Jade has been quarried on Brett Creek, 1.25 kilometres up from its confluence with Marshall Creek, 26 kilometres west-northwest of Lillooet.

Northwest of Lillooet, cherts, argillites and minor limestone beds of the Mississippian to Middle Jurassic Bridge River Complex trend east and are intruded by the Permian and older Shulaps Ultramafic Complex, consisting mainly of serpentinized peridotite altered to talc or chloritic schist. Sill-like dacite bodies related to the Tertiary Rexmount Porphyry also intrude the sediments.

At the Greenbay deposit, a large tectonic inclusion of chert lies adjacent to a mass of serpentinite. Metasomatic alteration along the margins of the inclusion has resulted in the development of rodingite, an alteration assemblage of hydrogarnet, clinozoisite and talc. The rodingite contains prominent small masses of thulite (pink zoisite). In places, lenses or vein-like selvages of nephrite occur either within the serpentinite body or along the rodingite-serpent- inite contact. Four lenses, up to 15 metres long by 3 metres wide, contain 9 cubic feet per ton nephrite. The quality of the jade is claimed to improve with depth. Approximately 800 tonnes of nephrite have been removed and about 200 tonnes remain.

Greenbay Mining is reported to have quarried this deposit in the early 1970's (Geological Survey of Canada Paper 72-53, page 44).