Quartz veins, which host gold mineralization occur in the basal section of a lustrous, porphyroblastic phyllite. These rocks, which lie on the upright, southwesterly dipping limb of the Eureka syncline, have been locally deformed into asymmetric drag folds. Subsequent rotation of the folds by an axial plane crenulation cleavage produced minor folds which plunge slightly northwest of the earlier drag folds. It is in quartz-filled fold hinges of the youngest structures that gold is thought to be concentrated.