36%, respectively. There were significant differences in the Fe 3+ occupancies in the Y sites of the {211} c sector were random and different from that of the {110} c sector. Different cation distributions between the growth sectors in the Mali garnet indicate that cation ordering in the crystal structure was formed during growth. These observations suggest that the differences in the Fe 3+ distribution between the {110} c and {211} c sectors are strongly affected by the growth process in each sector.

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Section: Single-crystal X-ray Diffraction Experimentsmentioning

confidence: 99%

Section: Acknowledgementsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Cation ordering of {110} and {211} sectors in grandite garnet from Mali

Nakamura

Kuribayashi

Nagase

2016

Journal of Mineralogical and Petrological Sciences

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“…The crystal structures of birefringent ugrandite were reported as orthorhombic structure with the space group Fddd or triclinic structure with the space group I 1 (e.g. Takéuchi et al, 1982;Allen and Buseck, 1988;Wildner and Andrut, 2001;Frank-Kamenetskaya et al, 2007;Kobayashi et al, 2013;Nakamura et al, 2016). Kingma and Downs (1989) examined the crystal structure of iridescent andradite from a skarn deposit in the Sonoma Range, Nevada, USA.…”

Section: Introductionmentioning

confidence: 99%

Cation ordering in iridescent garnet from Tenkawa village, Nara prefecture, Japan

Nakamura

Kuribayashi

Nagase

et al. 2017

Journal of Mineralogical and Petrological Sciences

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The crystal structure of iridescent garnet from Tenkawa village, Nara prefecture, Japan was investigated by means of Single-crystal X-ray diffraction method. The garnet crystal is composed of {110} c and {211} c growth sectors and shows birefringence under the crossed polarizer. The BSE image of the cross section shows very fine lamellae texture consisting of andradite-rich and grossular-rich layers. The average chemical composition was determined as Ca 3.01 (Fe 1.93 Al 0.09 ) Σ2.02 Si 2.99 O 12 . The unit-cell parameters were obtained as follows; a = 12.0540(17), b = 12.0580(13), c = 12.0612(13) Å, α = 89.986(9), β = 89.994(10) and γ = 89.994 (10)°. Some reflections which violate the extinction rule for the space group Ia 3d were observed and indicated that all glide planes are absent. Triclinic symmetry with the space group I 1 should be suitable for the structure refinement. The refinement with a I 1 model was convergent with R1 = 3.19%. The Fe 3+ occupancies of the Y11, Y12, Y13, Y14, Y 21, Y22, Y 23, and Y 24 were determined as 86.9(6), 96.1(6), 90.9(6), 98.0(6), 95.1(6), 91.3(6), 93.7(6), and 99.6(6)%, respectively. The Fe 3+ occupancy of the Y11 site is relatively lower, and that of the Y 24 site is higher. The iridescent garnet from Tenkawa shows very fine lamellae texture consisted of Fe-rich and Al-rich layers, therefore, the refined crystal structure of the Tenkawa garnet should be a superimposed structure of these chemically distinct layers. The Fe-rich layer have almost pure andradite composition, so cation ordering in the Fe-rich layer is negligible. The Al-rich layer should have more obvious ordered cation distribution than the Ferich layer. The ordered cation distribution in the Al-rich layer should mainly contribute the cation ordering in the refined crystal structure of the Tenkawa garnet.

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