The Castle Mountain showing is located approximately 1.2 kilometres southwest of the former Baker mine (094E 026), some 280 kilometres north of Smithers. The showing lies within the Omineca-Cassiar mountains at the southern end of the Toodoggone gold camp.

The Castle Mountain showing 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 Tertiary sediments, volcanics and intrusions bounded to the east by the Omineca Belt and to the west and southwest by the Sustut and Bowser basins.

Permian Asitka Group crystalline limestones are the oldest rocks exposed in the region. They are commonly in thrust contact with Upper Triassic Takla Group andesite flows and pyroclastic rocks. Takla volcanics have been intruded by the granodiorite to quartz monzonite Black Lake Suite of Early Jurassic age and are in turn unconformably overlain by or faulted against Lower Jurassic calcalkaline volcanics of the Toodoggone Formation, Hazelton Group.

The dominant structures in the area are steeply dipping faults which define a prominent regional northwest structural fabric trending 140 to 170 degrees. In turn, high angle northeast-striking faults (approximately 060 degrees) appear to truncate and displace northwest-striking faults. Collectively these faults form a boundary for variably rotated and tilted blocks underlain by monoclinal strata.

The Castle Mountain showing is underlain by limestone of the Asitka Group and volcanic rocks of the Takla Group. Dark green augite plagioclase phyric andesite to basalt flows with lesser interbedded siltstone, tuffaceous sediments and chert comprise lithologies of the Takla Group. These lithologies have in turn been intruded by Early Jurassic granodiorite to quartz monzonite of the Black Lake stock.

The intrusion of the Black Lake stock has led to the development of skarn mineralization at the Castle Mountain showing, which was first recognized and explored by Cominco in the early 1930s. Sphalerite, galena, chalcopyrite, magnetite, pyrite and pyrrhotite mineralization is sporadically distributed in pods rarely more than 1 to 2 metres long, but are traceable over a strike length of 304 to 426 metres in a zone up to 3 metres thick. Associated skarn mineralogy includes green amphibole, garnet and epidote.

In 1967, a sample (44706) of mineralized limestone (skarn?) assayed 1.05 per cent lead, 12.0 per cent zinc and 390 grams per tonne silver (Property File - Cordilleran Exploration Corp. Ltd [1968-02-01]: Report - 1967-69 Toodoggone).

In 1973, a sample taken across 4.5 metres from the southern end of the main skarn zone is reported to have yielded 10.6 grams per tonne silver, 0.20 per cent copper and 4.0 per cent zinc (Property File – Crowhurst, J.J. [1973-06-25]: Report of the Castle Mountain Property of Oswood G. MacDonald to Macsan Explorations Ltd.).

In 1986, sampling yielded erratic silver content with values of up to 1714.28 grams per tonne but averages closer to 68.57 to 102.85 grams per tonne; gold values are generally low. The highest values from assays were 9.25 grams per tonne gold, 1904.91 grams per tonne silver and 76.7 per cent lead from a small skarn lens on the Castle Mountain 3 Crown grant. Another small lens on the Castle Mountain 4 Crown grant yielded trace gold, 47.99 grams per tonne silver, 32.5 per cent zinc, 3.9 per cent lead and 0.79 per cent copper (Assessment Report 14979).

In 1989, three samples (PD-84 to -86) from the main Castle massive galena-sphalerite skarn zone yielded values from 33.4 to 70.6 grams per tonne silver, 0.253 to 1.802 per cent copper, 4.112 to 5.198 per cent lead and 6.408 to 18.410 per cent zinc, whereas two other samples (PD-98 and -106) of mineralized skarn, taken approximately 400 metres west and 600 metres to the south of the main zone, assayed 0.443 and 0.007 gram per tonne gold, 37.2 and 5.1 grams per tonne silver, 0.419 and 0.298 per cent lead with 4.198 and 1.497 per cent zinc, respectively (Property File - Delancy, P.R. [1989-10-01]: Final report on the 1989 exploration program Chappelle Property).

Work History

The area is reported to have been original examined by Cominco Ltd. in early 1930s, with programs of prospecting and hand trenching being performed.

In 1967, Quebec Cartier Mining Co. prospected, mapped and sampled the area as the Castle 1-4 claims.

The area has been explored in conjunction with the nearby Baker (MINFILE 094E 026) occurrence since the late 1960s and a complete exploration history can be found there.

In 1973, a 3.4 line-kilometre ground magnetic and electromagnetic survey was completed on the area as the Castle Mountain and R claims. Minor sampling was also completed at this time.

In 1981, Dynamic Oil Ltd. completed a program of soil sampling and ground electromagnetic and magnetic surveys on the Castle Mountain claims.

In 1985 and 1986, Caprock Energy Ltd. completed programs of geological mapping and an induced polarization survey on the area.

In 1989, Multinational carried out an extensive exploration program consisting of 15 kilometers of VLF-magnetic geophysics, trenching and the analysis of 653 soil and 316 rock samples on the area including the Castle Mountain claim.

In 2020, TDG Gold Corp. completed a 11.9 line-kilometre ground induced polarization survey on the area northwest of Oxide Peak and an airborne geophysical survey on the area as part of the Baker-Shasta-Oxide Peak property.