Scanning electron micrographs of contracts of feldspar weathering to kaolin minerals show the formation of at least two morphologies of kaolin-a platy, book type and an elongate, halloysite type. The morphology of an elongate kaolin mineral, hitherto not illustrated, is micro-graphed. Kaolin minerals are interpreted as originating from a solution phase intermediate between parent feldspar and daughter kaolin. Platy, book-type kaolinite is interpreted as forming under geologic conditions of a “weathering crust, ” which geochemical conditions persisted essentially at equilibrium over a very long time. Elongate kaolin minerals apparently form under relatively higher land conditions, and/or where kaolinization was governed by shorter time kinetic processes.

This content is PDF only. Please click on the PDF icon to access.

First Page Preview

First page PDF preview
You do not have access to this content, please speak to your institutional administrator if you feel you should have access.