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|Title:||Desilication of Halloysite and Its Relation to Gibbsite Formation|
|Publisher:||University of Hawai'i Press|
|Citation:||Uehara G, Ikawa H, Sherman GD. 1966. Desilication of halloysite and its relation to gibbsite formation. Pac Sci 20(1): 119-124.|
|Abstract:||The evidence presented points to the alteration of halloysite to gibbsite.
Mineralogical data, as determined by X-ray and differential analysis, verify
identification of halloysite and gibbsite. Chemical data confirm the expected lower
silica and higher alumina content for samples which are predominantly gibbsitic. It
is reasonable to assume from petrographic evidence that gibbsite develops by desilicarion
of halloysite. Halloysite amygdules undergo desilication along the outer peripheries,
where acid silica-deficient waters pass, attacking the halloysite by dissolving
silica. Halloysite is stable only if it is protected from such solutions, or if the solution
passing by is saturated with silica.
Whereas alteration of feldspar to halloysite involves a gain in volume, a loss in
volume follows desilication of halloysite. This loss in volume is exemplified by the
surface cracks clearly visible in the desilicated halloysite.
|Appears in Collections:||Pacific Science Volume 20, Number 1, 1966|
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