MUTINAÍTE IN ZEOLITE ASSEMBLAGE IN METABASALTS OF VILLEGAS, NORTHERN PATAGONIAN ANDES, RIO NEGRO, ARGENTINA

MARIA ELENA VATTUONE; LEAL, PABLO; MARTINEZ ANDREA

Zeolites and Related Materials: Trends, Targets and Challenges

Elsevier B.V.-A. Gedeon, P. Massiani and F. Babonneau

Lugar: Amsterdam; Año: 2008 vol. 174 p. 505 - 508

In Northern Patagonian Andes, mutinaite in assemblage with clinoptilolite in amygdales of altered Jurassic/Cretacic metabasalts was found. The zeolites were studied by optic, SEM, EDS and XRD methods. The rocks have fresh pyroxene and andesine altered to pumpellyite, in a matrix with albite, interstratified chlorite/smectite, pumpellyite and epidote. There are veins with laumontite and amygdales infilled with heulandite/clinoptilolite and mutinaite. This last mineral is white and pinky with perfect cleavage parallel to {100} and imperfect cleavage parallel to {001}. It is orthorhombic, the elongation is negative, 2Vα = 70°/80° and a0 = 19.166Å, b0 = 21.025Å, c0 = 14.558Å. Amygdales filled by mutinaite–clinoptilolite-quartz and veinlets with wairakite-laumontite suggest that their crystallization was related to low grade hydrothermal/geothermal metamorphism. The temperature of formation should be  200°C/250°C range.