CONICET | Buscador de Institutos y Recursos Humanos

Argentina is a vast territory with different geological settings. In this scenery, dolomitic rocks are abundant and widespread. The economic importance of both this lithology and the main mineral constituent (dolomite) is the first cause for the studies carried out on these types of rocks. Dolomitic rocks in Argentina have been exploited for hundreds of years for different purposes. They are used as refractories, concrete aggregates and mastics, among other applications. Marble processing varies depending on its use and could include chemical treatments, burning, crushing, milling, and polishing. More impure marbles are crushed and used for construction, or discarded in spoil heaps in quarries. This chapter describes the mineralogical characteristics, textures, origin, mineral assemblages, and application of some dolostones, calcitic dolostones, dolomitic limestones, and marbles from the provinces of Buenos Aires, Río Negro and Córdoba (Argentina). The origin of these rocks varies even in close areas. In the province of Río Negro there are several deposits. One of them is composed of a dolostone formed from a preexisting hydrothermal limestone by circulation of hypersaline fluids rich in Mg and Na. It is a porous fine-grained (10 to 30 µm) rock consisting of dolomite with minor amounts of quartz, feldspar, and rhyolite particles. Clay minerals (montmorillonite, illite and sepiolite) were also identified. The alkali?carbonate reactivity of this rock when used as concrete aggregate has been analyzed. Another deposit is composed of a dolomitic marble generated by the metamorphism of a preexisting dolostone. The only mineral present is dolomite, but the further circulation of hydrothermal fluids in cracks developed talc veins with a sepiolite + calcite + amphibole (tremolite) assemblage.