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    20 June 2000, Volume 6 Issue 2
    Article
    Progress in Searching Natural High—Pressure Minerals and Its Significance in the Earth’s Mantle Mineralogy
    CHEN Ming, XIE Xian-de
    2000, 6(2):  121-125. 
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    The study of shock-metamorphic effects on the rocks of terre strial impact craters and on meteorites has been an approach in searching natura l high-pressure minerals. Recently, several high-pressure phases including α -PbO2, post-stishovite, (Na,K,Ca)AlSi3O8-hollandite and a high-press ure polymorph of apatite, which could occur in the Earth's mantle, have been fou nd in the meteorites. The findings of natural high-pressure minerals have promo ted the development in the mantle's mineralogy.
    RE-Nb-Ta Mineralogical Investigations in China
    ZHANG Pei-shan, TAO Ke-jie, YANG Zhu-ming
    2000, 6(2):  126-131. 
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    Up to the present day more than one hundred RE-Nb-Ta mine ral species are known in China. Most of their properties, such as chemical compo sitions, physical and optical properties, X-ray diffraction data, occurrences a nd mineral associations, have been described in detail. Majority of these min erals are widespread and a few of them are less common or very rare. These phenomena reveal the special geological conditions and metallogeneses of RE, Nb -Ta in China. The main scientific achievements on RE, Nb-Ta mineralogy in Chin a are summarized as follows: Considerable amount of new mineral species of RE, Nb -Ta have been discovered, s uch as huanghoite, cebaite and zhonghuacerite of fluorocarbonates, ashanite, qit i anlingite and changbaiite of oxides, fergusonite-(Ce), fergusonite-(Nd), f ergu sonite-beta-(Ce), and fergusonite-beta-(Nd) of tantalo-niobates, aeschynite -(Nd), nioboaeschynite-(Ce) and nioboaeschynite-(Nd) of meta-titano-tantalo-niobat es, m onazite-(Nd) of phosphates, daqingshanite of phosphates-carbonates, hingganite , baotit e and saimaite of silicates. The morphotropic series of rare earths-alkaline ea rths-fluoro-carbonate minerals have been discovered and established. The isomorphous series of Na-Ca-Sr-RE fluorocarbonate minerals was also disc ove red, and the regularities of isovalent and heterovalent cation isomorphism was p roved. Through a detailed investigation of meta-RE-Ti-niobate minerals the re gu larity of double isomorphism was established and proved. Two mineral groups, aes chy nite and fergusonite, have been established and developed. The concentration reg ularity of odd number light RE in the Bayun Obo Deposit was discovered. The c rystal structure relationship between complex oxide minerals of Nb, Ta, Fe, Mn a nd W, such as columbite-tantalite, ixiolite, wolframoixiolite, wodginite and qi t ianlingite were clarified. Based on a detailed study of the metamict minerals th e metamict mineralogy has been established as a branch of mineralogy. The regula rity of secondary enrichment of rare earth in the weathering surface of granite bodies has been found. The RE-Nb-Ta ore deposits of ion type and their metallo genic model have been worked out. The Chinese geologists and mineralogists have much to do in RE, Nb and Ta minera logy and they will gain important achievements in the future.
    Structural Ordering and Modulation in Lazurite and Its Relationship with Optical Anomaly
    LUO Gu-feng1, ZHAO Ming1, GE Xiao-yue1, ZHANG Fu-sheng2
    2000, 6(2):  132-136. 
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    In general, lazurites are sweepingly described as symmetr ically cubic and optically isotropic. It was observed that, however, some lazuri tes are of optical anomaly, i.e. they are optically anisotropic. By means of the TEM investigation on lazurite from Baikal, Russia, a diversified variance in la zurite structure is observed, and combining with these diversified structures, t he cause of optical anomaly of lazurite is discussed in this paper as follows: ( 1) The disordered structure of lazurite has a space group of P43n, and consequently it is optically isotropic; (2) The structural ordering, which r esults from that the centers and corners of cubic cells of lazurite are orderly occupied by two different clusters respectively, would lead to an ordered supers trcture. The latter keeps cubic symmetry (but space group becomes P23) and o riginal cell size. Therefore it is still optically isotropic; (3) In the lazurit e studied, the authors discoveried an ordered superstructure which is one-dime ntionally commensurate-modulated along [110] direction with a repeated period of 4d110. This kind of structural modulation makes crystal to b ecome optically anisotropic, because its symmetry is non-cubic; (4) In lazurite the structural modulation resulting from partial ordering is usually incommens urate. It takes place frequently along one or several directions of <110>, <100> and/or <112>etc. Such modulated structure is also generally symmetrically non -cubic and optically anisotropic; (5) However, whether the modulation is commen surate or incommensurate, the structure will be symmetrically modulated-cubic a nd optically isotropic if the modulation concurred along all the symmetrically e quivalent directions. Based on a way proposed by the present authors, the existe nce of suc h modulated-cubic structure in the lazurite studied has been confirmed.
    Using Electron Energy-Loss Spectroscopy(EELS) Associated with Transmission Electron Microscopy to Determine Oxidation States of Ce and Fe in Minerals
    XU Hui-fang
    2000, 6(2):  137-144. 
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    EELS based on features of ELNES of M4 and M5 ed ges can provide information regarding oxidation states of Ce in proposed host ph ases of radioactive wastes (e.g., pyrochlore) and other REE- bearing minerals. M4 and M5 edges of Ce4+ have higher energy-loss than those of Ce3+. Intensity ratio between M4 and M5 edges and weak peaks after the M4 and M5 edges can be used for quantifica tion of Ce3+ and Ce4+. EELS data from an unaltered area of pyrochlo refrom Inner Mongolia o f China indicate Ce3+ and other rare earth elements (REE). However, EELS spectrum from the neighboring altered area shows Ce4+, Ba and other REE. The oxidation of Ce results in loss of REE, U, and alpha decay product Pb during the alteration of the pyrochlore. Based on features of ELNES of L3 edges, EELS spectra can also provide quantitative information regarding oxidati on states of Fe in Fe-bearing amphiboles, Fe-bearing pyroxenes, and other sili ca te minerals. There is a large difference in Fe oxidation states of the amphibole between the directly measured and indirectly calculated methods.
    Bonded Hydrogen in Diamond
    PENG Ming-sheng, YANG Zhi-jun, LIN Bing
    2000, 6(2):  145-148. 
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    The research of purity in diamond has been focused on B & N atoms for a long time. But the research of hydrogen in diamond is just begun rec ently. With the help of vibration spectra including infra-red & Raman spectra, we studied some natural diamonds from Hunan Province and Australia. The hydroge n is bonded in diamond. The first kind of bonded hydrogen is C-H. Where hydroge n can substitute for the carbon atom. Two sharp lines in the Infra-red spectrum at 1405cm-1 and 3107cm-1 are associated with the bending and str etching vibrations of the C-H bond; The second kind of bonded hydrogen is hydr ogen molecule (H2). A sharp line at 4156cm-1 (theoretical value) in Ram an spectrum and a sharp line at 4106cm-1 in Infra-red spectrum due to distorti on field are observed. The experimental value is lower than theoretical value be cause of the isotopic substitution possible (e.g. HD substitutes for H2). The molecular hydrogen is stable in the tetrahedral interstitial sites. But the most stable form of H2 in diamond is the association of a H atom at an anti-bond ing site with a bond-centered H atom;The third kind of bonded hydrogen is O-H & H2O. There are two sharp lines at 3230cm[-1] and 3814cm[-1 ] in Raman spectrum. Owing to different surroundings, hydrogen would be bonde d to different atoms. Consequently, there could be different bonded hydrogen in diamond.
    Some Microstructures of Copper Sulfides in Dongxiang Copper Mine, Jiangxi Province, and Their Geological Implications
    XUE Ji-yue1, SUN Tao1, ZHANG Wen-1an2, CHEN Wu1
    2000, 6(2):  149-155. 
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    Based on the optical microscopy, electron microprobe studies and X-ray powder diffraction analysis it is revealed that the djurleite and dig enite are freguently found in copper ores of Dongxiang Copper Mine, Jiangxi Prov ince. The digenite occurs as the lamellae or lens in the djurleite. These two minerals also appear together with a mutual boundary texture. Their average chemical formulas can be expressed as Cu1.827Zn0.004Ag0. 001S and Cu1.929Fe0.002Zn0.003Ag0.001S,  respectively . Near the area of the metasomatic relicts of pyrites the bornite-digenite z oning is commonly seen. The core is composed of bornite, whereas the digenite oc curs at the rim. The optical property and chemical composition of the digenites in these two different textures are different. These two kinds of digenite are b oth blue gray in reflection color, but the reflection color in digenite intergro wn with djurleite is lighter than that in the zoning one. As for the composition s the digenite intergrown with djurleite does not contain iron, whereas in the z oned digenite the iron contents range from 2.8%(wt.) to 9.1%(wt.). The iron cont ents also decrease toward the rim of the zoning, and the color is getting lighte r under reflected microscope with the iron contents decreasing. The two texture s mentioned above represent two kinds of cooling texture of Cu-S and Cu-Fe- S systems respectively. The intergrowth between the iron-free digenite and the dj urleite was produced by exsolution of high digenite solid solution upon coo ling. The zoning texture of bornite and Fe-bearing digenite is produced by the segregation of the Cu1.8S-CuFeS4 solid solution in the disequilibrium c ondition. It is believed that it represents a kind of texture that forms with ra pid cooling.
    Genesis and Characteristics of Gold Hosted by Pyrite
    GAO Zhen-min, YANG Zhu-sen, LI Hong-yang, LUO Tai-yi, YAO Lin-bo, RAO Wen-bo
    2000, 6(2):  156-162. 
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    Many geological facts show that pyrite is an important gold -hosting mi neral in gold deposits. Many geologists have studied the genesis of this phenome non in the past based on the geochemical properties of elements and adsorption e xperiments. In this paper, the genesis and characteristics of gold hosted by pyr ite is studied mainly in the light of mineral structures and properties as well as crystal growth of pyrite and native gold so as to comprehend this phenomenon further.   According to the statistical data of gold-hosting minerals from 102 gold deposi ts with different genetic types, there are more than 19 species of minerals cons idered as gold-hosting minerals, which include sulfides, oxides, silicates, car bonates and sulfates. Of these gold-hosting minerals, pyrite is the most common and most important gold-hosting mineral in gold deposits. The number of gold d eposits with pyrite as gold-hosting mineral is up to 98% of the total 102 gold deposits, and the number of gold deposits with pyrite as major gold-hosting min eral is about 85%.   The cause for pyrite to be a major gold-hosting mineral comprises three mineral ogical factors: the structural factor,nucleation factor and electrochemical fact or. The biatomic sulfur [S2]2- in the crystal structure of pyrite may cause the reduction of Au+ and Au3+ to Au0 during the biatomic sulfur formtion. The crystal nucleation of native gold usually selects the pyrite surf ace as backing in order to decrease the energy barrier of crystal nucleation, be cause the arrangement of atoms in pyrite is closest to that in native gold. The electrochemical reaction caused by the thermoelectricity of pyrite may take plac e on the pyrite surface, which in turn may reduce the ionic gold to Au0 to cry stallize.   Analysis on the gold-hosting capacity of pyrite shows that the fine-grained,an hedral, cracked pyrites with higher contents of As and Sb, and with P-type the rmoelectricity have higher capacity of gold-hosting. The euhedral pyrites with {210}, step-face {100} and combined form also have higher capacity of gold-hos ting.
    Micro-Mineralogical Approaches in Discoveries of Natural High-Pressure Minerals
    XIE Xian-de, CHEN Ming
    2000, 6(2):  163-166. 
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    11 high-pressure minerals have been found in naturally shocked chondrites.These minerals are main phases of the Earth mantle transition zone and the lower mantl e.Since the grain sizes of the high-pressure minerals are very small, only 1-2 to several tens microns, various micro-mineralogical techniques have been deve loped for study and identification of these tiny minerals,espicially the laser m icro-Raman spectroscopy and the Brucker in-situ micro analytical X-ray system become the key technical approaches for identification of fine-grained new min erals in general, and the tiny new high-pressure polymorph minerals in thin sec tions of meteorites in particular. Some examples in discovery of new mineral pha ses in shock melt veins of chondrites using these techniques are demonstrated by the authors in this paper.
    A Microanalysis Study on Monazite Composition Distribution
    HONG Wen-xing1, ZHU Xiang-kun2
    2000, 6(2):  167-172. 
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    The monazite samples of various genetic types are taken fro m different localities in China and have been analysed by EPMA. The available analytical data show that the monazites of magmatic granite and pegmatite have l ower contents of La (4%~13%), Ce (18%~28%) and higher contents of Sm (2% ~5%), Gd (1%~3%), Y (1%~3%), Th (3%~7%). The monazite of hydrothermal metasomatic origin has higher contents of La (12%~18%), Ce (>28%), and lowe r contents of Gd (<0.3%), Th (0.1%~0.3%) and Y (0.06%~0.14%). The composi tional change profiles of monazite demonstrate a heterogeneous distribution of e lements La, Ce, Nd, P, Th, Si, Ca and U. This was caused by the differences in geological environments, temperatures, pressures and compositions of the hy drothermal solutions.
    Ore-Forming Environmental Indicator Minerals from the Sullivan Giant Pb-Zn-Ag Ore Deposit, Canada
    JIANG Shao-Yong
    2000, 6(2):  173-177. 
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    Sullivan Pb-Zn-Ag deposit (British Columbia, Canada) is a classic SEDE X-type massive sulfide deposit, which occurs conformably within clastic metased i mentary rocks of the Middle Proterozoic Aldridge Formation. Several typical mine rals from this deposit are studied, including B-rich (tourmaline), Cl-rich (sc apolite and biotite), Ba-rich (feldspar and mica), and Mn-rich (garnet, chlori te, carbonate and ilmenite) minerals. Tourmaline shows a wide variation of chemi cal compositions, from Mg-rich dravite to Fe-rich schorl and Ca-rich uvite. T he δ11B values of the tourmalines are from-11.1 to-2.9‰, which is si milar to the range (-15.4 to-1.7‰) found worldwide in tourmalines from mass ive sulfide deposits and tourmalinites in dominantly clastic metasedimentary ter ranes. Multiple stages of tourmaline formation are distinguished in the Sullivan deposit. Cl-rich scapolites occur in the bedded sulfide ores at Sullivan. The scapolite porphyro blasts are more Ca-rich (EqAn= 40.8~50.9) and Cl-poor (XCl= 0.38~0.54) than t he fine-grained euhedral scapolite crystals (EqAn= 22.4~35.1 and XCl= 0. 72~0.8 1) in the same sample. Cl-rich biotites are found only in the bedded sulfide or e s with 0.76 to 1.46 wt% Cl and a limited variation of Mg/(Mg+Fe) ratios (0.34~ 0.37). Other biotites are commonly Cl-poor (<0.2 wt%Cl) and have a wider range of Mg/(Mg+Fe) ratios (0.24~0.69). Ba-rich feldspar and muscovite with BaO up to 6.8 wt% also occur within the bedded sulfide ores in association with to urmaline, carbonates, and sulfides. Mn-rich garnets (up to 79% end-member spe ss artine) at Sullivan constitute coticules (spessartine-quartz rocks) and spessar t ine-rich tourmalinites; they also disseminated in sulfide ores and other countr y rocks. Other Mn-rich minerals include chlorite (up to 4.7 wt% MnO), carbonate s (up to 30 wt% MnO), and ilmenite (up to 16.7 wt% MnO). It is suggested that th e existences of aforementioned B-, Cl-, Ba-, and Mn-rich minerals at Sulliva n ar e indicative of possible non-marine evaporite involvement in the ore-forming s ys tem and the bedded sulfide ores were likely precipitated in a dense brine pool i n the Proterozoic sea floor at Sullivan.
    A Review of Tellurium Minerals
    QIAN Han-dong, CHEN Wu, XIE Jia-dong, HUANG Jing
    2000, 6(2):  178-187. 
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    This paper preliminary summarises 172 tellurium miuerals which have been reported in literatures and formally approved by the Commission on Minerals and Mineral Names (CNMMN) of the International Mi neralogical Association (IMA). A list of these minerals is given as a table. The major element chemical compositions, geochemical features, geochemistry and mod es of occurrences of tellurium minerals, and the achievements acquired in tellur ium mineralogy of China are reviewed. Finally the problems concerning the furthe r studies of tellurium mineralogy and geochemistry are also discussed.
    Two Types of Micrographic Textures in the Tsumoite of Dashuigou Independent Tellurium Deposit, Sichuan Province
    ZHANG Pei-hua1, ZHAO Zhen-hua1, ZHAO Wen-xia1, LAI Ming-yuan2, CAO Zhi-min3
    2000, 6(2):  188-193. 
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    According to the textural features of the guttate, myrmekitic, or threa dlike minerals and the occurrences of host tsumoites under optical and scann ing electronic microscopes, the micrographic textures of tsumoite and sulfides i n Dashuigou tellurium deposit are of two types. The first type shows metasomatic relicts of earlier pyrrhotites hosted in tsumoite, while the second type has t he `guest minerals or mineral mixtures' elongated in specific directions and d istributed metrically in tsumoite `hoster'. They suggest simultaneously two co ntradictory formation mechanisms in traditional meaning-metasomatism and exso lution. However, the mineral paragenesis and occurrence, similarity in chemical comp ositions by EPMA between the "guest minerals" and accompanying sulfides and tell urides of earlier stages, and contrast letween the 2nd texturetype and the ideal model of `exsolution' eliminate the possibility of `exsolution' and conclude a comprehensive metasomatism under varying environments by which these two types o f textures have been formed. From the first to the second type texture, metasoma tism of earlier pyrrhotite and chalcopyrite by Te, Bi rich fluids is intensified with the fluid/sulfides ratios increased and the environment stabilized. Weak a lteration in fluctuational environments would produce tsumoites with typical met asomatic features, whereas complete alteration in a stable environment could dis solve earlier pyrrhotites and/or chalcopyrites in the fluids and produce exsolut ion-like micrographic texture.
    Different Coordination between Hf4+ and Y3+ on Prismatic Faces of Zircon and Its Morphological Constraint
    ZHOU Dong-shan, WANG Xiang
    2000, 6(2):  194-200. 
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    The morphology of naturally grown zircon does not simply confor mto Ha rtman's PBC theory. It is often affected by the physical parameters such as grow th temperature, diffusion coefficient etc. Furthermore, it is ubiquitously restr icted by the anisotropic growth retardarce as the result of the anisotropic subs titution of various ions. After semi-quantitative analysis on {100} and {110} p rism faces, it can be found that the number of chemical bonds between Hf4+ or Y3+ and O2-- on {100} face (n{100} ) differs from that of {110} face (n{110}), and that the streng th of Hf-O, Zr-O and Y-O declines orderly. Because the growth of zircon is ge nerally slow enough, it can be assumed that local equilibrium exists between magmaticmelt and various single crystals during crystallization of zircon. Using the general therm odynamic equation of energy and concentration, the concentration difference of H f4+ and Y3+ ions on {100} and {110} faces can be formulated as: Cx{110}/Cx{100} = A{100}/ A{110}exp[(n{100}-{110})/RT×(EX-O – EZr-O)/RT] where X refers to Hf4+ or Y3+ ions, Zr refers to Zr4+ ions, O refers to O2- ions, E refers to the energy of the chemical bonds between the subscript ions, C and n refer to the concentration. o f subst itutional ions and number of formed chemical bonds on the subscript crystal face respectively. A is related to growth mechanism of zircon, but its differenc e between {100} and {110} faces of zircon is generally small enough to be ignore d. Thus, the concentration difference is mainly determined by the difference in coordination structure of zircon crystal faces and the difference in energy of c orresponding chemical bonds.   When reference data of the energy for Hf-O, Zr-O and Y-O bonds are cited, it can be drawn that Hf tends to enrich itself on {100} face, while Y tends to enrich itself on {110} face. As the result of growth retardarce of the impurity ions, { 100} will be preferentially developed in Hf-rich ziron, while {110} will be pre f erentially developed in Y-rich zircon, which agrees well with previous statisti c s. Finally, as the anisotropic substitution of Hf and Y on {100} and {110} is de pendent on the temperature strongly and with a concise mathematical correlation, a potential geothermometer based on the above relation is proposed.
    Vibrational Spectra of Beryl from Xuebaoding, Pingwu County, Sichuan Province
    GUO Yan-jun, WANG Ru-chang, XU Shi-jin
    2000, 6(2):  201-204. 
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    The natural beryl crystals are commonly prismatic. The tab ular ones are rarely observed. In this paper is given an example of tabular cry stal of beryl from the Xubaodi ng greisen, which merits a study of IR and Raman spectra and comparisons with tw o prismatic crystal samples of beryl from Xuebaoding quartz vein and Altai pegma tite. Both the tabular and prismatic beryls from Xubaoding are rich in Li and Na, their IR and Raman spectra are very similar, and the channel occupied water is mainly of type II, while the channel occupied water for Altai pegmatite is ma inly of type I. Spectral difference between beryl from Xuebaoding and that from Altai is mainly due to the replacement of Be by Li,which is in fact more strong in beryl from Xuebaoding.
    Carbon and Oxygen Isotope Characteristics of the REE-Rich Carbonatite Dyke from Bayun Obo, Inner Mongolia, North China
    YANG Xue-ming1;2, YANG Xiao-yong1;2, ZHENG Yong-fei1, GUO Fan1, ZHANG Zhao-feng1, ZHANG Pei-shan3, M.J. Le Bas4
    2000, 6(2):  205-209. 
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    This contribution analyses the geochemical features of carbo n and oxygen isotope compositions for a REE-rich carbonatite dyke which is loca ted at Dulahala and lies 2 km NNE of the eastern ore body of Bayun Obo giant RE E-Nb-Fe min eral deposit. The dyke cuts across H1 coarse grained quartz sandstone and H3 sha les of the Proterozoic Bayun Obo Group. The analytical results indicate that car bon isotope compositions of the carbonatites vary in a narrow range, with δ 1 3C values between -6.6‰ and -4.7‰ (PDB), which are within the mantle value s ( -5±2‰); while oxygen isotope compositions δ18O have a large range of v ariation from 11.9‰ to 17.7‰ (SMOW) which are apparently higher than mantl e values (5.7±1.0‰), It requires that the carbonatite dyke is more li kely to be related to exchange with low temperature hydrothermal fluids during m agma crystallization or at some later stage after carbonatite magmatism. Both ca rbon and oxygen isotope fractionations between dolomite and calcite from the dyk e is less than 0‰, being in conflict with the sequence of 13 C - and 18 O-enrichment in dolomite relative to calcite at thermodynamic equi librium. The disequilibrium dolomite-calcite paires are not cogenetic, and dolomite might b e of secondary origin, which could be related to the extensive dolomitization in the Bayun Obo area.
    Selenium Concentration and Characteristics of Famatinite from Qiongmo Gold Deposit,Western Qinling Mountains
    LIU Jia-jun1 ;2, LIU Jian-ming3, LU Wen-quart4, LIU Xian-fan1, LING Hong-fei2
    2000, 6(2):  210-214. 
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    The Qiongmo gold deposit occurs in the Cambrian silicalite and slate in the sou th subzone of western Qinling Mountains. The Se-bearing and selenium famatinite are found in quartz-barite veins in the form of dissemination or veinlets. The associated minerals include tiemannite, clasthalite, antimonselite, kullerudi te, penroseite, selenium stibnite, native gold, barite and quartz. The mineral is lead-gray in colour, brashy, with metallic luster, and 0.01~0.1mm in size. The average microhardness is 247.5kg/mm2 (for 50g load) corresponing to Moh s' hardness=4.2. The reflectance values (SiC standard) are given in 10nm steps. The representative R values are: (470nm), Rγ'=22.84~22.50, Rα'= 27.92~27 .99; (550nm), Rγ'= 22.63~22.76, Rα'=27.79~28.11; (590nm), Rγ'=22. 92~ 22.08, Rα'=28.27~28.72; (650nm), Rγ'=23.08~23.76, Rα'=28.79~29.13. E lectron microprobe analyses of eleven points on famatinite gave the results as f ollows (wt%): Sb, 24.42~28.12 (25.79 in average ); Cu, 36.60~39.94 (38.2 0 in average);S, 14.49~25.74 (21.12 in average);Se, 6.11~23.89 (12.76 in average ). Based on Se/(S+Se) ratios of microprobe analyses the mineral is classified as Se-bearing famatinite and selenium famatinite, corresponding to the formula (C u2.84Hg0.01)2.85(Sb1.00As0.07)1.07(S3.54 Se0.46)4.00 and (Cu3.05Hg0.03)3.08(Sb1.07A s0.03)1.10(S2.77Se1.23)4.00 respectively.
    Characteristics of Garnets from the Harlik Metamorphic Belt in Eastern Xinjiang
    ZHAO Ming, WANG Ci-yin
    2000, 6(2):  215-219. 
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    Garnet is often seen in the Harlik metamorphic belt. It is di stinguishe d as two different types by its morphology. The one is of a better crystal shape and formed during regional metamorphism, and the other is usually broken with c racks and recognized as a residue of early stage thermal metamorphism. Both garn ets may occur sometimes in the same samples. This study mainly focuses on the co mposi tions of garnets and their variations. The composition zoning characteristic s of the garnets, in which MnO and CaO decrease and MgO and FeO increase from co re to rim, indicate that the garnet crystallization temperatures were increasing from core to rim. The microprobe analyses reveal remarkable correlation between the MnO concentration in garnet core and its grain size. This suggests that the large garnet porphyoblasts nucleated at earlier stage and lower temperature.
    Mineralogical Paragenetic Relationships of Au-Ag Tellurides in Some Gold Deposits of China
    QIAN Han-dong, CHEN Wu, HUANG Jin, XIE Jia-dong
    2000, 6(2):  220-224. 
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    The paragenetic association of Au-Ag tellurides in Jinjushan, Yinkengshan, Guil a izhuang and Jialu gold deposits has been studied based on the experimental resul ts in Au-Ag-Te ternary system. The space and time paragenetic association of Au-Ag tellurides and their non-paragenetic relationship have been r evealed as well. The experiments show that Au-Ag tellurides are the most import a nt minerals in this kind of gold deposits. The species and quantity of these min erals are controlled by the concentrations of Au, Ag, Te elements and their rati os in solutions of mineralizing system. The existence of petzite and hessite as low-temperature isomorphic modifications indicates that this kind of deposits h as been formed in the low temperature and low pressure environment .
    Surface Function Groups and Surface Reactions of Minerals
    WU Da-qing, DIAO Gui-yi, WEI Jun-feng, YUAN Peng
    2000, 6(2):  225-232. 
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    Because the normal lattice is interrupted, there exists exces s charge density at mineral surface in the "dangling" bonds, which request the surface at oms to be reconstructed. All cleavage surfaces, which by definition have stoichi ometric numbers of surface anions and cations, are autocompensated. However, at fracture and growth surfaces, which can exhibit many possible stoichiometries, t he excess charge may not be autocompensated. In the latter case we refer to pola r surfaces. The polar surfaces are chemically active which can react with water in wet atmosphere or in solution and form hydroxyl functional groups. The surfac e hydroxyl together with surface permanent charges and Lewis site (or Bronsted s ite) as well as sulfhydryl groups of sulfides or salt groups of salt minerals co nstitute the main kind of surface functional groups of minerals. The surface fun ctional groups, which vary with changes of crystal structure and surface composi tion as well as surface topography of minerals, activate as functional groups of chemical agents and control the mineral surface reactivity with other ions and molecules in media. The major types of surface or interface reactions are coordi nation, complexation, oxidation-reduction and ionic exchange as well as heterog eneous catalysis.   The driving force of surface reactions include polarity, charge, Lewis acidity a nd Lewis basicity. The surface coordination is resulted from the electrostatic a ttraction of adions and ionized surface, and depends on charges and radii of ad ions and medium condition as well as mineral surface structure. The functional g roups of organic compounds may form surface complexes with surface hydroxyl grou ps or Lewis site with a variety of arrangements on mineral surfaces. The surface ionic exchange is usually observed on the surfaces of sulfide and carbonate min erals. The sulfur atoms of sulfide minerals are electron donor as they react wit h high oxidation potential ions and may be oxidized to monomorphic sulfur or S 2O32- and SO42-. The heterogeneous catalysis is based on abi li ty of electron coupling of Lewis site or proton donor of Bronsted site on minera l surfaces.   The mineral surface or interface reactions play an important role in the geoche mical processes of element cycling, for example, mineral dissolution and crystal growth are controlled by surface site concentration. The mineral surface functi onal groups and their reactivity are of great significance in material science a nd environmental science.
    Environmental Mineralogy: Environmental Application of Mineralogy to Sciences Studies
    XU Hui-fang
    2000, 6(2):  233-244. 
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    The application of mineralogy in environmental sciences will be a major aspect of mineralogical studies in the 21st century. Thi s article provides some e xamples of environmental mineralogy studies carried out in author's laboratory, such as nuclear waste disposal, mineral surfaces, microbial effects on toxic met al reduction and immobilization, atmospheric aerosol particles, and theoretical calculation of intrinsic sorption constants of metal cations on mineral surfaces . Quantitative study of the interactions in the system of mineral-water-micro be at the molecular level will be important for understanding low-temperature g eochemical and biogeochemical processes.
    Development of Properties of Mineralogy from Resource to Environmental
    LU An-huai
    2000, 6(2):  245-251. 
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    The minerals have been used from the earlier times by their resource properties. Nowadays the minerals are also intensively used by their environmental properties. The environmental mineralogy is a branch of scie nce dealing with interaction between the natural minerals and the spheres of the earth surface, as well as with reflection of global changes, prevention of ecol ogical destruction, remediation of environmental pollution, and interaction of n ano-minerals with bacteria (biomineralogy) and so on. Some details in above-me nt ioned fields are described to show that mineralogists are facing great responsib ilities in promoting both economic and social progress.
    The Mineralogical Problems in Study on Disposal of High Level Radioactive Waste
    CHEN Zhang-ru
    2000, 6(2):  252-254. 
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    The concept on geological disposal of high level radioactive waste (H LW) is a multi-barrier sysytem, including waste container, buffer/backfill mate rial and geological formation. Some significant mineralogical problems related t o geological disposal of HLW are shown below: 1.Mineralogical study of montmoril lonite in bentonite is very important in study on buffer/backfill material of HL W repository. Bentonite mainly consisting of Na-montmorillonite and that of Ca -montmorillonite are very different in many properties. What kind of bentonite is better as a buffer/backfill material in HLW repository? 2.Sorption capacity o f 99 Tc and 129 I on stibnite, boulaugerite and tiemannite is very good. However, these minerals are rare in the nature. It is necessary for miner alogists to find substitutes of those minerals as additives in buffer/backfill m aterials of HLW repository. 3.Zeolite has a good sorption capac ity for some nuclides. Mineralogists should pay attention to application of zeol ite in geological disposal of nuclear wastes.
    An XPS Study on Surfaces of Common Sulfide Minerals
    JIA Jian-ye1, XIE Xian-de1, WU Da-qing1 WANG Jian-cheng2, WANG Yan3
    2000, 6(2):  255-259. 
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    Surface mineralogy is a boundary science between mineralogy and surface sciences, and is also one of the important frontier branches of moder n mineralogy. Research on mineral surface and mineral-liquid interface provides direct or indirect valuable reference not only for the theory of geosciences and environme ntal protection, but also for mineral-rock materials and other related fields. T he surface mineralogy study of sulfides as a common group of important minerals is limited at present. The surface composition and the surface chemical state of sulfides such as pyrite, pyrrhotite, galena, chalcopyrite, sphalerite and arsen opyrite have been studied in this paper by XPS. Some valuable and interesting re sults related to oxidation and secondary change on sulfide surfaces have been g ained from this study. They include: (1) Sulfide surfaces are easy to be oxidize d in air and the products of oxidation are very complex including their metal hi gh valence oxides, hydroxides and sulfates. (2) Pyrite is more stable as compare d with other common sulfides. (3) The atom ratios on sulfide surfaces show an excess sulfur after oxidation. (4) Among the iron-bearing sulfides, the iron o n arsenopyrite surface is relatively stable, besides the iron on pyrite surf ace. However the isomorphic iron on sphalerite surface is easily to be oxidized.
    Characteristics of Zn-Clays Catalysts for Catalytic Ozonation Degrading Process of Dye Wastewater
    YIN Lin
    2000, 6(2):  260-264. 
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    For the difficultly biodegradated organic dye wast ewater, the comparatively ideal experimental results were obtained using Zn- clays c atalysts for multi-catalytic ozonation process. The solid catalysts, made of cl ay carrier and carried Zn oxide, were used to treat the man-made dye wastewat er to raise the catalytic efficiency of ozonation and reduce the costs of trea tment. These solid catalyses can be used repeatedly.
    A Discussion on the Adsorption Mechanism of Palygorskite Clay to Pollutants in Wastewater
    CHEN Tian-hu
    2000, 6(2):  265-270. 
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    Palygorskite is a chain-layered silicate, with a a perture pass of 3.8 ×6.3A.It is gene?rally regarded that because this mineral has microapertur e pass and relatively larger specific surface area, the palygorskite clay is capable o f adsorbing the pollutants in wastewater. Based on the crystal structure of paly gorskite,its adsorption selectivity and our adsorption experiments, the present author holds the following opinion: because most molecules and hydrated ions hav e the diameters larger than that for the aperture pass of palygorskite, they u sually can not get into the aperture pass of palygorskite. Moreover, the inner ape rture pass of palygorskite preferentially adsorbs the water molecules. Terefore, in most cases during wastewater disposal processing the adsorption of palygorsk ite to pollutants is not an inner-surface adsorption, but an outer-surface ad sorption. This outer-surface adsorption is a kind of colloidal and ion exchange ad s orption. Besides the acidity of the solutions, the interaction of coexisting col loidal montmorillonite and palygorskite may play an important role in adsorption ability of palygorskite clay.
    Characteristics of pH Variation in the Cr(VI)-bearing Wastewater Disposed by Clino-Pyrrhotite and Hexa-Pyrrhotite
    LU Xiao-ying, LU An-huai, CHEN Jie, TANG Jun-li, YAO Zhi-jian
    2000, 6(2):  271-277. 
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    The content of Fe in the structure of clino-pyrrhotite is l ower than that in the structure of hexa-pyrrotite. The experiments have been ma de to measure the pH variation of the Cr (VI) - bearing wastewater after treatment b y clino-pyrrhotite and hexa-pyrrhotite respectively. The initial pH values are 3 .40~9.66 and 3.47~9.66 respectively; while after treatment, the pH values beco me 3.61~4.47 and 5.39~6.57 respectively. The disposal efficiency of Cr(VI) by c lino-pyrrhotite is higher than that by hexa-pyrrhotite. However, the disposal ef ficiency of Cr(VI) increases with the oxidized hexa-pyrrhotite. Electro-chemic al analysis shows that increase of pH values in acidic media and decrea se of pH valus in basic media during redox reaction are beneficial to practical disposal due to consuming H+ in acidic media and combination of Fe(II) with OH - in basic media which are also verified by the experimental results.
    Microbial Mineralizations of Iron in Modern Sedimentation Environments
    CHE Yao1, SUN Zhen-ya2, CHEN Jin-zhong1
    2000, 6(2):  278-281. 
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    Bacterial cells, growing naturally in freshwater and marine environments or experimentally in culture, can precipitate a variety of authigen ic iron minerals. Iron hydroxides and oxides are commonest among them. This pape r introduces several mechanisms of microbial mineralizations of iron, including hydroxides, oxides, magnetite, and silicates etc. According to the relationship between biomineralizations and living things, there are two kinds of biominerali zations: the biologic ally induced mineralization and the biologically controlled mineralization. Bact eria may bind metals on charge surface, and their metabolic waste products in th e surrounding environment may induce mineralizations. From the freshwater to the marine environments, from the ancient to the modern geochemical cycles, bacteria get involved in iron circulation from the microcycles to the world scale. The u b iquitous presence of bacteria in aquatic systems and their inherent ability to b iomineralizations, therefore, makes them important agents in driving both modern and ancient geochemical cycles. In addition, the study of biomineralizations can be applied to a variety of fields, including civil engineering, nano-materials and environment protection.
    Application of Clay Minerals in Catalytic Cracking Catalysts
    XIAO Jin-kai1, RONG Tian-jun2
    2000, 6(2):  282-286. 
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    The application of clay minerals in catalytic cracking catalysts is discussed in three aspects in this paper. (1) Before the introduction of amorphous Si and Al gel, the activated white clay represented a historical period.(2) At present th e pillared clay study is one of the frontiers of new catalytic materials worldwi dely. The pillared montnorillonite is currently the most attractive trend in re seach. The pillars of Al multi-nucleus hydroxyl metallic cations or multi-nucl eus hydroxyl bimetallic cations with Al is a major topic at the moment. Furtherm ore there exists a tendeney of development trend in pillar research from the single Al multi-nucleus hydroxyl polyxocation to the bimetallic multi-nucleus hydr oxyl polyxocation of Al and other metals. The pillared illite/smectite inte rstr atified clay minerals are very important for new catalyst carrier.(3) Using kaol inite as a catalytic cracking catalyst carrier is still playing a significant role at the present and in the near future. The catalytic properties of kaolinite are affected by the genesis, mineral compositions, impurities, thermal stability of st ructural hydroxyl and physical properties. Searching for non-active carrier o ut of the natural kaolin may be possible. A study on relationship between the miner alogical characteristics and catalytic properties of catalysts should be stren gthened.
    Study on Passivation of Clay Minerals and Its Mechanism
    ZHANG Hui-fen, FENG Huang, GUO Jiu-gao, WANG Fu-ya, WU Ping-xiao, WANG De-qiang
    2000, 6(2):  287-291. 
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    Clay minerals occur extensively in various geologic enviro nments. In g eotechnical engineering aproblem is always involved about the precaution again st natural calamities and the treatment of soft ground. The key of the problem is controlling and reducing the content of water in clays, and transforming clay minerals from hydrophilic into hydrophobic. In this way the clays won't adsorb w ater an d swell as they were in contact with water, and thus the soil stability could be m aintained. We call the modification of clays for retaining the soil stability in geotechnical engineering ‘passivation’. As the surface of clay minerals inter acts with passivators during the process of passivation, the surface structure of cl a y minerals will be changed and the hydrophobility of clay minerals increased, th us the mechanical strength of clay mineral in the whole will be raised. The surf actant is a very important component in the passivator. However, the adsorption o f surfactants at the interface between solid and liquid is controlled not only b y the properties of surfactants, but also by the properties of solids, pH of sol utions and temperatures etc. So research about the surface structure and the pr operties of solids and the interaction of clay minerals with passivators is an i mport ant way to increase the passivation effect.   Physical and chemical study of mineral surface is an extremely active frontier f ield of scientific research. Our study is based on the physics-chemistry of min e ral surface, and involves many analytical methods: XRD, IR, Raman, MAS NMR, SEM, TEM, AFM, and the parameter measurement of solid mechanics and engineering mec hanics. This paper systematically investigates the change of surface structu re and properties of clay minerals (kaolinite, illite and montmorillonite) befor e and after passivation. In order to clarify the mechanism of clay mineral passi vation and to provide theoretical basis for the clay stabilization in resolving various engineering and calamity problems, analyses and preparation work of pass ivators of clay minerals have been done. The work combines the basic research of mineralogy with the experimental investigation of geotechnical engineering.
    Experimental Study on Preparation of Activated White Clay by Bontonite from Shangtianti District, Xinyang Area, Henan Province
    HUANG Yan-lin, ZHOU Yi-min, LI Ying-tang
    2000, 6(2):  292-297. 
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    The bentonite of Shangtianti district belongs to Ca-bentonite. Its major mineral is Ca-montmorillonite; its colloidal dispersion is not go od; its cation exchange capacity is low; and its exchangeable cations are Ca 2+ and Mg2+. The studies on crystallochemical structure of montmorilloni te indicates that the montmorillonite has a higer ordering degree and a larger l ayer charge. The crystallochemical data indicate that the Shangtianti bentonite is suitable for preparing the activated white clay. The influence of acid curin g, solid-liquid ratios, activation time on the products properties were analyse d. The optium technoloqical conditions were obtained.At the beginning the pur ification of ore was made by pounding of raw ore to the serous liquid. Later on the ore was activated by 16%~20% sulfuric acid solution. The activat ion time was 6~8 hours. The solid-liquid ratio was 1:2. The decolouring forc e of the activated white clay was 156~218 and its activity degree was above 222 m.mol/100g. The main quality parameters of the white clay reach or outstrip the required trade standards. The decolourization effect was very good.
    A Study on the Compositions and Thermophysical Characteristics of Kaolin in Guizhou Province
    CHEN Da-mei, JIANG Ze-chun, JIANG Jiu-yu
    2000, 6(2):  298-305. 
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    Kaolin samples collected from Guiyang, Zunyi, Xiuwen and other localities of Guizhou Province were analyzed by means of X-ray diffraction, electron microprobe, electronp aramagnetic resonance and infrared spectrometry for their compositions and therm ophysical characteristics. The chemical compositions, mineral compositions and me chanism of coloration and whiteness of kaolin provide strong evidence suggesting that the kaolin samples contain iron and titanium. In addition, studies have al so been made on the influence of iron and titanium on the whiteness of kaolin. K aolin samples from different localities are different in texture, shape, whitene ss and color. The existing forms of iron and titanium in kaolin have a great eff ect on the whiteness of kaolin. Moreover, the thermophysical characteristics of kaolin have also documented, demonstrating that kaolin from Guizhou Province is characterized by low thermal expansion coefficient and high emittance. The produ cts of phase transition of kaolin are mullite and cristobalite.
    Application of Non-Metallic Minerals in Antibacterial Materials
    WANG Nin1, LI Bo-wen2, LI Hui-wen1, FENG Jun-ming1
    2000, 6(2):  306-309. 
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    The market of antibacterial products is enlarged rapidly all over the world. The present research and development situation of inorganic a ntibacterial agents and the materials based on non-metallic minerals, such as zeolite and montmorillonite is introduced. The problem in development of anti bacterial agents using natural zeolite, montmorillonite is also disscussed.
    A Discussion on Assessment Index System of Mineral Ultrafine Effects
    DONG Fa-qin1, ZHANG Wu-han2, WAN Pu1, PENG Tong-jiang1, SONG Gong-bao1
    2000, 6(2):  310-314. 
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    This paper mainly studies the ultrafine effects of the miner al ultrafine powders in the property assessment index system of ordinary powders , heteromorphic powders and functional powders. The common testing methods are a lso discussed. It has been shown that the granularity, purity, surface property and micro-particle mechanics are the four major aspects to evaluate the ultrafi ne effects of mineral powders. The mechanical behavior, shape index and unsticking percentage of heteromorphic powders and ordinary powders are essential criteria. More perf ect method for describing the essential behavior of these powders is requested so that the special functions of the heteromorphic mineral powders can be created and designed.
    Experimental Study on Mineral Transformation in Sandstone Reservoir under EOR Conditions
    DENG San-hong, XU Shi-jin, WANG Ru-cheng, LIU Jun-cheng, JIN-Ying
    2000, 6(2):  315-321. 
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    The changes in clay mineral compositions and system fabrics in reservoir sandstone were studied under the high temperature-pressure and fluid circulation condition. The original samples contain quartz, feldspar and clay m inerals. Two core samples were taken for experiments at the temperatures of 150 ℃, 200℃, 250℃ and the pH values of 9, 11, 13. We find that the condition with a temperature of 250℃~300℃ and a pH of 9 is good for enhanced oil recovery ( EOR). The samples were also studied by means of X-ray diffraction and electron m icroprobe analysis. The results suggested that the transformation and migration of the clay minerals is the most important factor that causes damage of reservoir. Some tra nsitional products such as illite, zeolite, gibbsite and montmorillonite, were f ound. It's also detected that some ions in the injection water heavily infl uence EOR because they control the clay minerals reactions. How to prev ent the appearance of swellable and migratable clays is the key to protect perme ability of the reservoir. The results of this paper can be applied to the process of the steam injection or flood injection in reservoir sandstone.
    The Chemical States of Lithium in Lithium-Exchanged Montmorillonite Mineral
    CHEN Wen1;2, XU Qing1;2, YUAN Run-zhang2
    2000, 6(2):  322-326. 
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    The montmorillonite is an aluminosilicate mineral which has 2:1 type la yered structure. The cation exchange in interlayer is an important feature. The montmorillonite is treated by means of lithium exchange in this paper. The che mical states of lithium in lithium-exchanged montmorillonite are analyzed by X RD, IR and XPS etc. The results show that the lithium-exchange is different fro m the other cation-exchange in montmorillonite. Because of smaller ionic radius of Li+ ion, Li+ ions can not only exchange with the absorbed cations in mon tmorillonite interlayer, but also replace the cations in the octahedral sites an d enter into the interstitial positions of montmorillonite lattice. There are th ree chemical states of lithium existing in montmorillonite lattice structure. Among them, number of absorbed Li+ ions in interlayer is more than that of Li+ ions in the replacement and interstitial positions.
    A Study on the Mineralogical Characteristics of Ceramic Glazes
    GONG Guo-hong, TANG Rong-bing, YIN Zuo-ying
    2000, 6(2):  327-332. 
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    This paper introduces the research results of ceramic glazes used in industry and human life. The analyses show that the major compositi ons of ceramic glazes are Al2O3, SiO2; a small quantity of K2O, Na2O, CaO, MgO; and a trace amount of TiO2, Fe2O3, S etc. The major minerals a r e quartz, illite, calcite, feldspar, kaolinite, and talc etc. After baking the raw glazes at differnt temperatures, their chemical compositions, mineral phases and valence states of trace impurity elements are changed. This paper discusse s these changes cau sed by baking at different temperatures. The results are significant in improvin g prescription for ceramic gazes, exploring the optimum temperature of baking a nd manufacturing the high quality ceramic products.
    An Overview of Crystal Chemistry Study on Thermal Expansion of Minerals
    LI Suo-zai, LIAO Li-bing
    2000, 6(2):  333-339. 
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    Thermal expansion is one of the important properties of m inerals and o f theoretical and practical significance. This paper is a review of the crystal chemistry studies on mineral thermal expansion. With some examples, the correlat ions between the thermal expansion coefficients of minerals and the types of cr ystal structures, the nature of chemical bonds, the valencies of ions , the interionic distances, the percentage ionic characters, the electronic conf igurations of ions and the chemical compositions are discussed and summarised . The crystal chemistry approach has been used in the calculation of the th ermal expansion coefficients for minerals with simple structures and composition s. Models suitable for calculation of the thermal expansion coefficients for m inerals with complex structures and compositions are to be developed. To calculate the thermal expansion coefficients of minerals in a wide range, the minerals should be classified according to their crystal chemistry properties. In the light of framework structures upon heatig during which the polyhedra are tilted or fixed, the thermal expansion properties can be divided into two catego ries, the bond-length expansion caterory and the structures with tilts category . The transition metal cation compounds should be considered separately. Based on the above-mentioned types, for the bond-length expansion category only the expansion of bonds in the framework should be considered, but for the structur e with tilts category both the expansion of bonds and the tilts of the polyhedra in framework should be considered.
    Micron Sized Inorganic Porous Non-metallic 0res in China and Their Applications
    MU Shi-chun
    2000, 6(2):  340-344. 
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    Inorganic porous non-metallic ores can be grouped i nto three types according to the size of pore diameter and their applications: n anometer sized (1~100nm), micron sized (0.1~100μm) and millimeter sized (0.1 ~1.0mm). Among them, micron sized porous non-metallic ores chiefly include dia tomaceouse earth, light-weighted opal, porous tuff and siliceous rock etc. Mos t of them occur in activated regions of platform as the results of post-platfor m mineralization at a stable stage.   The principal mineral phase of micron sized porous non-metallic ores is opal, microquartz crystals and rhyolitic glass. The porous siliceous rock mainly consi sts of microquartz crystals and has a high degree of hardness and stability.The opal as a major mineral phase of diatomaceouse earth and light-weighted opal, a nd the rhyolitic glass as a major mineral phase of the porous tuff, are usually unstable. They are very easily to undergo crystallization in nature.   Chemically, the micron sized porous non-metallic ores have the features of higher silicon and lower aluminium, iron etc.. Among them the porous siliceous r ock has the highest contents of SiO2 ( >92%), the diatomaceouse earth and lig ht-weighted opal--less (<92%), and the porous tuff--the lowest(<70%). This is one of the most effective markers to identify porous siliceous rock and diato maceouse earth.   There are similar and different aspects in pore features of micron  sized porou s non-metallic ores. Their similarities are high porosity, low cumulus density and frequent open-pores; Their differences are mainly expressed in size, shape and compression strength of the pores.   The micron sized porous non-metallic ores have strong adsorbability and heat p reservation capacity and can be used as the adsorbents, catalysts, carriers, fi llings and thermal insulation materials. Because of their remarkable functio n in removing particles in filtration and separation, they are the best raw mate rials in making filter aids. Presently, most of micron  sized porous non-metal lic ores as potential non-metallic mineral resources have been gradually utiliz ed in the fields of building materials, chemical engineering, agriculture, food and environmental protection etc.
    The Studies on Dephosphorization of Phosphorus-Rich Rhodochrosite by Microorganisms
    ZHENG Shao-kui1, YANG Min1, GUAN Xiao-hui2, WEI De-zhou3, ZHANG Wei-qing3
    2000, 6(2):  345-348. 
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    Manganese ore in China is rich in phosphorus which is often required to be removed in iron and steel industry. Biological dephosphorization was teste d in this study. Bacillus pulvifaciens and a kind of fungi were comp ared in te rms of organic acid production, and the former was found to be more effective fo r organic acid production and was used in the experiments. The dephosphoriza tion tests on an apatite ore were done in two steps: (1)Phosphate dissolution by lowering pH to 3 via organic acid formation; (2) Phosphate is uptaken by bacteria. The first step could be replaced by adding inorganic acid to adjusting pH.
    Biogenic Lorandite and Its Geological Significance in Xingren County, Guizhou Province
    ZHANG Bao-gui, ZHANG Zhong
    2000, 6(2):  349-355. 
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    Thallium is a very dispersed element and it seldom o ccurs in the form of independent minerals and in independent ore deposits. Biogenic loran dite is the major industrial mineral of the Lanmuchang Tl deposit in Xingren Cou nty, Guizhou Province. It was formed as a result of bioenrichment during sedimen tary diagenesis. A large number of micro-paleofossils, especially foramina and zoaria are still observed in the Tl ores. Most of micro-paleofossils have been replaced by Tl-bearing ore fluid, hence forming T1 minerals with bio-pseudomor phs, such as lorandite and christite.   Bio-enrichment and hydrothermal reworking are the two important metallogenic fe atures for the Tl deposit studied. Biogenic lorandite provides an evidence for t he ore- formation mechanism and timing. An analysis on the time-bound nature of biocoen oses, sulfur isotopic composition and bio-enrichment metallogenic phenomenon sh ows that the Lanmuchang Tl diposit was originally formed in the Late Permian, an d the hydrothermal reworking took place during the Middle Triassic. No Tl minera ls in the form of bio-pseudomorphs have been identified in the Tl ores of hydro thermal reworking stage, indicating that these minerals have been replaced by ty pical hydrothermal Tl-minerals.
    Tourmaline from Xizangite, Eastern Tibet
    SHEN Gan-fu, YAO Peng
    2000, 6(2):  356-363. 
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    Xizangite is a tourmalitic volcanic rocks, discovered and nam ed according to its locality by the authors. This is a new type of igne ous rock. As one of the most important rock-forming minerals within xizangite, the tourm aline from xizangite remarkably differs from that of plutonite, metasomatite a nd tourmalinite in occurrence, texture and structure. Based on the macroscop ic and microscopic mineralogical features of studied tourmaline, and the publish ed experimental data derived from studies of granitic system with added boron, t hi s paper suggests that the majority of tourmaline from xizangite was crystallized directly from a suddenly condensing B- and H2O-rich acid magmatic-hydr othermal transitional fluid. However, it bears even more analogy with magma in overall nature, or the washanite magma. While approaching the earth's surfac e, the internal pressure of washanite magma was much higher than the external p ressure and the space was limited. A cryptoexplosion-explosion took place, and tourmaline cemented the breccia together with quartz and crystals-clasts. Durin g washanite magma overflowing tourmaline and quartz could accumulatively crystal lize separately and form the rhythmic “layering structure.”
    Study on Hard-Dressing SiO2 in Coal and Approach of Its Utilization
    ZHANG Hui, ZHANG Ke-xuan, XIAO Wen-zhao
    2000, 6(2):  364-365. 
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    A Preliminary study in Controlling the Red Tide Calamity by Using Pillared Clay
    WANG Fu-ya, ZHANG Hui-fen, FENG Huang, GUO Jiu-gao, WANG De-qiang
    2000, 6(2):  366-366. 
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    A study to increase the efficiency of Inorganic (Mineral) Modified Ammonium Bicarbonate for Water Spinach
    Wu Ping-xiao, Liao Zong-wen, Mao Xiao-yun
    2000, 6(2):  367-367. 
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