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Dehydroxylation, Rehydroxylation, and Stability of Kaolinite

Published online by Cambridge University Press:  02 April 2024

Vernon J. Hurst  and
Albert C. Kunkle
Vernon J. Hurst
Affiliation:
Geology Department, University of Georgia, Athens, Georgia 30602
Albert C. Kunkle
Affiliation:
Research Department, J. M. Huber Corporation, Macon, Georgia 31298
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Abstract

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From hydrothermal experiments three pressure-temperature-time curves have been refined for the system Al2O3−SiO2−H2O and reversal temperatures established for two of the principal reactions involving kaolinite. The temperatures of three isobaric invariant points enable the Gibbs free energy of formation of diaspore and pyrophyllite to be refined and the stability field of kaolinite to be calculated. The maximal temperature of stable kaolinite decreases from 296°C at 2 kb water pressure to 284°C at water's liquid/vapor pressure, and decreases rapidly at lower pressures. On an isobaric plot of [H4SiO4] vs. °K-1, kaolinite has a wedge-shaped stability field which broadens toward lower temperature to include much of the [H4SiO4] range of near-surface environments. If [H4SiO4] is above kaolinite's stability field and the temperature is < 100°C, halloysite forms rather than pyrophyllite, an uncommon pedogenic mineral. Pyrophyllite forms readily instead of kaolinite above 150°C if [H4SiO4] is controlled by cristobalite or noncrystalline silica.

Kaolinite and a common precursor, halloysite, are characteristic products of weathering and hydro-thermal alteration. In sediments, relatively little halloysite has survived due to its low dehydration temperature and instability at low water pressure, but kaolinite commonly has survived since the Devonian Period. In buried sediments, the water pressure and [H4SiO4] requisite for stable kaolinite generally are maintained. In oxidized sediments and in pyritic reduced sediments, kaolinite commonly has survived, but where alkalies, alkaline earths, or aqueous iron has concentrated in the pore fluid, kaolinite has tended to transform to illite, zeolites, berthierine, or other minerals.

Резюме

Резюме

На основе гидротермальных экспериментов были усовершенствованы три кривые давление-температура-время для системы Al2O3-SiO2-H2O и были определены реверсные температуры для двух из числа основных реакций, включающих каолинит. Величины температуры трех изобарных инвариантных точек позволили усовершенствовать величину свободной энергии Гиббса образования диаспора и пирофиллита, а также рассчитать поле стабильности каолинитов. Максимальная температура стабильного каолинита уменьшается от 296°С при давлении воды 2 кбар до 284°С при давлении жидкость/пар (для воды) и уменьшается быстро при низших давлениях. На изобарной кривой зависимости [H4SiO4] от °K-1, каолинит имеет клинообразное поле стабильности, которое расширяется по направлению к низшим температурам, чтобы включить большую часть [H4SiO4] области близких к поверхности сред. Если [H4SiO4] больше, чем для поля стабильности каолинита и температура < 100°С, галлуазит образуется вместо пирофиллита, необычного педогенического материала. Пирофиллит легко образуется вместо каолинита при температуре свыше 150°С, если [H4SiO4] контролируется кристобалитом или некристаллическим кремнеземом.

Каолинит и обычний предшественник, галлуазит, являются характерными продуктами выветривания и гидротермальных изменений пород. В осадочных отложениях сохранилось сравнительно небольшое количество галлуазита вследствие его низкой температуры дегидратации и нестабильности при низких давлениях воды, тогда как каолинит обычно сохраняется со времени девонского периода. В захороненных осадочных отложениях необходимые для стабильного каолинита давление воды и количество [H4SiO4] в основном поддерживаются. В окисленных отложениях и в отложениях с уменьшенным количеством пирита каолинит обычно сохраняется, но каолинит стремится видоизмениться в иллит, цеолит, бертьерин или другие минералы там, где в жидкости пор сосредотачиваются щелочи, щелочные почвы или осадочное железо. [E.G.]

Resümee

Resümee

Aus hydrothermalen Experimenten wurden drei Druck-Temperatur-Zeit-Kurven für das System Al2O3-SiO2-H2O bestimmt, und die Temperaturen für zwei der wichtigsten Kaolinitreaktionen gewonnen. Die Temperaturen von drei isobar invarianten Punkten ermöglichen die Bestimmung der Gibbs'schen Freien Energie für die Bildung von Diaspor und Pyrophyllit und die Berechnung des Stabilitätsfeldes von Kaolinit. Die maximale Temperatur für stabilen Kaolinit nimmt von 296°C bei 2 kBar Wasserdampfdruck auf 284°C bei gesättigtem Wasserdampfdruck ab und verringert sich sehr schnell bei niedrigeren Drucken. Auf einem isobaren Diagramm, in dem [H4SiO4] gegen °K-1 aufgetragen ist, hat Kaolinit ein keilförmiges Stabilitätsfeld, das sich gegen niedrigere Temperaturen hin verbreitert, um viel von [H4SiO4]-Bereich der Oberflächenzone mit einzuschließen. Wenn [H4SiO4] über dem Kaolinitstabilitätsfeld liegt, und die Temperatur unter 100°C ist, dann bildet sich eher Halloysit als Pyrophyllit, ein unübliches Bodenmineral. Pyrophyllit bildet sich sehr leicht anstelle von Kaolinit bei Temperaturen über 150°C,wenn [H4SiO4] durch Cristobalit oder nichtkristallisiertes SiO2 kontrolliert wird.

Kaolinit und eine häufige Übergangsphase, Halloysit, sind typische Produkte der Verwitterung und hydrothermalen Umwandlung. In Sedimenten ist relativ wenig Halloysit aufgrund seiner niedrigen Dehydratationstemperatur und seiner Instabilität bei niedrigem H2O-Druck zu finden, während Kaolinit im allgemeinen seit dem Devon überlebt hat. In Versenkungssedimenten bleiben der für stabilen Kaolinit geforderte H2O-Druck und die notwendige [H4SiO4]-Aktivität im allgemeinen erhalten. In oxidierten Sedimenten und in pyritisch reduzierten Sedimenten bleibt Kaolinit gewöhnlich erhalten. Wenn jedoch Alkalien, Erdalkalien oder hydratisiertes Eisen in den Porenlösungen konzentriert sind, dann wandelt sich Kaolinit leicht in Illit, Zeolithe, Berthierit und anderen Minerale um. [U.W.]

Résumé

Résumé

A partir d'expériences hydrothermiques, 3 courbes pression-température-temps ont été rafinées pour le système Al2O3-SiO2-H2O et des températures de revers ont été établies pour deux des réactions principales impliquant la kaolinite. Les températures de trois points invariants isobariques permet le rafinement de l’énergie libre de Gibbs de formation de la diaspore et de la pyrophyllite et le calcul du champ de stabilité de la kaolinite. La température maximale de kaolinite stable décroit de 296°C a 2 kb de pression d'eau a 284°C à la pression liquide/vapeur d'eau, et décroit rapidement à des pressions plus basses. Sur un diagramme isobarique de [H4SiO4] vs. °K-1, la kaolinite a un champ de stabilité éffilé à trois coins qui s’élargit vers la température plus basse pour inclure une grande partie de la gamme [H4SiO4] d'environements proches de la surface. Si [H4SiO4] est au delà du champ de stabilité de la kaolinite et la température est < 100°C, l'halloysite est formée plutôt que la pyrophyllite, un minéral pédogénique peu commun. La pyrophyllite est formée promptement à la place de la kaolinite au delá de 150°C si [H4SiO4] est contrôlée par la cristobalite ou par la silice non cristalline.

La kaolinite et un précurseur commun, l'halloysite, sont des produits caractéristiques de l'altération à l'air et hydrothermique. Dans des sédiments, relativement peu d'halloysite a survécu à cause de sa température de déshydratation basse et de son instabilité à de basses pressions d'eau, mais la kaolinite a communément survécu depuis la période dévonienne. Dans des sédiments ensevelis, la pression d'eau et l’[H4SiO4] nécéssaires pour la kaolinite stable sont généralement maintenues. Dans des sédiments oxidés et dans des sédiments pyritiques réduits, la kaolinite a communément survécu, mais là où des alkalins, des terres alkalines, ou du fer aqueux a été concentré dans les fluides de pores, la kaolinite a eu tendance à se transformer en illite, zéolite, berthierine ou en d'autres minéraux. [D.J.]

Keywords

DehydroxylationGibbs free energyHalloysiteHydralsiteHydrothermalKaolinitePyrophyllite
Type
Research Article
Information
Clays and Clay Minerals , Volume 33 , Issue 1 , February 1985 , pp. 1 - 14
Copyright
Copyright © 1985, The Clay Minerals Society

References

Achar, N. N., Brindley, G. W., Sharp, J. H., Heller, L. and Weiss, A., 1966 Kinetics and mechanism of dehydroxylation processes, III. Applications and limitations of dynamic methods Broc. Int. Clay Conf. Jerusalem .Google Scholar
Anderson, G. M. and Burnham, C. W., 1965 The solubility of quartz in supercritical water Amer. J. Sci 263 494–511.CrossRefGoogle Scholar
Aramaki, S. and Roy, Rustu, 1963 A new polymorph of Al2SiO5 and further studies in the system Al2O3-SiO2-H2O Amer. Mineral 48 1322–1347.Google Scholar
Barany, R. and Kelley, K. K., 1961 Heats and free energies of formation of gibbsite, kaolinite, halloysite, and dickite U.S. Bur. Mines Rept. Inv 5825 1–13.Google Scholar
Bhattacharyya, D. P., 1983 Origin of berthierine in ironstones Clays & Clay Minerals 31 173–182.CrossRefGoogle Scholar
Bricker, O. P., Godfrey, A. E., Cleaves, E. T. and Gould, R. F., 1968 Mineral-water interaction during the chemical weathering of silicates Trace Inorganics in Water 128–142.CrossRefGoogle Scholar
Busenberg, Eurybiade, 1978 The product of the interaction of feldspars with aqueous solutions at 25°C Geochim. Cosmochim. Acta 42 1679–1686.CrossRefGoogle Scholar
Carr, R. M. and Fyfe, W. S., 1960 Synthesis fields of some aluminum silicates Geochim. Cosmochim. Acta 21 99–109.CrossRefGoogle Scholar
Crerar, D. A. and Anderson, G. M., 1971 Solubility and solvation reactions of quartz in dilute hydrothermal solutions Chem. Geology 8 107–122.CrossRefGoogle Scholar
Day, H. D. and Kumin, H. J., 1980 Thermodynamic analysis of the aluminum silicate triple point Amer. J. Sci 280 265–287.CrossRefGoogle Scholar
von Dietzel, A. and Dhekne, B., 1957 Über die Rehydratation von Metakaolin Ber. Deut. Keram. Ges 34 366–377.Google Scholar
Eberl, D. D. and Hower, J., 1975 Kaolinite synthesis: the role of the Si/Al and (alkali)/H+ ratio in hydrothermal systems Clays & Clay Minerals 23 301–309.CrossRefGoogle Scholar
Fisher, J. R. and Zen, E.-A., 1971 Thermochemical calculations from hydrothermal phase equilibrium data and the free energy of H2O Amer. J. Sci 270 297–314.CrossRefGoogle Scholar
Fyfe, W. S. and Hollander, M. A., 1964 Equilibrium dehydration of diaspore at low temperature Amer. J. Sci 262 709–712.CrossRefGoogle Scholar
Garrels, R. M. and Christ, C. L., 1965 Solutions, Minerals, and Equilibria New York Harper and Row.Google Scholar
Haas, Herber, 1972 Diaspore-corundum equilibrium determined by epitaxis of diaspore on corundum Amer. Mineral 57 1375–1385.Google Scholar
Haas, H. and Holdaway, M. J., 1973 Equilibrium in the system Al2O3-SiO2-H2O involving the stability limits of pyrophyllite and thermodynamic data of pyrophyllite Amer. J. Sci 273 449–464.CrossRefGoogle Scholar
Hass, J. L. Jr., 1970 Fugacity of H2O from 0° to 350°C at the liquid-vapor equilibrium and at 1 atmosphere Geochim. Cosmochim. Acta 34 920–932.CrossRefGoogle Scholar
Helgeson, H., 1969 Thermodynamics of hydrothermal systems at elevated temperatures and pressures Amer. J. Sci 267 729–804.CrossRefGoogle Scholar
Helgeson, H. C. and Kirkham, D. H., 1974 Theoretical prediction of the thermodynamic behavior of aqueous electrolytes at high pressures and temperatures: I. Summary of the thermodynamic/electrostatic properties of the solvent Amer. J. Sci 274 1089–1198.CrossRefGoogle Scholar
Hemingway, B. S., Robie, R. A. and Kittrick, J. A., 1978 Revised values for the Gibbs free energy of formation of Al(OH)4 aq., diaspore, boehmite, and bayerite at 298.15°K and 1 bar, the thermodynamic properties of kaolinite to 800°K and 1 bar, and the heats of solution of several gibbsite samples Geochim. Cosmochim. Acta 42 1533–1554.CrossRefGoogle Scholar
Hemley, J. J., 1959 Some mineralogical equilibria in the system K2O-Al2O3-SiO2-H2O Amer. J. Sci 257 241–270.CrossRefGoogle Scholar
Hemley, J. J., Montoya, J. W., Marinenko, J. W. and Luce, R. W., 1980 Equilibria in the system Al2O3-SiO2-H2O and some general implications for alteration/mineralization processes Econ. Geol 75 210–228.CrossRefGoogle Scholar
Henley, R. W., 1973 Solubility of gold in hydrothermal chloride solutions Chem. Geol 11 73–87.CrossRefGoogle Scholar
Hill, R. D., 1953 The rehydration of fired clay and associated minerals Trans. Brit. Ceram. Soc 52 589–613.Google Scholar
Hill, R. D., 1955 14Å spacing in kaolin minerals Acta Crystallogr 8 120.CrossRefGoogle Scholar
Hughes, I. R., 1966 Mineral changes of halloysite on drying N.Z.J. Sci 9 103–113.Google Scholar
Hurst, V. J. and Basio, N. J., 1975 Rio Capim kaolin deposits, Brazil Econ. Geol 70 990–992.CrossRefGoogle Scholar
Keller, W. D., Pickett, E. E. and Reesman, A. L., 1966 Elevated dehydroxylation temperature of the Keokuk geode kaolinite—a possible reference mineral Proc. Inter. Clay Conf. Jerusalem 1966 1 75–85.Google Scholar
Keller, W. D., 1978 Kaolinization of feldspars as displayed in scanning electron micrographs Geology 6 184–188.2.0.CO;2>CrossRefGoogle Scholar
Kennedy, G. C., 1944 The hydrothermal solubility of silica Econ. Geol 39 25–36.CrossRefGoogle Scholar
Kittrick, J. A., 1969 Soil minerals in the Al2O3-SiO2-H2O system and a theory of their formation Clays & Clay Minerals 17 157–167.CrossRefGoogle Scholar
Kremer, Thoma, 1983 SEM and XRD investigation of mineralogical transformations during weathering .Google Scholar
La Iglesia, A. and Galan, E., 1975 Halloysite-kaolinite transformation at room temperature Clays & Clay Minerals 23 109–113.CrossRefGoogle Scholar
Laubengayer, A. W. and Weisz, R. S., 1943 A hydrothermal study of equilibria in the system alumina-water J. Amer. Chem. Soc 65 247–250.CrossRefGoogle Scholar
Marshall, C. E., 1977 The Physical Chemistry and Mineralogy of Soils New York Wiley-Interscience.Google Scholar
McKeague, J. A. and Cline, M. G., 1963 Silica in soils Adv. Agron 15 339–396.CrossRefGoogle Scholar
Minato, H., Aoki, M., Mortland, M. M. and Farmer, V. C., 1979 Rate of transformation of halloysite to metahalloysite under hydrothermal conditions Proc. Inter. Clay Conf. Amsterdam Elsevier 619–627.Google Scholar
Minato, H., Kusakabee, H., Inoue, Atsuyuk, van Olphen, H. and Veniale, F., 1982 Alteration reactions of halloysite under hydrothermal conditions with acidic solutions Proc. Int. Clay Conf, Bologna, Pavia, 1981 Amsterdam Elsevier 565–571.Google Scholar
Morey, G. W., Fournier, R. O. and Rowe, J. J., 1962 The solubility of quartz in water in the temperature interval from 25°C to 300°C Geochim. Cosmochim. Acta 26 1029–1043.CrossRefGoogle Scholar
Parham, W. E., 1969 Formation of halloysite from feldspar: low temperature, artificial weathering versus natural weathering Clays & Clay Minerals 17 13–22.CrossRefGoogle Scholar
Reed, B. L. and Hemley, J. J., 1966 Occurrences of pyrophyllite in the Kekiktuk conglomerate, Brooks Range, Northeast Alaska U.S. Geol. Surv. Prof Pap 550–C 162–166.Google Scholar
Robie, R. A., Hemingway, B. S., and Fisher, J. R. (1979) Thermodynamic properties of minerals and related substances at 298.15°K and 1 bar (155 Pascals) pressure and at higher temperatures: U.S. Geol. Surv. Bull. 1452, 456 pp.Google Scholar
Roy, R., Brindley, G. W. and Swineford, A., 1956 A study of the hydrothermal reconstitution of the kaolin minerals Clays and Clay Minerals, Proc. 4th Natl. Conf, State College, Pennsylvania, 1955 125–132.CrossRefGoogle Scholar
Roy, R. and Osborn, E. F., 1954 The system Al2O3-SiO2-H2O Amer. Mineral 39 853–885.Google Scholar
Saalfeld, H., 1955 The hydrothermal formation of clay minerals from metakaolin Ber. Deut. Keram. Ges 32 150–152.Google Scholar
Schachtschabel, P., 1930 Dehydration and rehydration of kaolin Chem. Erde 4 375–419.Google Scholar
Siever, R., 1962 Silica solubility, 0°-200°C, and the diagenesis of siliceous sediments J. Geol 70 127–150.CrossRefGoogle Scholar
Van Nieuwenberg, C. J. and Pieters, H. A. J., 1929 Rehydration of metakaolin and the synthesis of kaolin Ber. Deut. Keram. Ges 10 260–263.Google Scholar
Velde, B. and Kornprobst, J., 1969 Stabilité des silicates d’alumine hydrates Contrib. Mineral Petrol 21 63–74.CrossRefGoogle Scholar
Walther, J. V. and Helgeson, H. C., 1977 Calculation of the thermodynamic properties of aqueous silica and the solubility of quartz and its polymorphs at high pressures and temperatures Amer. J. Sci 277 1315–1351.CrossRefGoogle Scholar
Wefers, Karl and Bell, G. M., (1972) Oxides and hydroxides of aluminum: Technical Paper No. 19, Alcoa Research Laboratories, Pittsburgh, Pennsylvania, 51 pp.Google Scholar