L. A. Pautov, A. A. Agakhanov, I. V. Pekov, V. Yu. Karpenko, O. I. Siidra, E. V. Sokolova, F. C. Hawthorne, A. R. Fayziev
{"title":"Garmite, CsLiMg2(Si4O10)F2, a New Mica-Group Mineral from “Quartz Blocks” of the Darai-Pioz Alkaline Massif, Tajikistan","authors":"L. A. Pautov, A. A. Agakhanov, I. V. Pekov, V. Yu. Karpenko, O. I. Siidra, E. V. Sokolova, F. C. Hawthorne, A. R. Fayziev","doi":"10.1134/s1075701523070073","DOIUrl":null,"url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>A new trioctahedral mica garmite, CsLiMg<sub>2</sub>(Si<sub>4</sub>O<sub>10</sub>)F<sub>2</sub>, a Cs analogue of tainiolite, was found in an substantially quartz rock in the Darai-Pioz alkaline massif, Rasht district (formerly Garm district), Central Tajikistan, and was named after the town Garm, an administrative center of the Rasht district. It is closely associated with Mn-bearing pectolite, aegirine, Sr-rich fluorite, quartz, datolite, and polylithionite. Garmite forms lamellae up to 0.2 mm across and up to 0.02 mm thick. The mineral is transparent, colorless, with perfect, mica-like cleavage on (001). The Moh’s hardness is 2.5; micro-indentation hardness VHN<sub>20</sub> = 90 kg/mm<sup>2</sup>. <i>D</i><sub>meas</sub> = 3.34(2) and <i>D</i><sub>calc</sub> = 3.336 g/cm<sup>3</sup>. Garmite is optically biaxial (–), 2<i>V</i><sub>meas</sub> = –10(5)°, α = 1.582(2), β = 1.601(2), γ = 1.602(2). The chemical composition (electron microprobe, Li and H by SIMS, wt %): SiO<sub>2</sub> 47.39, Al<sub>2</sub>O<sub>3</sub> 0.71, TiO<sub>2</sub> 0.71, Nb<sub>2</sub>O<sub>5</sub> 0.12, FeO 2.12, MnO 0.85, MgO 9.01, ZnO 2.23, K<sub>2</sub>O 0.16, Cs<sub>2</sub>O 26.98, Li<sub>2</sub>O 3.57, H<sub>2</sub>O 0.08, F 7.23, –O=F<sub>2</sub> 3.04, total 99.90. The empirical formula calculated on the basis of 12 (O + F) apfu is (Cs<sub>0.95</sub>K<sub>0.02</sub>)<sub>Σ0.97</sub>Li<sub>1.21</sub>(Mg<sub>1.37</sub>Zn<sub>0.16</sub>Fe<sub>0.15</sub>Al<sub>0.07</sub>Mn<sub>0.06</sub>Ti<sub>0.04</sub>)<sub>Σ1.85</sub>Si<sub>3.99</sub>O<sub>10.04</sub>(F<sub>1.92</sub>OH<sub>0.04</sub>)<sub>Σ1.96</sub>. Garmite is monoclinic, space group <i>C</i>2/<i>m</i>, <i>C</i>2 or C<i>m</i>; polytype 1<i>M.</i> The unit-cell parameters are <i>a</i> = 5.234(2), <i>b</i> = 9.042(4), <i>c</i> = 10.780(4) Å, β = 99.73(4)°; <i>V</i> = 502.8(6) Å<sup>3</sup>; <i>Z</i> = 2. The strongest reflections of the powder X‑ray diffraction pattern (<i>d</i> Å, <i>I</i>, <i>hkl</i>) are 4.48, 35, 110; 3.70, 70, –112; 3.45, 44, 022; 2.608, 70, –201, 130; 2.580, 100, 200, –131; 2.241, 45, 220; 2.187, 80, –133. The holotype specimen is deposited in the Fersman Mineralogical Museum, Russian Academy of Sciences, Moscow catalogue no. 95894.</p>","PeriodicalId":12719,"journal":{"name":"Geology of Ore Deposits","volume":"37 1","pages":""},"PeriodicalIF":0.8000,"publicationDate":"2024-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Geology of Ore Deposits","FirstCategoryId":"89","ListUrlMain":"https://doi.org/10.1134/s1075701523070073","RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"GEOLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
A new trioctahedral mica garmite, CsLiMg2(Si4O10)F2, a Cs analogue of tainiolite, was found in an substantially quartz rock in the Darai-Pioz alkaline massif, Rasht district (formerly Garm district), Central Tajikistan, and was named after the town Garm, an administrative center of the Rasht district. It is closely associated with Mn-bearing pectolite, aegirine, Sr-rich fluorite, quartz, datolite, and polylithionite. Garmite forms lamellae up to 0.2 mm across and up to 0.02 mm thick. The mineral is transparent, colorless, with perfect, mica-like cleavage on (001). The Moh’s hardness is 2.5; micro-indentation hardness VHN20 = 90 kg/mm2. Dmeas = 3.34(2) and Dcalc = 3.336 g/cm3. Garmite is optically biaxial (–), 2Vmeas = –10(5)°, α = 1.582(2), β = 1.601(2), γ = 1.602(2). The chemical composition (electron microprobe, Li and H by SIMS, wt %): SiO2 47.39, Al2O3 0.71, TiO2 0.71, Nb2O5 0.12, FeO 2.12, MnO 0.85, MgO 9.01, ZnO 2.23, K2O 0.16, Cs2O 26.98, Li2O 3.57, H2O 0.08, F 7.23, –O=F2 3.04, total 99.90. The empirical formula calculated on the basis of 12 (O + F) apfu is (Cs0.95K0.02)Σ0.97Li1.21(Mg1.37Zn0.16Fe0.15Al0.07Mn0.06Ti0.04)Σ1.85Si3.99O10.04(F1.92OH0.04)Σ1.96. Garmite is monoclinic, space group C2/m, C2 or Cm; polytype 1M. The unit-cell parameters are a = 5.234(2), b = 9.042(4), c = 10.780(4) Å, β = 99.73(4)°; V = 502.8(6) Å3; Z = 2. The strongest reflections of the powder X‑ray diffraction pattern (d Å, I, hkl) are 4.48, 35, 110; 3.70, 70, –112; 3.45, 44, 022; 2.608, 70, –201, 130; 2.580, 100, 200, –131; 2.241, 45, 220; 2.187, 80, –133. The holotype specimen is deposited in the Fersman Mineralogical Museum, Russian Academy of Sciences, Moscow catalogue no. 95894.
期刊介绍：
Geology of Ore Deposits is a periodical covering the topic of metallic and nonmetallic mineral deposits, their formation conditions, and spatial and temporal distribution. The journal publishes original scientific articles and reviews on a wide range of problems in theoretical and applied geology. The journal focuses on the following problems: deep geological structure and geodynamic environment of ore formation; distribution pattern of metallogenic zones and mineral deposits; geology and formation environment of large and unique metallic and nonmetallic deposits; mineralogy of metallic and nonmetallic deposits; physicochemical and isotopic characteristics and geochemical environment of ore deposition; evolution of ore-forming systems; radiogeology and radioecology, economic problems in exploring, developing, and mining of ore commodities.
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