Hallazgo de estellerita en rocas de la Serie Andesítica, Aluminé, Neuquen

BUCETA, MARÍA GUADALUPE; MARIA ELENA VATTUONE; LATORRE, CARLOS OSCAR

FCEyN- UBA

Congreso; VIII Congreso de Mineralogía y Metalogenia 2006; 2006

Catedras de Mineralogía y Petrologia FCEyN-UBA

Abstract The present contribution describes the mineralogy of stellerite, present in veins of a mesosilic volcanite from the Auca Pan formation, aged Paleoge, affected by very low grade metamorphism. The stellerite presents millimetric crystals in the form of agreggates with a botroydal habit. It’s orange, with a {010} cleavage, parallel extinction and a 2V α of aproximately 50º. The chemical analysis by EDS show a calcic composition, with with no Na+ and only one case with K+ subordinated. The Si/Al ratio ranges between 3,21 and 3,44 and the TSi ranges between 0,762 y 0,775. The unit cell parameters calculated from an X-ray difracction are a = 13.5999Å; b = 18.1953Å and c = 17.8639Å. The metamorphic assemblages suggests crystallization conditions at temperatures lower than 200ºC from hydrotermal fluids that altered the rock’s vitreous matrix.