Abstract Boulders are an important material in debris flow and their source is coupled with spheroidal weathering profiles that produce corestones. The goal of this work was to establish the geochemical transformations that produced corestones and distinguished them from the surrounding grus in two tropical granite weathering profiles (P1 and P2). Sampling was not performed in a vertical profile; instead, we gathered 13 (P1) to 16 (P2) samples displaying different weathering degrees (corestone and saprolite) and spatial positions in the profiles. We conducted the geochemistry (EDXRF/EDX and INAA) and mineralogy (petrography and XRD) of the samples. The CIA values ranged from 46 (corestones) to 93 (saprolite). Granite spheroidal weathering under a tropical mountainous slope develops mostly due to feldspar weathering (foremost plagioclase) in the following sequence: porosity growth, kaolinite, and gibbsite crystallization. Zircon weathering stability and its probable mobility as grain along the weathering profile play an important role in REE concentration. Spheroidal weathering is mainly a lixiviation process, yet specific locations (below the individualized corestones) presented REE enrichment due to translocation. They are hosted mainly by clay minerals and, to some extent, by amorphous Fe oxyhydroxide. The evolution of spheroidal weathering results in a vertical patchy weathering profile.

This paper describes the main activities regarding scientific dissemination in the field of Chemistry at Casa da Descoberta (CD) - a Scientific Dissemination Center of the Fluminense Federal University. It presents a brief history of CD and discusses the difficulties concerning the dissemination of Chemistry at Scientific Dissemination Centers. This work also approaches some activities developed throughout the years: experiments performed in relation to the visitors' daily life, training of monitors to act as mediators in the non-formal teaching of Chemistry, production of dissemination materials, elaboration of books, as well as activities that relate formal to non-formal education.