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octahedra

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Journal Article
Published: 01 May 2025
American Mineralogist (2025) 110 (5): 731–747.
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Journal Article
Published: 01 April 2025
American Mineralogist (2025) 110 (4): 570–581.
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Journal Article
Published: 01 April 2025
American Mineralogist (2025) 110 (4): 643–649.
... is monoclinic, C 2/ m , a = 10.2054(11), b = 13.3772(13), c = 4.7382(4) Å, β = 105.057(7)°, V = 624.66(11) Å 3 , and Z = 2. The mineral has a vivianite-type structure ( R 1 = 0.0353 for 668 I > 2σ I reflections) in which M lO 2 (H 2 O) 4 octahedra and M 2 2 O 6 (H 2 O) 4 edge-sharing octahedral dimers...
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Journal Article
Published: 01 February 2025
American Mineralogist (2025) 110 (2): 241–254.
... ends sealed by an electric spot welder, and 1 μL of distilled H 2 O was added to the starting material to guarantee saturated water fugacity. The 14/8 assemblages (i.e., 14 mm periclase octahedra and 25.4 mm tungsten carbide anvils with 8 mm corner truncations) were adopted to synthesize the CaCl 2...
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Journal Article
Published: 30 December 2024
American Mineralogist (2024)
Journal Article
Published: 18 December 2024
The Canadian Journal of Mineralogy and Petrology (2024) 62 (6): 881–889.
... of Zn(OH) 6 octahedra and Zn(OH) 4 tetrahedra. A Pb 2+ cation, an SO 4 2− group, and several H 2 O groups are located between successive sheets. The new mineral described herein is named siligiite (/si: li: 'gi: ait/) based on the Cherokee word siligi (ᏏᎵᎩ in the Tsalagi language) meaning silk...
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Journal Article
Published: 01 October 2024
American Mineralogist (2024) 109 (10): 1738–1747.
... (IMA2022-142). The structure of wenlanzhangite-(Y) is composed of a -axis-oriented chains of [VO 6 ] octahedra consisting of edge-sharing octahedra linked by insular [SiO 4 ] tetrahedra, leaving open channels occupied by rare earth elements. Observed compositional variation and crystal structure...
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Journal Article
Published: 20 September 2024
American Mineralogist (2024)
... or a Mg atom onto an Fe2+ atom centering two octahedra. 82 In order for a twin to form, a substantial substructure should cross the interface, more or less 83 unperturbed. The values of D for each crystallographic orbit measure the degree of perturbation. 84 The distribution of values of D around...
Journal Article
Published: 01 July 2024
American Mineralogist (2024) 109 (7): 1162–1170.
... the first-principles molecular dynamics (FPMD) based vertical energy gap method. Fe(II) and Fe(III) substitutions resulted, respectively, in a significant increase and decrease in p K a values of amphoteric groups directly associated with Fe octahedra. In addition, Fe(II) substitution increased the p K...
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Journal Article
Published: 18 June 2024
The Canadian Journal of Mineralogy and Petrology (2024) 62 (3): 513–527.
... general description of the crystal structure of the paulkerrite-group minerals is in terms of a structural unit plus an interstitial complex, using the terminology of Hawthorne ( Hawthorne 1992 , Hawthorne & Schindler 2008 ). The structural unit is a 3D anionic framework of corner-connected octahedra...
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Journal Article
Published: 18 June 2024
The Canadian Journal of Mineralogy and Petrology (2024) 62 (3): 529–536.
... with chenite. In the crystal structure ( R 1 = 0.0874 for 936 I > 2σ I ), short bonds between the Pb atoms and OH groups define a chain along [011] and these chains are bridged by ZnO 2 (OH) 4 octahedra to form sheets parallel to . SO 4 tetrahedra decorate both sides of the sheets. The sheets are linked...
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Journal Article
Published: 01 May 2024
American Mineralogist (2024) 109 (5): 872–881.
... Fe ions in bridgmanite and their effects on unit-cell volumes ( Hsu et al. 2010 , 2011 , 2012 ; Shukla et al. 2016 ). For an ideal perovskite structure, the A and B sites have twelve-fold and sixfold coordination to form AO 12 dodecahedra and BO 6 octahedra, respectively ( Fig. 3a ). Kudoh...
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Journal Article
Published: 01 May 2024
American Mineralogist (2024) 109 (5): 949–959.
... (CO 3 ) 2 ] double sheet (with Zn 2+ both in octahedra and tetrahedra), which is connected to a thick interlayer that hosts U 6+ , Ca 2+ , and H 2 O molecules. The linkage between structural units and the interlayer occurs via the vertices of ZnO 4 tetrahedra protruding from the sheet...
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Journal Article
Published: 25 April 2024
Mineralogical Magazine (2024) 88 (5): 536–545.
... type includes one tetrahedral sheet and one octahedral sheet (Cao et al. , 2021 ), whereas the 2:1 type includes two tetrahedral sheets with one octahedral sheet situated between them (Bodart et al. , 2018 ). The octahedra come in two forms: (1) dioctahedral, wherein two thirds of the octahedral...
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Journal Article
Published: 01 April 2024
American Mineralogist (2024) 109 (4): 633–655.
... et al. 2006 ). Natural Mt predominantly exhibits a cis -vacant T-O-T layer comprising both cis -(OH groups on adjacent corners) and trans -octahedra (OH groups on opposite corners) within the octahedral sheet ( Gao et al. 2023 ), while the trans -vacant variant is relatively less abundant...
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Journal Article
Published: 21 March 2024
Mineralogical Magazine (2024) 88 (3): 302–311.
... to unity. The crystal structure of zilbermintsite-(La) ( Fig. 4 ) consists of the chains of edge-sharing octahedra running along the b axis: single chains of the M (2)- and M (4)-centred octahedra and branched chains with the M (1)-centred octahedra in the central part, and the M (3)-centred...
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Journal Article
Published: 19 March 2024
Mineralogical Magazine (2024) 88 (3): 327–334.
... octahedra that share corners with PO 4 tetrahedra to form 10-member rings parallel to (010). K + cations and water molecules are located in interstitial sites within the rings. Additional corner-sharing of the PO 4 tetrahedra with MnO 2 (H 2 O) 4 octahedra occurs along [010] to complete the 3D framework...
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Journal Article
Published: 18 January 2024
The Canadian Journal of Mineralogy and Petrology (2024) 62 (1): 117–132.
... of chains of distorted octahedrally coordinated Na + and regular Mg[O(H 2 O) 5 ] octahedra. The observed low incident bond valence to the V1 site (4.45 vu ) and marked deviation in vanadyl and V–O eq bond lengths indicate that this site is host to the essential Ti 4+ identified during chemical analyses...
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Journal Article
Published: 02 January 2024
American Mineralogist (2024) 109 (1): 144–149.
... of alternating layers of FeO 6 and TiO 6 octahedra and ulvöspinel, Fe 2 TiO 4 , consists of FeO 4 tetrahedra and (Fe, Ti)O 6 octahedra. End-member feiite (Fe 2+ ) 3 TiO 5 , based on electron backscatter diffraction analyses of natural feiite grains from Shergotty ( Ma et al. 2021 ), is assumed to adopt...
FIGURES
Journal Article
Published: 02 January 2024
American Mineralogist (2024) 109 (1): 157–166.
..., displays euhedral crystals with flat smooth faces and sharp edges. The second, also rare, shows flattened (111) twins. A third rather unusual type shows octahedra having square pits at the vertices. The fourth, most common crystal type, includes individuals with several triangular growth plates of variable...
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