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前言纤鈉铁矾（Sideronatrite）,是一种并不常見的硫酸盐矿物,化学分子式为2Na2O·Fe2O3·4SO3·7H2O。它在国内文献中还未曾报导过。在我们研究过的西北若干硫化物矿床氧化带中,发現有三个矿床氧化带产纤鈉鉄矾,其中两个矿床的纤鈉铁矾发育較好,含量很多。作者在“西北干旱地区多金属矿床氧化带研究”一文里,曾将纤鈉鉄矾与叶绿矾这两种矿物混为一談,在此特作修正。 相似文献
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一、前言柱钾铁矾（Goldichite）,是1955年在美国犹他州发现的一种新矿物。其化学成分为 K2O·Fe2O3·4SO3·8H2O。在以后的国外文献中尚未发现柱钾铁矾的报导,它在我国的发现可能是文献中的第二次报导。我国西北某矿床氧化带产柱钾铁矾的事实早巳被人们知道。在地质部地质博物馆,北京地质学院陈列馆及中国科学院地质研究所等单位均保存着这种矿物标本。前人曾将柱钾铁矾误定名锰明矾,或更形象地称它叫紫矾。 相似文献
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前言作者等于1956-1957年在柴达木北緣某鉛鋅矿床氧化带中找到若干含鋅很高的硫酸盐矿物。其中二种,經过1962-63年的室內工作肯定为鋅赤铁矾（Zincobotryogen）和鋅叶綠矾（Zincocopiapite）。前者是赤铁矾族的新变种,后者是叶綠矾族的新变种。它們在成分上接近于这两族矿物的鋅的极端組分,即鋅赤铁矾的理論分子式为ZnFe3+（SO4）2（OH）·7H2O,鋅叶綠矾的理論分子式为ZnFe43+（SO4）6（OH）2·2OH2O。工作中曾利用了叶韵琴同志采集的部分标本。 相似文献
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云南东川地区,元古界昆阳群落雪白云岩中规模巨大的层状铜矿,1941年由谢家荣命名为“东川式铜矿”[1],用以代表与闪长岩有关的岩浆热液矿床。李洪谟、王尚文(1941年)、孟宪民等(1948年)[3]对这一成因观点都有详细的论述。1960年后,孟宪民指出,东川铜矿可能为沉积成因。笔者在东川白锡腊、因民、落雪、汤丹等地,发现铜矿床中保留了很多沉积成岩的标志,同时根据脉状铜矿是变质脉、岩浆岩的同位素年龄小于层状铜矿等特征,从而提出了沉积变质的成因认识。1975年,桂林冶金地质研究所提出此类矿床应更名为火山—沉积—浅变质矿床[4]。近年来,通过对含矿层的岩相和岩石学的研究、铜矿与藻类叠层石关系的研究,笔者认为,“东川式铜矿”的成因不是单一的,是沉积成岩、蒸发成岩、变质改造等多成因、多阶段形成的一种复合矿床,本文就此进行了探讨。 相似文献
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一、引言黄钾铁矾是硫化矿床氧化带最发育的矿物之一,以数量而论,它仅次于褐铁矿而居第二位。如果以矾类矿物而论,可以说是矾中之王。一般来说,在硫化矿床氧化带中或多或少都有黄钾铁矾的存在。祁连山金属硫化矿床中的黄钾铁矾是相当发育的,而某些硫化矿床(例如锡铁山、照壁山等)的氧化带中黄钾铁矾的数量占绝对优势,这种情况在苏联乌拉尔等矿床中也同样见到。黄钾铁矾在质纯量多的情况下经煅烧后可以作研磨原料,亦可制造明矾和肥料之用。 相似文献
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广西灵山矿区锰钴土产于矿床氧化带中。其上部是风化的铁帽,下部是黄铁矿。锰钴土结构疏松,富于孔隙,颜色随风化程度强弱而有所变化。其主要矿物成分为高岭土和水云母,其次为褐铁矿、石英、镍华、钴华、黄铁矿等。锰钴土中含有丰富的铜(0.338%)、钴(0.06-0.418%)、镍(0.05%)等16种元素。为了查明锰钴土中铜的赋存状态,为选矿、冶炼及综合利用提供资料,我们进行了电渗析研究。 相似文献
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微量銻的测定在寻找有色金属及貴金属硫化物矿床时有一定的地貭意义,因为它可以作为一个原生矿或伴生矿物的指示元素。銻的光譜分析灵敏度为n×10-2％,根据В.И.納尔納茨基和А.П.維诺格拉多夫的材料,銻在岩石及土壤中的平均含量約在1×10-5-4×10-5％之間,所以我在工作中試驗出了一个灵敏的快速測定銻的方法。一、提示:在含有6N盐酸的亚硝酸钠溶液中,三价銻被氧化而轉变成鉻阴离子[SbCl6]-,此铬阴离子在2.9N的盐酸溶液中,与甲基紫形成稳定的蓝色鉻合物,此有色鉻合物能很好地被甲苯萃取出来。 相似文献
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矿床的氧化带对闡明成矿規律和找矿勘探有着重要的意义。我們在調查西北多金属矿床的同吋,曾对氧化带的形成和物貭成分进行了一些研究,特别是对几个具有代表意义矿床(A、B、C、D、E)的氧化带进行了比較詳細的工作。文內主要叙述这五个矿床的氧化带。本文资料来源根据叶韵琴、賀灌之、任英忱、李錫林的研究报告。初稿写成后經涂光熾先生詳細审閱和修改,文中有关化学分析和光譜分析由本所中心室完成,脫水分析由李夷等同志完成;部分X-光分析由任培祐、郑耀宗等同志完成,謹向他們致謝。 相似文献
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《International Geology Review》2012,54(6):639-644
In studying the conditions of formation of stony meteorites, we assume that 1) they are fragments of asteroids fallen to the surface of the earth. During their flight through the atmosphere, the meteorites develop a melted surface layer but their texture and mineralogic composition remain unchanged. 2) According to V. M. Goldschmidt, stone meteorites crystallize in a lesser gravity field than that of the earth, which is the reason for their chondritic texture and high porosity (about 4%). 3) Meteorites were formed in a medium with a deficiency of free oxygen. As a result, part of their iron and nickel was segregated as native metal; in addition, lawrencite and oldhamite, sulfides typical of meteorites, were formed. We identify three stages of meteorite formation: magmatic, pneumatolytic, and hydrothermal. The interval 1450-850°C. corresponds to the magmatic stage at which a silicate phase and native iron with nickel were formed. As a result of thermal dissociation of water and because of the deficiency of oxygen required for a complete oxidation of metals and carbon, in the gaseous phase, free oxygen and H2O were absent and the phase consisted probably of H2, CH4, CO2, and CO. The temperature interval 750-500°C. corresponds to the pneumatolytic phase. Here, H2S, CH4, CO2, and CO were the principal agents of the gaseous phase. CH4 was formed in a high temperature reaction between hydrogen and elementary carbon. As the temperature dropped to 750°C., electrolytic dissociation of H2O rendered possible the formation of sulfides, especially of troilite. Mineralization at the hydrothermal stage with a temperature interval of 400 to 300°C. has been observed only in carbon meteorites with a considerable graphitic carbon content. Here, a small portion of the ferrous iron is oxidized to the ferric, in the presence of CO2 and at a temperature of 450° to 500°C.; the iron sulfide so formed is represented by pyrrhotite. Simultaneously, colored silicates are chloritized, with a separation of CaCO3.—Auth. English summ. 相似文献
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Vishnevsky A. V. Belogub E. V. Charykova M. V. Krivovichev V. G. Blinov I. A. 《Geology of Ore Deposits》2018,60(7):559-567
Selenium is one of the most important minor elements in massive sulfide ores. This study focuses on selenium minerals present in the oxidation zone of the Yubeleinoe massive sulfide deposit, the South Urals, Russia: clausthalite (PbSe), tiemannite (HgSe), and naumannite (Ag2Se). These minerals are associated with goethite and siderite. Thermodynamic modeling was used to estimate the physicochemical parameters of selenide stability and the possible formation of Pb, Hg, and Ag selenites as a result of sulfide ore oxidation. The Eh–pH diagrams for the Fe–S–CO2–H2O and Fe–Se–CO2–H2O systems were calculated to estimate the physicochemical formation conditions of the Yubileinoe oxidation zone, as well as for the M–Se–Н2О and M–S–H2O (M = Hg, Pb, Ag) systems. The physicochemical parameters of clausthalite, naumannite, and tiemannite stability are consistent with these conditions. Only the formation of PbSeO3 is theoretically possible among Pb, Ag, and Hg selenites.
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Major uncertainties exist with respect to the aqueous geochemical evolution of the Martian surface. Considering the prevailing cryogenic climates and the abundance of salts and iron minerals on Mars, any attempt at comprehensive modeling of Martian aqueous chemistry should include iron chemistry and be valid at low temperatures and high solution concentrations. The objectives of this paper were to (1) estimate ferrous iron Pitzer-equation parameters and iron mineral solubility products at low temperatures (from < 0 °C to 25 °C), (2) incorporate these parameters and solubility products into the FREZCHEM model, and (3) use the model to simulate the surficial aqueous geochemical evolution of Mars.Ferrous iron Pitzer-equation parameters were derived in this work or taken from the literature. Six new iron minerals [FeCl2·4H2O, FeCl2·6H2O, FeSO4·H2O, FeSO4·7H2O, FeCO3, and Fe(OH)3] were added to the FREZCHEM model bringing the total solid phases to 56. Agreement between model predictions and experimental data are fair to excellent for the ferrous systems: Fe-Cl, Fe-SO4, Fe-HCO3, H-Fe-Cl, and H-Fe-SO4.We quantified a conceptual model for the aqueous geochemical evolution of the Martian surface. The five stages of the conceptual model are: (1) carbonic acid weathering of primary ferromagnesian minerals to form an initial magnesium-iron-bicarbonate-rich solution; (2) evaporation and precipitation of carbonates, including siderite (FeCO3), with evolution of the brine to a concentrated NaCl solution; (3) ferrous/ferric iron oxidation; (4) either evaporation or freezing of the brine to dryness; and (5) surface acidification.What began as a dilute Mg-Fe-HCO3 dominated leachate representing ferromagnesian weathering evolved into an Earth-like seawater composition dominated by NaCl, and finally into a hypersaline Mg-Na-SO4-Cl brine. Weathering appears to have taken place initially under conditions that allowed solution of ferrous iron [low O2(g)], but later caused oxidation of iron [high O2(g)]. Surface acidification and/or sediment burial can account for the minor amounts of Martian surface carbonates. This model rests on a large number of assumptions and is therefore speculative. Nevertheless, the model is consistent with current understanding concerning surficial salts and minerals based on Martian meteorites, Mars lander data, and remotely-sensed spectral analyses. 相似文献
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《Applied Geochemistry》2006,21(7):1216-1225
The aim of the study was to determine whether the application of bulk industrial chemicals (potassium permanganate and water-soluble phosphate fertilizer) to partly oxidized, polyminerallic mine wastes can inhibit sulfide oxidation, and metal and metalloid mobility. The acid producing waste rocks were metal (Pb, Zn, Cu) and metalloid (As, Sb) rich and consisted of major quartz, dickite, illite, and sulfide minerals (e.g., galena, chalcopyrite, tetrahedrite, sphalerite, pyrite, arsenopyrite), as well as minor to trace amounts of pre- and post-mining oxidation products (e.g., hydrated Fe, Cu, Pb, and alkali mineral salts). SEM-EDS observations of treated waste material showed that metal, metal–alkali, and alkali phosphate coatings developed on all sulfides. The abundance of phosphate phases was dependant on the fertilizer type and the availability of metal and alkali cations in solution. In turn, the release of cations was dependent on the amount of sulfide oxidation induced by KMnO4 during the experiment and the dissolution of soluble sulfates. Mn, Ca, Fe, and Pb phosphates remained stable during H2O2 leaching, preventing acid generation and metal release. In contrast, the lack of complete phosphate coating on arsenopyrite allowed oxidation and leaching of As to proceed. The mobilized As did not form phosphate phases and consequently, As displayed the greatest release from the coated waste. Thus, the application of KMnO4 and the water-soluble phosphate fertilizer Trifos (Ca(H2PO4)2) to partly oxidized, polyminerallic mine wastes suppresses sulfide oxidation and is most effective in inhibiting Cu, Pb, and Zn (Sb) release. However, the technique appears ineffective in suppressing oxidation of arsenopyrite and preventing As leaching. 相似文献
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Lev N. Neretin Michael E. Böttcher Igor I. Volkov Katharina Hilgenfeldt 《Geochimica et cosmochimica acta》2004,68(9):2081-2093
Pyritization in late Pleistocene sediments of the Black Sea is driven by sulfide formed during anaerobic methane oxidation. A sulfidization front is formed by the opposing gradients of sulfide and dissolved iron. The sulfidization processes are controlled by the diffusion flux of sulfide from above and by the solid reactive iron content. Two processes of diffusion-limited pyrite formation were identified. The first process includes pyrite precipitation with the accumulation of iron sulfide precursors with the average chemical composition of FeSn (n = 1.10-1.29), including greigite. Elemental sulfur and polysulfides, formed from H2S by a reductive dissolution of Fe(III)-containing minerals, serve as intermediates to convert iron sulfides into pyrite. In the second process, a “direct” pyrite precipitation occurs through prolonged exposure of iron-containing minerals to dissolved sulfide. Methane-driven sulfate reduction at depth causes a progressive formation of pyrite with a δ34S of up to +15.0‰. The S-isotopic composition of FeS2 evolves due to contributions of different sulfur pools formed at different times. Steady-state model calculations for the advancement of the sulfidization front showed that the process started at the Pleistocene/Holocene transition between 6360 and 11 600 yr BP. Our study highlights the importance of anaerobic methane oxidation in generating and maintaining S-enriched layers in marine sediments and has paleoenvironmental implications. 相似文献
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《Applied Geochemistry》2006,21(8):1259-1273
Grains of naturally oxidized arsenopyrite [FeAsS] collected from the oxidation zone in W-mine tailings were investigated, primarily using transmission electron microscopy. The grains are severely pitted and are surrounded by secondary minerals. The pitted nature of the grains is related to mechanisms governing the electrochemical oxidation of sulfide minerals, with prominent cusp-like features occurring at cathodic regions of the surface, and pits occurring at anodic regions. In general, the oxidation of arsenopyrite leads to the formation of an amorphous (or nanocrystalline) Fe–As–O-rich coating that contains small amounts of Si, Ca, Cu, Zn, Pb and Bi; nanoscale variation in the As, Pb, Bi and Zn contents of the coating was noted. Secondary Cu sulfides, thought to be chalcocite [Cu2S] and (or) djurleite [Cu31S16], occur as a layer (generally <500 nm thick) along the arsenopyrite grain boundary, and also within the coating as aggregates, and as layers that parallel the grain boundary. Although the precipitation of secondary Cu minerals along the grain boundary is a nanoscale feature, the process of formation is thought to be analogous to the supergene enrichment that occurs in weathered sulfide deposits. As the oxidation of arsenopyrite proceeds, layers and clusters of secondary Cu sulfides become isolated in the Fe–As–O coating. Secondary wulfenite [PbMoO4] and an unidentified crystalline Bi–Pb–As–O mineral occur in voids within the coating, suggesting that these minerals precipitated from the local pore-water. Small and variable amounts of W, Ca, Bi, As and Zn are associated with the wulfenite, and Zn, Fe and Ca are associated with the Bi–Pb–As–O mineral. Some of the wulfenite is in contact with inclusions of molybdenite [MoS2], suggesting that the oxidation of molybdenite in the presence of aqueous Pb(II) led to the formation of wulfenite. Mineralogical analyses at the nanoscale have improved the understanding of geochemical sources and sinks at this location. The results of this study indicate that the mineralogical controls on aqueous elemental concentrations at this tailings site are complex and are not predicted by thermodynamic calculations. 相似文献
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《Geochimica et cosmochimica acta》1999,63(19-20):3159-3169
Using zinc sulfide as an example, we demonstrate a plausible stepwise process for the formation of minerals from low temperature aqueous solutions. The process occurs with the formation of soluble complexes that aggregate into soluble rings and clusters. The final moiety in solution has a structure similar to the moiety in the first formed solid, which is a restatement of the Ostwald step rule. Titrations of aqueous Zn(II) with bisulfide indicate that sulfide clusters form at concentrations of 20 μM (or less) of metal and bisulfide. Precipitation does not occur according to voltammetric measurements using a mercury electrode and UV-VIS (ultra-violet to visible) spectroscopic data. UV-VIS data and filtration experiments indicate that the material passes through 0.1 μm Nuclepore and 1000 dalton filters. The complexes form rapidly (kf > 108 Ms−1), are kinetically inert to dissociation and thermodynamically strong. Although a neutral complex of 1:1 (ZnS) empirical stoichiometry initially forms, an anionic complex with an empirical 2 Zn:3 S stoichiometry results with continued addition of sulfide. Gel electrophoresis confirms the existence of a cluster that is negatively charged with a molecular mass between 350 and 750 daltons. On the basis of known mineral and thiol complex structures for these systems, a tetrameric cluster unit of Zn4S6(H2O)44− is likely. Molecular mechanic calculations show that this cluster is structurally analogous to ZnS minerals (particularly sphalerite) and is a viable precursor to mineral formation and a product of mineral dissolution.The formation of Zn4S6(H2O)44− can occur from condensation of Zn3S3(H2O)6 rings, which are neutral molecular clusters. The Zn atoms on one Zn3S3(H2O)6 ring combine with the S atoms on another Zn3S3(H2O)6, to lead to higher order clusters with loss of water. The Zn4S64− species form by the cross-linking of two neutral Zn3S3 rings by added sulfide; thus a Zn–S–Zn bridge forms across the rings with subsequent rearrangement and condensation to Zn4S64−; this combination results in a sphalerite-like cluster. If the rings condense without additional sulfide, a wurtzite-like structure could form. All condensations result in sulfide displacement of water from Zn to form Zn–S bonds. Water loss is an example of an entropy-driven process, which leads to a more favorable thermodynamic process. These clusters would be resistant to oxidation by O2. Voltammetric experiments indicate neutral and anionic clusters for Zn and agree with ion chromatographic data from the sulfidic waters of the Black Sea. 相似文献
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Arsenic sulfide (AsS (am), As2S3 (am), orpiment, and realgar) oxidation rates increase with increasing pH values. The rates of arsenic sulfide oxidation at higher pH values relative to those at pH∼2 are in the range of 26-4478, 3-17, 8-182, and 4-10 times for As2S3 (am), orpiment, AsS (am), and realgar, respectively.Numerical simulations of orpiment and realgar oxidation kinetics were conducted using the geochemical reaction path code EQ3/6 to evaluate the effects of variable DO concentrations and mineral reactivity factors on water chemistry evolution during orpiment and realgar oxidation. The results show that total As concentrations increase by ∼1.14 to 13 times and that pH values decrease by ∼0.6 to 4.2 U over a range of mineral reactivity factors from 1% to 50% after 2000 days (5.5 yr). The As release from orpiment and realgar oxidation exceeds the current U.S. National Drinking Water Standard (0.05 ppm) approximately in 200-300 days at the lowest initial dissolved oxygen concentration (3 ppm) and a reactivity factor of 1%. The results of simulations of orpiment oxidation in the presence of albite and calcite show that calcite can act as an effective buffer to the acid water produced from orpiment oxidation within relatively short periods (days/months), but the release of As continues to increase.Pyrite oxidation rates are faster than orpiment and realgar from pH 2.3 to 8; however, pyrite oxidation rates are slower than As2S3 (am) and AsS (am) at pH 8. The activation energies of arsenic sulfide oxidation range from 16 to 124 kJ/mol at pH∼8 and temperature 25 to 40°C, and pyrite activation energies are ∼52 to 88 kJ/mol, depending on pH and temperature range. The magnitude of activation energies for both pyrite and arsenic sulfide solids indicates that the oxidation of these minerals is dominated by surface reactions, except for As2S3 (am). Low activation energies of As2S3 (am) indicate that diffusion may be rate controlling.Limestone is commonly mixed with sulfide minerals in a mining environment to prevent acid water formation. However, the oxidation rates of arsenic sulfides increase as solution pH rises and result in a greater release of As. Furthermore, the lifetimes of carbonate minerals (i.e., calcite, aragonite, and dolomite) are much shorter than those of arsenic sulfide and silicate minerals. Thus, within a geologic frame time, carbonate minerals may not be present to act as a pH buffer for acid mine waters. Additionally, the presence of silicate minerals such as pyroxenes (wollastonite, jadeite, and spodumene) and Ca-feldspars (labradorite, anorthite, and nepheline) may not be important for buffering acid solutions because these minerals dissolve faster than and have shorter lifetimes than sulfide minerals. However, other silicate minerals such as Na and K-feldspars (albite, sanidine, and microcline), quartz, pyroxenes (augite, enstatite, diopsite, and MnSiO3) that have much longer lifetimes than arsenic sulfide minerals may be present in a system. The results of our modeling of arsenic sulfide mineral oxidation show that these minerals potentially can release significant concentrations of dissolved As to natural waters, and the factors and mechanisms involved in arsenic sulfide oxidation warrant further study. 相似文献