The SOUTH MEX occurrence is located in a stream valley approximately 3 kilometres south the Mex prospect (094E 057), 17 kilometres northeast of the north end of Thutade Lake, and 109 kilometres northwest of the community of Tsay Keh Dene at the north end of Williston Lake.

Regionally, the area is situated within a Mesozoic volcanic arc assemblage, which lies along the eastern margin of the Intermontane Belt, a northwest-trending belt of Paleozoic to Paleogene sediments, volcanics and intrusions bounded to the east by the Omineca Belt and to the west and southwest by the Sustut and Bowser basins.

The oldest rocks exposed in the region are Permian Asitka Group crystalline limestones, which are commonly in thrust contact with Upper Triassic Takla Group andesite flows and pyroclastic rocks, and marine sedimentary and volcanic rocks of the Lower to Middle Jurassic Hazelton Group. These rocks have been intruded by plutons and other bodies of the mainly granodiorite to quartz monzonite Early Jurassic Black Lake Suite and are in turn unconformably overlain by, or faulted against, Lower Jurassic calc-alkaline volcanics of the Toodoggone Formation (Hazelton Group).

The dominant structures in the area are steeply dipping faults that define a prominent regional northwest structural fabric trending 140 to 170 degrees. In turn, high angle (approximately 60 degrees), northeast-striking faults appear to truncate and displace northwest-striking faults. Collectively these faults form a boundary for variably rotated and tilted blocks underlain by monoclinal strata.

South Mex is centered on a glacial valley, with surrounding ridges exposing Triassic Takla Group mafic volcanic rocks, unconformably overlying and moderately west-dipping Lower Toodoggone Formation intermediate volcanic rocks, and the Jurassic Giegerich granodiorite pluton (Black Lake Intrusive Suite). Pyrite-rich (2-10 per cent, mainly disseminated) sericitic and chlorite-sericite alteration hosted in Takla Group and Toodoggone Formation host rocks.

Amarc Resources Ltd. consolidated the Joy Project mineral tenure through a series of agreements concluded between 2017 and 2019. In 2019, Amarc gained a one-hundred per cent interest in the Pine property under agreements with Gold Fields and previously Cascadero (Press Release, Amarc Resources Ltd., Dec 19. 2019).

From 2016 through 2024, Amarc completed exploration programs of prospecting, mapping, geochemical soil and rock sampling historical core logging at Pine (094E 016), Mex (094E 057) and Fin (094E 312), induced polarization and airborne magnetic surveys and diamond drilling. In 2021, 4322 metres of NQ and HQ diamond drilling in 9 holes. Four holes (2,299 metres) were drilled at the Pine deposit, two on the Mex trend (1,111 metres), two at the Canyon zone (620 metres) and one (302 metres) in the Twins area (Assessment Report 40024).

In 2022, drilling at the Joy Project totaled 15,427 metres in 37 drill holes at Pine, Canyon, South Mex, SWT, Twins, Wrich, North Finlay, South Finlay and CT geophysical targets. A single scout drill hole targeting a new IP chargeability anomaly was completed at South Mex. Hole JP22041 intersected 72 metres of mainly disseminated pyrite (2-10 per cent), with sparse fine calcite ± pyrite veinlets and one silicified zone containing a cm-scale chalcedonic quartz-bladed calcite – pyrite ± galena ± sphalerite vein, grading 0.02 per cent copper, 0.1 gram per tonne gold and 3.4 grams per tonne silver (Assessment Report 40912). The drill hole cut feldspar crowded ash flow tuff and andesite-dacite volcanic units. The 2023 exploration program had the goal of identifying and refining porphyry copper-gold deposit targets occurring in several previously identified target areas across the JOY project (Assessment Report 41856).

Refer to Pine (094E 016) and Mex (094 057) for further details of the Joy Project geology and work history.