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1.
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 K3.04(Na2.07Ca0.03)Σ2.10(Mn4.95Fe0.13Mg0.06Ti0.03Zn0.03)Σ5.20(Si11.94Al0.06)Σ12O27.57(OH)8.26F0.17 · 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 Å3, 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.  相似文献   

2.
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 Cu4.91Pb0.02O1.86(ScO3)2Cl2.14. 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).  相似文献   

3.
A new pyroxene with formula (Na0.86Mg0.14)(Mg0.57Ti0.43)Si2O6, synthesized in a high-pressure toroidal ‘anvil-with-hole’ apparatus at P = 7 GPa and T = 1700 °C, was characterized by X-ray single-crystal diffraction and Raman spectroscopy. The compound was found to be monoclinic (R1 = 2.56 %), space group C2/c, with lattice parameters a = 9.687(2), b = 8.814(1), c = 5.290(1) Å, β = 107.853(2)°, V = 430.08(1) Å3. The coexistence of Mg and Ti4+ at the M1 site does not induce strong modifications either to the M1 site or to the adjacent M2 site. The Raman spectrum of synthetic Na–Ti-pyroxene was obtained for the first time and compared with that of Mg2Si2O6 (with very low concentrations of Na and Ti). The structural characterization of the Na–Ti–Mg-pyroxene is important, because the study of its thermodynamic constants provides new constraints on thermobarometry of the upper mantle assemblages.  相似文献   

4.
Dachiardite-K (IMA No. 2015-041), a new zeolite, is a K-dominant member of the dachiardite series with the idealized formula (К2Са)(Al4Si20O48) · 13H2О. It occurs in the walls of opal–chalcedony veinlets cutting hydrothermally altered effusive rocks of the Zvezdel paleovolcanic complex near the village of Austa, Momchilgrad Municipality, Eastern Rhodopes, Bulgaria. Chalcedony, opal, dachiardite-Ca, dachiardite-Na, ferrierite-Mg, ferrierite-K, clinoptilolite-Ca, clinoptilolite-K, mordenite, smectite, celadonite, calcite, and barite are associated minerals. The mineral forms radiated aggregates up to 8 mm in diameter consisting of split acicular individuals. Dachiardite-K is white to colorless. Perfect cleavage is observed on (100). D meas = 2.18(2), D calc = 2.169 g/cm3. The IR spectrum is given. Dachiardite-K is biaxial (+), α = 1.477 (calc), β = 1.478(2), γ = 1.481(2), 2V meas = 65(10)°. The chemical composition (electron microprobe, mean of six point analyses, H2O determined by gravimetric method) is as follows, wt %: 4.51 K2O, 3.27 CaO, 0.41 BaO, 10.36 A12O3, 67.90 SiO2, 13.2 H2O, total is 99.65. The empirical formula is H26.23K1.71Ca1.04Ba0.05Al3.64Si20.24O61. The strongest reflections in the powder X-ray diffraction pattern [d, Å (I, %) (hkl)] are: 9.76 (24) (001), 8.85 (58) (200), 4.870 (59) (002), 3.807 (16) (202), 3.768 (20) (112, 020), 3.457 (100) (220), 2.966 (17) (602). Dachiardite-K is monoclinic, space gr. C2/m, Cm or C2; the unit cell parameters refined from the powder X-ray diffraction data are: a = 18.670(8), b = 7.511(3), c = 10.231(4) Å, β = 107.79(3)°, V= 1366(1) Å3, Z = 1. The type specimen has been deposited in the Earth and Man National Museum, Sofia, Bulgaria, with the registration number 23927.  相似文献   

5.
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: Ca2.94Cu 1.93 2+ Al1.97Mg0.04Fe 0.02 2+ [(As3.74S0.16P0.12)Σ4.02O16.08](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) Å3, 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.  相似文献   

6.
The pseudo-binary system CaMgSi2O6-KAlSi2O6, modeling the potassium-bearing clinopyroxene (KCpx) solid solution, has been studied at 7 GPa and 1,100–1,650 °C. The KCpx is a liquidus phase of the system up to 60 mol% of KAlSi2O6. At higher content of KAlSi2O6 in the system, grossular-rich garnet becomes a liquidus phase. Above 75 mol% of KAlSi2O6 in the system, KCpx is unstable at the solidus as well, and garnet coexists with kalsilite, Si-wadeite and kyanite. No coexistence of KCpx with kyanite was observed. Above the solidus, KAlSi2O6 content of the KCpx coexisting with melt increases with decreasing temperature. Near the solidus of the system (about 1,250 °C) KCpx contains up to 5.6 wt% of K2O, i.e. about 22–26 mol% of KAlSi2O6. Such high concentration of potassium in KCpx is presumably the maximal content of KAlSi2O6 in the Fe-free clinopyroxene at 7 GPa. In addition to the major substitution MgM1C2Al1K2, the KCpx solid solution contains Ca-Eskola and only minor Ca-Tschermack components. Our experimental results indicate that the natural assemblage KCpx+grossular-rich garnet might be a product of crystallization of the ultra-potassic SiO2-rich alumino-silicate mantle melts (>200 km).Editorial responsibility: J. Hoefs  相似文献   

7.
High-pressure single-crystal X-ray diffraction measurements of lattice parameters of the compound Li2VOSiO4, which crystallises with a natisite-type structure, has been carried out to a pressure of 8.54(5) GPa at room temperature. Unit-cell volume data were fitted with a second-order Birch-Murnaghan EoS (BM-EoS), simultaneously refining V 0 and K 0 using the data weighted by the uncertainties in V. The bulk modulus is K 0 = 99(1) GPa, with K′ fixed to 4. Refinements of third order equations-of-state yielded values of K′ that did not differ significantly from 4. The compressibility of the unit-cell is strongly anisotropic with the c axis (K 0(c) = 49.7 ± 0.5 GPa) approximately four times more compressible than the a axis (K 0(a) = 195 ± 3 GPa).  相似文献   

8.
A new picromerite-group mineral, nickelpicromerite, K2Ni(SO4)2?·?6H2O (IMA 2012–053), was found at the Vein #169 of the Ufaley quartz deposit, near the town of Slyudorudnik, Kyshtym District, Chelyabinsk area, South Urals, Russia. It is a supergene mineral that occurs, with gypsum and goethite, in the fractures of slightly weathered actinolite-talc schist containing partially vermiculitized biotite and partially altered sulfides: pyrrhotite, pentlandite, millerite, pyrite and marcasite. Nickelpicromerite forms equant to short prismatic or tabular crystals up to 0.07 mm in size and anhedral grains up to 0.5 mm across, their clusters or crusts up to 1 mm. Nickelpicromerite is light greenish blue. Lustre is vitreous. Mohs hardness is 2–2½. Cleavage is distinct, parallel to {10–2}. D meas is 2.20(2), D calc is 2.22 g cm?3. Nickelpicromerite is optically biaxial (+), α?=?1.486(2), β?=?1.489(2), γ?=?1.494(2), 2Vmeas =75(10)°, 2Vcalc =76°. The chemical composition (wt.%, electron-microprobe data) is: K2O 20.93, MgO 0.38, FeO 0.07, NiO 16.76, SO3 37.20, H2O (calc.) 24.66, total 100.00. The empirical formula, calculated based on 14 O, is: K1.93Mg0.04Ni0.98S2.02O8.05(H2O)5.95. Nickelpicromerite is monoclinic, P21/c, a?=?6.1310(7), b?=?12.1863(14), c?=?9.0076(10) Å, β?=?105.045(2)°, V?=?649.9(1) Å3, Z?=?2. Eight strongest reflections of the powder XRD pattern are [d,Å-I(hkl)]: 5.386–34(110); 4.312–46(002); 4.240–33(120); 4.085–100(012, 10–2); 3.685–85(031), 3.041–45(040, 112), 2.808–31(013, 20–2, 122), 2.368–34(13–3, 21–3, 033). Nickelpicromerite (single-crystal X-ray data, R?=?0.028) is isostructural to other picromerite-group minerals and synthetic Tutton’s salts. Its crystal structure consists of [Ni(H2O)6]2+ octahedra linked to (SO4)2? tetrahedra via hydrogen bonds. K+ cations are coordinated by eight anions. Nickelpicromerite is the product of alteration of primary sulfide minerals and the reaction of the acid Ni-sulfate solutions with biotite.  相似文献   

9.
To examine the effect of KCl-bearing fluids on the melting behavior of the Earth’s mantle, we conducted experiments in the Mg2SiO4–MgSiO3–H2O and Mg2SiO4–MgSiO3–KCl–H2O systems at 5 GPa. In the Mg2SiO4–MgSiO3–H2O system, the temperature of the fluid-saturated solidus is bracketed between 1,200–1,250°C, and both forsterite and enstatite coexist with the liquid under supersolidus conditions. In the Mg2SiO4–MgSiO3–KCl–H2O systems with molar Cl/(Cl + H2O) ratios of 0.2, 0.4, and 0.6, the temperatures of the fluid-saturated solidus are bracketed between 1,400–1,450°C, 1,550–1,600°C, and 1,600–1,650°C, respectively, and only forsterite coexists with liquid under supersolidus conditions. This increase in the temperature of the solidus demonstrates the significant effect of KCl on reducing the activity of H2O in the fluid in the Mg2SiO4–MgSiO3–H2O system. The change in the melting residues indicates that the incongruent melting of enstatite (enstatite = forsterite + silica-rich melt) could extend to pressures above 5 GPa in KCl-bearing systems, in contrast to the behavior in the KCl-free system.  相似文献   

10.
Nickeltalmessite, Ca2Ni(AsO4)2 · 2H2O, a new mineral species of the fairfieldite group, has been found in association with annabergite, nickelaustinite, pecoraite, calcite, and a mineral of the chromite-manganochromite series from the dump of the Aït Ahmane Mine, Bou Azzer ore district, Morocco. The new mineral occurs as spheroidal aggregates consisting of split crystals up to 10 × 10 × 20 μm in size. Nickeltalmessite is apple green, with white streak and vitreous luster. The density measured by the volumetric method is 3.72(3) g/cm3; calculated density is 3.74 g/cm3. The new mineral is colorless under a microscope, biaxial, positive: α = 1.715(3), β = 1.720(5), γ = 1.753(3), 2V meas = 80(10)°, 2V calc = 60.4. Dispersion is not observed. The infrared spectrum is given. As a result of heating of the mineral in vacuum from 24° up to 500°C, weight loss was 8.03 wt %. The chemical composition (electron microprobe, wt %) is as follows: 25.92 CaO, 1.23 MgO, 1.08 CoO, 13.01 NiO, 52.09 As2O5; 7.8 H2O (determined by the Penfield method); the total is 101.13. The empirical formula calculated on the basis of two AsO4 groups is Ca2.04(Ni0.77Mg0.13Co0.06)Σ0.96 (AsO4)2.00 · 1.91H2O. The strongest reflections in the X-ray powder diffraction pattern [d, Å (I, %) (hkl)] are: 5.05 (27) (001) (100), 3.57 (43) (011), 3.358 (58) (110), 3.202 (100) (020), 3.099 (64) (0\(\bar 2\)1), 2.813 (60), (\(\bar 1\)21), 2.772 (68) (2\(\bar 1\)0), 1.714 (39) (\(\bar 3\)31). The unit-cell dimensions of the triclinic lattice (space group P1 or P) determined from the X-ray powder data are: a = 5.858(7), b = 7.082(12), c = 5.567(6) Å, α = 97.20(4), β = 109.11(5), γ = 109.78(5)°, V = 198.04 Å3, Z = 1. The mineral name emphasizes its chemical composition as a Ni-dominant analogue of talmessite. The type material of nickeltalmessite is deposited at the Fersman Mineralogical Museum, Russian Academy of Sciences, Moscow, Russia, registration number 3750/1.  相似文献   

11.
Mangazeite, a new mineral species, has been found at the Mangazeya silver deposit (300 km east of the Lena River, 65°43′40″ N and 130°20′ E) in eastern Yakutia (Sakha Republic, Siberia, Russia). The new mineral was described from fractured, sericitized, and pyritized granodiorite adjacent to a quartz-arsenopyrite vein. Associated minerals are gypsum and chlorite. The new mineral occurs as radial fibrous segregations of thin lamellar crystals. The size of the fibers does not exceed 40 μm in length and 1 μm across. The mineral is white, with a white streak and a vitreous luster. Mangazeite is transparent in isolated grains. No fluorescence is observed. The Mohs hardness is 1–2. The calculated density is 2.15 g/cm3. The new mineral is biaxial; its optical character was not determined; α = 1.525(9), β was not measured, and γ = 1.545(9). The average chemical composition is as follows (wt %): Al2O3 36.28, SO3 28.81, H2O+ 34.35, total 99.44, H2O? 9.27. The H2O? content was neither included in the total nor used in formula calculation. The empirical formula is Al1.99(SO4)1.01(OH)3.94 · 3.37H2O. The simplified formula is Al2(SO4)(OH)4 · 3H2O. The theoretical chemical composition calculated from this formula is (wt %) Al2O3 37.47, SO3 29.42, H2O 33.11, total 100.00. The new mineral is triclinic; the unit cell parameters refined from X-ray powder diffraction data are a = 8.286(5), b = 9.385(5), c = 11.35(1) Å, α = 96.1(1), β = 98.9(1), γ = 96.6(1)°, and Z = 4. The strongest lines in the X-ray powder diffraction pattern (d(I, %)) are 8.14(19), 7.59(49), 7.16(46), 4.258(100), 4.060(48), and 3.912(43). Mangazeite is supergene in origin and crystallized in a favorable aluminosilicate environment in the presence of sulfate ion due to pyrite oxidation.  相似文献   

12.
Calcioolivine has been included into the MDI mineral database in the list of grandfathered minerals. Its history, together with related artificial compounds, is extremely complex: various minerals and compounds received this name, including natural orthorhombic Ca orthosilicate. In this paper, the crystal structure and properties of natural calcioolivine are described for the first time. The new mineral has been found at Mt. Lakargi, Upper Chegem Plateau, the northern Caucasus, Kabarda-Balkaria Republic, Russia. It has been identified in skarnified, primary carbonate xenoliths entrained by middle to late Pliocene silicic ignimbrites of the Upper Chegem caldera. These xenoliths of a few centimeters to a few meters in size are located close to the volcanic vent. Calcioolivine rims relics of larnite and occurs as relict grains among crystals of spurrite, rondorfite, wadalite or secondary hillebrandite, afwillite, thaumasite, and ettringite. Hillebrandite is the major product of alteration of calcioolivine; larnite is relatively more resistant to low-temperature alteration. Spurrite, larnite, tilleyite, kilchoanite, cuspidine, wadalite, rondorfite, reinhardbraunsite, lakargiite (CaZrO3), members of ellestadite series, afwillite, ettringite, katoite, and thaumasite are associated minerals. It is inferred that calcioolivine has been produced as a result of interaction of host carbonate rocks in xenoliths with volcanic lava and gases during eruption. The name calcioolivine was approved by the Commission on New Minerals and Mineral Names, International Mineralogical Association, September 6, 2007 (no. 07-B).  相似文献   

13.
A new mineral, yegorovite, has been identified in the late hydrothermal, low-temperature assemblage of the Palitra hyperalkaline pegmatite at Mt. Kedykverpakhk, Lovozero alkaline pluton, Kola Peninsula, Russia. The mineral is intimately associated with revdite and megacyclite, earlier natrosilite, microcline, and villiaumite. Yegorovite occurs as coarse, usually split prismatic (up to 0.05 × 0.15 × 1 mm) or lamellar (up to 0.05 × 0.7 × 0.8 mm) crystals. Polysynthetic twins and parallel intergrowths are typical. Mineral individuals are combined in bunches or chaotic groups (up to 2 mm); radial-lamellar clusters are less frequent. Yegorovite is colorless, transparent with vitreous luster. Cleavage is perfect parallel to (010) and (001). Fracture is splintery; crystals are readily split into acicular fragments. The Mohs hardness is ～2. Density is 1.90(2) g/cm3 (meas) and 1.92 g/cm3 (calc). Yegorovite is biaxial (?), with α = 1.474(2), β = 1.479(2), and γ = 1.482(2), 2V meas > 70°, 2V calc = 75°. The optical orientation is X ∧ a ～ 15°, Y = c, Z = b. The IR spectrum is given. The chemical composition determined using an electron microprobe (H2O determined from total deficiency) is (wt %): 23.28 Na2O, 45.45 SiO2, 31.27 H2Ocalc; the total is 100.00. The empirical formula is Na3.98Si4.01O8.02(OH)3.98 · 7.205H2O. The idealized formula is Na4[Si4O8(OH)4] · 7H2O. Yegorovite is monoclinic, space group P21/c. The unit-cell dimensions are a = 9.874, b= 12.398, c = 14.897 Å, β = 104.68°, V = 1764.3 Å3, Z = 4. The strongest reflections in the X-ray powder pattern (d, Å (I, %)([hkl]) are 7.21(70)[002], 6.21(72)[012, 020], 4.696(44)[022], 4.003(49)[211], 3.734(46)[\(\bar 2\) 13], 3.116(100)[024, 040], 2.463(38)[\(\bar 4\)02, \(\bar 2\)43]. The crystal structure was studied by single-crystal method, R hkl = 0.0745. Yegorovite is a representative of a new structural type. Its structure consists of single chains of Si tetrahedrons [Si4O8(OH)4]∞ and sixfold polyhedrons of two types: [NaO(OH)2(H2O)3] and [NaO(OH)(H2O)4] centered by Na. The mineral was named in memory of Yu. K. Yegorov-Tismenko (1938–2007), outstanding Russian crystallographer and crystallochemist. The type material of yegorovite has been deposited at the Fersman Mineralogical Museum of Russian Academy of Sciences, Moscow.  相似文献   

14.
The join CaMgSi2O6–KAlSi3O8 has been studied at 6 GPa (890–1,500°C) and 3.5 GPa (1,000–1,100°C). K-rich melts in the join produce assemblages Cpx + Grt, Cpx + Opx, Cpx + San, and Cpx + Grt + San at 1,100–1,300°C. At NSansystem<~70 mol%, sanidine is unstable on the solidus and appears at the liquidus, if NSansystem>90 mol%. This explains a scarcity of San in mantle Cpx-rich assemblages and its association with high-K aluminosilicate melt inclusions in diamonds. In absence of San, KCpx is the only host for potassium. The K-jadeite content in KCpx systematically increases with decreasing temperature and reaches 10–12 mol% near the solidus. However, KCpx coexists with San at NSansystem>70 mol% and <1,300°C, being formed via reaction San + L=KCpx. The KJd content in KCpx is controlled by the equilibrium San=KJd + SiO2L that displaces to the right with increasing pressure and decreasing both the temperature and This equilibrium is considered to be responsible for the formation of San lamellae in natural UHP Cpx. In our experiments at 3.5 GPa, garnet is absent whereas the KJd and Ca-Eskola contents in Cpx are low, and the join CaMgSi2O6–KAlSi3O8 is close to binary (with the eutectic Cpx + San + L). Different topologies of the join at 6 and 3.5 GPa define a sequence of mineral crystallization from K-rich aluminosilicate melts during cooling and decompression: from KCpx + Grt without San at P>4 GPa to Cpx + San at P<4 GPa. Similar sequence of assemblages is observed in some eclogitic xenoliths from kimberlites and Grt–Cpx rocks of the Kokchetav Complex (Northern Kazakhstan).  相似文献   

15.
The paper reports new findings of avdoninite from deposits of active fumaroles in the Second Scoria Cone at the Northern Breach of the Great Fissure Tolbachik Eruption, Tolbachik Volcano, Kamchatka Peninsula, Russia. The crystal structure of the mineral has been determined for the first time, which has allowed reliable determination of its space group and unit cell dimensions, refinement of its formula K2Cu5-Cl8(OH)4 · 2H2O, and correct indexing of its X-ray powder diffraction pattern. Avdoninite is monoclinic, space group P21/c, a = 11.592(2), b = 6.5509(11), c = 11.745(2) Å, β = 91.104(6)°, V = 891.8(3) Å3, Z = 2. The crystal structure of this mineral has been determined on a single crystal R 1 [F > 4σ (F)] = 0.063. It is based on sheets of copper–oxo-chloride complexes [Cu5Cl8(OH)4]2– parallel to (100). The K+ cation and H2O molecules are interlayers.  相似文献   

16.
We have collected high resolution neutron powder diffraction patterns from Na2SO4·10D2O over the temperature range 4.2–300 K following rapid quenching in liquid nitrogen, and over a series of slow warming and cooling cycles. The crystal is monoclinic, space-group P21/c (Z = 4) with a = 11.44214(4) Å, b = 10.34276(4) Å, c = 12.75486(6) Å, β = 107.847(1)°, and V = 1436.794(8) Å3 at 4.2 K (slowly cooled), and a = 11.51472(6) Å, b = 10.36495(6) Å, c = 12.84651(7) Å, β = 107.7543(1)°, V = 1460.20(1) Å3 at 300 K. Structures were refined to R P (Rietveld powder residual, \( R_{P} = {{\sum {\left| {I_{\text{obs}} - I_{\text{calc}} } \right|} } \mathord{\left/ {\vphantom {{\sum {\left| {I_{\text{obs}} - I_{\text{calc}} } \right|} } {\sum {I_{\text{obs}} } }}} \right. \kern-\nulldelimiterspace} {\sum {I_{\text{obs}} } }} \)) better than 2.5% at 4.2 K (quenched and slow cooled), 150 and 300 K. The sulfate disorder observed previously by Levy and Lisensky (Acta Cryst B34:3502–3510, 1978) was not present in our specimen, but we did observe changes with temperature in deuteron occupancies of the orientationally disordered water molecules coordinated to Na. The temperature dependence of the unit-cell volume from 4.2 to 300 K is well represented by a simple polynomial of the form V = ? 4.143(1) × 10?7 T 3 + 0.00047(2) T2 ? 0.027(2) T + 1437.0(1) Å3 (R 2 = 99.98%). The coefficient of volume thermal expansion, α V , is positive above 40 K, and displays a similar magnitude and temperature dependence to α V in deuterated epsomite and meridianiite. The relationship between the magnitude and orientation of the principal axes of the thermal expansion tensor and the main structural elements are discussed; freezing in of deuteron disorder in the quenched specimen affects the thermal expansion, manifested most obviously as a change in the behaviour of the unit-cell parameter β.  相似文献   

17.
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 H31.41Ca3.00(Al0.76Si0.25)Σ1.01 · (B0.72S0.65C0.59)Σ1.96O24.55. 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(Аl0.70Si0.30) · {[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}(ОН5·73О0.27) · 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.  相似文献   

18.
Avdoninite, a new mineral species, has been found together with euchlorite, paratacamite, atacamite, belloite, and langbeinite hosted in exhalation sediments of the Yadovitaya fumarole in the Second Cinder Cone at the Northern Breach of the Great Fissure Tolbachik Eruption, Tolbachik volcano, Kamchatka Peninsula, Russia. Avdoninite occurs as imperfect, short prismatic and thick tabular crystals up to 0.2 mm long, with (001) and (100) forms, crystal aggregates, and pseudomorphs (together with atacamite) after melanothallite observed. The new mineral is brittle, with the Mohs hardness 3 (for aggregates). Density is 3.03 g/cm3 (meas.) and 3.066 g/cm3 (calc.). Avdoninite is biaxial and optically neutral, with α = 1.669, β = 1.688, γ = 1.707, 2V = ?90°. Dispersion is not observed. Optical orientation: Y = c, X = b? Pleochroism is absent. The infrared spectrum suggests the presence of water molecules in avdoninite. Electron microprobe chemical analysis has given (wt %) K2O 11.94 (±0.4), CuO 51.43 (±0.7), Cl 37.07 (±0.6), H2O (determined by the Penfield method) 6.9, ?O=Cl2 ?8.37, total 98.97. The empirical formula is K1.96Cu5.00Cl8.09(OH)3.87. · 1.03H2O. Avdoninite is monoclinic, space group P2/m, P2, or Pm; a = 24.34(2) Å, b = 5.878(4) Å, c = 11.626(5) Å, β = 93.3(1)°, V = 1660.6(20) Å3, Z = 4. The compatibility index is good: 1 ? K p/K c = 0.056 for D calc and 0.044 for D meas. The strongest lines in the X-ray powder diffraction pattern (d, Å (I, %) (hkl)) are 11.63(100)(001), 5.88(20)(010), 5.80(27)(002), 5.73(17)(\(\overline 1 \)02), 2.518(19)(21\(\overline 4 \)), 2.321(17)(005). Avdoninite is identical to a technogenic analogue previously described from the Blyava volcanic-hosted massive sulfide deposit, Orenburg oblast, Russia. The new mineral is named after Vladimir Nikolaevich Avdonin (born 1925), a senior researcher of the Ural Geological Museum of the Ural State Mining University. The type material of avdoninite from Kamchatka is deposited in the Mineralogical Museum of the Department of Mineralogy, St. Petersburg State University, St. Petersburg, Russia. The registration number is 19175.  相似文献   

19.
Elastic and thermoelastic constants of large single crystals of Ca2MgSi2O7 and Ca2ZnSi2O7 have been derived from ultrasonic resonance frequencies of plane-parallel plates and their shift upon variation of temperature, respectively. In addition, coefficients of thermal expansion and dielectric constants were determined. Both species possess quite similar properties. As observed in other isotypic magnesium and zinc compounds, the mean elastic stiffness and the deviation from the Cauchy relations are significantly larger in the zinc compound, due to a covalent contribution of the Zn–O bond. Positive thermoelastic constants T44 and T66 in Ca2MgSi2O7 allow temperature-independent ultrasonic generators and oscillators to be manufactured.  相似文献   

20.
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 Ca0.03Fe 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) Å3, 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.  相似文献   

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