The Mount Hickman occurrence is located along the northern boundary of the Middle to Late Triassic Mount Hickman Ultramafic complex, itself located along the southeast boundary of the Middle to Late Triassic Hickman batholith.

Middle to Late Triassic plutons fall into two groups: small, Alaskan-type ultramafic bodies and larger calcalkaline plutons. Both intruded at shallow levels and are coeval with Stuhini Group volcanism. As of 1995, the ultramafic suite, known as the Polaris Ultramafic Suite included the Gnat Lakes Complex, the Mount Hickman Ultramafic Complex and two smaller bodies discovered just before 1995 (Bulletin 95).

The ultramafic complex is composed mainly of medium to coarse-grained, buff to brown to black weathering olivine clinopyroxenite to peridotite. These rocks contain anywhere form 5 to 20 per cent olivine which is generally wholly or partly serpentinized. Accessory magnetite and chromite are ubiquitous. In the central portion of the complex, several bodies of lighter weathering dunite occur within the pyroxenite. The contacts are sharp but the genetic relationship between the two main rock types is uncertain. Along the southeast margin of the complex, the olivine pyroxenites grade into hornblende-pyroxene gabbros with 5 to 15 per cent chalky white feldspar filling interstices between pyroxene grains. Magnetite is also abundant. This "border phase" of the complex appears to intrude pyroxene and feldspar porphyritic volcanic flows of the Upper Triassic Stuhini Group. To the north, a narrow belt of variably metamorphosed and altered volcanic rocks of uncertain age separate the ultramafic complex from hornblende diorite to hornblendite of the mafic phase of the Hickman pluton. These rocks grade into more intermediate quartz monzonites and granodiorites of the main phase of the pluton located to the north. The ultramafic rocks are unequivocally intruded by the main phase of the Hickman pluton; the genetic relationship between the pluton and ultramafic complex is uncertain.

Mineralization is comprised of narrow seams of antigorite which have partly or completely replaced olivine in the olivine clinopyroxenites of the ultramafic complex.