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New Stability Diagrams of Some Phyllosilicates in the SiO2-Al2O3-K2O-H2O System

Published online by Cambridge University Press:  01 July 2024

W. H. Huang
Affiliation:
Department of Geology, University of South Florida, Tampa, Florida 33620, U.S.A.
W. D. Keller
Affiliation:
Department of Geology, University of South Florida, Tampa, Florida 33620, U.S.A.

Abstract

Aluminum is treated as a mobile, reactive component in newly designed stability diagrams for the SiO2-Al2O3-K2O-H2O system. The diagrams show that the stability field of kaolinite is strongly dependent on pH at or below 6·7 but at 6·7 or greater the stability field is independent of pH, and also that in present sea water, K-mica is a stable phase with respect to kaolin minerals. Natural waters from present-day, kaolin-forming localities in Mexico and Kentucky are consistent with theoretical interpretations from these stability diagrams.

Résumé

Résumé

L’aluminium est traité comme un composant mobile et réactif, dans le cadre de diagrammes de stabilité nouveaux concernant le système SiO2-Al2O3-K2O-H2O. Les diagrammes montrent que l’halloysite et le mica -K ne peuvent pas coexister à l’équilibre, que le domaine de stabilité de la kaolinite dépend fortement du pH en dessous de 6, 7 mais qu’il n’en dépend plus au dessus de cette valeur, et que, en présence d’eau de mer, le mica K est une phase stable par rapport aux minéraux du type kaolin. Les eaux naturelles actuelles et les sites où se forme le kaolin au Mexique et dans le Kentucky présentent des conditions en accord avec les interprétations théoriques tirées de ces diagrammes de stabilité.

Kurzreferat

Kurzreferat

Aluminium wird in neu entworfenen Stabilitätsdiagrammen für das SiO2-Al2O3-K2O-H2O-System als beweglicher, reaktionsfähiger Bestandteil behandelt. Die Diagramme zeigen, daß Halloysit und K-Glimmer im Gleichgewicht nicht koexistieren können, daß das Stabilitätsfeld von Ka-olinit eine starke pH-Abhängigkeit bei Werten von 6,7 oder darunter aufweist, daß das Stabilitätsfeld bei pH-Werten über 6,7 dagegen pH-unabhängig ist, und schließlich, daß im heutigen Seewasser K-Glimmer im Verhältnis zu Kaolinmineralen eine stabile Phase darstellt. Natürliche Wässer von Gegenden in Mexico und Kentucky, in denen heute Kaolinbildung erfolgt, stimmen mit den theoretischen Auswertungen dieser Stabilitätsdiagramme überein.

Резюме

Резюме

Во вновь составленных диаграммах устойчнивости системы SiO2-Al2O3-K2O-H2O, алюминий рассматривается как мобильный реакционноспособный компонент. По диаграммам видно, что галлуазит и К-слюда не могут сосуществовать в равновесных соотношениях и, что поле устойчивости каолинита преимущественно зависит от рН равному или ниже 6,7, но при 6,7 или выше поле устойчивости не зависит от рН, также видно, что в морской воде К-слюда является устойчивой фазой по отношению к каолиновым минералам. Природные воды Мексики и Кентукки образующие в настоящее время каолин не противоречат теоретическим интерпретациям этих диаграмм устойчивости.

Type
Research Article
Copyright
Copyright © 1973 The Clay Minerals Society

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