The NSS Bulletin - ISSN 1090-6924
Volume 47 Number 1: 45-48 - October 1985

A publication of the National Speleological Society

Allophane Flowstone from Newton Cave, Western Washington State
John A. Webb and Brian L. Finlayson


Yellow-orange flowstone collected from a marble cave in a small area of alpine karst is composed of allophane, an amorphous aluminosilicate clay mineral. This deposit of allophone is notable in that it has a very low molar Si/Al ration (0.06), and its infra-red absorption spectrum almost completely lacks peaks in the 350-500/cm region. This is the first reported occurrence of allophane speleothems in limestone caves. The allophane is probably forming as a result of weathering of plagioclase and amphibole minerals in the hornfels layers within the marble sequence in which the cave has formed.

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