Hafnian zircon as a tracer for rare metal exploration

Abstract

The major difficulty for the application of tracer minerals as mineralogical tool in geological exploration is to differentiate, in geochemical samples (like soil or stream sediment), the ore-related resistant indicator minerals from the barren-related grains. Hafnian zircon or high hafnium zircon can be such a tool to prospect rare metal granite and pegmatite bodies. Here we present some habits of the Hf-rich zircon associated to granites and pegmatites from the southeastern Brazil. Some particular characteristics of the mineral, like its luster, colour and especially its crystal forms, would allow the separation, with a simple visual analysis under a stereomicroscope, of the possible hafnian zircon from the common zircon grains. Microprobe or SEM/EDS analysis are still necessary to confirm the hafnium content in zircon crystals