Kalyuzhnyite-(Ce), NaKCaSrCeTi(Si8O21)OF(H2O)3, a new mineral from the Darai-Pioz alkaline massif, Tien-Shan mountains, Tajikistan: mineral description, crystal structure and a new double (Si8O21) sheet
Atali A. Agakhanov, Elena Sokolova, Vladimir Yu. Karpenko, Frank C. Hawthorne, Leonid A. Pautov, Anatoly V. Kasatkin, Igor V. Pekov, Vitaliya A. Agakhanova
{"title":"Kalyuzhnyite-(Ce), NaKCaSrCeTi(Si8O21)OF(H2O)3, a new mineral from the Darai-Pioz alkaline massif, Tien-Shan mountains, Tajikistan: mineral description, crystal structure and a new double (Si8O21) sheet","authors":"Atali A. Agakhanov, Elena Sokolova, Vladimir Yu. Karpenko, Frank C. Hawthorne, Leonid A. Pautov, Anatoly V. Kasatkin, Igor V. Pekov, Vitaliya A. Agakhanova","doi":"10.1180/mgm.2023.74","DOIUrl":null,"url":null,"abstract":"<p>Kalyuzhnyite-(Ce), ideally NaKCaSrCeTi(Si<span>8</span>O<span>21</span>)OF(H<span>2</span>O)<span>3</span>, is a new mineral from the Darai-Pioz alkaline massif, Tien-Shan mountains, Tajikistan. It occurs as equant grains up to 0.05 × 0.07 mm in a quartz–pectolite aggregate in a silexite-like peralkaline pegmatite. Associated minerals are quartz, fluorite, pectolite, baratovite, aegirine, leucosphenite, neptunite, reedmergnerite, orlovite, sokolovaite, mendeleevite-(Ce), odigitriaite, pekovite, zeravshanite, kirchhoffite and garmite. The mineral is colourless with a vitreous lustre and a white streak, and <span>D</span><span>calc.</span> is 3.120 g/cm<span>3</span>. Kalyuzhnyite-(Ce) is monoclinic, <span>P</span>2/<span>c</span>, <span>a</span> = 18.647(4), <span>b</span> = 11.214(2), <span>c</span> = 14.642(3) Å, β = 129.55(3)° and <span>V</span> = 2360.9(11) Å<span>3</span>. The chemical composition of kalyuzhnyite-(Ce) is Nb<span>2</span>O<span>5</span> 0.53, TiO<span>2</span> 0.16, SiO<span>2</span> 43.85, Er<span>2</span>O<span>3</span> 0.13, Ho<span>2</span>O<span>3</span> 0.10, Gd<span>2</span>O<span>3</span> 0.09, Sm<span>2</span>O<span>3</span> 0.47, Nd<span>2</span>O<span>3</span> 6.22, Pr<span>2</span>O<span>3</span> 1.21, Ce<span>2</span>O<span>3</span> 6.34, La<span>2</span>O<span>3</span> 0.82, PbO 4.90, BaO 0.85, SrO 11.39, CaO 1.86, Cs<span>2</span>O 3.80, K<span>2</span>O 1.59, Na<span>2</span>O 2.99, H<span>2</span>O 5.24, F 1.55, O = F –0.65, total 100.31 wt.%. The empirical formula calculated on 26.11 (O + F) apfu is Na<span>1.07</span>K<span>0.37</span>Cs<span>0.30</span>Sr<span>1.21</span>Ca<span>0.37</span>Pb<span>0.24</span>Ba<span>0.06</span>(Ce<span>0.43</span>Nd<span>0.41</span>Pr<span>0.08</span>La<span>0.06</span>Sm<span>0.03</span>Gd<span>0.01</span>Er<span>0.01</span>Ho<span>0.01</span>)<span>Σ1.04</span>(Ti<span>0.97</span>Nb<span>0.04</span>)<span>Σ1.01</span>Si<span>8.06</span>O<span>25.21</span>F<span>0.90</span>H<span>6.42</span>, <span>Z</span> = 4. The simplified formula is (Na,□)(K,Сs)(Ca,Pb,Sr,Na)Sr<span>Ln</span><span>3+</span>Ti(Si<span>8</span>O<span>21</span>)OF(H<span>2</span>O)<span>3</span>, where Ce is the dominant lanthanoid. The crystal structure was solved by direct methods and refined to an <span>R</span><span>1</span> index of 2.74%. In kalyuzhnyite-(Ce), the main structural units are a heteropolyhedral Na–Sr–Ce–Ti sheet, ideally [NaSrCeTiOF]<span>7+</span>, and a double (Si<span>8</span>O<span>21</span>)<span>10–</span> sheet parallel to (010). In the Si–O sheet, the Si tetrahedra form ten-membered rings. This is the first occurrence of such a double Si–O sheet in a mineral. The two sheets connect via common vertices of Na-, Sr-, Ce- and Ti-polyhedra and SiO<span>4</span> tetrahedra to form a framework. The interstitial cations and H<span>2</span>O groups, ideally [(CaK)(H<span>2</span>O)<span>3</span>]<span>3+</span><span>,</span> occur within the Si–O sheet. The mineral is named in honour of Vasily Avksentievich Kalyuzhny (1899–1993) in recognition of his contributions to the geology of ore deposits of Komi Republic (USSR) and the mineralogy of granitic pegmatites (Tajikistan).</p>","PeriodicalId":18618,"journal":{"name":"Mineralogical Magazine","volume":null,"pages":null},"PeriodicalIF":2.8000,"publicationDate":"2023-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Mineralogical Magazine","FirstCategoryId":"89","ListUrlMain":"https://doi.org/10.1180/mgm.2023.74","RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"MINERALOGY","Score":null,"Total":0}
引用次数: 0
Abstract
Kalyuzhnyite-(Ce), ideally NaKCaSrCeTi(Si8O21)OF(H2O)3, is a new mineral from the Darai-Pioz alkaline massif, Tien-Shan mountains, Tajikistan. It occurs as equant grains up to 0.05 × 0.07 mm in a quartz–pectolite aggregate in a silexite-like peralkaline pegmatite. Associated minerals are quartz, fluorite, pectolite, baratovite, aegirine, leucosphenite, neptunite, reedmergnerite, orlovite, sokolovaite, mendeleevite-(Ce), odigitriaite, pekovite, zeravshanite, kirchhoffite and garmite. The mineral is colourless with a vitreous lustre and a white streak, and Dcalc. is 3.120 g/cm3. Kalyuzhnyite-(Ce) is monoclinic, P2/c, a = 18.647(4), b = 11.214(2), c = 14.642(3) Å, β = 129.55(3)° and V = 2360.9(11) Å3. The chemical composition of kalyuzhnyite-(Ce) is Nb2O5 0.53, TiO2 0.16, SiO2 43.85, Er2O3 0.13, Ho2O3 0.10, Gd2O3 0.09, Sm2O3 0.47, Nd2O3 6.22, Pr2O3 1.21, Ce2O3 6.34, La2O3 0.82, PbO 4.90, BaO 0.85, SrO 11.39, CaO 1.86, Cs2O 3.80, K2O 1.59, Na2O 2.99, H2O 5.24, F 1.55, O = F –0.65, total 100.31 wt.%. The empirical formula calculated on 26.11 (O + F) apfu is Na1.07K0.37Cs0.30Sr1.21Ca0.37Pb0.24Ba0.06(Ce0.43Nd0.41Pr0.08La0.06Sm0.03Gd0.01Er0.01Ho0.01)Σ1.04(Ti0.97Nb0.04)Σ1.01Si8.06O25.21F0.90H6.42, Z = 4. The simplified formula is (Na,□)(K,Сs)(Ca,Pb,Sr,Na)SrLn3+Ti(Si8O21)OF(H2O)3, where Ce is the dominant lanthanoid. The crystal structure was solved by direct methods and refined to an R1 index of 2.74%. In kalyuzhnyite-(Ce), the main structural units are a heteropolyhedral Na–Sr–Ce–Ti sheet, ideally [NaSrCeTiOF]7+, and a double (Si8O21)10– sheet parallel to (010). In the Si–O sheet, the Si tetrahedra form ten-membered rings. This is the first occurrence of such a double Si–O sheet in a mineral. The two sheets connect via common vertices of Na-, Sr-, Ce- and Ti-polyhedra and SiO4 tetrahedra to form a framework. The interstitial cations and H2O groups, ideally [(CaK)(H2O)3]3+, occur within the Si–O sheet. The mineral is named in honour of Vasily Avksentievich Kalyuzhny (1899–1993) in recognition of his contributions to the geology of ore deposits of Komi Republic (USSR) and the mineralogy of granitic pegmatites (Tajikistan).
期刊介绍：
Mineralogical Magazine is an international journal of mineral sciences which covers the fields of mineralogy, crystallography, geochemistry, petrology, environmental geology and economic geology. The journal has been published continuously since the founding of the Mineralogical Society of Great Britain and Ireland in 1876 and is a leading journal in its field.
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