The Whitehorse Copper Belt is located west of Whitehorse and contains 30+ mines, deposits and showings. Many of the occurrences in the Copper Belt are skarns. The skarns form on or near the contact between the Whitehorse batholith and the Lewes River group. The Whitehorse batholith is commonly a grey coarse-grained hornblende granite and ranges from quartz monzonite to granodiorite to diorite. The Lewes River group contains numerous different rock types, most importantly of which is the limestone group, which is essential in the formation of skarns in the area.  A small number of occurrences within the Copper Belt are vein and/or replacement and occur within the Whitehorse batholith granite.

The Grafter deposit and mine is located in close proximity to the Best Chance deposit and therefore the geology is assumed to be quite similar. The geological description for the Best Chance deposit is given below as reference:

The Best Chance deposit is exposed as a large outcrop of magnetite and skarn over a maximum length of 420 ft (128 m) to the north and widths up to 80 ft (24 m). The deposit is bounded by limestone on the west and granite on the east. The ore within the garnet-magnetite skarn consists of chalcopyrite, bornite and sections of massive magnetite. The major part of the copper mineralization is concentrated near the roof or around a large unreplaced lens of limestone within the skarn and the copper values are frequently found in massive magnetite.

Production at the Grafter mine was 1 800 tonnes at 7.0 % Cu between 1899 – 1907, and 10 400 tonnes at 6.0% Cu between 1915 – 1917. The ore also contains small amount of Au and Ag.