Weathering of hornblende to ferruginousproducts by a dissolution-reprecipitation mechanism: petrography and stoichiometry. Velbel, M. Clays and Clay Minerals, 1989.
Weathering of hornblende to ferruginousproducts by a dissolution-reprecipitation mechanism: petrography and stoichiometry. [pdf]Paper  abstract   bibtex   
Hornblende of the Carrol Knob mafic complex weathered under humid, temperate conditions has a dissolution-reprecipitation reaction, in which hornblende dissolved stoichiometrically, and the ferruginous and aluminous weathering products (goethite, gibbsite, and kaolinite) precipitated from solution. During the earliest state of alteration, ferruginous weathering products formed aslinings of fractures within and around crystals and cleavage fragments of hornblende. Coalescence of etch pits during more advanced weathering produced denticulated terminations on hornblende remnants in dissolution cavities bounded by ferruginous boxworks. Dissolution cavities are devoid of weathering products. Only Al and Fe were conserved over microscopic distances; alkali andalkaline-earth elements were stoichiometrically removed from the weathering microenvironment during the weathering process.

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