Mineralogia y genesis de la combarbalita en el norte de Chile
ABSTRACT. Mineralogy and genesis of the combarbalita in Northern Chile. Combarbalita is the local name of an ornamental stone formed by advanced argillic alteration of volcanic materials. Combarbalita is mined as a decorative stone from quarries that are near the town of Combarbala (31°19'S-70°59'W) in the Coquimbo Region. The rock is fragmented and shows flow-texture. The principal minerals are kaolinite and alunite, with minor presence of hematite and quartz. lts color is determined by the relative abundance of the following minerals or mineral mixtures: hematite (reddish), hematite-kaolinite (pink-brown), kaolinite (white) and schlossmacherite (turquoise green). Combarbalita has unusually high concentrations of Sr, As and Pb (trace elements). The advanced argillic alteration that formed combarbalita, probably, ocurred during the interval 80-70 Ma, which affected volcanic rocks erupted during Barremian-Albian time.