| Reference Type | Journal (article/letter/editorial) |
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| Title | Fluorapophyllite-(Cs), CsCa4(Si8O20)F(H2O)8, a new apophyllite-group mineral from the Darai-Pioz Massif, Tien-Shan, northern Tajikistan |
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| Journal | The Canadian Mineralogist |
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| Authors | Agakhanov, Atali A. | Author |
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| Pautov, Leonid A. | Author |
| Kasatkin, Anatoly V. | Author |
| Karpenko, Vladimir Yu. | Author |
| Sokolova, Elena | Author |
| Day, Maxwell C. | Author |
| Hawthorne, Frank C. | Author |
| Muftakhov, Vyacheslav A. | Author |
| Pekov, Igor V. | Author |
| Cámara, Fernando | Author |
| Britvin, Sergey N. | Author |
| Year | 2019 (November 30) | Volume | 57 |
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| Issue | 6 |
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| Publisher | Mineralogical Association of Canada |
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| Download URL | https://rruff.info/rruff_1.0/uploads/CM57_965.pdf+ |
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| DOI | doi:10.3749/canmin.1900038Search in ResearchGate |
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| Generate Citation Formats |
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| Classification | Not set | LoC | Not set |
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| Mindat Ref. ID | 65628 | Long-form Identifier | mindat:1:5:65628:3 |
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| GUID | 0 |
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| Full Reference | Agakhanov, Atali A., Pautov, Leonid A., Kasatkin, Anatoly V., Karpenko, Vladimir Yu., Sokolova, Elena, Day, Maxwell C., Hawthorne, Frank C., Muftakhov, Vyacheslav A., Pekov, Igor V., Cámara, Fernando, Britvin, Sergey N. (2019) Fluorapophyllite-(Cs), CsCa4(Si8O20)F(H2O)8, a new apophyllite-group mineral from the Darai-Pioz Massif, Tien-Shan, northern Tajikistan. The Canadian Mineralogist, 57 (6) 965-971 doi:10.3749/canmin.1900038 |
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| Plain Text | Agakhanov, Atali A., Pautov, Leonid A., Kasatkin, Anatoly V., Karpenko, Vladimir Yu., Sokolova, Elena, Day, Maxwell C., Hawthorne, Frank C., Muftakhov, Vyacheslav A., Pekov, Igor V., Cámara, Fernando, Britvin, Sergey N. (2019) Fluorapophyllite-(Cs), CsCa4(Si8O20)F(H2O)8, a new apophyllite-group mineral from the Darai-Pioz Massif, Tien-Shan, northern Tajikistan. The Canadian Mineralogist, 57 (6) 965-971 doi:10.3749/canmin.1900038 |
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| In | (2019, November) The Canadian Mineralogist Vol. 57 (6) Mineralogical Association of Canada |
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| Abstract/Notes | Fluorapophyllite-(Cs) (IMA 2018-108a), ideally CsCa4(Si8O20)F(H2O)8, is an apophyllite-group mineral from the moraine of the Darai-Pioz glacier, Tien-Shan, Northern Tajikistan. Associated minerals are quartz, pectolite, baratovite, aegirine, leucosphenite, pyrochlore, neptunite, fluorapophyllite-(K), and reedmergnerite. Fluorapophyllite-(Cs) is a hydrothermal mineral. It is colorless and has a vitreous luster and a white streak. Cleavage is perfect; it is brittle and has a stepped fracture. Mohs hardness is 4.5–5. Dmeas. = 2.54(2) g/cm3, Dcalc. = 2.513 g/cm3. Fluorapophyllite-(Cs) is unixial (+) with refractive indices (λ = 589 nm) ω = 1.540(2), ε = 1.544(2). It is non-pleochroic. Chemical analysis by electron microprobe gave SiO2 48.78, Al2O3 0.05, CaO 22.69, Cs2O 10.71, K2O 1.13, Na2O 0.04, F 1.86, H2Ocalc. 14.61, –O=F2 –0.78, sum 99.09 wt.%; H2O was calculated from crystal-structure analysis. The empirical formula based on 29 (O + F) apfu, H2O = 8 pfu, is (Cs0.75K0.24)Σ0.99(Ca3.99Na0.01)Σ4(Si8.01Al0.01)Σ8.02O20.03F0.97(H2O)8, Z = 2. The simplified formula is (Cs,K)(Ca,Na)4(Si,Al)8O20F(H2O)8. Fluorapophyllite-(Cs) is tetragonal, space group P4/mnc, a 9.060(6), c 15.741(11) Å, V 1292.10(19) Å3. The crystal structure has been refined to R1 = 4.31% based on 498 unique (Fo > 4σF) reflections. In the crystal structure of fluorapophyllite-(Cs), there is one [4]T site occupied solely by Si, <T–O> = 1.615 Å. SiO4 tetrahedra link to form a (Si8O20)8– sheet perpendicular to [001]. Between the Si–O sheets, there are two cation sites: A and B. The A site is coordinated by eight H2O groups [O(4) site], A–O(4) = 3.152(4) Å; the A site contains Cs0.75K0.24□0.01, ideally Cs apfu. The Cs–O bond length of 3.152 Å is definitely larger than the K–O bond length of 2.966–2.971 Å in fluorapophyllite-(K), KCa4(Si8O20)F(H2O)8. The [7]B site contains Ca3.99Na0.01, ideally Ca4apfu; <B–φ> = 2.417 Å (φ = O, F, H2O). The Si–O sheets connect via A and B polyhedra and hydrogen bonding; two H atoms have been included in the refinement. Fluorapophyllite-(Cs) is isostructural with fluorapophyllite-(K). Fluorapophyllite-(Cs) is a Cs-analogue of fluorapophyllite-(K). |
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