Aqualite,a new mineral species of the eudialyte group from the Inagli alkaline pluton,Sakha-Yakutia,Russia, and the problem of oxonium in hydrated eudialytes

Aqualite, a new eudialyte-group mineral from hydrothermally altered peralkaline pegmatites of the Inagli alkaline pluton (Sakha-Yakutia, Russia) is described in this paper. Natrolite, microcline, eckermanite, aegirine, batisite, innelite, lorezenite, thorite, and galena are associated minerals. Aqualite occurs as isometric crystals up to 3-cm across. The color is pale pink, with a white streak and vitreous luster. The mineral is transparent. The fracture is conchoidal. The mineral is brittle; no cleavage or parting is observed. The Mohs’ hardness is 4 to 5. The density is 2.58(2) g/cm³ (measured by the volumetric method) and 2.66 g/cm³ (calculated). Aqualite is optically uniaxial (+), α = 1.569(1) and β = 1.571(1). The mineral is pleochroic from colorless to pale pink on X and pink on Y, α < β. Aqualite is weakly fluorescent with a dull yellow color under ultraviolet light. The mineral is stable in 50% HCl and HNO₃ at room temperature. Weight loss after ignition at 500°C is 9.8%. Aqualite is monoclinic, and the space group is R3. The unit-cell dimensions are a = 14.078(3) Å, c = 31.24(1) Å, V = 5362 ų, and Z = 3. The strongest reflections in the X-ray powder pattern [d, Å (I)(hkl)] are: 4.39(100)(2005), 2.987(100)(315), 2.850(79)(404), 10.50(44)(003), 6.63(43)(104), 7.06(42)(110), 3.624(41)(027), and 11.43(39)(101). The chemical composition (electron microprobe, H₂O determined with the Penfield method) is as follows (wt %): 2.91 Na₂O, 1.93 K₂O, 11.14 CaO, 1.75 SrO, 2.41 BaO, 0.56 FeO, 0.30 MnO, 0.17 La₂O₃, 0.54 Ce₂O₃, 0.36 Nd₂O₃, 0.34 Al₂O₃, 52.70 SiO₂, 12.33 ZrO₂, O.78 TiO₂, 0.15 Nb₂O₅; 1.50 Cl, 9.93 H₂O,-O=Cl₂ 0.34; where the total is 99.46. The empirical formula calculated on the basis of Si + Zr + Ti + Al + Nb = 29 apfu is as follows: [(H₃O)_7.94Na_2.74K_1.20Sr_0.49Ba_0.46Fe_0.23Mn_0.12]_Σ13.18(Ca_5.79REE_0.19)_Σ5.98 (Zr_2.92Ti_0.08)_Σ3.0(Si_25.57Ti_0.21Al_0.19Nb_0.03)S_26.0[O_66.46(OH)_5.54]_Σ72.0 [(OH)_2.77Cl_1.23]_Σ4.0. The simplified formula is (H₃O)₈(Na,K,Sr)₅Ca₆Zr₃Si₂₆O₆₆(OH)₉Cl. Aqualite differs from typical eudialyte by the extremely low contents of Na and Fe, with more than 50% Na being replaced with the (H₃O)⁺ group. The presence of oxonium ions is confirmed by IR spectroscopic and X-ray single-crystal diffraction analysis. The mineral is compared with five structurally studied high-oxonium analogues from alkaline plutons of other regions. All of these minerals were formed at a relatively low temperature through the ion-exchange transformation of “protoeudialytes”; the successor minerals inherited the principal structural and compositional features of the precursor minerals. The name aqualite is derived from the Latin aqua in reference to its specific chemical composition. The type material of aqualite is deposited in the Fersman Mineralogical Museum, Russian Academy of Sciences, Moscow.     

Voloshinite,a new rubidium mica from granitic pegmatite of Voron’i Tundras,Kola Peninsula,Russia

Voloshinite, a new mineral of the mica group, a rubidium analogue of lepidolite, has been found from the rare-element granitic pegmatite at Mt. Vasin-Myl’k, Voron’i Tundras, Kola Peninsula, Russia. It is closely associated with pollucite and lepidolite and commonly with muscovite, albite, and quartz; K,Rb-feldspar, rubicline, spodumene, montebrasite, and elbaite are among associated minerals as well. Voloshinite, a late mineral that formed after pollucite, commonly fills polymineralic veinlets and pods within the pollucite aggregates. It occurs as rims up to 0.05 mm thick around lepidolite, as intergrowths of tabular crystals up to 0.25 mm in size, and occasionally replaces lepidolite. The new mineral is colorless, transparent, with vitreous luster. Cleavage is eminent parallel to {001}; flakes are flexible. The calculated density is 2.95 g/cm³. The new mineral is biaxial (?), with 2V = 25°, α calc = 1.511, β = 1.586, and γ = 1.590. The optical orientation is Y = b, Z = a. The chemical composition of the type material determined by electron microprobe (average of five point analyses; Li has been determined with ICP-OES) is as follows (wt %): 0.03 Na₂O, 3.70 K₂O, 12.18 Rb₂O, 2.02 Cs₂O, 4.0 Li₂O, 0.03 CaO, 0.02 MgO, 0.14 MnO, 21.33 Al₂O₃, 53.14 SiO₂, 6.41 F, -O = F₂ 2.70, total is 100.30. The empirical formula is: (Rb_0.54K_0.33Cs_0.06)_Σ0.93(Al_1.42Li_1.11Mn_0.01)_Σ2.54(Si_3.68Al_0.32)_Σ4O₁₀ (F_1.40(OH)_0.60)_Σ2. The idealized formula is as follows: Rb(LiAl_1.5□_0.5)[Al_0.5Si_3.5O₁₀]F₂. Voloshinite forms a continuous solid solution with lepidolite. According to X-ray single crystal study, voloshinite is monoclinic, space group C2/c. The unit-cell dimensions are: a = 5.191, b = 9.025, c = 20.40 Å, β = 95.37°, V= 951.5 ų, Z = 4. Polytype is 2M ₁. The strongest reflections in the X-ray powder diffraction pattern (d, Å-I[hkl]) are: 10.1-60[001]; 4.55-80[020, 110, 11\(\bar 1\)]; 3.49-50[11\(\bar 4\)]; 3.35-60[024, 006]; 3.02-45[025]; 2.575-100[11\(\bar 6\), 131, 20\(\bar 2\), 13\(\bar 4\)], 2.017-50[136, 0.0.10]. The mineral was named in honor of A.V. Voloshin (born in 1937), the famous Russian mineralogist. The type material is deposited at the Fersman Mineralogical Museum of the Russian Academy of Sciences, Moscow.     

Cancrinite and cancrisilite in the Khibina-Lovozero alkaline complex: Thermochemical and thermal data

The paper presents the results of a thermochemical and thermal study of cancrinite, (Na_6.93Ca_0.545K_0.01)_Σ7.485[(Si_6.47Al_5.48Fe_0.05)_Σ12O₂₄](CO₃)_1.25 · 2.30 H₂O, and cancrisilite, (Na_7.17 Ca_0.01)_Σ7.18[(Si_7.26Al_4.70Fe_0.04)_Σ12O₂₄][(CO₃)_1.05(OH)_0.21(PO₄)_0.04(SO₄)_0.01] · 2.635 H₂O, from the Khibina-Lovozero Complex, Kola Peninsula, Russia. Stages of the thermal decomposition of these minerals were studied using IR spectroscopy. The enthalpies of formation of the minerals from elements were determined by melt drop solution calorimetry: Δ _f H _el ⁰ (298.15 K) = ?14 490 ± 16 kJ/mol for cancrinite and ?14302 ± 17 kJ/mol for cancrisilite. The values of Δ _f H _el ⁰ (298.15 K), S ^o(298.15 K), and Δ _f H _el ⁰ (298.15 K) are determined for cancrinite and cancrisilite of theoretical composition.     

Tatarinovite Са<Subscript>3</Subscript>Al(SO<Subscript>4</Subscript>)[В(ОH)<Subscript>4</Subscript>](ОH)<Subscript>6</Subscript> · 12H<Subscript>2</Subscript>O,a new ettringite-group mineral from the Bazhenovskoe deposit,Middle Urals,Russia, and its crystal structure

A new mineral, tatarinovite, ideally Са₃Аl(SO₄)[В(ОН)₄](ОН)₆ · 12Н₂O, has been found in cavities of rhodingites at the Bazhenovskoe chrysotile asbestos deposit, Middle Urals, Russia. It occurs (1) colorless, with vitreous luster, bipyramidal crystals up to 1 mm across in cavities within massive diopside, in association with xonotlite, clinochlore, pectolite and calcite, and (2) as white granular aggregates up to 5 mm in size on grossular with pectolite, diopside, calcite, and xonotlite. The Mohs hardness is 3; perfect cleavage on (100) is observed. D _meas = 1.79(1), D _calc = 1.777 g/cm³. Tatarinovite is optically uniaxial (+), ω = 1.475(2), ε = 1.496(2). The IR spectrum contains characteristic bands of SO₄ ^2?, CO₃ ^2?, B(OH)₄ ^?, B(OH)₃, Al(OH)₆ ^3-, Si(OH)₆ ^2-, OH^–, and H₂O. The chemical composition of tatarinovite (wt %; ICP-AES; H₂O was determined by the Alimarin method; CO₂ was determined by selective sorption on askarite) is as follows: 27.40 CaO, 4.06 B₂O₃, 6.34 A1₂O₃, 0.03 Fe₂O₃, 2.43 SiO₂, 8.48 SO₃, 4.2 CO₂, 46.1 H₂O, total is 99.04. The empirical formula (calculated on the basis of 3Ca apfu) is H_31.41Ca_3.00(Al_0.76Si_0.25)_Σ1.01 · (B_0.72S_0.65C_0.59)Σ_1.96O_24.55. Tatarinovite is hexagonal, space gr. P6₃, a = 11.1110(4) Å, c = 10.6294(6) Å, V = 1136.44(9) A³, Z = 2. Its crystal chemical formula is Са₃(Аl_0.70Si_0.30) · {[SO₄]_0.34[В(ОН)₄]_0.33[СO₃]0.₂₄}{[SO₄]_0.30[В(ОН)₄]_0.34[СО₃]_0.30[В(ОН)₃]_0.06}(ОН_5·73О_0.27) · 12Н₂O. The strongest reflections of the powder X-ray diffraction pattern [d, Å (I, %) (hkl)] are 9.63 (100) (100), 5.556 (30) (110), 4.654 (14) (102), 3.841 (21) (112), 3.441 (12) (211), 2.746 (10) (302), 2.538 (12) (213). Tatarinovite was named in memory of the Russian geologist and petrologist Pavel Mikhailovich Tatarinov (1895–1976), a well-known specialist in chrysotile asbestos deposits. Type specimens have been deposited at the Fersman Mineralogical Museum of the Russian Academy of Sciences, Moscow.     

Middendorfite,K<Subscript>3</Subscript>Na<Subscript>2</Subscript>Mn<Subscript>5</Subscript>Si<Subscript>12</Subscript>(O,OH)<Subscript>36</Subscript> · 2H<Subscript>2</Subscript>O,a new mineral species from the Khibiny pluton,Kola Peninsula

Middendorfite, a new mineral species, has been found in a hydrothermal assemblage in Hilairite hyperperalkaline pegmatite at the Kirovsky Mine, Mount Kukisvumchorr apatite deposit, Khibiny alkaline pluton, Kola Peninsula, Russia. Microcline, sodalite, cancrisilite, aegirine, calcite, natrolite, fluorite, narsarsukite, labuntsovite-Mn, mangan-neptunite, and donnayite are associated minerals. Middendorfite occurs as rhombshaped lamellar and tabular crystals up to 0.1 × 0.2 × 0.4 mm in size, which are combined in worm-and fanlike segregations up to 1 mm in size. The color is dark to bright orange, with a yellowish streak and vitreous luster. The mineral is transparent. The cleavage (001) is perfect, micalike; the fracture is scaly; flakes are flexible but not elastic. The Mohs hardness is 3 to 3.5. Density is 2.60 g/cm³ (meas.) and 2.65 g/cm³ (calc.). Middendorfite is biaxial (?), α = 1.534, β = 1.562, and γ = 1.563; 2V (meas.) = 10°. The mineral is pleochroic strongly from yellowish to colorless on X through brown on Y and to deep brown on Z. Optical orientation: X = c. The chemical composition (electron microprobe, H₂O determined with Penfield method) is as follows (wt %): 4.55 Na₂O, 10.16 K₂O, 0.11 CaO, 0.18 MgO, 24.88 MnO, 0.68 FeO, 0.15 ZnO, 0.20 Al₂O₃, 50.87 SiO₂, 0.17 TiO₂, 0.23 F, 7.73 H₂O; ?O=F₂?0.10, total is 99.81. The empirical formula calculated on the basis of (Si,Al)₁₂(O,OH,F)₃₆ is K_3.04(Na_2.07Ca_0.03)_Σ2.10(Mn_4.95Fe_0.13Mg_0.06Ti_0.03Zn_0.03)_Σ5.20(Si_11.94Al_0.06)_Σ12O_27.57(OH)_8.26F_0.17 · 1.92H₂O. The simplified formula is K₃Na₂Mn₅Si₁₂(O,OH)₃₆ · 2H₂O. Middenforite is monoclinic, space group: P2₁/m or P2₁. The unit cell dimensions are a = 12.55, b = 5.721, c = 26.86 Å; β = 114.04°, V = 1761 ų, Z = 2. The strongest lines in the X-ray powder pattern [d, Å, (I)(hkl)] are: 12.28(100)(002), 4.31(81)(11\(\overline 4 \)), 3.555(62)(301, 212), 3.063(52)(008, 31\(\overline 6 \)), 2.840(90)(312, 021, 30\(\overline 9 \)), 2.634(88)(21\(\overline 9 \), 1.0.\(\overline 1 \)0, 12\(\overline 4 \)), 2.366(76)(22\(\overline 6 \), 3.1.\(\overline 1 \)0, 32\(\overline 3 \)), 2.109(54)(42–33, 42–44, 51\(\overline 9 \), 414), 1.669(64)(2.2.\(\overline 1 \)3, 3.2.\(\overline 1 \)3, 62\(\overline 3 \), 6.1.\(\overline 1 \)3), 1.614(56)(5.0.\(\overline 1 \)6, 137, 333, 71\(\overline 1 \)). The infrared spectrum is given. Middendorfite is a phyllosilicate related to bannisterite, parsenttensite, and the minerals of the ganophyllite and stilpnomelane groups. The new mineral is named in memory of A.F. von Middendorff (1815–1894), an outstanding scientist, who carried out the first mineralogical investigations in the Khibiny pluton. The type material of middenforite has been deposited at the Fersman Mineralogical Museum, Russian Academy of Sciences, Moscow.     

Crystal structure and refined formula of garyansellite Mg<Subscript>2</Subscript>Fe<Superscript>3+</Superscript>(PO<Subscript>4</Subscript>)<Subscript>2</Subscript>(OH) · 2H<Subscript>2</Subscript>O

Single-crystal study of the structure (R = 0.0268) was performed for garyansellite from Rapid Creek, Yukon, Canada. The mineral is orthorhombic, Pbna, a = 9.44738(18), b = 9.85976(19), c = 8.14154(18) Å, V = 758.38(3) ų, Z = 4. An idealized formula of garyansellite is Mg₂Fe³⁺(PO₄)₂(OH) · 2H₂O. Structurally the mineral is close to other members of the phosphoferrite–reddingite group. The structure contains layers of chains of M(2)O₄(OH)(H₂O) octahedra which share edges to form dimers and connected by common edges with isolated from each other M(1)O₄(H₂O)₂ octahedra. The neighboring chains are connected to the layer through the common vertices of M(2) octahedra and octaahedral layers are linked through PO₄ tetrahedra.     

Parageorgbokiite, β-Cu<Subscript>5</Subscript>O<Subscript>2</Subscript>(SeO<Subscript>3</Subscript>)<Subscript>2</Subscript>Cl<Subscript>2</Subscript>, a new mineral species from volcanic exhalations,Kamchatka Peninsula,Russia

Parageorgbokiite, β-Cu₅O₂(SeO₃)₂Cl₂, has been found at the second cinder cone of the Great Fissure Tolbachik Eruption, Kamchatka Peninsula, Russia. Ralstonite, tolbachite, melanothallite, chalcocyanite, euchlorine, Fe oxides, tenorite, native gold, sophiite, Na, Ca, and Mg sulfates, cotunnite, and some copper oxoselenites are associated minerals. The estimated temperature of the mineral formation is 400–625°C. The color is green, with a vitreous luster; the streak is light green. The mineral is brittle, with the Mohs hardness ranging from 3 to 4. Cleavage is not observed. The calculated density is 4.70 g/cm³. Parageorgbokiite is biaxial (+); α = 2.05(1), β = 2.05(1), and γ = 2.08(1); 2V _(meas.) is ～0³, and 2V _(calc.) = 0(5)°. The optical orientation is X = a; other details remain unclear. The mineral is pleochroic, from grass green on X and Y to yellowish green on Z. The empirical formula calculated on the basis of O + Cl = 10 is Cu_4.91Pb_0.02O_1.86(ScO₃)₂Cl_2.14. The simplified formula is Cu₅O₂(ScO₃)₂Cl₂. Parageorgbokiite pertains to a new structural type of inorganic compounds. Its name points out its dimorphism with georgbokiite, which was named in honor of G.B. Bokii, the prominent Russian crystal chemist (1909–2000).     

Attikaite,Ca<Subscript>3</Subscript>Cu<Subscript>2</Subscript>Al<Subscript>2</Subscript>(AsO<Subscript>4</Subscript>)<Subscript>4</Subscript>(OH)<Subscript>4</Subscript> · 2H<Subscript>2</Subscript>O,a new mineral species

Attikaite, a new mineral species, has been found together with arsenocrandalite, arsenogoyazite, conichalcite, olivenite, philipsbornite, azurite, malachite, carminite, beudantite, goethite, quartz, and allophane at the Christina Mine No. 132, Kamareza, Lavrion District, Attiki Prefecture (Attika), Greece. The mineral is named after the type locality. It forms spheroidal segregations (up to 0.3 mm in diameter) consisting of thin flexible crystals up to 3 × 20 × 80 μm in size. Its color is light blue to greenish blue, with a pale blue streak. The Mohs’ hardness is 2 to 2.5. The cleavage is eminent mica-like parallel to {001}. The density is 3.2(2) g/cm³ (measured in heavy liquids) and 3.356 g/cm³ (calculated). The wave numbers of the absorption bands in the infrared spectrum of attikaite are (cm^?1; sh is shoulder; w is a weak band): 3525sh, 3425, 3180, 1642, 1120w, 1070w, 1035w, 900sh, 874, 833, 820, 690w, 645w, 600sh, 555, 486, 458, and 397. Attikaite is optically biaxial, negative, α = 1.642(2), β = γ = 1.644(2) (X = c) 2V _means = 10(8)°, and 2V _calc = 0°. The new mineral is microscopically colorless and nonpleochroic. The chemical composition (electron microprobe, average over 4 point analyses, wt %) is: 0.17 MgO, 17.48 CaO, 0.12 FeO, 16.28 CuO, 10.61 Al₂O₃, 0.89 P₂O₅, 45.45 As₂O₅, 1.39 SO₃, and H₂O (by difference) 7.61, where the total is 100.00. The empirical formula calculated on the basis of (O,OH,H₂O)₂₂ is: Ca_2.94Cu _1.93 ²⁺ Al_1.97Mg_0.04Fe _0.02 ²⁺ [(As_3.74S_0.16P_0.12)_Σ4.02O_16.08](OH)_3.87 · 2.05H₂ O. The simplified formula is Ca₃Cu₂Al₂(AsO₄)₄(OH)₄ · 2H₂O. Attikaite is orthorhombic, space group Pban, Pbam or Pba2; the unit-cell dimensions are a = 10.01(1), b = 8.199(5), c = 22.78(1) Å, V = 1870(3) ų, and Z = 4. In the result of the ignition of attikaite for 30 to 35 min at 128–140°, the H₂O bands in the IR spectrum disappear, while the OH-group band is not modified; the weight loss is 4.3%, which approximately corresponds to two H₂O molecules per formula; and parameter c decreases from 22.78 to 18.77 Å. The strongest reflections in the X-ray powder diffraction pattern [d, Å (I, %)((hkl)] are: 22.8(100)(001), 11.36(60)(002), 5.01(90)(200), 3.38(5)(123, 205), 2.780(70)(026), 2.682(30)(126), 2.503(50)(400), 2.292(20)(404). The type material of attikaite is deposited in the Fersman Mineralogical Museum, Russian Academy of Sciences, Moscow. The registration number is 3435/1.     

Zinclipscombite,ZnFe<Stack><Subscript>2</Subscript><Superscript>3+</Superscript></Stack>(PO<Subscript>4</Subscript>)<Subscript>2</Subscript>(OH)<Subscript>2</Subscript>, a new mineral species

Zinclipscombite, a new mineral species, has been found together with apophyllite, quartz, barite, jarosite, plumbojarosite, turquoise, and calcite at the Silver Coin mine, Edna Mountains, Valmy, Humboldt County, Nevada, United States. The new mineral forms spheroidal, fibrous segregations; the thickness of the fibers, which extend along the c axis, reaches 20 μm, and the diameter of spherulites is up to 2.5 mm. The color is dark green to brown with a light green to beige streak and a vitreous luster. The mineral is translucent. The Mohs hardness is 5. Zinclipscombite is brittle; cleavage is not observed; fracture is uneven. The density is 3.65(4) g/cm³ measured by hydrostatic weighing and 3.727 g/cm³ calculated from X-ray powder data. The frequencies of absorption bands in the infrared spectrum of zinclipscombite are (cm^?1; the frequencies of the strongest bands are underlined; sh, shoulder; w, weak band) 3535, 3330sh, 3260, 1625w, 1530w, 1068, 1047, 1022, 970sh, 768w, 684w, 609, 502, and 460. The Mössbauer spectrum of zinclipscombite contains only a doublet corresponding to Fe³⁺ with sixfold coordination and a quadrupole splitting of 0.562 mm/s; Fe²⁺ is absent. The mineral is optically uniaxial and positive, ω = 1.755(5), ? = 1.795(5). Zinclipscombite is pleochroic, from bright green to blue-green on X and light greenish brown on Z (X > Z). Chemical composition (electron microprobe, average of five point analyses, wt %): CaO 0.30, ZnO 15.90, Al₂O₃ 4.77, Fe₂O₃ 35.14, P₂O₅ 33.86, As₂O₅ 4.05, H₂O (determined by the Penfield method) 4.94, total 98.96. The empirical formula calculated on the basis of (PO₄,AsO₄)₂ is (Zn_0.76Ca_0.02)_Σ0.78(Fe _1.72 ³⁺ Al_0.36)_Σ2.08[(PO₄)_1.86(AsO₄)_0.14]_Σ2.00(OH)_{1. 80} · 0.17H₂O. The simplified formula is ZnFe ₂ ³⁺ (PO₄)₂(OH)₂. Zinclipscombite is tetragonal, space group P4₃2₁2 or P4₁2₁2; a = 7.242(2) Å, c = 13.125(5) Å, V = 688.4(5) ų, Z = 4. The strongest reflections in the X-ray powder diffraction pattern (d, (I, %) ((hkl)) are 4.79(80)(111), 3.32(100)(113), 3.21(60)(210), 2.602(45)(213), 2.299(40)(214), 2.049(40)(106), 1.663(45)(226), 1.605(50)(421, 108). Zinclipscombite is an analogue of lipscombite, Fe²⁺Fe ₂ ³⁺ (PO₄)₂(OH)₂ (tetragonal), with Zn instead of Fe²⁺. The mineral is named for its chemical composition, the Zn-dominant analogue of lipscombite. The type material of zinclipscombite is deposited in the Mineralogical Collection of the Technische Universität Bergakademie Freiberg, Germany.     

The crystal structure of alumoklyuchevskite,K<Subscript>3</Subscript>Cu<Subscript>3</Subscript>AlO<Subscript>2</Subscript>(SO<Subscript>4</Subscript>)<Subscript>4</Subscript>

The crystal structure of the unstable mineral alumoklyuchevskite K₃Cu₃AlO₂(SO₄)₄ [monoclinic, I2, a = 18.772(7), b = 4.967(2), c = 18.468(7) Å, β = 101.66(1)°, V = 1686(1) Å] was refined to R ₁ = 0.131 for 2450 unique reflections with F ≥ 4σF _hkl. The structure is based on oxocentered tetrahedrons (OAlCu ₃ ⁷⁺ ) linked into chains via edges. Each chain is surrounded by SO₄ tetrahedrons forming a structural complex. Each complex is elongated along the b axis. This type of crystal structure was also found in other fumarole minerals of the Great Tolbachik Fissure Eruption (GTFE, Kamchatka Peninsula, Russia, 1975–1976), klyuchevskite, K₃Cu₃Fe³⁺O₂(SO₄)₄; and piypite, K₂Cu₂O(SO₄)₂.     

Elastic behavior of vanadinite,Pb<Subscript>10</Subscript>(VO<Subscript>4</Subscript>)<Subscript>6</Subscript>Cl<Subscript>2</Subscript>, a microporous non-zeolitic mineral

The high-pressure behavior of a vanadinite (Pb₁₀(VO₄)₆Cl₂, a = b = 10.3254(5), c = 7.3450(4) Å, space group P6₃/m), a natural microporous mineral, has been investigated using in-situ HP-synchrotron X-ray powder diffraction up to 7.67 GPa with a diamond anvil cell under hydrostatic conditions. No phase transition has been observed within the pressure range investigated. Axial and volume isothermal Equations of State (EoS) of vanadinite were determined. Fitting the P–V data with a third-order Birch-Murnaghan (BM) EoS, using the data weighted by the uncertainties in P and V, we obtained: V ₀ = 681(1) Å³, K ₀ = 41(5) GPa, and K′ = 12.5(2.5). The evolution of the lattice constants with P shows a strong anisotropic compression pattern. The axial bulk moduli were calculated with a third-order “linearized” BM-EoS. The EoS parameters are: a ₀ = 10.3302(2) Å, K ₀(a) = 35(2) GPa and K′(a) = 10(1) for the a-axis; c ₀ = 7.3520(3) Å, K ₀(c) = 98(4) GPa, and K′(c) = 9(2) for the c-axis (K ₀(a):K ₀(c) = 1:2.80). Axial and volume Eulerian-finite strain (fe) at different normalized stress (Fe) were calculated. The weighted linear regression through the data points yields the following intercept values: Fe _a (0) = 35(2) GPa for the a-axis, Fe _c (0) = 98(4) GPa for the c-axis and Fe _V (0) = 45(2) GPa for the unit-cell volume. The slope of the regression lines gives rise to K′ values of 10(1) for the a-axis, 9(2) for the c-axis and 11(1) for the unit cell-volume. A comparison between the HP-elastic response of vanadinite and the iso-structural apatite is carried out. The possible reasons of the elastic anisotropy are discussed.     

Discovery of low aluminium nevadaite from the Kara-Chagyr Area,Kyrgyzstan

The rare phosphate—nevadaite has been found at Kara-Chagyr (Batken region, Kyrgyzstan) in a zone of alteration of vanadium bearing “black shales”. It occurs as blue crusts of spherulitic aggregates of tiny tabular crystals (0.1–10 μm). It is associated with metahewettite, hummerite, carnotite, minyulite, fluellite, crandallite, variscite, and woodhouseite. Optical properties: n = 1.542–1.555, D _meas (for aggregates) = 2.58(1) g/cm³, D _calc = 2.582 g/cm³. The most intense X-ray powder reflections are as follows: [d/n, Å, (I _meas), (hkl)]: 9.54 (80) (020), 6.03 (100) (200), 5.61 (100) (130), 3.91 (60) (310), 3.41 (80) (041), 2.982 (100) (241), 2.804 (60) (331), 2.672 (70) (061), 1.845 (60) (352) 1.507 (70) (243). Calculated cell dimensions are: a = 12.072(10) Å, b = 18.958(15) Å, c = 4.969(5) Å, α = β = γ = 90°, V = 1137.2 ų. Electron microprobe analyses gives (wt %): (observed (average of 8 analyses); (calculated for 22H₂O)): P₂O₅ 34.69 (31.85), SiO₂ 0.25 (0.24), Al₂O₃ 25.61 (23.50), V₂O 5.58 (5.13), Fe₂O₃ 0.48 (0.46), MnO 0.03 (0.03), CuO 10.79 (9.90), ZnO 0.69 (0.65), CaO 0.18 (0.15), MgO 0.17 (0.17), K₂O 0.08 (0.08), F 7.40 (6.79), H₂O 17.16 (by diff.) (23.90), ?F₂ =O \(\bar 3\).11 (\(\bar 2\).86), total 100.00 (100.00).The crystal-chemical formula of the mineral is (Cu _2.2 ⁺² □_2.03V _1.21 ⁺³ Al_0.15Zn_0.14Fe_0.10Mg_0.07Ca_0.05K_0.03Mn_0.01)_6.00(Al_8.00(P_7.93Si_0.07O₃₂)F_6.32(OH)_2.98 · 22(H₂O) for the ideal number of water molecules. Nevadaite from Kara-Chagyr differs from that from the type locality, Gold Quarry (Nev., USA), by its lower Al content. The IR-spectrum, and microphotographs of nevadaite and associated minerals are given.     

Chesnokovite,Na<Subscript>2</Subscript>[SiO<Subscript>2</Subscript>(OH)<Subscript>2</Subscript>] · 8H<Subscript>2</Subscript>O,the first natural sodium orthosilicate from the Lovozero alkaline pluton,Kola Peninsula: Description and crystal structure of a new mineral species

Chesnokovite, a new mineral species, is the first natural sodium orthosilicate. It has been found in an ussingite vein uncovered by underground mining at Mt. Kedykverpakhk, Lovozero alkaline pluton, Kola Peninsula, Russia. Natrolite, sodalite, vuonnemite, steenstrupine-(Ce), phosinaite-(Ce), natisite, gobbinsite, villiaumite, and natrosilite are associated minerals. Chesnokovite occurs as intergrowths with natrophospate in pockets up to 4 × 6 × 10 cm in size consisting of chaotic segregations of coarse lamellar crystals (up to 0.05 × 1 × 2 cm in size) flattened along [010]. The crystals are colorless and transparent. The aggregates are white to pale brownish yellowish, with a white streak and a vitreous luster. The cleavage is perfect parallel to (010) and distinct to (100) and (001). The fracture is stepped. The Mohs’ hardness is 2.5. The measured density is 1.68 g/cm³; the density calculated on the basis of an empirical formula is 1.60 g/cm³ and 1.64 g/cm³ on the basis of an idealized formula. The new mineral is optically biaxial, positive, α = 1.449, β = 1.453, γ = 1.458, 2V _meas = 80°, and Z = b. The infrared spectrum is given. The chemical composition (Si determined with electron microprobe; Na, K, and Li, with atomic emission analysis; and H₂O, with the Alimarin method) is as follows, wt %: 21.49 Na₂O, 0.38 K₂O, 0.003 Li₂O, 21.42 SiO₂, 54.86 H₂O, total is 98.153. The empirical formula calculated on the basis of O₂(OH)₂ is as follows: (Na_1.96K_0.02)_Σ1.98Si_1.005O₂(OH)₂ · 7.58H₂O. The simplified formula (Z = 8) is Na₂[SiO₂(OH)₂] · 8H₂O. The new mineral is orthorhombic, and the space group is Ibca. The unit-cell dimensions are: a = 11.7119, b = 19.973, c = 11.5652 Å, and V = 2299.0 ų. The strongest reflections in the X-ray powder pattern [d, Å (I, %)(hkl)] are: 5.001(30)(211), 4.788(42)(022), 3.847(89)(231), 2.932(42)(400), 2.832(35)(060), 2.800(97)(332, 233), and 2.774(100)(341, 143, 114). The crystal structure was studied using the Rietveld method, R _p = 5.77, R _wp = 7.77, R _B = 2.07, and R _F = 1.74. The structure is composed of isolated [SiO₂(OH)₂] octahedrons and the chains of edge-shared [Na[H₂O)₆] octahedrons. The Si and Na polyhedrons are linked only by H-bonds, and this is the cause of the low stability of chesnokovite under atmospheric conditions. The new mineral is named in memory of B.V. Chesnokov (1928–2005), an outstanding mineralogist. The type material of chesnokovite is deposited in the Fersman Mineralogical Museum, Russian Academy of Sciences, Moscow.     

Kamarizaite,Fe<Stack><Subscript>3</Subscript><Superscript>3+</Superscript></Stack>(AsO<Subscript>4</Subscript>)<Subscript>2</Subscript>(OH)<Subscript>3</Subscript> · 3H<Subscript>2</Subscript>O,a new mineral species,arsenate analogue of tinticite

Kamarizaite, a new mineral species, has been identified in the dump of the Kamariza Mine, Lavrion mining district, Attica Region, Greece, in association with goethite, scorodite, and jarosite. It was named after type locality. Kamarizaite occurs as fine-grained monomineralic aggregates (up to 3 cm across) composed of platy crystals up to 1 μm in size and submicron kidney-shaped segregations. The new mineral is yellow to beige, with light yellow streak. The Mohs hardness is about 3. No cleavage is observed. The density measured by hydrostatic weighing is 3.16(1) g/cm³, and the calculated density is 3.12 g/cm³. The wavenumbers of absorption bands in the IR spectrum of kamarizaite are (cm^?1; s is strong band, w is weak band): 3552, 3315s, 3115, 1650w, 1620w, 1089, 911s, 888s, 870, 835s, 808s, 614w, 540, 500, 478, 429. According to TG and IR data, complete dehydration and dehydroxylation in vacuum (with a weight loss of 15.3(1)%) occurs in the temperature range 110–420°C. Mössbauer data indicate that all iron in kamarizaite is octahedrally coordinated Fe³⁺. Kamarizaite is optically biaxial, positive: n _min = 1.825, n _max = 1.835, n _mean = 1.83(1) (for a fine-grained aggregate). The chemical composition of kamarizaite (electron microprobe, average of four point analyses) is as follows, wt %: 0.35 CaO, 41.78 Fe₂O₃, 39.89 As₂O₅, 1.49 SO₃, 15.3 H₂O (from TG data); the total is 98.81. The empirical formula calculated on the basis of (AsO₄,SO₄)₂ is Ca_0.03Fe _2.86 ³⁺ (AsO₄)_1.90(SO₄)_0.10(OH)_2.74 · 3.27H₂O. The idealized formula is Fe ₃ ³⁺ (AsO₄)₂(OH)₃ · 3H₂O. Kamarizaite is an arsenate analogue of orthorhombic tinticite, space group Pccm, Pcc2, Pcmm, Pcm2₁, or Pc2m; a = 21.32(1), b = 13.666(6), c =15.80(1) Å, V= 4603.29(5) ų, Z= 16. The strongest reflections of the X-ray powder diffraction pattern [\(\bar d\), Å (I, %) (hkl)] are: 6.61 (37) (112, 120), 5.85 (52) (311), 3.947 (100) (004, 032, 511), 3.396 (37) (133, 431), 3.332 (60) (314), 3.085 (58) (621, 414, 324). The type material of kamarizaite is deposited in the Mineralogical Collection of Technische Universität Bergakademie Freiberg, Germany, inventory number 82199.     

On the crystal chemistry and elastic behavior of a phlogopite 3<Emphasis Type="Italic">T</Emphasis>

The crystal chemistry and the elastic behavior under isothermal conditions up to 9 GPa of a natural, and extremely rare, 3T-phlogopite from Traversella (Valchiusella, Turin, Western Alps) [(K_0.99Na_0.05Ba_0.01)(Mg_2.60Al_0.20Fe _0.21 ²⁺ )[Si_2.71Al_1.29O₁₀](OH)₂, space group P3₁12, with a = 5.3167(4), c = 30.440(2) Å, and V = 745.16(9) ų] have been investigated by electron microprobe analysis in wavelength dispersion mode, single-crystal X-ray diffraction at 100 K, and in situ high-pressure synchrotron radiation powder diffraction (at room temperature) with a diamond anvil cell. The single-crystal refinement confirms the general structure features expected for trioctahedral micas, with the inter-layer site partially occupied by potassium and sodium, iron almost homogeneously distributed over the three independent octahedral sites, and the average bond distances of the two unique tetrahedra suggesting a disordered Si/Al-distribution (i.e., 〈T1-O〉 ~ 1.658 and 〈T2-O〉 ~ 1.656 Å). The location of the H-site confirms the orientation of the O–H vector nearly perpendicular to (0001). The refinement converged with R ₁(F) = 0.0382, 846 unique reflections with F _O > 4σ(F _O) and 61 refined parameters, and not significant residuals in the final difference-Fourier map of the electron density (+0.77/?0.37 e ^?/ų). The high-pressure experiments showed no phase transition within the pressure range investigated. The P–V data were fitted with a Murnaghan (M-EoS) and a third-order Birch-Murnaghan equation of state (BM-EoS), yielding: (1) M-EoS, V ₀ = 747.0(3) ų, K _T0 = 44.5(24) GPa, and K′ = 8.0(9); (2) BM-EoS, V ₀ = 747.0(3) ų, K _T0 = 42.8(29) GPa, and K′ = 9.9(17). A comparison between the elastic behavior in response to pressure observed in 1M- and 3T-phlogopite is made.     

Crystal chemistry of selenates with mineral-like structures. IV. Crystal structure of Zn(SeO<Subscript>4</Subscript>)(H<Subscript>2</Subscript>O)<Subscript>2</Subscript>, a new compound with a mixed framework of the variscite type

The crystal structure of a new compound Zn(SeO₄)(H₂O)₂ (orthorhombic, Pbca, a = 9.0411(13), b = 10.246(2), c = 10.3318(15) Å, V = 957.1(3) ų) has been solved by direct methods and refined to R ₁ = 0.033 on the basis of 1076 observed reflections with |F _hkl | ≥ 4σ|F _hkl |. The structure contains one independent Zn²⁺ cation coordinated by two water molecules and four oxygen atoms of selenate group. The only independent (SeO₄)^2? tetrahedral oxoanion is tetradentate, sharing its corners with four adjacent [Zn²⁺O₂(H₂O₄)]²⁺ octahedrons. The structure can be described as consisting of heteropolyhedral sheets parallel to the (001) plane and linked together into a three-dimensional network. The compound belongs to the variscite structure type and is the first structurally characterized selenate of this group.     

Application of IR and Raman spectroscopy for the determination of the role of oxygen fugacity in the formation of N–С–О–Н molecules and complexes in the iron-bearing silicate melts at high pressures

Large-scale melting of the Earth’s early mantle under the effect of global impact processes was accompanied by the generation of volatiles, which concentration was mainly controlled by the interaction of main N, C, O, and H gas-forming elements with silicate and metallic melts at low oxygen fugacity (fO₂), which predominated during metallic segregation and self-oxidation of magma ocean. The paper considers the application of Raman and IR (infrared) Fourier spectroscopy for revealing the mechanisms of simultaneous dissolution and relative contents of N, C, O, and H in glasses, which represent the quench products of reduced model FeO–Na₂O–Al₂O₃–SiO₂ melts after experiments at 4 GPa, 1550°C, and fO₂ 1.5–3 orders of magnitude below the oxygen fugacity of the iron—wustite buffer equilibrium (fO₂(IW)). Such fO₂ values correspond to those inferred for the origin and evolution of magma ocean. It was established that the silicate melt contains complexes with N–H bonds (NH₃, NH ₂ ⁺ , NH ₂ ^- ), N₂, H₂, and CH₄ molecules, as well as oxidized hydrogen species (OH^– hydroxyl and molecular water H₂O). Spectral characteristics of the glasses indicate significant influence of fO₂ on the N–C–O–H proportion in the melt. They are expressed in a sharp decrease of NH ₂ ⁺ , NH ₂ ^- (O–NH₂), OH^–, H₂O, and CH₄ and simultaneous increase of NH ₂ ^- (≡Si–NH₂) and NH₃ with decreasing fO₂. As a result, NH₃ molecules become the dominant nitrogen compounds among N–C–H components in the melt at fO₂ two orders of magnitude below fO₂(IW), whereas molecular СН₄ prevails at higher fO₂. The noteworthy feature of the redox reactions in the melt is stability of the ОН^– groups and molecular water, in spite of the sufficiently low fO₂. Our study shows that the composition of reduced magmatic gases transferred to the planet surface has been significantly modified under conditions of self-oxidation of mantle and magma ocean.     

Abundances of carbon,nitrogen, oxygen,and other elements in the atmospheres of the giants 25 Mon and HR 7389

An analysis of high-resolution CCD spectra of the giant 25 Mon, which shows signs of metallicity, and the normal giant HR 7389 is presented. The derived effective temperatures, gravitational accelerations, and microturbulence velocities are T_eff = 6700 K, log g = 3.24, and ξ _t = 3.1 km/s for 25 Mon and T_eff = 6630 K, log g = 3.71, and ξ _t = 2.6 km/s for HR 7389. The abundances (log ε) of nine elements are determined: carbon, nitrogen, oxygen, sodium, silicon, calcium, iron, nickel, and barium. The derived excess carbon abundances are 0.23 dex for 25 Mon and 0.16 dex for HR 7389. 25 Mon displays a modest (0.08 dex) oxygen excess, with the oxygen excess for HR 7389 being somewhat higher (0.15 dex). The nitrogen abundance is probably no lower than the solar value for both stars. The abundances of iron, sodium, calcium (for HR 7389), barium, and nickel exceed the solar values by 0.22–0.40 dex for both stars. The highest excess (0.62 dex) is exhibited by the calcium abundance for 25 Mon. Silicon displays a nearly solar abundance in both stars—small deficits of ?0.03 dex and ?0.07 dex for 25 Mon and HR 7389, respectively. No fundamental differences in the elemental abundances were found in the atmospheres of 25 Mon and HR 7389. Based on their T_eff and log g values, as well as theoretical calculations, A. Claret estimated the masses, radii, luminosities, and ages of 25 Mon (M/M_⊙ = 2.45, log(R/R_⊙) = 0.79, log(L/L_⊙) = 1.85, t = 5.3 × 10⁸ yr) and HR 7389 (M/M_⊙ = 2.36, log(R/R_⊙) = 0.50, log(L/L_⊙) = 1.24, t = 4.6 × 10⁸ yr), and also of the stars 20 Peg (M/M_⊙ = 2.36, log(R/R_⊙) = 0.73, log(L/L_⊙) = 1.79, t = 4.9 × 10⁸ yr) and 30 LMi (M/M_⊙ = 2.47, log(R/R_⊙) = 0.73, log(L/L_⊙) = 1.88, t = 4.8 × 10⁸ yr) studied by the author earlier.     

Crystal chemistry of selenates with mineral-like structures. III. Heteropolyhedral chains in the crystal structure of [Mg(H<Subscript>2</Subscript>O)<Subscript>4</Subscript>(SeO<Subscript>4</Subscript>)]<Subscript>2</Subscript>(H<Subscript>2</Subscript>O)

The crystal structure of a new compound [Mg(H₂O)₄(SeO₄)]₂(H₂O) (monoclinic, P2 ₁/a, a = 7.2549(12), b = 20.059(5), c = 10.3934(17) Å, β = 101.989(13), V = 1479.5(5) ų) has been solved by direct methods and refined to R ₁ = 0.059 for 2577 observed reflections with |F _hkl | ≥ 4σ|F _hkl |. The structure consists of [Mg(H₂O)₄(SeO₄)]⁰ chains formed by alternating corner-sharing Mg octahedrons and (SeO₄)^2? tetrahedrons. O atoms of Mg octahedrons that are shared with selenate tetrahedrons are in a trans orientation. The heteropoly-hedral octahedral-tetrahedral chains are parallel to the c axis and undulate within the (010) plane. The adjacent chains are linked by hydrogen bonds involving H₂O molecules not bound with M²⁺ cations.     

Magnetic field models for HD 116458 and HD 126515

We have modeled the magnetic fields of the slowly rotating stars HD 116458 and HD 126515 using the “magnetic charge” technique. HD 116458 has a small angle between its rotation axis and dipole axis (β = 12°), whereas this angle is large for HD 126515 (β = 86°). Both stars can be described with a decentered-dipole model, with the respective displacements being r = 0.07 and r = 0.24 in units of the stellar radius. The decentered-dipole model is able to satisfactorily explain the phase relations for the effective field, B_e(P), and the mean surface field, B_s(P), for both stars, along with the fact that the B_e(P) phase relation for HD 126515 is anharmonic. We discuss the role of systematic measurement errors possibly resulting from instrumental or methodical effects in one or both of the phase relations. The displacement of the dipole probably reflects real asymmetry of the stellar field structure, and is not due to measurement errors. Using both phase relations, B_e(P) and B_s(P), in the modeling considerably reduces the influence of the nonuniform distribution of chemical elements on the stellar surface.