Zeolite mineralization in the pyroclastic flow deposit from Allai Unit (Central Sardinia, Italy).

Zeolite mineralization occurrs in central, in central Nureci-Fordongianus sector. The most intensively zeolitized flows occur in the unwelded ash- and pumice-rich pyroclastic facies of Allai-Samugheo, where the highest concentrations in zeolite-group minerals have been recognized, and in the Asuni units. Mineral-chemical features of zeolites were studied. The deposit of Allai display vertical zoning characterized by an increase in Cl and a decrease in Mo contents, from the top to the bottom of the series, and local occurrences of minor analcime.