The Hattie Brown occurrence is underlain by augite porphyry (diorite) of the Jurassic Rossland sill. The sill intrudes the upper part of the Lower Jurassic Elise Formation (Rossland Group) and is included as a unit of this formation. The rocks lie within several hundred metres to the south of the southern edge of the Lower Jurassic Rossland monzonite, possibly within the zone of thermal metamorphism associated with the intrusion. On the west side of the property, the Middle Eocene Coryell Intrusions, comprised of a monzonite to syenite stock, intrudes the country rock.

In 1909, just over 14 tonnes of ore were reported shipped from the Hattie Brown property (Minister of Mines Annual Report 1909). The character of the ore was described as having a gold-silver-lead nature. A mineralized fracture mapped on the Hattie Brown claim has a northwest strike and a dip of 55 degrees northeast (Bulletin 74, Figures 2 and 3). This fracture is depicted as being hosted by augite porphyry adjacent to a stock of the Coryell Intrusions.