凤成石:异性石族矿物N(5)位贫钠的空位类似物新种

作为异性石族矿物新种凤成石是首个该族已知成员中N(5)位贫Na且以空位居优的类似物,其理想化学式为:Na_(12)□_3Ca_6(Fe~(3+),□)_3Zr_3Si(Si_(25)O_(73))(H_2O)_3(OH)_2。它发现于我国东北辽宁省凤城市赛马钠质碱性正长岩内,多呈它形-半自形晶产出,单个晶体粒径1~7mm,最大粒径者>1.5cm。与之共生的矿物有微斜长石、正长石、钠长石、霞石和钠角闪石亚族矿物、霓石、榍石和闪叶石族矿物、"贫钠的层硅钛铈矿"("Napoor rinkite")、钛铌钙铈矿、钠锆石、锆石、铁金云母、氟磷灰石、富稀土的羟硅磷灰石和何作霖矿等。矿物为半透明-透明,玻璃光泽,条痕白色,性脆,摩氏硬度约5,偶见不完全解理和裂开,一轴晶正光性。N_e=1.607,N_o=1.603。凤成石属三方晶系,具R3m空间群;a=1.42467(6)nm,c=3.00330(2)nm,V=5.27908(50)nm~3,Z=3。6条强粉晶衍射线[面网间距(衍射强度)(指标化)]是:0.7186(55)(110),0.5761(44)(113),0.4187(53)(123),0.3201(47)(028),0.2978(61)(135)和0.2857(100)(044)。16点矿物成分的电子探针等分析均值为:Na_2O 11.64%,K_2O 0.52%,CaO 8.96%,MgO 0.07%,SrO_3.53%,BaO 0.02%,MnO0.10%,FeO 0.69%,Mn_2O_30.92%,Fe_2O_35.98%,La_2O_30.12%,Ce_2O_30.23%,Nd_2O_30.13%,Sc_2O_30.01%,TiO_20.38%,ZrO_211.72%,Nb_2O_50.23%,SiO_251.73%,Cl 1.13%,H_2O 2.09%,O≡Cl-0.26%,总量100.14%。根据晶体结构精测和(O+OH+F+Cl)=78计算的矿物经验化学式:[(Na_(3.00)Na_(3.00))Σ_(6.00)(Na_(5.28)K_(0.33)□_(0.39))]_(12.00)□_(2.71)Sr_(0.20)REE_(0.09))_(3.00)Ca_(4.80)Sr_(0.82)Fe_(0.29)~(2+)Mg_(0.05)Mn_(0.04)~(2+))_(6.00)(Fe_(2.25)~(3+)Mn_(0.35)~(3+)Cr_(0.08)□_(0.32))_(3.00)(Zr_(2.86)Ti_(0.09)Nb_(0.05))_(3.00)(Si_(0.87)Ti_(0.05)□_(0.08))_(1.00)Si_(1.00)(Si_(24.00)O_(72.00))[(H_2O)_(2.93)O_(1.00)(OH)_(0.07)]_(3.00)[(OH)_(1.04)Cl_(0.96_]_(2.00)。矿物实测密度2.93g/cm~3;计算密度2.88g/cm~3。基于野外和室内研究,借鉴有关合成异性石族矿物的实验资料,凤成石由一类富REE、U、Th、Zr、和挥发分的钠质碱性正长岩岩浆直接结晶而成。     

汞银黝铜矿Ag6 (Cu4Hg2) Sb4S13——黝铜矿族新矿物

作为黝铜矿族矿物的新成员,汞银黝铜矿(Argentotetrahedrite-(Hg),IMA 2020-079),Ag6(Cu4 Hg2) Sb4S13,发现于湘黔汞矿带北段之保靖东坪Hg-Ag矿床中,是该矿床的主要矿石矿物和回收对象.汞银黝铜矿单晶晶体尺寸约为5～20 μm,呈粒径20～300 μm的粒状、片状集合...     

Na+,K+,Mg2+,Ca2+//Cl-,SO42——H2O六元体系中杂卤石形成条件的再认识

研究海水体系(即Na⁺,K⁺,Mg²⁺,Ca²⁺∥Cl^-,$SO_{4}^{2-}$-H₂O六元体系)中杂卤石的形成条件不仅有助于理解海相蒸发盐成因,对开发杂卤石钾资源利用技术也具有重要的指导作用。但杂卤石以及其他含有硫酸钙矿物(如二水石膏、半水石膏、无水石膏、钾石膏、多钙钾石膏、钙芒硝和水钙芒硝)的相平衡,无论是在实验研究方面还是在热力学模拟方面都仍然存在很多争议。由于缺乏杂卤石在复杂水溶液体系中可靠的相平衡数据,使人们对认识杂卤石成因和利用杂卤石钾资源带来巨大障碍。本工作对海水体系中杂卤石的形成条件进行了热力学模拟和实验研究。超过一年的长时间固液平衡实验表明25 ℃下Na⁺,K⁺,Mg²⁺,Ca²⁺∥Cl^-,$SO_{4}^{2-}$-H₂O六元体系中杂卤石的形成区域极为可观,且较前人实验结果均大数倍;同时证实了热力学模型预测结果的可靠性。这些结果为讨论盐矿床中杂卤石的形成条件提供了物理化学依据。25 ℃下可靠的热力学信息表明:杂卤石与其他盐类矿物的共生情况丰富多样,并且与前人看法不同,杂卤石的形成并不需要极高的钾、镁浓度。这给以杂卤石为指示寻找可溶性固体钾盐带来了挑战,但却指示了以杂卤石为线索更容易找到钾、镁盐未饱和的富钾卤水。     

Thermodynamics of (Fe2+, Mn2+, Mg, Ca)3− Al2Si3O12 garnet: a review and analysis

Summary The thermodynamic properties of garnets in the system (Fe²⁺, Mn²⁺, Mg, Ca)₃A1₂Si₃O₁₂ are reviewed. The thermodynamic properties of the three end-member garnets pyrope, almandine and grossular, including their volume, enthalpy of formation, entropy, compressibility and thermal expansion have been well determined. For spessartine enthalpy of formation and heat capacity at low temperatures are needed. Pyrope's unusual behavior in some of its properties is probably related to the presence of the small, light Mg cation, which has a large anisotropic thermal vibration. The thermodynamic mixing properties of the six binaries are also discussed. Good volume of mixing data exist now for all of the binaries, but much work is still required to determine the enthalpies and third-law vibrational entropies of mixing. It is shown that the magnitude of the positive deviations in the volumes of mixing is related to the volume difference between the two end-member components. It is probable that excess entropies, if present, originate at low temperatures below 200 K. Recent²⁹Si NMR experiments have demonstrated the presence of short-range ordering (SRO) of Ca and Mg in pyrope-grossular solid solutions. Short-range order will have to be considered in new models describing the entropies of mixing. Its possible presence in all garnet solid solutions needs to be examined. The mixing properties of pyrope-grossular garnets, which are the best known for any garnet binary, can, in part, be described by the Quasi-Chemical approximation, which gives insight into the microscopic interactions which determine the macroscopic thermodynamic mixing properties. Microscopic properties are best investigated by spectroscopic and computational approaches. Hard mode IR measurements on binary solid solutions show that the range of local microscopic structural distortion is reflected in the macroscopic volumes of mixing. The nature of The contents of this contribution was presented at the IMA Meeting in Toronto in August, 1998. It precedes issues of Mineralogy and Petrology containing thematic sets of IMApapers strain tiields and site relaxation needs to be studied in order to obtain a better understanding of the solid-solution process and energetics in garnet. Critical areas for future experimentation are also addressed.[/p]

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Eine kritische Zusammenstellung und Analyse der thermodynamischen Daten der (Fe²⁺, Mn²⁺, Mg, Ca)₃Al₂Si₃O₁₂ granate

Zusammenfassung In dieser Studie werden die thermodynamischen Eigenschaften der Granate im System (Fe²⁺,Mn²⁺, Mg, Ca)₃Al₂Si₃O₁₂ kritisch zusammengestellt. Die thermodynamischen Eigenschaften der drei Endglied-Granate Pyrop, Almandin und Grossular, einschließlich ihrer Volumina, Bildungswärmen, Entropien, Kompressibilitäten und thermischen Ausdehnungen wurden bereits hinreichend gut bestimmt. Dagegen müssen die Bildungswärme und Tieftemperatur-Wärmekapazität von Spessartin noch gemessen werden. Die Eigenschaften des Pyrops sind wahrscheinlich mit den großen anisotropen Schwingungen des kleinen, leichten Mg-Kations verbunden. Die thermodynamischen Mischungseigenschaften der sechs binären Mischkristallreihen werden ebenfalls diskutiert. Während die Mischungs-Volumendaten der binären Mischreihen gut bekannt sind, müssen ihre Mischungs-Enthalpien und Standard-Mischungsentropien noch ermittelt werden. Es wurde gezeigt, daß die Größe der positiven Exzeß-Volumina mit dem Volumen-Unterschied der zwei Endglied-Komponenten der jeweiligen Mischreihe verknüpft ist. Es ist wahrscheinlich, daß Exzeß-Entropien, wenn vorhanden, erst bei Tieftemperaturen unter 200 K auftreten. Neue²⁹Si NMR-Experimente belegen, daß in Pyrop-Grossular-Mischkristallen Nahordnung von Mg und Ca vorliegt. Der Effekt der Nahordnung muß in künftigen thermodynamischen Modellen berücksichtigt werden. Hieraus ergibt sich die Notwendigkeit, alle Granat-Mischreihen auf mögliche Nahordnung hin zu untersuchen. Die Mischungseigenschaften der Pyrop-Grossular-Mischreihe, die von sämtlichen Granat-Mischreihen am besten bestimmt wurden, können teilweise mit dem Quasi-Chemical-Model beschrieben werden. Dieses Modell ermöglicht die Beschreibung der mikroskopischen Wechselwirkungen, die die makroskopischen thermodynamischen Eigenschaften bestimmen. Mikroskopische Eigenschaften werden am besten mit spektroskopischen Messungen und theoretischen Berechnungen untersucht. Hard-mode IR-Spektroskopie-Messungen an binären Mischreihen zeigen, daß die lokalen mikroskopischen strukturellen Verzerrungen in den makroskopischen Mischungs-Volumina widergespiegelt werden. Die Art der Spannungsfelder und Platz-Relaxationen muß detaillierter untersucht werden, um ein besseres Verständnis des Mischkristall-Bildungsprozsses und der Energetik der Granate zu erreichen. Darüber hinaus werden wichtige künftige Forschungsgebiete diskutiert.

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With 11 Figures     

Hillesheimite, (K,Ca,□)2(Mg,Fe,Ca,□)2[(Si,Al)13O23(OH)6](OH) · 8H2O, a new phyllosilicate mineral of the Günterblassite group

A new mineral, hillesheimite, has been found in the Graulai basaltic quarry, near the town of Hillesheim, the Eifel Mountains, Rhineland-Palatinate (Rheinland-Pfalz), Germany. It occurs in the late assemblage comprising nepheline, augite, fluorapatite, magnetite, perovskite, priderite, götzenite, lamprophyllite-group minerals, and åkermanite. Colorless flattened crystals of hillesheimite reaching 0.2 × 1 × 1.5 mm in size and aggregates of the crystals occur in miarolitic cavities in alkali basalt. The mineral is brittle, with Mohs’ hard-ness 4. Cleavage is perfect parallel to (010) and distinct on (100) and (001). D _calc = 2.174 g/cm³, D _meas = 2.16(1) g/cm³. IR spectrum is given. Hillesheimite is biaxial (?), α = 1.496(2), β = 1.498(2), γ = 1.499(2), 2V _meas = 80°. The chemical composition (electron microprobe, mean of 4 point analyses, H₂O determined from structural data, wt %) is as follows: 0.24 Na₂O, 4.15 K₂O, 2.14 MgO, 2.90 CaO, 2.20 BaO, 2.41 FeO, 15.54 Al₂O₃, 52.94 SiO₂, 19.14 H₂O, total is 101.65. The empirical formula is: K_0.96Na_0.08Ba_0.16Ca_0.56Mg_0.58Fe _0.37 ²⁺ [Si_9.62Al_3.32O₂₃(OH)₆][(OH)_0.82(H₂O)_0.18] · 8H₂O. The crystal structure has been determined from X-ray single-crystal diffraction data, R = 0.1735. Hillesheimite is orthorhombic, space group Pmmn, the unit-cell dimensions are: a = 6.979(11), b = 37.1815(18), c = 6.5296(15) Å; V=1694(3) ų, Z = 2. The crystal structure is based on the block [(Si,Al)₁₃O₂₅(OH)₄] consisting of three single tetrahedral layers linked via common vertices and is topologically identical to the triple layers in günterblassite and umbrianite. The strong reflections [d Å (I %)] in the X-ray powder diffraction pattern are: 6.857(58), 6.545(100), 6.284(53), 4.787(96), 4.499(59), 3.065(86), 2.958(62), 2.767(62). The mineral was named after its type locality. Type specimens are deposited in the Fersman Mineralogical Museum, Russian Academy of Sciences, Moscow, registration number 4174/1.     

Alumovesuvianite,Ca19Al(Al,Mg)12Si18O69(OH)9, a new vesuvianite-group member from the Jeffrey mine,asbestos, Estrie region,Québec,Canada

Mineralogy and Petrology - Alumovesuvianite (IMA 2016–014), ideally Ca19Al(Al,Mg)12Si18O69(OH)9, is a new vesuvianite-group member found in the rodingite zone at the contact of a gabbroid...     

Thermodynamic properties of tooeleite,Fe63+(As3+O3)4(SO4)(OH)4·4H2O

Tooeleite, nominally Fe₆³⁺(As³⁺O₃)₄(SO₄)(OH)₄·4H₂O, is a relatively uncommon mineral of some acid-mine drainage systems. Yet, if it does occur, it does so in large quantities, indicating that some specific conditions favor the formation of this mineral in the system Fe-As-S-O-H. In this contribution, we report the thermodynamic properties of synthetic tooeleite. The sample was characterized by powder X-ray diffraction, scanning electron microscopy, extended X-ray absorption fine-structure spectroscopy, and Mössbauer spectroscopy. These methods confirmed that the sample is pure, devoid of amorphous impurities of iron oxides, and that the oxidation state of arsenic is 3+. Using acid-solution calorimetry, the enthalpy of formation of this mineral from the elements at the standard conditions was determined as −6196.6 ± 8.6 kJ mol⁻¹. The entropy of tooeleite, calculated from low-temperature heat capacity data measured by relaxation calorimetry, is 899.0 ± 10.8 J mol⁻¹ K⁻¹. The calculated standard Gibbs free energy of formation is −5396.3 ± 9.3 kJ mol⁻¹. The log K_sp value, calculated for the reaction Fe₆(AsO₃)₄(SO₄)(OH)₄·4H₂O + 16H⁺ = 6Fe³⁺ + 4H₃AsO₃ + SO₄²⁻ + 8H₂O, is −17.25 ± 1.80. Tooeleite has stability field only at very high activities of aqueous sulfate and arsenate. As such, it does not appear to be a good candidate for arsenic immobilization at polluted sites. An inspection of speciation diagrams shows that the predominance field of Fe³⁺ and As³⁺ overlap only at strongly basic conditions. The formation of tooeleite, therefore, requires strictly selective oxidation of Fe²⁺ to Fe³⁺ and, at the same time, firm conservation of the trivalent oxidation state of arsenic. Such conditions can be realized only by biological systems (microorganisms) which can selectively oxidize one redox-active element but leave the other ones untouched. Hence, tooeleite is the first example of an “obligatory” biomineral under the conditions prevailing at or near the Earth's surface because its formation under these conditions necessitates the action of microorganisms.     

Günterblassite, (K,Ca)3 − x Fe[(Si,Al)13O25(OH,O)4] · 7H2O, a new mineral: the first phyllosilicate with triple tetrahedral layer

A new mineral, günterblassite, has been found in the basaltic quarry at Mount Rother Kopf near Gerolstein, Rheinland-Pfalz, Germany as a constituent of the late assemblage of nepheline, leucite, augite, phlogopite, åkermanite, magnetite, perovskite, a lamprophyllite-group mineral, götzenite, chabazite-K, chabazite-Ca, phillipsite-K, and calcite. Günterblassite occurs as colorless lamellar crystals up to 0.2 × 1 × 1.5 mm in size and their clusters. The mineral is brittle, with perfect cleavage parallel to (001) and less perfect cleavage parallel to (100) and (010). The Mohs hardness is 4. The calculated and measured density is 2.17 and 2.18(1) g/cm³, respectively. The IR spectrum is given. The new mineral is optically biaxial and positive as follows: α = 1.488(2), β = 1.490(2), γ = 1.493(2), 2V _meas = 80(5)°. The chemical composition (electron microprobe, average of seven point analyses, H₂O is determined by gas chromatography, wt %) is as follows: 0.40 Na₂O, 5.18 K₂O, 0.58 MgO, 3.58 CaO, 4.08 BaO, 3.06 FeO, 13.98 Al₂O₃, 52.94 SiO₂, 15.2 H₂O, and the total is 98.99. The empirical formula is Na_0.15K_1.24Ba_0.30Ca_0.72Mg_0.16F _0.48 ²⁺ [Si_9.91Al_3.09O_25.25(OH)_3.75] · 7.29H₂O. The crystal structure has been determined from a single crystal, R = 0.049. Günterblassite is orthorhombic, space group Pnm2₁; the unit-cell dimensions are a = 6.528(1), b = 6.970(1), c = 37.216(5) Å, V = 1693.3(4) ų, Z = 2. Günterblassite is a member of a new structural type; its structure is based on three-layer block [Si₁₃O₂₅(OH,O)₄]. The strong reflections in the X-ray powder diffraction pattern [d Å (I, %) are as follows: 6.532 (100), 6.263 (67), 3.244 (49), 3.062 (91), 2.996 (66), 2.955 (63), and 2.763 (60). The mineral was named in honor of Günter Blass (born in 1943), a well-known amateur mineralogist and specialist in electron microprobe and X-ray diffraction. The type specimen of günterblassite is deposited in the collections of the Fersman Mineralogical Museum of the Russian Academy of Sciences, Moscow, Russia, with the registration number 4107/1.     

Taipingite-(Ce), (Ce73+, Ca2)Σ9Mg(SiO4)3[SiO3(OH)]4F3, a new mineral from the Taipingzhen REE deposit,North Qinling Orogen,central China

A new cerite group mineral species, taipingite-(Ce), ideally (Ce₇³⁺, Ca₂)_Σ9Mg(SiO₄)₃[SiO₃(OH)]₄F₃, has been found in the Taipingzhen rare earth element (REE) deposit in the North Qinling Orogen (NQO), Central China. It forms subhedral grains (up to approximately 100 ​μm ​× ​200 ​μm) commonly intergrown with the REE mineral assemblages and is closely associated with allanite-(Ce), gatelite-(Ce), törnebohmite-(Ce), fluocerite-(Ce), fluocerite-(La), fluorite, bastnäsite-(Ce), parisite-(Ce) and calcite. Taipingite-(Ce) is light red to pinkish brown under a binocular microscope and pale brown to colorless in thin section, and it is translucent to transparent with a grayish-white streak and vitreous luster. This mineral is brittle with conchoidal fracture; has a Mohs hardness value of approximately 5½ and exhibits no cleavage twinning or parting. The calculated density is 4.900(5) g/cm³. Optically, taipingite-(Ce) is uniaxial (+), with ω ​= ​1.808(5), ε ​= ​1.812(7), c ​= ​ε, and a ​= ​b ​= ​ω. Furthermore, this mineral is insoluble in HCl, HNO₃ and H₂SO₄. Electron microprobe analysis demonstrated that the sample was relatively pure, yielding the empirical formula (with calculated H₂O): (Ce_4.02La_1.64Nd_1.49Pr_0.41Sm_0.10Gd_0.02Ho_0.02Tm_0.01Lu_0.02Y_0.03Ca_0.66Mg_0.05Th_0.01–0.51)_Σ9(Mg_0.75Fe_0.25³⁺)_Σ1(SiO₄)₃{[SiO₃(OH)]_3.98[PO₃(OH)]_0.02}_Σ4(F_1.81OH_1.17Cl_0.02)_Σ3. Taipingite-(Ce) is trigonal and exhibits space group symmetry R3c with unit cell parameters a ​= ​10.7246(3) Å, c ​= ​37.9528(14) Å, V ​= ​3780.39(20) ų and Z ​= ​6. The strongest eight lines in the X-ray diffraction pattern are [d in Å(I)(hkl)]: 4.518(50)(202), 3.455(95)(122), 3.297(85)(214), 3.098(35)(300), 2.941(100)(02,10), 2.683(65)(220), 1.945(40)(238) and 1.754(40)(30,18). The crystal structure has been refined to a R₁ factor of 0.025, calculated for the 2312 unique observed reflections (Fo ​≥ ​4σ). The mineral is named after its discovery locality and is characterized as the F-dominant analogue of cerite-(Ce).     

Heidornit Na2Ca3[Cl · (SO4)2 · B5O8(OH)2] ein neues Bormineral aus dem Zechsteinanhydrit Mit einer röntgenographischen Untersuchung

Ohne Zusammenfassung     

Lavoisierite, Mn2+ 8[Al10(Mn3+Mg)][Si11P]O44(OH)12, a new mineral from Piedmont, Italy: the link between “ardennite” and sursassite

The new mineral species lavoisierite, ideally Mn²⁺ ₈[Al₁₀(Mn³⁺Mg)][Si₁₁P]O₄₄(OH)₁₂, has been discovered in piemontite-bearing micaschists belonging to the Piedmontese Nappe from Punta Gensane, Viù Valley, Western Alps, Italy. It occurs as yellow-orange acicular to prismatic-tabular crystals up to a few millimeters in length, with white streak and vitreous luster, elongated along [010] and flattened on {001}. Lavoisierite is associated with quartz, “mica,” sursassite, piemontite, spessartine, braunite, and “tourmaline.” Calculated density is 3.576 g cm^?3. In plane-polarized light, it is transparent, pleochroic, with pale yellow parallel to [010] and yellow-orange normal to this direction; extinction is parallel and elongation is positive. Birefringence is moderate; the calculated average refraction index n is 1.750. Lavoisierite is orthorhombic, space group Pnmm, with a 8.6891(10), b 5.7755(3), c 36.9504(20) Å, V 1854.3(2) Å³, Z = 2. Calculated main diffraction lines of the X-ray powder diffraction pattern are [d in Å, (I), (hkl); relative intensities are visually estimated]: 4.62 (m) (112), 2.931 (vs) (1110), 2.765 (s) (1111), 2.598 (s) (310), 2.448 (ms) (028). Chemical analyses by electron microprobe give (in wt%) P₂O₅ 2.08, V₂O₅ 0.37, SiO₂ 34.81, TiO₂ 0.13, Al₂O₃ 22.92, Cr₂O₃ 0.32, Fe₂O₃ 0.86, Mn₂O₃ 6.92, MnO 19.09, MgO 5.73, CaO 1.94, Na₂O 0.01, H₂O 5.44, sum 100.62 wt%. H₂O content was calculated from structure refinement. The empirical formula, based on 56 anions, is (Mn _5.340 ²⁺ Mg_1.810Ca_0.686Na_0.006)_Σ=7.852(Al_8.921Mn _1.739 ³⁺ Mg_1.010Fe _0.214 ³⁺ Cr_0.084Ti_0.032)_Σ=12.000(Si_11.496P_0.582V_0.081)_Σ=12.159O_43.995(OH)_12.005. The crystal structure of lavoisierite was solved by direct methods and refined on the basis of 1743 observed reflections to R ₁ = 4.6 %. The structure is characterized by columns of edge-sharing octahedra running along [010] and linked to each other by means of [SiO₄], [Si₂O₇], and [Si₃O₁₀] groups. Lavoisierite, named after the French chemist and biologist Antoine-Laurent de Lavoisier (1743–1794), displays an unprecedented kind of structure, related to those of “ardennite” and sursassite.