Abstract
A thorough understanding of the mineralogy and geochemistry of rocks in the subsurface is key to exploration and assessments for (critical) mineral resources. To achieve this, datasets of various types must be rapidly acquired and interpreted across a range of scales in 3-D. This approach was applied to the stratabound Iron Creek Co-Cu deposit in the Idaho Cobalt belt. The deposit is hosted in the Apple Creek Formation of the Mesoproterozoic Belt-Purcell basin. At Iron Creek, three discrete Co-rich intervals were identified that are associated with a chlorite-rich alteration halo. X-ray fluorescence, hyperspectral, and magnetic susceptibility data on drill core paired with optical petrography and SEM-based automated mineralogy analysis of thin sections reveal the occurrence of early cobaltiferous pyrite at Iron Creek and magnetite in the Ruby zone. Later main-stage ore minerals include cobaltiferous pyrite with abundant Bi-telluride inclusions and chalcopyrite that are associated with chlorite alteration. Cretaceous syn-metamorphic silicification and quartz veins contain cobaltiferous pyrrhotite and minor galena and sphalerite. Post-metamorphic reequilibration of pyrrhotite resulted in the formation of marcasite/pyrite, and cobaltite-vaesite.