| Reference Type | Journal (article/letter/editorial) |
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| Title | Juansilvaite, Na5Al3[AsO3(OH)]4[AsO2(OH)2]2(SO4)2·4H2O, a new arsenate-sulfate from the Torrecillas mine, Iquique Province, Chile |
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| Journal | Mineralogical Magazine |
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| Authors | Kampf, Anthony R. | Author |
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| Nash, Barbara P. | Author |
| Dini, Maurizio | Author |
| Molina Donoso, Arturo A. | Author |
| Year | 2017 (June) | Volume | 81 |
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| Issue | 3 |
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| Publisher | Mineralogical Society |
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| Download URL | https://rruff.info/rruff_1.0/uploads/MM81_619.pdf+ |
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| DOI | doi:10.1180/minmag.2016.080.113Search 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 | 244897 | Long-form Identifier | mindat:1:5:244897:2 |
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| GUID | 0 |
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| Full Reference | Kampf, Anthony R., Nash, Barbara P., Dini, Maurizio, Molina Donoso, Arturo A. (2017) Juansilvaite, Na5Al3[AsO3(OH)]4[AsO2(OH)2]2(SO4)2·4H2O, a new arsenate-sulfate from the Torrecillas mine, Iquique Province, Chile. Mineralogical Magazine, 81 (3) 619-628 doi:10.1180/minmag.2016.080.113 |
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| Plain Text | Kampf, Anthony R., Nash, Barbara P., Dini, Maurizio, Molina Donoso, Arturo A. (2017) Juansilvaite, Na5Al3[AsO3(OH)]4[AsO2(OH)2]2(SO4)2·4H2O, a new arsenate-sulfate from the Torrecillas mine, Iquique Province, Chile. Mineralogical Magazine, 81 (3) 619-628 doi:10.1180/minmag.2016.080.113 |
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| In | (2017, June) Mineralogical Magazine Vol. 81 (3) Mineralogical Society |
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| Abstract/Notes | The new mineral juansilvaite (IMA2015-080), Na5Al3[AsO3(OH)]4[AsO2(OH)2]2(SO4)2·4H2O, was foOptically, juansilvaiteund at the Torrecillas mine, Iquique Province, Chile, where it occurs as asecondary alteration phase in association with anhydrite, canutite, halite, sulfur and a mahnertite-like phase. Juansilvaite occurs as bright pink blades up to ∼0.5 mm long grouped in tightly intergrown radial aggregates and also as opaque dull pale pink rounded aggregates. Blades areflattened on {001}, elongated on [100] and exhibit the forms {001}, {111} and {201}. Crystals are transparent, with vitreous lustre and white streak. The Mohs hardness is ∼2½, tenacity is brittle and fracture is irregular. Cleavage is very good on {001}. The measured density is3.01(2) g cm–3 and the calculated density is 3.005 g cm–3. Optically, juansilvaite is biaxial (+) with α= 1.575(1), β = 1.597(1), γ= 1.623(1) and 2V = 86(1)° (measured in white light). Dispersion is r < v, slight, and the orientation is X = b; Z ^ c = 27° in the obtuse angle β. The pleochroism is X > Y ≈ Z in shades of pale pink. The mineral is slowly soluble in dilute HCl at room temperature. The empirical formula, determined from electron-microprobeanalyses, is Na4.95Al2.28Fe0.503+Mn0.213+Cu0.04As5.92S1.83O36H17.37. Juansilvaite is monoclinic, C2/c, a = 18.1775(13), b = 8.6285(5), c= 18.5138(13) Å, β = 90.389(6)°, V = 2903.7(3) Å3 and Z = 4. The eight strongest powder X-ray diffraction lines are [dobs Å(I)(hkl)]: 9.25(100)(002), 7.20(34)(111), 4.545(34)(400), 3.988(39)(114), 3.363(42)(314), 3.145(66)(512,420), 2.960(68)(422,422) and 2,804(33)(131,423). The structure of juansilvaite (R1 = 3.82% for 2040 Fo > 4σF reflections) contains layers made up of alternating corner-linked Al–O octahedra and acid-arsenate tetrahedra. Sodium cations occur both peripheral to the layers and within cavities in the layers. An SO4 tetrahedron and an H2O group also are in the interlayer region. |
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