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 orebody at the Pueblo deposit occurs within the grey crystalline limestone (Lewes River) intruded by grey hornblende granite (Whitehorse batholith), and are typical contact-metamorphic deposits. The limestone is northerly and northeasterly trending unit up to 800 ft. (244 m) wide. Ore minerals include fine and specular hematite, malachite, azurite, chalcopyrite, bornite, chrysocolla and cuprite. The skarn also presents tremolite, epidote and garnet.

Nearby to the North, scheelite occurs within quartz veins in the granite. The lenticular vein is 110 ft. (34 m) long and 3 ft. (0.9 m) wide at its widest and occurs along a small fault. The vein carries 1-3% bornite and 1-3% scheelite. A second pegmatitic quartz vein stained with copper and has 2% scheelite is located nearby.

The highest production at Pueblo occurred between 1912 and 1920 when 127 000 tonnes of ore was produced at 3.9% Cu.