The Choate property lies within an ultrabasic complex between the southern tip of the Coast Plutonic Complex and the northern end of a belt of intrusions termed the Chelan batholith. The intrusive rocks within this belt are granites, granodiorites and quartz diorites of Jurassic age and younger. They form the core of an uplifted block of regionally metamorphosed upper Paleozoic rocks which trend north, and are bounded by the Fraser River fault system on the east and west by somewhat less metamorphosed Mesozoic rocks.

The ultramafic complex hosting the Giant Nickel mine (092HSW004) mineralized zones is composed of hypersthene diorite and quartz diorites, norites and ultrabasic rocks, termed the Pacific Nickel Complex, which intrudes schists and earlier intrusive rocks. The older, noritic rocks are found northwest and southwest of the ultramafic complex. Potassium-argon ages from the ultramafic complex range from about 120 to 95 million years. The older ages were obtained from the hornblende pyroxenite phase with late hornblende dikes having the youngest ages.

The ultramafic rocks of the Pacific Nickel Complex form an irregular stock-like mass about 3.0 kilometres across. The northeast half of the stock consists of barren pyroxenites and peridotites which contain little or no hornblende. The southwest half of the stock is a highly variable, hornblende-rich assemblage of peridotites and pyroxenites which are mineralized and contain some seventeen orebodies associated with the Giant Nickel mine. These orebodies are scattered along a line trending about 285 degrees.

Mineralization occurs within the ultramafic rocks as pipe-like concentrations of enstatite, olivine and hypersthene containing pyrrhotite, pentlandite, chalcopyrite, magnetite with lesser amounts of chromite and cobalt minerals. In the deposits where the sulphides are relatively massive and comprise about 50 per cent of the rock, there is about four times as much pyrrhotite as pentlandite. Chalcopyrite, magnetite and chromite each make up about 2 to 3 per cent of the rock.

Magnetite and chromite occur as the principal metallic minerals in several places within nickeliferous bodies along Stulkawhits Creek near Choate. In particular, this type of mineralization is said to be located near the surface above the north end of the 512 foot crosscut of the No. 1 tunnel.

Both magnetite and chromite occur as small crystals or as rounded grains scattered throughout the sulphide bodies and the hornblende pyroxenite. Both minerals occasionally occur within the silicate minerals and were the first to crystallize from the magma. The concentration of magnetite and chromite either with the sulphide or in separate bodies at certain loci, can be explained as primary magmatic segregation. Limonite occurs in narrow sinuous veinlets that cut both sulphide and gangue minerals.

In 1936, 18 samples of ore were taken by the Mines Branch from several different sulphide bodies and analysed an average of 18.38 per cent iron, 1.89 per cent nickel, 0.14 per cent cobalt, 0.31 per cent chromium, 10.87 per cent sulphur, 0.7 per cent copper and only a trace of arsenic (Minister of Mines Annual Report 1936, page F64).

In 1987, 63 rock samples were collected and all were anomalous for chromium with assays up to 1.28 per cent (Assessment Report 16553).

Production is included with Pride of Emory (092HSW004).