The Robert E. Lee/Maid of Erin occurrence is hosted by a sequence of the Lower Jurassic Elise Formation, Rossland Group consisting of volcanic conglomerate, volcanic breccia and sandstone. These rocks are intruded by the Lower Jurassic Rossland monzonite which is comprised of a biotite-hornblende-augite monzonite stock. The old mine workings lie within the zone of thermal metamorphism associated with the monzonite intrusive.

The ore in the vein is classed as Transitional-type which is a gradational mineralogy and metal content between the Rossland-type and the South Belt-type (Bulletin 74, pages 32-41). Mineralization in the area occurs in disseminations, veinlets and as massive sulphide sections up to 6.7 metres wide. The gangue may consist of altered host rock with some quartz and calcite.

The mineralized vein strikes 248 degrees and dips 60 degrees north with sulphide mineralization ranging between 0.6 to 0.9 metres in width. Mineralization consists of fine-grained arsenopyrite, auriferous pyrrhotite, pyrite with minor chalcopyrite and sphalerite. Native gold and bismuth were also found to be associated with the ore (Thorpe, 1967). About 150 metres to the south of this vein is a second vein of arsenopyrite, 5 to 36 centimetres wide, said to assay well in gold and has the same attitude as the main vein.

In 1896, 11 tonnes of ore were mined from the vein system and 684 grams gold recovered.

The North prospect (082FSW128) to the southwest is reported to occur along an extension of the same shear zone which hosts the Robert E. Lee/Maid of Erin deposit. Refer to that deposit for further details of the host structure.