Contributions to the clay mineralization and zeolitization of the Miocene tuffs in the Mecsek Mts., Hungary

Z. Mathe, I. Forizs, M. Toth, M. Polgari

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Rhyolite, dacite and rhyodacite tuff and tuffite layers of Miocene age in the Mecsek Mountains, Hungary, partly or completely altered to containing clay (mostly smectite) and zeolite (clinoptilolite) minerals as dominant alteration product. The (authors') model for this alteration process is: Hydrolysis → increase in pH → precipitation of smectite with d value of >14 Å → increase in pH → precipitation of clinoptilolite → decrease in pH → ion exchange between pore fluid and smectite (Ca is replaced by Na, which causes decrease in smectite d value to <14 Å) → precipitation of K-feldspar. The excess silica precipitated as Opal-C at different stages.

Original languageEnglish
Pages (from-to)47-55
Number of pages9
JournalGeological Carpathica - Clays
Issue number1
Publication statusPublished - Dec 1 1997


ASJC Scopus subject areas

  • Environmental Science(all)
  • Earth and Planetary Sciences(all)

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