The Sugar gold prospect, located 20 km southeast of the Coffee gold deposits in Yukon, is hosted in the mid-Cretaceous Dawson Range batholith, of which three mappable sub-units are recognized: a biotite hornblende quartz monzodiorite; a K-feldspar phyric hornblende biotite syenogranite; and a biotite hornblende diorite. Plutonic rocks are cut by steep, west to northwest-striking andesite dikes of uncertain age. Alteration and mineralized zones coincide with fault-fracture zones that are parallel and proximal to dikes and their margins. Alteration is characterized by an early phase of calc-sodic (albite-amphibole) and potassic (pervasive biotite and fracture-controlled K-feldspar) alteration and a later phase of silica flooding and sericite alteration. Gold mineralization is associated with disseminated sulphides in zones of silica flooding and with variably sheared veins of quartz-carbonate-arsenopyrite ± pyrite ± freibergite ± stibnite ± sphalerite. Late chalcedonic quartz-carbonate and ferroan carbonate veins mark the collapse of the hydrothermal system.