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Goldhillite, Cu5Zn(AsO4)2(OH)6⋅H2O, a new mineral species, and redefinition of philipsburgite, Cu5Zn[(AsO4)(PO4)](OH)6⋅H2O, as an As–P ordered species
- Rezeda M. Ismagilova, Branko Rieck, Anthony R. Kampf, Gerald Giester, Elena S. Zhitova, Christian L. Lengauer, Sergey V. Krivovichev, Andrey A. Zolotarev, Justyna Ciesielczuk, Julia A. Mikhailova, Dmitry I. Belakovsky, Vladimir N. Bocharov, Vladimir V. Shilovskikh, Natalia S. Vlasenko, Barbara P. Nash, Paul M. Adams
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- Journal:
- Mineralogical Magazine / Volume 86 / Issue 3 / June 2022
- Published online by Cambridge University Press:
- 13 May 2022, pp. 436-446
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Philipsburgite has been redefined as the intermediate member of the goldhillite–philipsburgite–kipushite isomorphous series with the ideal formula Cu5Zn[(AsO4)(PO4)](OH)6⋅H2O due to the site-selective As–P substitution. The new mineral goldhillite, ideally Cu5Zn(AsO4)2(OH)6⋅H2O [or Cu5Zn(AsO4)(AsO4)(OH)6⋅H2O], is the arsenate end-member of this series. Goldhillite occurs on fracture surfaces in a rock comprised mostly of quartz with iron hydroxides in association with mixite, cornwallite and conichalcite. Goldhillite forms transparent, bright emerald-green, tabular crystals with vitreous lustre, flattened on {100}, up to 1 mm across and in rosettes up to 1.5 mm. The mineral is brittle with uneven fracture and perfect cleavage on {100}; the Mohs hardness is 3.5. The calculated density for the holotype is 4.199 g cm–3. The Raman spectrum is consistent with the presence of H2O-molecules, OH-groups, AsO4 tetrahedra and traces of PO4. Electron microprobe analyses of goldhillite (H2O content based on the crystal structure) provided: CuO 48.91, ZnO 13.18, As2O5 26.06, P2O5 3.25, H2O 8.97, total 100.37 wt.%. The empirical formula for goldhillite based on O = 15 apfu is (Cu4.69Zn1.23)Σ5.92(As0.86P0.18O4)2(OH)5.61⋅H2O. The crystal structures of goldhillite and philipsburgite were determined using single-crystal X-ray diffraction data and refined to R1 = 0.054 (for 2365 I > 2σI reflections) and 0.052 (for 2308 I > 2σI reflections), respectively. Goldhillite is monoclinic, P21/c, a = 12.3573(5), b = 9.2325(3), c = 10.7163(4) Å, β = 97.346(4)°, V = 1212.59(8) Å3 and Z = 4. Philipsburgite is monoclinic, P21/c, a = 12.3095(9), b = 9.2276(3), c = 10.7195(3) Å, β = 97.137(7)°, V = 1208.16(10) Å3 and Z = 4. The strongest lines of the powder X-ray diffraction pattern of goldhillite [d, Å (I, %)(hkl)] are: 4.09 (28)(300), 3.41 (23)(12$\bar{2}$, 221, 311), 2.57 (100)(132, 11$\bar{4}$, 20$\bar{4}$), 2.17 (18)(42$\bar{3}$, 332), 1.95 (22)(432) and 1.54 (20)(13$\bar{6}$, 060). Goldhillite is named after its type locality, the Gold Hill mine, Tooele County, Utah, USA.
Structural and chemical complexity of minerals: an update
- Sergey V. Krivovichev, Vladimir G. Krivovichev, Robert M. Hazen, Sergey M. Aksenov, Margarita S. Avdontceva, Alexander M. Banaru, Liudmila A. Gorelova, Rezeda M. Ismagilova, Ilya V. Kornyakov, Ivan V. Kuporev, Shaunna M. Morrison, Taras L. Panikorovskii, Galina L. Starova
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- Journal:
- Mineralogical Magazine / Volume 86 / Issue 2 / April 2022
- Published online by Cambridge University Press:
- 04 April 2022, pp. 183-204
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The complexities of chemical composition and crystal structure are fundamental characteristics of minerals that have high relevance to the understanding of their stability, occurrence and evolution. This review summarises recent developments in the field of mineral complexity and outlines possible directions for its future elaboration. The database of structural and chemical complexity parameters of minerals is updated by H-correction of structures with unknown H positions and the inclusion of new data. The revised average complexity values (arithmetic means) for all minerals are 3.54(2) bits/atom and 345(10) bits/cell (based upon 4443 structure reports). The distributions of atomic information amounts, chemIG and strIG, versus the number of mineral species fit the normal modes, whereas the distributions of total complexities, chemIG,total and strIG,total, along with numbers of atoms per formula and per unit cell are log normal. The three most complex mineral species known today are ewingite, morrisonite and ilmajokite, all either discovered or structurally characterised within the last five years. The most important complexity-generating mechanisms in minerals are: (1) the presence of isolated large clusters; (2) the presence of large clusters linked together to form three-dimensional frameworks; (3) formation of complex three-dimensional modular frameworks; (4) formation of complex modular layers; (5) high hydration state in salts with complex heteropolyhedral units; and (6) formation of ordered superstructures of relatively simple structure types. The relations between symmetry and complexity are considered. The analysis of temporal dynamics of mineralogical discoveries since 1875 with the step of 25 years show the increasing chemical and structural complexities of human knowledge of the mineral kingdom in the history of mineralogy. In the Earth's history, both diversity and complexity of minerals experience dramatic increases associated with the formation of Earth's continental crust, initiation of plate tectonics and the Great Oxidation event.
Ammoniovoltaite, (NH4)2Fe2+5Fe3+3Al(SO4)12(H2O)18, a new mineral from the Severo-Kambalny geothermal field, Kamchatka, Russia
- Elena S. Zhitova, Oleg I. Siidra, Dmitry I. Belakovsky, Vladimir V. Shilovskikh, Anton A. Nuzhdaev, Rezeda M. Ismagilova
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- Mineralogical Magazine / Volume 82 / Issue 5 / October 2018
- Published online by Cambridge University Press:
- 15 May 2018, pp. 1057-1077
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Ammoniovoltaite, (NH4)2Fe2+5Fe3+3Al(SO4)12(H2O)18, is a new voltaite-group mineral. The mineral was discovered at the Severo-Kambalny (North-Kambalny) geothermal field, Kambalny volcanic ridge, Southern Kamchatka, Russia. Ammoniovoltaite forms at ~100°C around geothermal gas/steam vents in association with alunogen, tschermigite and pyrite. Crystals of ammoniovoltaite have euhedral habit, are up to 50 µm in size and grow on alunogen plates. Ammoniovoltaite is black with vitreous lustre, opaque, brittle and water-soluble. Neither cleavage nor parting is found, the fracture is conchoidal. The mineral is isotropic, with the refractive index n = 1.602(2) (589 nm). Infrared spectra contain an absorption band at 1433 cm–1 distinctive for the ammonium ion. The chemical composition is (iron content is given in accordance with Mössbauer data, H2O calculated from a crystal-structure refinement, wt.%): FeO 13.26, Fe2O3 11.58, MgO 2.33, ZnO 0.04, Al2O3 2.74, SO3 47.46, K2O 0.19, CaO 0.11, (NH4)2O 2.96, H2O 16.03, total 96.70. The empirical formula based on S = 12 atoms per formula unit is [(NH4)1.88K0.08Ca0.04]Σ2.00(Fe2+3.74Mg1.17Fe3+0.05Zn0.01)Σ4.97(Fe3+2.89Al0.09)Σ2.98Al1.00(SO4)12.00(H2O)18.00. The crystal structure has been refined to R1 = 0.031 and 0.030 on the basis of 1217 and 1462 unique reflections with I >2σ(I) collected at 100 K and room temperature, respectively. Ammoniovoltaite is the ammonium analogue of voltaite. The mineral is cubic, Fd$\bar{3}$c, a = 27.250(1) Å and V = 20234(3) Å3 (at 100 K); and a = 27.322(1) Å and V = 20396(3) Å3 (at RT), with Z = 16. The strongest lines of the powder X-ray diffraction pattern [d, Å (I, %) (hkl)] are: 9.67 (74) (022), 7.90 (56) (222), 5.58 (84) (422), 3.560 (100) (731), 3.418 (100) (008) and 2.8660 (37) (931). A brief review of ammonium minerals from various volcanically active geological environments is given.