Conceptual genetic model for the primary occurrence of garnet and corundum gemstones in the miteda region, Cabo Delgado province, Mozambique

Abstract

This study enhances the importance of primary, shear-related eclogite-granulite metasomatite, not only as a source of corundum and garnet gemstones for placers but also as a valuable deposit by itself. The focus of hydrothermal circulation in multistage shear zones is invoked as the main pathway to interpret the complex mineralization observed in Miteda. In this case, the structure of a corundum + garnet major spots is interpreted according to a model of pull-a-part structures associated with sinistral shear. There is a relation between the red saturation of Rubi and the content of Cr in corundum. Cr can be leached from the meta-ultramafic host rocks as a co-product of desilification.