The Mount Carter occurrence is located immediately east of Mount Carter, about 36 kilometres north of the community of Atlin.

At the showing, a minor amount of molybdenite flakes occur in quartz veins, hosted within alkali granite of the Fourth of July Creek batholith (Middle Jurassic Three Sisters Plutonic Suite). These are usually associated with aplitic dikes.

A roof pendant composed of chert of the Mississippian to Triassic Kedahda Formation (Cache Creek Complex), 75 metres wide, occurs within the batholithic rocks. The presence of malachite is common on fresh and weathered surfaces. Quartz veinlets are reported to permeate the pendant rock.

In 1980, the Pet 1-4 claims were staked on behalf of Mattagami Lake Exploration Limited in response to a regional stream sampling program that revealed several copper-molybdenum anomalies in the drainage system of a large plateau east of Atlin Lake. Follow-up field work during 1981 consisted of detailed geochemical sampling and geological mapping which yielded a total of 400 samples.