Naganori Yoshinaga

Ferrihydrite in volcanic ash soils of Japan

Abstract Eleven samples from a range of volcanic ash soils (Andisols or Andic Dystro-chrepts) and one sample from a paddy soil formed in alluvium (Inceptisol) have been investigated for the presence of ferrihydrite using dissolution analysis and differential X-ray diffraction (DXRD). The presence of ferrihydrite in six samples, including that from the paddy soil, was established by DXRD. Except where low concentrations probably limited the distinguishability of some bands, five XRD bands (centered near 0.25, 0.22, 0.20, 0.17, and 0.15 nm) attributable to ferrihydrite were observed. The detection limit for ferrihydrite using DXRD was about 5-10% depending on the way XRD patterns were obtained and the nature of the soil matrix. Five of the samples with ferrihydrite concentrations too low to be identified by DXRD were also studied using Moessbauer spectroscopy. Changes in the Moessbauer spectra following acid-oxalate extraction were consistent, qualitatively, with the presence of ferrihydrite and, quantitati...

THE OCCURRENCE OF IMOGOLITE IN SOME SCOTTISH SOILS

Abstract Imogolite, a hydrous aluminium silicate with a fibrous morphology and a well defined structure (3), has, since its discovery by YOSHINAGA and AOMINE in 1962 (12), been found as a weathering product of pyroclastic materials in a number of localities throughout the world (4, 9, 13, 14). However, the precise mechanism by which this mineral is formed has not been established. Material with the morphology of imogolite has been observed by electron optical techniques in the clay fraction of podzolic soils developed on dune sand (1) and on a quartz parent material (6), but no conclusive evidence of its presence has been presented. This note records the occurrence of imogolite in a number of Scottish soils developed on parent materials not affected by recent volcanic activity.

Imogolite and allophane formed in saprolite of basalt on Maui, Hawaii

Inorganic gel and allophane collected from basaltic saprolite on Maui, Hawaii, and studied by Patterson in 1964 were reexamined. The main constituent of the gel is imogolite, and gibbsite and allophane are the minor constituents. Electron and X-ray diffraction patterns, DTA curve, and an infrared spectrum of the gel are characteristic of imogolite. The allophane is virtually noncrystalline to X-rays but contains a small amount of imogolite in relatively short threads. High-resolution electron micrographs indicate differences in structural organization between allophane and imogolite and suggest crystallization of imogolite from allophane.The occurrence of imogolite as a weathering product has been reported in many localities from pyroclastic materials but not from massive rocks. Probably the exceptionally high rainfall, excellent subsurface permeability of the weathered material, and the low pH and high organic content of the leaching solution provide favorable conditions for formation of imogolite from basalt on Maui.RésuméUn gel minéral et une allophane recueillis dans une saprolite basaltique de Maui, Hawaii, et étudiés par Patterson en 1964, ont fait l’objet d’un nouvel examen. Le constituant principal du gel est l’imogolite, et la gibbsite et l’allophane en sont des constituants mineurs. Les diagrammes de diffraction électronique et de rayons X, la courbe d’ATD et le spectre infrarouge du gel sont caractéristiques de l’imogolite. L’allophane est virtuellement amorphe aux rayons X, mais elle contient une petite quantité d’imogolite en aiguilles relativement courtes. Les micrographies électroniques à haute résolution indiquent des différences dans l’organisation structurale de l’allophane et de l’imogolite et suggèrent que l’imogolite a cristallisé à partir de l’allophane.KurzreferatAnorganisches Gel und Allophan, erhalten aus basaltischem Saprolit auf Maui, Hawaii, und studiert von Patterson im Jahre 1964, wurde neu untersucht. Der Hauptbestandteil des Gels ist Imogolit, und die untergeordneten Bestandteile sind Gibbsit und Allophan. Die Elektron- und Röntgenbeugungsmuster, DTA Kurve und ein Ultrarotspektrum des Gels sind kennzeichnend für Imogolit. Das Allophan ist praktisch unkristallin gegenüber Röntgenstrahlen, erthält jedoch eine kleine Menge von Imogolit in verhältnismässig kurzen Fasern. Elektronmikrographien mit hoher Auflösung zeigen Unterschiede in der Gefügeanordnung zwischen Allophan und Imogolit und deuten auf mögliche Kristallisation von Imogolit aus Allophan.РезюмеПовторно рассматривались неорганический гель и аллофан, найденных на базальтовых сапропелитах в Мави, Гавайи, которые исследовались в 1964 г. Паттерсоном. Главный компонент геля — имоголит, а гиббсит и аллофан являются второстепенными компонентами. Электронограмма; дифракционная картина; кривая дифференциального термического анализа и инфракрасный спектр геля характерны для имоголита. По рентгенограмме видно, что аллофан почти что некристаллической структуры, но содержит малое количество волокнистного имоголита. Электронные микроснимки показывают разницу структурной организации аллофана и имоголита и наводят на мысль, что имоголит образовался от кристаллизации аллофана.

Effect of SiO 2 /Al 2 O 3 ratio on the thermal reactions of allophane; II, Infrared and X-ray powder diffraction data

Allophanes with SiO2/Al2O3 molar ratios from 1.38 to 1.92 were heated at temperatures up to 500°C, and the changes induced were investigated by means of infrared spectroscopy (IR) and X-ray powder diffraction (XRD). Heat treatment caused the IR absorption band near 1000 cm−1 due to Si-O stretching to shift towards higher frequencies, and the band near 450 cm−1 due to O-Si-O bending to increase markedly in intensity. These results are probably due to condensation of SiO tetrahedra, following breakdown of Si-O-Al linkages and dehydroxylation of SiOH groups. Concurrent intensity increase of the IR absorption at about 700 cm−1 suggested an increase in the amount of 4-coordinated Al in the heated materials. ‘Imogolite structures’ were decomposed progressively at higher temperatures and were almost absent at about 400°C, as indicated by the weakening and disappearance of the IR band at 348 cm−1 and of the XRD reflections at 2.25 and 1.40 Å. The XRD reflection at 3.3–3.45 Å shifted to about 3.6 Å, probably as a result of thermal condensation of the silica component. The observed thermal changes were much greater for samples with low SiO2Al2O3 ratios (1.38–1.51) than for those with high ratios (1.81–1.92), indicating a lower thermal stability for the former materials. Thus, the thermal stability of allophanes appears to be related to the content of ‘imogolite structures’ and to the polymerization status of the silica component.РезюмеАллофаны с молярным соотношением SiO2/Аl2Оэ в диапазоне от 1,38 до 1,92 нагревались в температурах до 500°С. Перемены, вызванные этим нагревом, исследовались при помощи инфракрасной спектроскопии (IR) и порошквой рентгеновской дифракции (XRD). Нагрев образцов вызывал сдвиг полосы абсорбции IR в поблизости 1000 см−1, принадлежащей к Si–O растягивающему колебанию, к более высоким частотам, и заметное увеличение интенсивности полосы около 450 см−1, принадлежащей O–Si–O изгибающему колебанию. Эти результаты были вызваны вероятно конденсацией тетраэдров SiO после резрыва связи Si–O–Аl и дегидроксилирования групп SiOH. Одновременное увеличение интенсивности абсорбции IR в поблизости 700 см−1 указывало на увеличение количества 4-координированных А1 в нагретых образцах.” Имоголитовые структуры” раскладывались постепенно в повышенных температурах и почти отсутствовали при 400°С, на что указывало ослабление и исчезновение полос IR при 348 см−1 и отражений XRD при 2,25 и 1,40 Å. Сдвиг отражения ХРD от 3,3-3,45 Å до около 3,6 Å есть, вероятно, результатом телловой конденсации кремниевого компонента. Наблюдаемые тепловые перемены были более интенсивные для образцов с низкими соотношениями SiO2/Аl2O3 (1,38-1.51), чем для образцов с высокими соотношениями (1,81-1,92), что указывает на более инзкую тепловую устойчивость первых. Таким образом тепловая устойчивость аллофанов кажется быть связанной с количествам “имоголитовых структур” и с полимеризацией кремниевого компонента. [Е.С.]ResümeeAllophane mit molaren SiO2/Al2O3-Verhältnissen von 1,38–1,92 wurden auf Temperaturen bis zu 500°C erhitzt. Die daraus resultierenden Veränderungen wurden mittels lnfrarotspektroskopie (IR) und Röntgenpulverdiffraktometrie (XRD) untersucht. Die Hitzebehandlung verursachte eine IR-Absorptions bande bei 1000 cm−1, die auf eine Verschiebung der Si-O-Streckschwingung nach höheren Frequenzen zurückzuführen ist. Weiters nahm die Bande bei etwa 450 cm−1, die durch eine O-Si-O-Deformationsschwingung hervorgerufen wird, beträchtlich an Intensität zu. Diese Ergebnisse werden wahrscheinlich durch eine dichtere Packung der SiO-Tetraeder verursacht, die dem Zusammenbrechen von Si-O-Al-Bindungen und einer Dehydroxylierung der SiOH-Gruppen folgt. Eine gleichzeitige Intensitätszunahme der IR-Absorption bei etwa 700 cm−1 deutete auf eine mengenmäßige Zunahme von 4-koordiniertem Al in den erhitzten Substanzen hin. “Imogolit-Strukturen” wurden bei höheren Temperaturen in zunehmendem Maße zersetzt und fehlten bei etwa 400°C nahezu vollständig. Dies ging aus der Schwächung und dem Verschwinden der IR-Bande bei 348 cm−1 und aus den XRD-Reflexen bei 2,25 und 1,40 Å hervor. Der XRD-Reflex bei 3,3–3,45 Å verschob sich nach etwa 3,6 Å, was wahrscheinlich durch eine dichtere Packung der Siliziumdioxid-Komponente auf thermischem Wege zurückzuführen ist. Die beobachteten thermischen Veränderungen waren bei Proben mit niedrigen SiO2/Al2O2-Verhältnissen (1,38–1,51) viel größer als bei Proben mit hohen Verhältnissen (1,81–1,92). Dies deutet auf eine geringere thermische Stabilität der ersten Proben hin. Aus diesem Grund scheint die thermische Stabilität der Allophane mit dem Gehalt an “Imogolit-Strukturen” und mit dem Polimerisationszustand der Siliziumdioxid-Komponente zusammenzuhängen. [U.W.]RésuméDes allophanes ayant des proportions molaires SiO2/Al2O3 de 1,38 à 1,92 ont été chauffés à des températures jusqu’à 500°C, et les changements induits ont été investigués au moyen de spectroscopie infrarouge (IR) et de diffraction poudrée aux rayons-X (XRD). Le traitement à la chaleur a causé la bande d’adsorption IR près de 1000 cm−1 à cause de 1’étirement Si-O de s’approcher de plus hautes fréquences, et la bande près de 450 cm−1 à cause du pliage de O-Si-O d’intensifier de manière marquée. Ces résultats sont probablement dus à la condensation de tétraèdres SiO, suivant la dissolution des liens Si-O-Al et la déshydroxylation des groupes SiOH. Un accroissement concourant d’intensité de l’adsorption IR à à peu près 700 cm−1 a suggéré un accroissement de la quantité d’Al coordonné-4 dans les matériaux échauffés. Des ’structures imogolites’ ont été progressivement décomposées à de plus hautes températures et étaient presqu’absentes à peu près 400°C, tel que l’ont montré l’affaiblissement et la disparition de la bande IR à 348 cm−1 et les réflections XRD à 2,25 et 1,40 Å. La réflection XRD à 3,3–3,45 Å s’est rapprochée de 3,6 Å, probablement un résultat de la condensation thermique du composé silice. Les changements thermiques observés étaient beaucoup plus importants pour les échantillons ayant des proportions SiO2/Al2O3 basses (1,38–1,51) que pour ceux ayant des proportions élevées ( 1,81–1,92), indiquant une stabilité thermique plus basse pour les premiers matériaux. Ainsi, il semble que la stabilité thermique des allophanes est apparentée au contenu des ’structures imogolites’ et au statut de polymérisation du composé silice. [D.J.]

Chemical composition and some thermal data of eighteen allophanes from ando soils and weathered pumices

Abstract The chemical composition, or rang of chemical composition, of allophane is not fully clear at present. Although many data have been published on chemical composition as well as on the other chemical and mineralogical properties of soil allophane, it seems that, in many cases, greater or smaller amounts of impurities such as free sesquihydroxides and crystalline minerals are included in the samples for analysis. There would be no guarantee, therefore, that these past data, especially the chemical composition data, accurately represent the properties of soil allophanes. The present author and Aomine (14) established early a method of separation of pure allophane from certain Ando soils and this threw light on the study of various properties, especially of chemical composition, of soil allophane. In the present study, the method was applied further to thirty-six samples of soil derived from volcanic ash (Ando soils) and pumice, and from eighteen samples of them the pure or nearly pure specimens of a...

Occurrence of imogolite as gel film in the pumice and scoria deds of western and central Honshu and Hokkaido

Abstract Since its first discovery in 1962 (24, 25), imogolite has been known to occur widely in ando-sols from subfrigid to temperate to tropical regions(1, 2, 3, 6, 7, 9, 14) and, peculiarly as gel films, in certain weathered pumice beds of Japan (11, 23). Its morphology and chemical and mineralogical properties have been investigated fairly well and the investigations have reached the stage where its structural models can be hypothesized (13, 16, 19, 20, 26). Relatively little attention has been paid, however, to the mechanism of its formation and to its genetic relationship to other clay minerals(18). Elucidation of these points will be very important in establishing imogolite as a member of weathering sequence in soils, and for this to be done will be needed much more extensive study of its distribution, clay mineral suits associated, environmental conditions in soils, etc.

Identification of imogolite in the filmy gel materials in the imaichi and shichihonzakura purlice beds

Abstract In this paper are described the properties of filmy gel substances occurring in the Imaichi (Imaichi-tsuchi) and Shichihonzakura (formerly called Jobukanuma-tsuchi (2,5)) pumice beds. The properties of such filmy materials from the Kanuma (Kanuma-tsuchi) , Imaichi, and Kitakami pumice beds have been described by many investigators (1,8, 9, 10,12, 13, 14, 15, 19, ). KANNO et al. (9) concluded that they were a mixture of poorly crystalline montmorillonite, allophane, and free sesquioxides. However, the presence of montmorillonite as an important constituent has been disproved by MIYAUCHIA nd AOMINE (12), ho concluded that the gel films from the Kitakami and Kanuma pumice beds consist principally of imogolite.

Mineralogy of red- and yellow-colored soils from Thailand

Samples from profiles of 14 Ultisols, 2 Oxisols, and 1 Inceptisol from Thailand have been investigated for mineralogy and some chemical and physical characteristics. The soils were generally strongly acid in reaction with pHKC1 values at around 4, with the exception of profile T-13 which was nearly neutral with relatively large amounts of exchangeable Ca and Mg. Organic matter content was low in general (<0.5% of fine-earth), except for some surface horizon samples (1-6%). Particle-size distribution varied widely with profiles depending apparently on the type of parent materials, and also with the depth of horizons within each profile probably as a result of eluviation and illuviation, as well as loss by surface runoff, of the clay materials. Jn general, the soils derived from old alluvium were sandy, those from granitic rocks were moderately so, and those from basaltic rocks and mixed residuum and colluvium were clayey, in texture. It was noted also that the silt content was generally very low as compare...

Formation of imogolite and allophane in shattered sandstone underlying brown forest soil

The occurrence of imogolite, as gel films associated with allophane, in the fractures of shattered sandstone is being reported. The sandstone was overlain by a Brown Forest soil about 50 cm thick, derived from the same sandstone, in which neither of the minerals was found to be formed. The mode of occurrence of the minerals was similar to that in a fresh gravel bed (Iapilli-fall deposit) underlying an ash-derived soil and in podzols from many locations. This, together with the results of a synthetic experiment with soil solutions extracted, suggested that imogolite and allophane in the shattered sandstone were formed by precipitation of a hydroxy-Al orthosilicate complex transported from the overlying soil horizons. The finding suggests that imogolite and allophane may be distributed in soils more widely than hitherto reported, irrespective of the type of parent materials and type of soils.

Chemical and mineralogical properties of volcanic ash soils from Java

Abstract Six profiles of soils of volcanic ash origin from Java have been examined for their chemical and mineralogical characteristics. The soils consisted of 4 Andosols and 2 Latosols (Indonesian classification). Soil reaction was weakly to moderately acid, except for one, the Sokarini soil, in which the reaction was strongly acid due to the smectitic clay mineralogy and influence of acid gases emitted from a nearby fumarole field. The content of exchangeable cations and percentage of base saturation were high and low in accordance with the soil reaction, respectively. Organic carbon content was relatively high in the Andosols and low in the Latosols. The silt and sand fractions were dominated as a whole by quartz, cristobalite, feldspars, magnetite, and volcanic glass, with appreciable amounts of pyroxenes, amphiboles, hematite, tridymite in some soils. Among the 4 Andosols, two (Tlahap and Karang Kulon) were allophanic with imogolite and the other two were either smectitic (Sokarini) or halloysitic (S...