Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevior  

Publisher：Clays and Clay Minerals  

DOI： 10.1007/s42860-019-00045-w

Scopus

Authorship：Lead author  

DOI： 10.1346/CCMN.2018.064105

Scopus

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Japan Association of Mineralogical Sciences  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：日本粘土学会  

Other Link： https://www.jstage.jst.go.jp/browse/jcssjclayscience/-char/ja/

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.11362/jcssjclayscience1960.12.1

DOI： 10.11362/jcssjclayscience.18.2_33

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.11362/jcssjclayscience.15.3_139

Authorship：Lead author  

DOI： 10.11362/jcssjclayscience.15.1_33

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English  

DOI： 10.11362/jcssjclayscience.14.6_219

Authorship：Lead author   Language：English  

DOI： 10.11362/jcssjclayscience.14.5_177

Language：English   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Publisher：The Clay Science Society of Japan  

Geochemical and mineralogical investigations of CaCO<SUB>3</SUB> precipitation in Anraku hot spring of Kagoshima Prefecture were carried out to evaluate the effects of cyanobacteria on precipitation rates and polymorphism of CaCO<SUB>3</SUB> minerals. The CaCO<SUB>3</SUB> precipitates form surface sediments of the hot spring along water passage about 5m length and 10m width. These CaCO<SUB>3</SUB> sediments consist mainly of aragonite (70-88 wt.%) with variable amounts of calcite, on which cyanobacterial biofilms were developed. Chemical analysis of the hot spring water collected along the water passage with intervals of 1.5m indicated that the water was highly supersaturated with respect to both aragonite and calcite with SI (log (<I>IAP/K</I>))=0.7-1.4. Such high SI values seem to be achieved mainly by the result of abiotic CO<SUB>2</SUB> degassing and also by CO<SUB>2</SUB> removal due to photosynthesis of cyanobacteria. To evaluate the effect of cyanobacteria, we performed experimental synthesis of CaCO<SUB>3</SUB> minerals using the hot spring water in the systems with and without cyanobacteria (<I>Phormidium</I> sp.) isolated from the hot spring. The experiment was conducted at 25&deg; for 10days under 4, 000Lx light condition. Results of the comparative experiment, it was found that the precipitation rates of CaCO<SUB>3</SUB> in biotic system were enhanced by 1.9 to 32 times compared with the abiotic system due to the cyanobacterial photosynthesis which cause rapid increase in solution pH and also in saturation states. In addition, extent of aragonite formation was greatly induced up to 94-97 wt.% relative to abiotic system by possibly interaction with acidic proteins released from the cyanobacterial cells into the solution.

DOI： 10.11362/jcssjnendokagaku1961.46.156

Publisher：The Clay Science Society of Japan  

Surface complexation model of Pb(II), Cu(II), Zn(II), Cd(II), As(V), Cr(VI), F(I), and B(III)ions on the surface of schwertmannite was examined with the fitting program FITEQL. Total numbers of surface sites and their protonation and deprotonation constants were initially determined by acid-base titration data with FITEQL analysis. Then, ion adsorption experiments were performed and the resulting adsorption data were used for modeling of the surface complexation. Results indicate that the cationic ions (Pb(II), Cu(II), Zn(II), Cd(II)) were strongly adsorped at pH>6-8 by complexation with the negatively charged surface sites. Whereas the anionic ions (As(V), Cr(VI), F(I)) were adsorped progressively with decreasing pH due to complexation with the positively charged sites. These adsorption properties on the schwertmannite surface were evaluated by complexation equilibrium constants of the surface species. In addition, effect of adsorped ions on the stability of schwertmannite structure was investigated by aging at 50℃. X-ray diffraction analysis indicated that adsorption of As(V) inhibited strongly phase transition to goethite.

Publisher：The Clay Science Society of Japan  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Publisher：鹿児島大学  

The Pliocene-Pleistocene Carcar Formation and the Quaternary Alluvium are two major lithologies that rim the entire island province of Cebu. The Carcar Formation (CaF) is predominantly limestone rock mass characterized by rolling to hilly topography while the Quaternary Alluvium (QA1) is generally unconsolidated sedimentary deposit on coastal plain marked by low relief and undulating landscape. Mineralogical examinations of the vertisolic soil/clay horizons that mantle these rock formations were conducted to identify and characterize the nature of clay minerals using X-ray diffraction (XRD), differential thermal analysis (DTA), thermogravimetry (TG), scanning electron microscopy (SEM), and energy dispersive x-ray (EDX). Analytical qualitative results show that the clays derived from the Carcar Formation are chiefly smectite-rich assemblage with supplemental association of mixed-layer kaolinite/smectite. Clays from the Quaternary Alluvium are the same as in the CaF, however, mixed-layer kaolinite/smectite in the QA1 appears relatively richer than in the CaF. Quantitative estimates by computer simulation yield slight to moderate variations in the proportions of kaolinite and smectite in the mixed-layer phase, and correlatively, the degree of ordering is determined to be random in both CaF and QA1 clay assemblages. Kaolinite content participating in the interstratified phase is discerned to be diagnostically higher in the alluvium than in the limestone. Calcite impurities occur greater in clays sourced from the Carcar Formation and are found comparatively rarer in the Quaternary Alluvium. Quartz is noted to be frequently present in minor to moderate amounts in both lithologies but is generally more persistent in the QA1. The mixed-layer kaolinite/smectite phase is observed in both CaF and QA1 and revealed that it is not an exotic clay phase exclusively confined in the red-burning clay area. Illite or illitic facies is found only in the QA1 and is envisaged as authigenically or neogenically formed. Smectite with high rehydration capacity is recorded only in the CaF and is believed to be a result of its structure and beidellitic composition.

Publisher：鹿児島大学  

Clay minerals of stratified tuff and mudrocks of the Middle Miocene Paghumayan Formation in Vallehermoso, Negros Oriental, Philippines were examined. The results showed homogeneity of clay mineralogy in the sedimentary sequence with single-phase smectite as the dominant phyllosilicate present and with little association of kaolinite. Feldspar, zeolite, cristobalite, quartz and calcite are typical non-sheeted accessories that yield to some mineral assemblages along with smectite. The signature mineral assemblage is smectite-feldspar-zeolite-silica. The smectite is of the dioctahedral montmorillonite type, the feldspar is plagioclase and the zeolite is of the clinoptilolite or heulandite species. Between the silica polymorphs, cristobalite is more prevalent than quartz in most of the assemblages. One sample is detected to contain almost entirely of crystalline calcite with smectite which authenticate the presence of calcareous horizon or several horizons intercalated with the tuff and mud beds. The minerals and mineral assemblages formation is strongly implicit of halmyrolysis in continuum with early diagenesis in a closed system submarine environ and envisaged to have been induced favorably by calcic-silicic-alkalic, moderate pH, and low-temperature-pressure conditions of shallow burial sedimentation.

Publisher：鹿児島大学  

Serpentinized peridotite is an ultramafic rock that intrudes, during Cretaceous time, as widely scattered diapiric bodies along the principal fault zones of central Cebu, Philippines. This rock is exposed to chemical weathering in tropical conditions and through the leaching reactions leave a friable mantle of in situ regolithic materials. It is envisaged that the serpentine was derived from a pyroxene-rich peridotite. The <2μm clay fraction of four regolithic materials obtained from this rockmass in Camp 7,Minglanilla were examined by means of x-ray diffractometry (XRD), differential thermal analysis (DTA), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and energy dispersive x-ray (EDX). Results of analyses showcase the polymineralic and heterogeneous nature of the weathered specimens with serpentine predominating, and could be differentiated possibly into two distinct assemblages. The first assemblage consists principally of serpentine-talc-chlorite-smectite and the second assemblage consists of serpentine-chlorite-smectite. Kaolinite is present in trace amounts in both suites. It is strongly perceived that these secondary minerals are genetic products from cadence of chemical alterations of primary ferromagnesian minerals particularly orthopyroxenes and clinopyroxenes. The two assemblages appear to interpret the weathering reaction stages that the hypermelanic peridotite protolith had undergone. The first assemblage possibly corresponds to saprock (friable rock zone) which suggests the earlier stage and lesser intensity of weathering while the second assemblage possibly relates to saprolite (argillized solifluxed zone) which indicates the more advanced and greater intensity of weathering. The transition from the first assemblage to the second assemblage appears telescoping as indicated by the gradating loss of talc in the system. Both assemblages appear highly magnesian, ferruginous, siliceous and non-aluminous.

Language：English  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English  

DOI： 10.1346/000986002761002865

Scopus

Language：English  

DOI： 10.11362/jcssjclayscience1960.11.585

DOI： 10.2465/jmps.96.109

Publisher：American Mineralogist  

DOI： 10.2138/am-2001-0403

Scopus

Publisher：The Clay Science Society of Japan  

DOI： 10.11362/jcssjnendokagaku1961.40.197

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (scientific journal)  

Publisher：Journal of Mineralogical and Petrological Sciences  

DOI： 10.2465/jmps.96.109

Scopus

Publisher：American Mineralogist  

DOI： 10.2138/am-2001-2-311

Scopus

Publisher：American Mineralogist  

DOI： 10.2138/am-2001-1005

Scopus

Publisher：日本鉱物科学会  

マビニのソロで，安山岩質岩石の熱水粘土化作用によって形成された変質ハローの中にアルミニウムに富む粘土鉱物を構成成分とする混合層鉱物が見出された。この粘土化変質は，低硫化熱水系中の塩素ガスが溜まっているゾーンか酸性の蒸気熱環境域の上部に見られる。混合層鉱物を多く含む部分には，微細結晶のカオリナイトと鉄明ばん石を伴って多くのイライト/スメクタイト型混合層鉱物（I/S）と少量の二八面体型クロライト/スメクタイト型混合層鉱物（C/S）が認められる。これらの鉱物は，変質ハローの中の内帯に存するカオリナイトースメクタイト帯と周辺部に存するクロライトーイライト帯の中間に産する。<br>&nbsp;&nbsp;&nbsp;アルミニウム質イライトとスメクタイトの混合層鉱物には，構成するそれぞれの鉱物層の比率およびそれらの継続確率，化学組成，結晶形態にいろいろ違いがみられた。これらの変化は，混合層鉱物がスメクタイトからイライトに変化する過程で種々の段階で形成されたためである。この変化過程における混合層鉱物の形成は必ずしも連続的ではなく，ライヒバイテ<i>R</i>=0 (>55% スメクタイト）から<i>R</i>=1 (50&sim;20% スメクタイト），そして最終的には<i>R</i>=2 (<20% スメクタイト）に変化している。I/S (65%&sim;10% スメクタイト）中のスメクタイト% は，カオリナイト/スメメクタイト帯から離れるにしたがって減少している。K₂Oの値は，クロライトーイライト帯に近づくほど増加している。アルミニウム質クロライト/スメクタイト混合層鉱物は，変質ハローの中には少量みられるだけである。スメクタイトからイライトへの変換の過程で生成される混合層鉱物の生成機構は，安山岩質岩石から溶脱されたAlやK⁺ を含んだ熱水溶液とスメクタイトの反応で形成されたものと考えられる。

DOI： 10.2465/ganko.95.37

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Publisher：一般社団法人 日本粘土学会  

The clay mineralogy of bentonite in Balamban, Cebu Province, Philippines was studied. Specimens were randomly collected from lenticular seams of bentonite concordantly intercalated with sequences of calcareous and tuffaceous shale and sandstone of the Middle Miocene Toledo Formation. Multiple analytical techniques of the <2&mu;m size fraction reveal that smectite is the dominant clay constitution of the bentonite. Minor association of mixed-layer kaolinite/smectite, kaolin, and mica is indicative. Diagenetic facies of calcium-rich bentonite and cristobalite-rich bentonite are diagnostic features. Non-phyllosilicate components are mainly quartz, feldspar, cristobalite, calcite, and zeolite. Volcanic glass shards, considered as the precursor material, occur sporadically in the clay-dominated matrix. Calcareous microfossils or nanofossils also exist as subordinate impurities.<BR>Rehydration capacity of the calcium-rich bentonite was observed to be generally greater than the cristobalite-rich bentonite.<BR>Bentonite formation is ascribed to be generated by halmyrolysis of the volcanic glass fragments contained in the vitric tuff exhalative unit of the Toledo Formation. The devitrification and transformation of the glass into nearly pure smectitic clay suite apparently ensued in a marine environment. Diagenetic formation of the calcium-rich facies appears syngenetic with the accumulation of the volcanic ash in saline waters while the cristobalite-rich facies appears authigenic, constituting the silica-rich layers.

DOI： 10.11362/jcssjclayscience1960.11.299

Publisher：日本ペドロジー学会  

DOI： 10.18920/pedologist.44.2_91

DOI： 10.5575/geosoc.105.699

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Publisher：一般社団法人 日本粘土学会  

Mixed-layer kaolinite/smectite minerals constitute the principal clay assemblage in the Quaternary alluvium type red-burning clay resource in Liloan, Cebu, Philippines, based on analytical testworks employing x-ray diffraction (XRD), differential thermal analysis (DTA), thermogravimetry (TG), infrared (IR) absorption spectroscopy, scanning electron microscopy (SEM), and energy dispersive x-ray (EDX) performed on several clay samples obtained from the area. Careful examination of diffraction curves indicate that the main constituent mineral is randomly interstratified kaolinite/smectite. Computer-simulated x-ray diffractograms of the mixed-layer kaolinite/smectite show good agreement with the observed x-ray diagrams in (001) and (002) basal reflections. Calculated values derived from simulation, moreover, illustrate the ratio of kaolinite to smectite to be generally higher at surface horizon but gradually becomes of almost equal proportion at depth. The slight variability in ratio may be linked to the effect or degree of differential weathering. Quartz and feldspar are ubiquitous accessory minerals detected in the non-clay fraction.

DOI： 10.11362/jcssjclayscience1960.11.11

Publisher：日本粘土学会  

Smectite was formed from some clays, such as pyrophyllite, kaolinite, sericite and talc by reaction with NaOH solution at 100℃ under atmospheric pressure.Smectite was formed well under the condition that the concentration of NaOH was near 2M〜3M.Furthermore, when the reaction time involved is within 50 days, the amount of starting material should be less than 0.5g in 100ml solution to form smectite.

DOI： 10.11362/jcssjclayscience1960.10.423

DOI： 10.11362/jcssjclayscience1960.10.395

Publisher：The Clay Science Society of Japan  

DOI： 10.11362/jcssjclayscience1960.10.271

Publisher：日本粘土学会  

Quantitative estimation of clay minerals in the clay fractions of the surface sediment samples from South Yatsushiro Kai is obtained from the X-ray diffraction patterns of the clay mineral suite that contains illite, chlorite, kaolinite, smectite and 10Å halloysite. Among the clay species, illite and chlorite are exceptionally abundant and they comprise more than 60% of the total clay minerals present in most sediments. Relative amounts of other clay minerals varies markedly with locality particularly kaolinite and 10Å halloysite and they tend to concentrate only near the point source except smectite which has a more unique behavior of transport and settling characteristics than other minerals. The relatively high supply of land-derived materials from various rock lithology surrounding South Yatsushiro Kai is the dominant contributing factor in outlining the trend of clay mineral distribution. Most, if not all, clay minerals are believed to be current-transported which shows that bottom water flow and shallow water currents are significant agents responsible for the distribution of various clay minerals.

Publisher：The Clay Science Society of Japan  

Experimental syntheses of kaolinite from powdered volcanic glass were performed using distilled water, 0.01N acetic acid solution, 0.01N, 0.05N, and 0.1N HCl solutions, and the same concentrations of HCl containing Al ions at 200℃ for a period of 1 to 30 days. X-ray powder diffraction confirmed that kaolinite was formed in all acid solutions of acetic acid and HCl, and smectite was produced in distilled water. The amount of kaolinite formed in HCl solutions containing Al ions reached above 50% of the residual solid, whereas that formed in solutions without Al ions was relatively less than 40%. Based on the stability diagram for the system of SiO_2-Al_2O_3-Na_2O-H_2O, it was observed that the compositions of acid solutions agree with the stable field of kaolinite, whereas that of the distilled water changed to a stable field of smectite due to rapid increase in pH. The pH values of acid solutions at which kaolinite was formed went down from 4.42 to 1.04 range The morphology and crystallinity of kaolinite appeared to be strongly dependent on the pH values. Spherical kaolinite was formed in acid solution with the highest pH value of 4.42, however irregular or lath shaped kaolinites tend to appear with decreasing pH, and hexagonal platy kaolinite was produced at the lowest pH value of 1.04. The spherical and hexagonal platy kaolinites formed at both conditions of the highest and lowest pH exhibited extremely high crystallinity, whereas kaolinites formed at pH values between 4.42 to 1.04 showed quite lower crystallinity.

Authorship：Lead author  

Publisher：日本岩石鉱物鉱床学会  

Publisher：一般社団法人 日本粘土学会  

Semi-quantitative analysis of the clay minerals in the bottom sediment samples from Kagoshima Bay was carried out to determine the distribution trends of the clay minerals and its relationship with the geology of the study area as well as certain physico-chemical conditions within the bay. The study utilized various methods such as XRD, DTA, IR and SEM. The clay minerals identified are 10&Aring;-halloysite, illite, smectite, kaolinite and chlorite. Non-clay mineral components are feldspar, quartz, cristobalite, gypsum, calcite and pyrite. 10&Aring;-halloysite is the most abundant clay mineral. Illite, smectite and kaolinite are the next abundant. Chlorite is the least common. Non-clay are also widely distributed in the sediments of Kagoshima bay. Feldspar, quartz, cristobalite and pyrite are common throughout the bay while calcite and gypsum vary in distribution.<BR>Based on the geology of the surrounding area, it has been shown that the terrigenous supply represents the dominant agent responsible for the distribution of the clay minerals. Certain environmental conditions, however are considered minor mechanisms that influence clay mineral distribution. The clay minerals were transported with feldspar, quartz and cristobalite.

DOI： 10.11362/jcssjclayscience1960.9.317

Publisher：Japan Association of Mineralogical Sciences  

Clay minerals are major constituents of the earth's surface materials and are widely distributed as weathering products of interior materials of the earth crust. It is well known that the clay minerals play an important role in environmental processes through its high reactivity with both inorganic and organic ions and/or molecules. Therefore, more studies concerning the earth's surface materials involving clay minerals are strongly required to understand the environments of life support systems. Generally, clay minerals can be divided into the following two categories; 1) crystalline materials, and 2) noncrystalline materials. Extensive studies have been conducted on mineralogy of the crystalline materials, whereas little is known for the noncrystalline materials. In this paper, the author reviews noncrystalline materials formed in weathering environments on the earth crust, and shows some examples of noncrystalline materials formed by natural weathering and artificial hydrothermal reactions. Two different natural materials are described; one is weathering products formed on the surface of volcanic glass in Ito pyroclastic flow deposit, the other is precipitates on the surface of K-feldspar in Yakushima granite. The noncrystalline materials formed by artificial hydrothermal reactions are products of the reaction between volcanic glass and aqueous solution, and precipitates in a oneelemental system of Al and a two-elemental system of Al-Si.

DOI： 10.2465/gkk1952.25.111

Publisher：一般社団法人 日本粘土学会  

Quantitative estimation of clay minerals in the clay fractions of the surface sediment samples from South Yatsushiro Kai is obtained from the X-ray diffraction patterns of the clay mineral suite that contains illite, chlorite, kaolinite, smectite and 10&Aring; halloysite. Among the clay species, illite and chlorite are exceptionally abundant and they comprise more than 60% of the total clay minerals present in most sediments. Relative amounts of other clay minerals varies markedly with locality particularly kaolinite and 10&Aring; halloysite and they tend to concentrate only near the point source except smectite which has a more unique behavior of transport and settling characteristics than other minerals.<BR>The relatively high supply of land-derived materials from various rock lithology surrounding South Yatsushiro Kai is the dominant contributing factor in outlining the trend of clay mineral distribution. Most, if not all, clay minerals are believed to be current-transported which shows that bottom water flow and shallow water currents are significant agents responsible for the distribution of various clay minerals.

DOI： 10.11362/jcssjclayscience1960.10.95

Publisher：The Clay Science Society of Japan  

Experimental syntheses of kaolinite from powdered volcanic glass were performed using distilled water, 0.01N acetic acid solution, 0.01N, 0.05N, and 0.1N HCl solutions, and the same concentrations of HCl containing Al ions at 200&deg;C for a period of 1 to 30 days. X-ray powder diffraction confirmed that kaolinite was formed in all acid solutions of acetic acid and HCl, and smectite was produced in distilled water. The amount of kaolinite formed in HCl solutions containing Al ions reached above 50% of the residual solid, whereas that formed in solutions without Al ions was relatively less than 40%. Based on the stability diagram for the system of Si0<SUB>2</SUB>-Al<SUB>2</SUB>0<SUB>3</SUB>-Na<SUB>2</SUB>0-H<SUB>2</SUB>O, it was observed that the compositions of acid solutions agree with the stable field of kaolinite, whereas that of the distilled water changed to a stable field of smectite due to rapid increase in pH. The pH values of acid solutions at which kaolinite was formed went down from 4.42 to 1.04 range The morphology and crystallinity of kaolinite appeared to be strongly dependent on the pH values. Spherical kaolinite was formed in acid solution with the highest pH value of 4.42, however irregular or lath shaped kaolinites tend to appear with decreasing pH, and hexagonal platy kaolinite was produced at the lowest pH value of 1.04. The spherical and hexagonal platy kaolinites formed at both conditions of the highest and lowest pH exhibited extremely high crystallinity, whereas kaolinites formed at pH values between 4.42 to 1.04 showed quite lower crystallinity.

DOI： 10.11362/jcssjnendokagaku1961.36.9

DOI： 10.2465/ganko.91.11

Publisher：The Clay Science Society of Japan  

Formation of clay minerals during experimental alteration of obsidian in acetic acid and oxalic acid solutions was investigated. The experiments were carried out using 0.01N or 0.02N acetic acid and oxalic acid solutions at 150' and 200℃ for 1 to 60 days. The clay minerals formed in these organic acid solutions were examined by X-ray powder diffraction, scanning electron microscopy, and transmission electron microscopy. Variations of pHs and concentrations of dissolved elements in solutions during the reactions were measured. By reactions using acetic acid solution, pH-values of solutions retained weak acidic region of pH3.4 - 4.9, and formation of kaolinite proceeded during the reactions and crystallization of smectite occurred at the final stages. On the other hand, pH-values of oxalic acid solution increased rapidly to alkaline region, and then crystallization of smectite began to take place at the initial stages and proceeded throughout the reactions. The rapid increase in pH of oxalic acid was due to thermal decomposition of the organic acid, and therefore solution compositions changed drastically to the stability filed of smectite.

Publisher：The Clay Science Society of Japan  

Experimental syntheses of clay minerals from obsidian were performed in 0.01N and 0.001N HNO_3 solutions at 150℃ and 200℃ for 1 to 60 days. Formation and transformation processes of the clay minerals during the reactions were examined by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray analysis, infrared absorption spectroscopy, and X-ray photoelectron spectroscopy. At 200℃ reaction, a small amount of boehmite was formed at the early stage, and spherical kaolinite appeared and grew successively as reaction proceeded in 0.01N HNO_3 solution. On the other hand, a flaky smectite was mainly formed in 0.001N HNO_3 solution. At 150℃ reaction, boehmite, allophane, spherical halloysite, and platy kaolinite were produced in both 0.01N and 0.001N HNO_3 solutions. Based on a stability diagram for the system of Na_2O-Al_2O_3-SiO_2-H_2O, it was found that the spherical and platy kaolinites and smectite were formed as a stable phase, whereas allophane and halloysite appeared as a metastable phase. In this paper, we discussed the following problems: 1) formation conditions of kaolinite and smectite, 2) formation conditions of spherical and platy kaolinites, and 3) formation conditions of kaolinite and halloysite.

Publisher：日本鉱物科学会  

大気圧下,85&deg;Cおよび90&deg;CでNaOH溶液との反応により黒曜石からスメクタイトと沸石が生成した。スメクタイトと種々の沸石の生成条件は火山ガラスの量 (g) と溶液中のNaOHの量 (g) の比によって決定される。スメクタイトは(火山ガラスの重量 (g)/NaOH (g)&times;1/40)の値が1と2の間の条件の時によく生成した。スメクタイトは溶液と黒曜石の表面の直接の反応で生成し,徐々に内部にまでスメクタイトが生成するのに対して,沸石類は溶解した溶液の中にまず沸石の核が形成され,それが成長していくと考えられる。

DOI： 10.2465/ganko.89.219

Publisher：The Clay Science Society of Japan  

Experimental alteration of obsidian was performed in distilled-deionized water at 100&deg;C for up to 365 days to elucidate formation processes of clay minerals at relatively low temperature condition. The alteration products were examined by transmission electron microscopy (TEM), scanning electron microscopy, and energy dispersive X-ray analysis. The surface compositions of obsidian before and after alteration were also examined by X-ray photoelectron spectroscopy (XPS) to clarify dissolution processes. For reaction products, allophane, fibrous boehmite, and halloysite were formed at early stage while fibrous smectite appeared later. Based on the activity diagram for the system of Na<SUB>2</SUB> OAl<SUB>2</SUB>O<SUB>3</SUB>-SiO<SUB>2</SUB>-H<SUB>2</SUB>O, it was found that allophane, boehmite, and halloysite appeared to be formed as a metastable phase, and that smectite was produced as a stable phase. TEM showed that allophane and boehmite were precipitated from the solution, and halloysite and smectite were then transformed from allophane and boehmite, respectively, as reaction proceeded. XPS indicated that preferential leaching of Na and enrichment of K occurred at the obsidian surface. Likewise, Al/Si ratio of the surface increased during the reaction. These results are probably due to formation of smectite structure in a leached layer produced on the obsidian surface.

DOI： 10.11362/jcssjnendokagaku1961.34.80

Publisher：The Clay Science Society of Japan  

Formation and transformation processes of clay minerals during experimental alteration of obsidian in H<SUB>2</SUB>SO<SUB>4</SUB> solution were examined by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy (TEM), and energy dispersive X-ray analysis. Dissolution mechanism of obsidian in H<SUB>2</SUB>SO<SUB>4</SUB> solution was also investigated byX-ray photoelectron spectroscopy (XPS). The experimental alteration was performed in 0.01N and 0.001N H<SUB>2</SUB>SO<SUB>4</SUB> solutions at 150&deg;C and 200&deg;C for 1 to 60 days, respectively. Concentrations of dissolvedelements in solutions and their pH values were also measured. At 200&deg;C reaction, alunite, fibrous boehmite, and platy kaolinite were produced in acidic solution, whereas flaky smectite appeared with increasing the pH value above 7. At 150&deg;C reaction, boehmite, allophane, and halloysite were producedat the early stage, and a small amount of spherical kaolinite appeared at later stage. Results of TEM indicated that flaky smectite was formed from fibrous boehmite by phase transition process, likewise halloysite was transformed from aggregates of allophane particles as alteration progressed.Based on stability diagram for the system of Na<SUB>2</SUB>O-Al<SUB>2</SUB>O3-SiO<SUB>2</SUB>-H<SUB>2</SUB>O, it was found that kaolinite andsmectite were formed as a stable phase, whereas boehmite, allophane, and halloysite appearedas a metastable phase. It was demonstrated by XPS that Na was preferentially leached from the obsidian surface independent on pH values of solutions. However, the rate of Al/Si leaching increased in solutions at pH<3, and the rate decreased above the value.

DOI： 10.11362/jcssjnendokagaku1961.34.48

Publisher：The Clay Science Society of Japan  

Experimental alteration of obsidian was performed in distilled-deionized water at 100℃ for up to 365 days to elucidate formation processes of clay minerals at relatively low temperature condition. The alteration products were examined by transmission electron microscopy (TEM), scanning electron microscopy, and energy dispersive X-ray analysis. The surface compositions of obsidian before and after alteration were also examined by X-ray photoelectron spectroscopy (XPS) to clarify dissolution processes. For reaction products, allophane, fibrous boehmite, and halloysite were formed at early stage while fibrous smectite appeared later. Based on the activity diagram for the system of Na_2O-Al_2O_3-SiO_2-H_2O, it was found that allophane, boehmite, and halloysite appeared to be formed as a metastable phase, and that smectite was produced as a stable phase. TEM showed that allophane and boehmite were precipitated from the solution, and halloysite and smectite were then transformed from allophane and boehmite, respectively, as reaction proceeded. XPS indicated that preferential leaching of Na and enrichment of K occurred at the obsidian surface. Likewise, Al/Si ratio of the surface increased during the reaction. These results are probably due to formation of smectite structure in a leached layer produced on the obsidian surface.

Publisher：The Clay Science Society of Japan  

Many hydrothermal alteration zones exist in the Ibusuki area, Kagoshima Prefecture. These alteration zones were formed within Ata caldera at the southern end of Kyushu. The original rocks of these altered ones are the in-filling volcanic rocks of the caldera. The altered zones were formed after the eruption of Ata pyroclastic flow which occurred 43, 910 years ago. Volcanic rocks erupted after the Ikeda pyroclastic flow deposits were scarcely altered. Therefore, these altered zones were probably formed after the eruption of the Ata pyroclastic flow and before the Ikeda pyroclastic flow. Clay minerals in some alteration zones were likewise studied. Altered minerals such as cristobalite, tridymite, alunite, kaolinite, 10 &Aring;-halloysite, boehmite, heulandite and some iron minerals were observed in this area. Some of these zones were divided into three zones characterized by the presence of altered minerals. These are cristobalite zone, kaolinite zone and smectite zone from the inner silicified part to the outer part.

DOI： 10.11362/jcssjnendokagaku1961.34.1

Publisher：Clays and Clay Minerals  

DOI： 10.1346/CCMN.1993.0410603

Scopus

Publisher：日本鉱物科学会  

1992年に新燃岳から噴出した火山灰が研究された。占有鉱物としては,長石,輝石,角閃石,クリストバル石の他にスメクタイトと石膏が認められた。このスメクタイトはEDX分析により,鉄を多く含むスメクタイトであることがわかった。このスメクタイトは,噴火が起こる前に火口中または火口直下で比較的低温の熱水によって岩石が変質されてでぎたものである。

DOI： 10.2465/ganko.88.114

Publisher：The Clay Science Society of Japan  

Experimental alterations of obsidian were performed in 20, 50, and 100ppm of AlCl<SUB>3</SUB> solutions at 150&deg; and 200&deg;C for 1 to 60days. The alteration products were examined by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive X-ray analysis. The surface morphology and composition of obsidian before and after alteration were examined by SEM and X-ray photoelectron spectroscopy (XPS), respectively. The pH-value of solution before reaction is approximately 2.0, and it increased progressively proceeding the dissolution of obsidian. The alteration products appeared in this reaction system were strongly dependent on pH-values of solutions. XRD and TEM showed that boehmite, spherical kaolinite and precursor of smectite exhibiting fibrous habit were mainly formed in acidic solutions. However, smectite appeared as predominant reaction product in solutions at pH>5.0, and the spherical kaolinite began to decompose at that pH range. XPS indicated that Al-rich layer was formed on the surface of obsidian by cation exchange reaction between Si and Al in solution during the initial dissolution stage. The Al-rich layer began to dissolve into the solution with increasing pH of solutions.

DOI： 10.11362/jcssjnendokagaku1961.33.59

Publisher：日本鉱物科学会  

琵琶湖底の1,400mボーリングコア試料について鉱物学的に検討した。組成鉱物は,主に石英,長石,それにスメクタイト,クロライト,イライト,カオリナイトの粘土鉱物である。この他に少量の沸石,角せん石,菱鉄鉱などが含まれている。石英,長石はどの試料にも含まれており,イライト,クロライト,カオリナイトもほとんどの試料に含まれている。スメクタイトに関しては極く少量含む試料やほとんど含んでいない試料がある。この事から,古い時代の琵琶湖の大きさの大小(水位の上下)の変化を推定することができる。スメクタイトの含有量の多い試料が堆積した時代は,琵琶湖は大きかったと推定され,少ない場合はその逆である。スメクタイト,石英,長石の含有量の変化から,これまでに琵琶湖におけるこれらの堆積物に変化を与えたような環境の変化が数回あったことが推定できる。

DOI： 10.2465/ganko.87.481

Publisher：The Clay Science Society of Japan  

Sudoite and tosudite were found in hydrothermal alteration aureole of Nansatsu-type silicified rock deposit in the Makurazaki area, Kagoshima Prefecture, Japan. The d(060) values of the sudoite and tosudite are 1.508 and 1.506A, respectively. The structural formula of the sudoite is (Al_<2.08> Mg_<2.56> Fe^<3+>_<0.40> Ti_<0.06> Li_<0.02> K_<0.04> Na_<0.02>)(OH)_<12> A1_<4.00>(Si_7.08> Al_<0.92>)O_<20>(OH)_4,and that of the tosudite is (Al_<1.26> Mg_<1.60> Fe^<3+>_<0.11> Ti_<0.01> Li_<0.01> Mn_<0.01> K_<0.17> Na_<0.03>)(OH)_6 A1_<4.00>(Si_<6.46> Al1.54)O_<20>(OH)_4. These specimens are characterized by relatively large amounts of Mg and very small amounts of Li. The basal spacing of tosudite is 29.77A under 50% relative humidity, and it changed to 31.37A after ethylene glycol solvation and to 23.74A after heating at 500℃ for 1 hr. The basal spacing of Mg-saturated tosudite sample expanded to 31.41 and 32.17A after ethylene glycol and glycerol solvation, respectively. However, K-saturated sample showed resistivity against the expansion by these treatments. Based on statistic analysis of chemical composition, a positive relationship was recognized between the number of tetrahedral Al and that of octahedral Mg. The result suggests that the small expansion ability of K-saturated present tosudite sample may be attributable to higher negative charge of the tetrahedral sheets.

Publisher：Japan Association of Mineralogical Sciences  

The alunite-natroalunite solid solution series were synthesized by precipitation from mixed solutions of K<SUB>2</SUB>SO<SUB>4</SUB>, Na<SUB>2</SUB>SO<SUB>4</SUB>, and Al<SUB>2</SUB> (SO<SUB>4</SUB>)<SUB>3</SUB> for 2 days' reaction at boiling temperature. The K ions in the initial solution were preferentially taken into structure during crystallization of the alunite, and amounts of products formed in this reaction decreased with decreasing K mol% of the solution. The calculated structural formulae on the basis of SO<SUB>4</SUB>=2 indicate that the synthetic alunites contain H<SUB>3</SUB>O ions in the A sites, which increased from 11 to 19 mol% with decreasing K mol%. In addition, the slight deficiency of Al ions suggests the presence of vacancies in the B sites. Structural changes of alunites were observed by the thermal treatment. At 530&deg;C, formation of KAl (SO<SUB>2</SUB>)<SUB>2</SUB> from alunite and Al<SUB>2</SUB> (SO<SUB>4</SUB>)<SUB>3</SUB> from natroalunite occurred simultaneously with the removal of OH ions. Removal of SO<SUB>4</SUB> ions from the dehydroxylated phases led to formation of amorphous phases at about 803&deg;C for alunite run and about 765&deg;C for natroalunite run. The amorphous phases then recrystallized into K<SUB>2</SUB>SO<SUB>4</SUB> and Al<SUB>2</SUB>O<SUB>3</SUB> in the alunite run and Na<SUB>2</SUB>SO<SUB>4</SUB> and Al<SUB>2</SUB>O<SUB>3</SUB> in the natroalunite run. The thermal behavior suggests the existence of compositional immiscibility between alunite and natroalunite.

DOI： 10.2465/gkk1952.20.13

Publisher：The Clay Science Society of Japan  

Sudoite and tosudite were found in hydrothermal alteration aureole of Nansatsu-type silicified rock deposit in the Makurazaki area, Kagoshima Prefecture, Japan. The <I>d</I> (060) values of the sudoite and tosudite are 1.508 and 1.506 &Aring;, respectively.The structural formula of the sudoite is (Al<SUB>2.08</SUB> Mg<SUB>2.56</SUB> Fe<SUP>3+</SUP><SUB>0.40</SUB>Ti<SUB>0.06</SUB> Li<SUB>0.02</SUB> K<SUB>0.04</SUB> Na<SUB>0.02</SUB>)(OH) <SUB>12</SUB> Al<SUB>4.00</SUB> (Si<SUB>7.08</SUB> Al<SUB>0.92</SUB>) O<SUB>20</SUB> (OH) <SUB>4</SUB>, and that of the tosudite is (Al<SUB>1.26</SUB> Mg<SUB>1.60</SUB> Fe<SUP>3+</SUP><SUB>0.11</SUB>Ti<SUB>0.01</SUB> Li<SUB>0.01</SUB> Mn<SUB>0.01</SUB> K<SUB>0.17</SUB> Na<SUB>0.03</SUB>)(OH) <SUB>6</SUB> Al<SUB>4.00</SUB> (Si<SUB>6.46</SUB> Al<SUB>.54</SUB>) O<SUB>20</SUB> (OH) <SUB>4</SUB>.These specimens are characterized by relatively large amounts of Mg and very small amounts of Li. The basal spacing of tosudite is 29.77 &Aring; under 50% relative humidity, and it changed to 31.37 &Aring; after ethylene glycol solvation and to 23.74 &Aring; after heating at 500&deg;C for 1 hr. The basal spacing of Mg-saturated tosudite sample expanded to 31.41 and 32.17&Aring; after ethylene glycol and glycerol solvation, respectively. However, K-saturated sample showed resistivity against the expansion by these treatments. Based on statistic analysis of chemical composition, a positive relationship was recognized between the number of tetrahedral Al and that of octahedral Mg. The result suggests that the small expansion ability of K-saturated present tosudite sample may be attributable to higher negative charge of the tetrahedral sheets.

DOI： 10.11362/jcssjnendokagaku1961.31.44

Publisher：The Clay Science Society of Japan  

The mineralogical properties and formation process of kaolinite from the Iriki kaolin deposit were studies. The Hinckley indices of the kaolinite samples have the value between 1.06 and 1.75 indicating relatively ordered structure. The IR absorption frequencies related to Si-0 vibration shifted linearly with increasing degree of disorder. The electron microscopic observation suggested that the kaolinite was formed from smectite under hydrothermal conditions. The growth process of the kaolinite can be divided into two stages. The first stage is formation of irregular-shaped particles. The second stage is dissolution of the irregular-shaped particles and growth of hexagonal-shaped particles. This formation process is controlled by the Ostwald ripening mechanism.

DOI： 10.11362/jcssjnendokagaku1961.30.229

Authorship：Lead author  

Authorship：Lead author  

DOI： 10.2465/minerj.15.19

Publisher：Japan Association of Mineralogical Sciences  

Altered volcanic rocks are distributed in the Kuwanokizuru area, Hitoyoshi City, Kumamoto Prefecture. Constituent minerals in the altered rocks are smectite, mixed-layered mica/smectite, mixed-layered chlorite/smectite, chlorite, kaolinite, pyrite, quartz and &alpha;-cristobalite. Distribution of clay minerals in this area could be divided into two zones, mixed-layered mica/ smectite zone and smectite zone. In the mixed-layered zone, mixed-layered mica/smectite having high % of mica is present at two places. Furthermore, smectite % of this mixed-layered mica/smectite decreases and its Reichweite changes from 1 to 3, from the margin toward these places.

DOI： 10.2465/gkk1952.19.Special_71

Publisher：Japan Association of Mineralogical Sciences  

Structural rearrangements for dioctahedral smectite after thermal treatment were investigated. The notable structural changes accompanying removal of interlayer water are contraction of basal spacing, migration of interlayer cation into silicate layer and expansion of b-parameter. The important factor affecting the migration of interlayer cation is considered to be turbostatic stacking of adjacent silicate layers. The dehydroxylated structures of octahedral sheet are similar to those of other dioctahedral clay minerals having 2:1 layer structure, that is, removal of 2OH- as H<SUB>2</SUB>O and relocation of residual O<SUP>2-</SUP> to the same level as that of the octahedral cations.

DOI： 10.2465/gkk1952.19.Special_11

Authorship：Lead author  

Authorship：Lead author  

Authorship：Lead author  

Authorship：Lead author  

Authorship：Lead author  

Authorship：Lead author  

Publisher：CLAY MINERALS SOC  

Amino acids are present in various geochemical environments and they interact with mineral surfaces. To evaluate the effects of amino acids on mineral dissolution at pH conditions less than their isoelectric points (pI), dissolution experiments of X-ray amorphous silica in solutions containing 10.0 mmol/L of various amino acids (cysteine, asparagine, serine, tryptophan, alanine, threonine, histidine, lysine, and arginine) at pH 4 were performed. The results confirmed that basic amino acids (histidine, lysine, and arginine) produce an 8- to 8.5-fold enhancement of the rate of dissolution of amorphous silica compared with an amino acid-free control. Neutral amino acids (cysteine, asparagine, serine, tryptophan, alanine, and threonine) enhanced rates of dissolution by a factor of similar to 3 to 3.5. The rate-enhancement effects of amino acids are controlled by concentrations of the amino acid&apos;s cationic species which interact with the negatively charged &gt;SiO(-) sites at the surface of the amorphous silica.

DOI： 10.1346/CCMN.2009.0570203

Web of Science

Scopus

Publisher：CLAY MINERALS SOC  

Amino acids are ubiquitous in the Earth's surface environments as reactive biological Molecules produced by every living thing including bacteria. To evaluate the effects of amino acids on mineral dissolution and to reveal the mechanism by which they interact with the mineral surface, we performed dissolution experiments of X-ray amorphous silica in Solution containing 0.1 mmol Na with 10.0 mmol amino acids such as cysteine, asparagine, serine, tryptophan, alanine, threonine, histidine, lysine and arginine in near-neutral solutions. Dissolution experiments in Solutions of 0.1, 1.0 and 10.0 mmol NaCl without amino acids were also conducted as amino acid-free controls. The results of this study indicate that basic amino acids such as histidine, lysine and arginine can interact more strongly with the negatively charged surface of amorphous silica than other non-basic amino acids due to their greater dissociation, thus forming cationic species. This electrostatical interaction enhanced dissolution rates of amorphous silica by approximately one order of magnitude compared with amino acid-free controls. In contrast, no significant effect on the dissolution rates of amorphous silica was observed in solutions containing cysteine, asparagine, serine, tryptophan, alanine and threonine because of lesser interaction with the surface of amorphous silica.

DOI： 10.1346/CCMN.2007.0550404

Web of Science

Scopus

Publisher：CLAY MINERALS SOCIETY  

Bacterial mineralization in weathered pyroclastic deposits of the Kaimondake volcanic ash (4040 ybp) and the Koya pyroclastic flow, (6400 ybp) was investigated to evaluate the impacts of bacteria on mineral formation, and to characterize the microbiogenic minerals in the weathering environment. The mineralogy of abiogenic weathering products was also investigated for comparison with the microbiogenic products. and mineral saturation indices were calculated for porewaters using the PHREEQC computer code. The results indicated that these weathered pyroclastic deposits contain 10(8)-10(9) cells/g, consisting of spherical to rod-shaped bacteria. Associated abiogenic allophane had an Al/Si ratio ranging from 1.01 to 2.13. The bacterial cell surfaces were completely or partially covered by poorly-ordered silicate minerals, which Could be divided into two groups based on their chemical and morphological characteristics. Group I was characterized by well developed fibrous to smectite-like flaky habits with variable Al, Si and Fe, corresponding to compositions between proto-imogolite allophane and chamosite. These Al-Si-Fe minerals were the most abundant and major microbiogenic products in both lithologies. Group II exhibited poorly-developed aggregates of allophane-like granular materials composed mainly of Al and Si with minor Fe. Geochemical calculations revealed that the porewaters were saturated with respect to allophane and other crystalline clay minerals such as halloysite, kaolinite, montmorillonite and nontronite. These microbiogenic minerals may be formed as the earliest phase of these clay minerals after interaction of the bacterial cell surfaces with dissolved cations mainly Si, Al and Fe, in the porewaters.

DOI： 10.1346/000986002761002865

Web of Science

DOI： 10.1346/000986002761002865

DOI： 10.11362/jcssjclayscience1960.11.585

DOI： 10.11362/jcssjclayscience1960.11.585

DOI： 10.11362/jcssjclayscience1960.11.601

DOI： 10.11362/jcssjclayscience1960.11.601

Publisher：MINERALOGICAL SOC AMER  

Microbial biomineralization in a weathered volcanic ash deposit from the 1914 to 1915 A.D. eruption of Sakurajima volcano was investigated by transmission electron microscopy (TEM) and energy dispersive X-ray analysis (EDX). The solution chemistry of pore water was also analyzed to elucidate saturation conditions. In addition, experimental incubations of bacteria collected from the volcanic ash were performed to confirm bacterial mineralization, TEM revealed that the weathered volcanic ash contains significant amounts of spherical to rod-shaped bacteria ranging from 1.3 x 10(8) to 2.6 x 10(8) cell/g, most of which have cell wall surfaces that are completely covered or decorated by either massive aggregates of allophane-like granular materials or irregular aggregates of smectite-like fibers and/or flakes. EDX confirmed that the granular minerals have chemical compositions similar to proto-imogolite allophane, whereas the smectite-like fibers and/or flakes show a wide range of chemical compositions corresponding to the compositional field between allophane and nontronite. The volcanic ash contains about 22 wt% of pore water, which is slightly acidic, relatively low redox potential, and enriched in Si, Na, Cl-, and SO42- ions. The saturation indices (SI) calculated by the PHREEQC geochemical code indicate that the pore water is almost saturated with respect to amorphous Al(OH)(3), ferrihydrite, amorphous silica, and cristobalite, and significantly oversaturated with respect to silicate minerals in the order: halloysite &lt; kaolinite &lt; montmorillonite &lt; allophane &lt; nontronite. The allophane-like granular minerals seems to be preferentially precipitated by bacterial interaction with Al and Si ions in the pore water as a metastable phase. The poorly ordered smectite-like fibers and/or flakes may be transformed from the allophane-like materials as a intermediate phase between allophane and nontronite by the driving force originated from the greatest SI value of nontronite. The experimental incubation confirmed that amorphous silica containing a small amount of Fe is formed on the bacterial cell surfaces in liquid media with both Fe and Si ions. Likewise, beidellite-like smectite associated with the bacterial surfaces is produced in liquid media containing both Al and Si ions. However, no minerals are produced in the same media containing no metal ions or no bacteria. These results imply that bacteria play an important role in the accumulation of metal ions and in the formation of silicate minerals during weathering of volcanic ash.

Web of Science

Publisher：MINERALOGICAL SOC AMER  

Microbial biomineralization in a weathered volcanic ash deposit from the 1914 to 1915 A.D. eruption of Sakurajima volcano was investigated by transmission electron microscopy (TEM) and energy dispersive X-ray analysis (EDX). The solution chemistry of pore water was also analyzed to elucidate saturation conditions. In addition, experimental incubations of bacteria collected from the volcanic ash were performed to confirm bacterial mineralization, TEM revealed that the weathered volcanic ash contains significant amounts of spherical to rod-shaped bacteria ranging from 1.3 x 10(8) to 2.6 x 10(8) cell/g, most of which have cell wall surfaces that are completely covered or decorated by either massive aggregates of allophane-like granular materials or irregular aggregates of smectite-like fibers and/or flakes. EDX confirmed that the granular minerals have chemical compositions similar to proto-imogolite allophane, whereas the smectite-like fibers and/or flakes show a wide range of chemical compositions corresponding to the compositional field between allophane and nontronite. The volcanic ash contains about 22 wt% of pore water, which is slightly acidic, relatively low redox potential, and enriched in Si, Na, Cl-, and SO42- ions. The saturation indices (SI) calculated by the PHREEQC geochemical code indicate that the pore water is almost saturated with respect to amorphous Al(OH)(3), ferrihydrite, amorphous silica, and cristobalite, and significantly oversaturated with respect to silicate minerals in the order: halloysite &lt; kaolinite &lt; montmorillonite &lt; allophane &lt; nontronite. The allophane-like granular minerals seems to be preferentially precipitated by bacterial interaction with Al and Si ions in the pore water as a metastable phase. The poorly ordered smectite-like fibers and/or flakes may be transformed from the allophane-like materials as a intermediate phase between allophane and nontronite by the driving force originated from the greatest SI value of nontronite. The experimental incubation confirmed that amorphous silica containing a small amount of Fe is formed on the bacterial cell surfaces in liquid media with both Fe and Si ions. Likewise, beidellite-like smectite associated with the bacterial surfaces is produced in liquid media containing both Al and Si ions. However, no minerals are produced in the same media containing no metal ions or no bacteria. These results imply that bacteria play an important role in the accumulation of metal ions and in the formation of silicate minerals during weathering of volcanic ash.

Web of Science

Publisher：MINERALOGICAL SOC AMER  

Transmission electron microscopy (TEM) and energy dispersive X-ray (EDX) analysis were used to characterize naturally weathered layers on the surface of volcanic glass, bytownite, hypersthene, and secondary precipitates in volcanic ash erupted from the Sakurajima volcano, Japan. TEM analysis of the volcanic ash revealed sharply, bounded, leached layers on the surface of the volcanic glass and bytownite that were thin structureless coatings mostly less than or equal to0.1 mum thick. EDX analysis showed that the leached layer on the volcanic glass surface is preferentially depleted in Si and enriched in Al relative to its parent matrix, whereas the leached layer on the bytownite surface is extremely depleted in Al and enriched in Si relative to the original bytownite matrix. These chemical characteristics of the weathered layers indicate that incipient dissolution of volcanic glass and bytownite proceeded by preferential leaching of Si and Al, respectively. On the surface of hypersthene, a noncrystalline weathered layer generally &lt;0.01 &lt;mu&gt;m in thickness, which has nearly the same composition as that of the parent matrix, was observed. This weathered layer was produced by precipitation of noncrystalline hydrous ferric oxide with partly developed to poorly crystallized Fe-Si-Mg rich phyllosilicate. The volcanic ash sample contains small amounts of noncrystalline secondary precipitates exhibiting three distinct morphologies: (1) aggregates of very fine fibers, (2) aggregates of fine fibers with crinkled fringes, and (3) spherical forms composed of roughly curled fringes. These noncrystalline precipitates are enriched in Al and Si and contain variable amounts of Fe, depending on their morphology. The Fe content of these materials decreases drastically in the sequence morphology 1 --&gt; morphology 2 --&gt; morphology 3, which is consistent with the transformation from Al-, Si-, and Fe-rich fine fibers to spherical halloysite by elimination of Fe from the fibers. These alterations of the volcanic ash took place in the crater of the Sakurajima volcano by interaction with near-neutral to weakly acidic solutions under relatively low-temperature conditions.

Web of Science

Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

Publisher：A A BALKEMA PUBLISHERS  

The bacterial formation of secondary minerals in a weathered pyroclastic deposit was examined by transmission electron microscopy (TEM) and energy dispersive X-ray analysis (EDX). The samples used in this study were collected from a weathering profile of rhyolitic, pyroclastic deposit distributed around southern Kyushu, Japan. The equilibrium conditions of pore waters were also investigated using PHREEQC geochemical code. TEM confirmed that the deposit contains a great number of spherical to rod-shaped bacteria covered or decorated with poorly ordered secondary minerals exhibiting aggregates of fine fibrous materials. EDX indicated that the secondary minerals are composed mainly of Al and Si, and variable amounts of Fe. The equilibrium calculations revealed that the pore waters are saturated with respect to allophane, halloysite, and montmorillonite. The results indicate that the bacterial cell surfaces provide adsorption sites for dissolved ions mainly Al, Si, and Fe and promote nucleation and precipitation of the poorly ordered silicate minerals. These microbiogenic minerals seem to be an initial phase for the transformation into major weathering products such as allophane and/or halloysite in this weathering environment.

Web of Science

Publisher：Tohoku University  

Localized deposit of Fe-rich pyrophyllite was encountered in the kaolinite-dominated alteration halo in Solo, Mabini, Philippines. The environment of formation of this dioctahedral mineral is related to low-temperature advanced argillic alteration found in shallow volcanic region. The pyrophyllite crystallizes as a two-layer monoclinic (2M) structure with the following unit cells, a=5.16Å, b=8.95Å, c=18.70Å, β=99.87° while its dehydroxylate form yields a slightly different unit cell parameters with a=5.17Å, b= 9.02Å, c= 18.76Å, β=99.80°. The expansion of b on dehydroxylation arises largely from the rearrangement of the Al ions in the octahedral layer and the insertions of oxygen ions in the Al planes. The obtained tetrahedral rotation (twisting of SiO4 groups) of 11°52′ in pyrophyllite is closely comparable to the 9°40′ angle of twist in the dehydroxylate. This strongly suggests that the tetrahedral networks of the original pyrophyllite are almost similarly twisted in the dehydroxylate phase. X-ray powder data demonstrate that the dehydroxylation process is accompanied by a significant enlargement of basal spacing with an observed expansion of about 1.99%. Thermal decomposition of pyrophyllite shows a single dehydration event, which takes place over a temperature range of 500-700°C with its peak at 604°C. The occurrence of this low-temperature dehydroxylation can be regarded as a consequence of significant replacement of Al by Fe in the octahedral layer and the presence of some impurities. Chemical data of pyrophyllite obtained from EDX analysis give an average structural formula of Ca0.10K0.10(Al1.81Fe3+ 0.16Ti0.01)(Si3.88Al0.12)O 10(OH)2 with an average Si/Al3+ + Fe3+ ratio of 1.86. Analyses of representative samples indicate that the octahedral site is filled with 1.76 to 1.84 Al cations, which is relatively lower than the 1.90 to 1.95 Al cations exhibited by ordinary pyrophyllite. This significant deficiency of Al is believed to be compensated by considerably high Fe3+ occupancy in the octahedral site. The source of Fe can be correlated to the previous decomposition of minor amount of pyrite associated with argillic alteration. SEM observations show common disoriented stacks of pyrophyllite plates, but the most visible component of the samples are the loosely compacted stacks in which thin elongated blade-like particles are randomly dispersed in the form of relatively porous aggregates. The coexistence of pyrophyllite and kaolinite in this environment is a consequence of sluggish crystallization of quartz caused by local variation of silica activity, which explains the crystallization of pyrophyllite instead of stable kaolinite at low temperature (&lt
300°C).

DOI： 10.2465/jmps.96.109

Scopus

Publisher：Tohoku University  

Localized deposit of Fe-rich pyrophyllite was encountered in the kaolinite-dominated alteration halo in Solo, Mabini, Philippines. The environment of formation of this dioctahedral mineral is related to low-temperature advanced argillic alteration found in shallow volcanic region. The pyrophyllite crystallizes as a two-layer monoclinic (2M) structure with the following unit cells, a=5.16Å, b=8.95Å, c=18.70Å, β=99.87° while its dehydroxylate form yields a slightly different unit cell parameters with a=5.17Å, b= 9.02Å, c= 18.76Å, β=99.80°. The expansion of b on dehydroxylation arises largely from the rearrangement of the Al ions in the octahedral layer and the insertions of oxygen ions in the Al planes. The obtained tetrahedral rotation (twisting of SiO4 groups) of 11°52′ in pyrophyllite is closely comparable to the 9°40′ angle of twist in the dehydroxylate. This strongly suggests that the tetrahedral networks of the original pyrophyllite are almost similarly twisted in the dehydroxylate phase. X-ray powder data demonstrate that the dehydroxylation process is accompanied by a significant enlargement of basal spacing with an observed expansion of about 1.99%. Thermal decomposition of pyrophyllite shows a single dehydration event, which takes place over a temperature range of 500-700°C with its peak at 604°C. The occurrence of this low-temperature dehydroxylation can be regarded as a consequence of significant replacement of Al by Fe in the octahedral layer and the presence of some impurities. Chemical data of pyrophyllite obtained from EDX analysis give an average structural formula of Ca0.10K0.10(Al1.81Fe3+ 0.16Ti0.01)(Si3.88Al0.12)O 10(OH)2 with an average Si/Al3+ + Fe3+ ratio of 1.86. Analyses of representative samples indicate that the octahedral site is filled with 1.76 to 1.84 Al cations, which is relatively lower than the 1.90 to 1.95 Al cations exhibited by ordinary pyrophyllite. This significant deficiency of Al is believed to be compensated by considerably high Fe3+ occupancy in the octahedral site. The source of Fe can be correlated to the previous decomposition of minor amount of pyrite associated with argillic alteration. SEM observations show common disoriented stacks of pyrophyllite plates, but the most visible component of the samples are the loosely compacted stacks in which thin elongated blade-like particles are randomly dispersed in the form of relatively porous aggregates. The coexistence of pyrophyllite and kaolinite in this environment is a consequence of sluggish crystallization of quartz caused by local variation of silica activity, which explains the crystallization of pyrophyllite instead of stable kaolinite at low temperature (&lt
300°C).

DOI： 10.2465/jmps.96.109

Scopus

DOI： 10.1346/CCMN.1997.0450313

Scopus

DOI： 10.1346/CCMN.1997.0450307

Scopus

Publisher：CLAY MINERALS SOCIETY  

Weathering products formed on the surface of K-feldspar in Yakushima Island, Japan were investigated by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX) and X-ray photoelectron spectroscopy (XPS). XRD confirmed that the weathering products were composed mainly of gibbsite and halloysite. SEM, TEM and EDX clearly showed formation of amorphous aluminum hydroxide exhibiting 2 distinct habits: 1) curled fibrous or circular forms less than 0.02 mu m in diameter; and 2) a spherical habit less than 1.0 mu m in diameter The fibrous aluminum hydroxide exhibited curled fibrous forms or circular forms less than 0.02 mu m in diameter and gave a diffuse electron diffraction halo. EDX indicated that the material consisted mainly of Al and very small amounts of Si and Fe. The spherical aluminum hydroxide also gave similar EDX and electron diffraction characteristics to the fibrous material. These fibrous and spherical aluminum hydroxides must be formed as a metastable phase in the earliest weathering stages, and transformed into a stable phase of gibbsite and halloysite as the reaction proceeded.

DOI： 10.1346/CCMN.1996.0440510

Web of Science

Scopus

DOI： 10.2465/gkk1952.25.111

DOI： 10.11362/jcssjnendokagaku1961.36.9

DOI： 10.2465/gkk1952.25.111

DOI： 10.11362/jcssjnendokagaku1961.36.9

Publisher：CLAY MINERALS SOCIETY  

Experimental alterations of K-feldspar in distilled-deionized water at 150 degrees, 175 degrees, 200 degrees and 225 degrees C were performed. The alteration products and dissolution mechanism of K-feldspar were examined by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX), and X-ray photoelectron spectroscopy (XPS). SEM, TEM, and EDX clearly showed formation of fibrous boehmite less than 1.0 mu m in length at the early alteration stages. The boehmite fibers decreased in abundance and rounded platy 1 M mica was produced as alteration proceeded. The mica exhibited initially angular shaped small flakes of 0.69 mu m in average size, which developed to rounded platy particles of 1.97 mu m. The main chemical reactions occurring in this experimental system can be expressed by:
[GRAPHICS]
XPS showed no significant changes in intensities of photoelectron lines excited from K, Si, and Al in the K-feldspar surface before and after alteration, however the K/Si molar ratios in the solutions were considerably smaller than that of the original K-feldspar. The results of XPS strongly indicate that no dealkalized layer was produced on the surface, and that dissolution of K-feldspar in aqueous solution proceeded congruently by a surface-reaction mechanism. The discrepancy of mass balance in the solutions may be mainly caused by adsorption of K on the surface of boehmite.

DOI： 10.1346/CCMN.1995.0430402

Web of Science

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DOI： 10.1346/CCMN.1995.0430516

Scopus

DOI： 10.1346/CCMN.1995.0430208

Scopus

DOI： 10.11362/jcssjnendokagaku1961.35.47

DOI： 10.11362/jcssjnendokagaku1961.34.235

DOI： 10.11362/jcssjnendokagaku1961.35.47

DOI： 10.11362/jcssjnendokagaku1961.34.235

DOI： 10.11362/jcssjnendokagaku1961.34.48

DOI： 10.11362/jcssjnendokagaku1961.34.80

DOI： 10.11362/jcssjnendokagaku1961.34.48

DOI： 10.1346/CCMN.1994.0420102

Scopus

DOI： 10.11362/jcssjnendokagaku1961.34.80

Publisher：CLAY MINERALS SOCIETY  

Experimental alteration of obsidian in distilled-deionized water at 150-degrees, 175-degrees, 200-degrees, and 225-degrees-C was studied. The alteration products were examined by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy (TEM), and energy dispersive X-ray analysis (EDX) to evaluate the formation process of clay minerals. The surface composition of obsidian before and after alteration was examined by X-ray photoelectron spectroscopy (XPS), and concentrations of released elements in solution were measured to elucidate alteration and dissolution processes. TEM clearly showed that allophane appeared as the first reaction product in each experiment. With increasing reaction length, noncrystalline straight fibrous material was formed in the aggregates of allophane particles as a metastable transitional phase, and tended to form curled or wavy bundles of fibers with longer reaction. The noncrystalline fibers were transformed into highly curled smectite exhibiting small circular forms less than 1.0 mum in diameter as reaction progressed. EDX confirmed that the smectite consisted mainly of Si, Al, and small amounts of Ca, K, and Fe. XPS revealed the formation of a dealkalized leached layer on the surface of obsidian during the reaction. The concentration of released elements suggested that nonstoichiometric dissolution proceeded during the reaction.

DOI： 10.1346/CCMN.1993.0410404

Web of Science

Scopus

Publisher：CLAY MINERALS SOCIETY  

The rehydration and rehydroxylation properties of homoionic rectorites (saturated with Ca2+, Mg2+, Na+, or K+) were further investigated. The rehydration properties of the rectorite were characterized as follows: (1) basal spacings of rehydrated materials after heating above 500-degrees-C changed to 22.5 angstrom for H2O-complexes, 26.85 angstrom for ethylene glycol-complexes, and 27.65 angstrom for glycerol-complexes; (2) rehydrated Ca- and Mg-materials exhibited single layer hydrates at &lt;50% RH, and rehydrated K-material showed double layer hydrates at 80% RH; (3) IR absorption spectra due to rehydrated H2O and OH exhibited the same or very close absorption intensities and frequencies to each other; (4) DTA-TGA curves of rehydrated materials indicated that the amount of rehydrated H2O approached about 4.2 wt. %, and about one-half of OH was rehydroxylated after heating at 800-degrees-C; and (5) interlayer cations of expandable layer components became non-exchangeable after heating above 500-degrees-C. These results suggest the following rehydration mechanism of rectorite: the interlayer cations migrate into the hexagonal holes of the SiO4 network by thermal dehydration. The cations migrated below 400-degrees-C easily return to the interlayer space and their original hydrated configurations have been recovered completely on rehydration. However, those migrated above 500-degrees-C are fixed to the hexagonal holes but water molecules are regained in the interlayer space. Consequently, electrostatic effects of interlayer cations on formation of water molecule layers are considerably reduced.

DOI： 10.1346/CCMN.1992.0400406

Web of Science

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DOI： 10.1346/CCMN.1992.0400606

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Publisher：CLAY MINERALS SOCIETY  

Two distinct zonal sequences of clay minerals (H- and L-type) were found around silicified rocks in the Makurazaki volcanic area, Kagoshima Prefecture, Japan. The clay mineral sequences from the inner to the outer parts of the alteration aureoles are: 1. H-type, pyrophyllite --&gt; dickite --&gt; 2M2 mica --&gt; sudoite --&gt; tosudite; and 2. L-type, kaolinite --&gt; rectorite --&gt; smectite. The structural formula for the sudoite is: (Al1.04Mg1.28Fe(0.20)3+Ti0.03Li0.01K0.02Na0.01)(OH)6Al2.00(Si3.54Al0.46)O10(OH)2. It is characterized by relatively large amounts of Mg and very small amounts of Li. The polytype is identified as IIb. The chemical analysis of tosudite shows that the sample is composed of an interstratification of sudoite-like and beidellite-like layers. The structural formula for rectorite is: (K0.45Na0.19Ca0.01Mg0.01)(Al1.81Fe(0.04)3+Mg0.13Ti0.03)(Si3.41Al0.59)O10(OH)2, suggesting that the nonexpandable and expandable layers have K-mica-like and beidellite-like compositions, respectively. These clay minerals in the H- and L-type alteration aureoles were formed under relatively high- and low-temperature conditions, respectively, with pH value and K- and Mg-activities increasing as the fluids ascended through the wall rocks.

DOI： 10.1346/CCMN.1991.0390605

Web of Science

Scopus

Publisher：CLAY MINERALS SOCIETY  

The rehydration properties and behavior of interlayer cations of Ca-, Mg-, Na-, and K-saturated homoionic saponite and vermiculite heated at various temperatures were examined and their rehydration mechanisms elucidated. The most notable features of saponite were (1) except for the Mg-saturated specimen, all saponite samples rehydrated until the crystal structure was destroyed by heating; (2) the rehydration rate in air after heating decreased in the order: K+ &gt; Na+ &gt; Ca2+ &gt; Mg2+; (3) the interlayer cations apparently migrated into hexagonal holes of the SiO4 network on thermal dehydration; and (4) the b-parameter expanded on thermal dehydration. The rehydration properties and behavior of interlayer cations of vermiculite were: (1) except for the K-saturated specimen, all vermiculite samples rehydrated until the crystal structure was destroyed by heating; (2) the rehydration rate in air after heating decreased in the order: Mg2+ &gt; Ca2+ &gt; Na+ &gt; K+; (3) the interlayer cations apparently did not migrate into the hexagonal holes, but remained at the center of the interlayer space, even after thermal dehydration; and (4) except for the K-saturated specimen, the b-parameters of the samples contracted on thermal dehydration. The different rehydration properties of saponite and vermiculite were apparently due to the behavior of the interlayer cations during thermal dehydration. For rehydration to occur, the interlayer cations of saponite had to migrate out of the hexagonal holes. Consequently, saponite saturated with a large cation rehydrated rapidly, whereas saponite saturated with a small cation rehydrated slowly. On the other hand, the interlayer cations of vermiculite remained in the interlayer space; therefore, the rehydration properties of vermiculite were strongly affected by the hydration energies of the interlayer cations. Furthermore, electron diffraction patterns suggested that the saponite and vermiculite consisted of random stacking and ordered stacking of adjacent 2:1 layers, respectively. The nature of the stacking of the minerals seemed to be the most important factor controlling the behavior of interlayer cations in the thermal dehydration process.

DOI： 10.1346/CCMN.1991.0390209

Web of Science

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Publisher：CLAY MINERALS SOCIETY  

The rehydration properties of Ca-, Mg-, Na-, and K-saturated homoionic beidellites after heating at various temperatures were compared with those of montmorillonites. The behavior of interlayer Na+ during dehydration and rehydration was also investigated by means of one-dimensional Fourier analysis. The K- and Mg-saturated specimens exhibited fast and slow rehydration rates, respectively, during exposure to air of 50% RH after heating at 800-degrees-C. These homoionic specimens showed strong rehydration properties on saturation with deionized water after heating &lt; 900-degrees-C for 1 hr. On the basis of Fourier analysis, the interlayer cations appeared to have migrated into the hexagonal holes of SiO4 network on thermal dehydration, and the migrated cations returned to the interlayer space on rehydration. This behavior of the interlayer cations appears to have been strongly dependent on value of the octahedral negative charge and on the sizes of interlayer cations. The small octahedral negative charge of beidellite produced a weaker attractive electrostatic force between the octahedral sheets and the migrated interlayer cations. Therefore, the migrated interlayer cations in beidellite were easily extracted from the hexagonal holes, and rehydration was rapid. The small cation migrated easily into hexagonal holes and was fixed to the holes. On the contrary, large cations were probably difficult to fix and were easily extracted from the hexagonal holes. Consequently, the rehydration rate of K-saturated beidellite was fast, and that of Mg-saturated beidellite was slow.

DOI： 10.1346/CCMN.1991.0390110

Web of Science

Scopus

DOI： 10.2465/gkk1952.20.13

DOI： 10.2465/gkk1952.20.13