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

Sokolova, Elena; Hawthorne, Frank C.; Pautov, Leonid A.

doi:10.2113/gscanmin.38.4.853

Cited by 15 publications

(18 citation statements)

References 6 publications

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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: 99%

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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Section: Discussionmentioning

confidence: 99%

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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“…Here, we report the crystal structure of faizievite as an assemblage of intercalated blocks of the structures of baratovite, K Li 3 Ca 7 Ti 2 (Si 6 O 18 ) 2 F 2 (Sandomirskii et al 1976), and berezanskite, K Li 3 Ti 2 (Si 12 O 30 ) (milarite group) (Pautov & Agakhanov 1997). Both baratovite and berezanskite were first described as accessory minerals in quartz -albite -aegirine pegmatitic veinlets in quartz-aegirine syenites and albitites of the Dara-i-Pioz massif, northern Tajikistan (Dusmatov et al 1975, andPautov &Agakhanov 1997, respectively). The crystal structure of baratovite was solved by Sandomirskii et al (1976) and refined by Menchetti & Sabelli (1979).…”

Section: Chemical Compositionmentioning

confidence: 99%

“…For the diagram of a hypothetical structure of berezanskite, we use atom coordinates of the crystal structure of sogdianite, K [9]  Li 3 Zr 2 (Si 12 O 30 ), as the crystal structure of berezanskite has not been yet refined. Sogdianite is a Zr-analogue of berezanskite, with a 10.1240(3), c 14.3198(5), space group P6/mcc, Z = 2 (Sokolova et al 2000).…”

Section: The Faizievite Structure: An Assemblage Of Intercalated Blocmentioning

confidence: 99%

THE CRYSTAL CHEMISTRY OF FAIZIEVITE, K2 Li6 Na (Ca6Na) Ti4 [Si6O18]2 [Si12O30] F2, A NOVEL STRUCTURE BASED ON INTERCALATED BLOCKS OF THE BARATOVITE AND BEREZANSKITE STRUCTURES

Uvarova

Sokolova

Hawthorne

et al. 2008

The Canadian Mineralogist

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The crystal structure of faizievite, ideally K 2 Li 6 Na (Ca 6 Na) Ti 4 [Si 6 O 18 ] 2 [Si 12 O 30 ] F 2 , a 9.8156(9), b 9.8249(9), c 17.3087(16) Å, a 99.209(2), b 94.670(2), g 119.839(1)°, V 1403.7(4) Å 3 , space group P1, Z = 1, D calc. 2.846 g/cm 3 , has been solved and refined to an R 1 index of 7.5% based on 5044 unique (F 0 > 4sF) reflections collected on a Bruker single-crystal P4 diffractometer with a 4K CCD detector and MoKa X-radiation. Electron-microprobe analysis gave SiO 2 60.65, TiO 2 13.44, Nb 2 O 5 0.11, CaO 14.52, K 2 O 3.93, Na 2 O 1.99, SrO 0.72, Rb 2 O 0.13, F 1.30, Li 2 O 3.76, sum 100.24 wt.%. Concentrations of Li 2 O, Rb 2 O, SrO and BaO were determined by ICP-OES. There are fifteen tetrahedrally coordinated sites: twelve sites are occupied by Si, with a grand of 1.613 Å; three sites are occupied by Li, with a grand distance of 1.928 Å. There are six octahedrally coordinated sites. The two Ti(1) and Ti(2) sites are occupied by Ti 2.00 with = 1.937 and 1.934 Å, respectively. The four M sites are occupied by Ca with minor Sr and Na: the M(1) site (= Ca 2.00), with = 2.441 Å, the M(2) site [= (Ca 1.87 Sr 0.13)], with = 2.424 Å, the M(3) site [= (Ca 1.56 Na 0.40 Sr 0.04)], with = 2.415 Å, and the M(4) site [= (Ca 0.73 Na 0.27)], with = 2.418 Å. There are two interstitial A sites: the A(1) site is [12]-coordinated and is occupied by (K 1.93 Ba 0.04 Rb 0.03), with = 3.092 Å; the A(2) site is [9]-coordinated and is occupied by (Na 0.86  0.14), with = 2.718 Å. The crystal structure of faizievite consists of four types of (001) sheets. The Si tetrahedra form two types of six-membered rings: a single (Si 6 O 18) ring, as in baratovite, and a double (Si 12 O 30) ring, as in milaritegroup minerals, in the ratio 2:1. Each type of ring forms a distinct sheet (Na atoms occur in a sheet of milarite double rings). Two other sheets are: a sheet of corner-sharing (LiO 4) tetrahedra and (TiO 6) octahedra with K atoms in large voids, and a sheet of edge-sharing M octahedra (M = Ca >> Na). Each sheet is characterized by a planar cell based on translation vectors, t 1 and t 2 , with t 1 ≈ t 2 ≈ 9.8 Å and t 1  t 2 close to 120°. The composition of the four individual sheets within the planar cell t 1 ,t 2 is: (1) (Si 6 O 18), (2) (Si 12 O 30)Na, (3) KLi 3 Ti 2 , (4) (Ca 6 Na)F 2. The crystal structure of faizievite is a hybrid of the structures of baratovite, KLi 3 Ca 7 Ti 2 (Si 6 O 18) 2 F 2 , and berezanskite, KLi 3 Ti 2 (Si 12 O 30) (milarite group). The baratovite block of composition [KLi 3 (Ca 6 Na)Ti 2 (Si 6 O 18) 2 F 2 ] comprises sheets (3)(1)(4)(1). The berezanskite block of composition [KNaLi 3 Ti 2 (Si 12 O 30)] comprises sheets (3)(2). In the faizievite structure, baratovite and berezanskite blocks alternate along [001] and sum to the following sequence: (3)(1)(4)(1)(3)(2). There are minor differences between the chemical compositions of baratovite and berezanskite and analogous blocks in the crystal structure of faizievite....

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“…The milarites exhibit large compositional variations at the T2 site with, e.g., Li, Be, B, Mg, Al, Si, Mn, Fe 2þ , Fe 3þ , and Zn, and at the A-site with Al, Fe 3þ , Sn 4þ , Fe 2þ , Mg, Zr, Ca, Na, Y, REE, Sc, and others (Sokolova et al, 2000;Hawthorne, 2002). The associated large variations in cation radii can be accommodated by low-energy distortions of edge-linked (T2)O 4 tetrahedra adjusting to predominantly regular AO 6 octahedra of variable size depending on the type of A-site cation.…”

Section: Introductionmentioning

confidence: 99%

“…Brannockite, ideally KSn 2 Li 3 Si 12 O 30 , was described by White et al (1973) from Li-Sn rich pegmatites of the Foote Mine, Kings Mountain, North Carolina, USA, and its structure refined by Armbruster & Oberhänsli (1988b). Closely related to brannockite, are the corresponding Zr end-member sogdianite KLi 3 Zr 2 [Si 12 O 30 ] (Dusmatov et al, 1968;Boggs, 1984;Cooper et al, 1999;Sokolova et al, 2000) (Armbruster & Oberhänsli, 1988b). Darapiosite K(Na,K,&) 2 (Mn 2þ , Zr 4þ , Y 3þ ) 2 (Li, Zn, Fe 2þ ) 3 [Si 12 O 30 ] (Semenov et al, 1975;Ferraris et al, 1999) in end-member composition with Zn 2 Li in T2-site is charge balancing the divalent A-site with two Na þ on the B-site (Hawthorne, 2002).…”

Section: Introductionmentioning

confidence: 99%

Crystal chemistry of brannockite, KLi3Sn2 Si12O30, from a new occurrence in the Golden Horn Batholith, Washington State, USA

Raschke

Anderson

Allaz

et al. 2016

ejm

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A second locality of the milarite-group mineral brannockite (ideally KLi 3 Sn 2 Si 12 O 30) has been discovered at Liberty Bell/Washington Pass in the peralkaline granite of the Golden Horn Batholith, Okanogan County, Washington, USA as millimeter sized euhedral bladed clear crystals in a single miarolitic cavity. The Washington Pass brannockite shows microscale compositional zoning involving tetravalent A-site Sn 4þ , Zr 4þ , Ti 4þ , and Hf 4þ substitution and the coupled substitution A X 4þ À Á þ B & , A Fe=Al ð Þ 3þ þ B Na; K ð Þ þ. In contrast, brannockite analyzed from the type locality in the late hydrothermal zone of the Li-Sn-rich pegmatite of the Foote Mine, Kings Mountain, North Carolina, USA exhibits near end-member composition with only minor Na þ , Al 3þ , and Ti 4þ. Single-crystal X-ray diffraction of Washington Pass brannockite confirms the space group P6/mcc with unit-cell parameters a ¼ 10.014(2) Å , c ¼ 14.268(5) Å , and V ¼ 1239.16(8) Å 3. Washington Pass brannockite co-exists with its Zr-analogues, both the milarite-group sogdianite and the related tuhualite-group mineral zektzerite. Selected samples of both minerals show Sn as minor element. The sogdianite contains unusually low Na and Ti compared to most other localities and has near end-member composition. The results emphasize the high compatibility of the milarite structure with different heterovalent cations, associated with the cation-size dependent coupled distortion of the octahedral A and tetrahedral T2 sites.

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

Cited by 15 publications

References 6 publications

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

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

THE CRYSTAL CHEMISTRY OF FAIZIEVITE, K2 Li6 Na (Ca6Na) Ti4 [Si6O18]2 [Si12O30] F2, A NOVEL STRUCTURE BASED ON INTERCALATED BLOCKS OF THE BARATOVITE AND BEREZANSKITE STRUCTURES

Crystal chemistry of brannockite, KLi3Sn2 Si12O30, from a new occurrence in the Golden Horn Batholith, Washington State, USA

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