The Mountain occurrence is located at an elevation of approximately 1900 metres on a south-facing slope, approximately 5.4 kilometres north-northeast of Mount Albert Dease.

Regionally, the area lies at the eastern edge of the Intermontane Belt near the Kutcho fault, marking the boundary with rocks of the Omineca Belt. The oldest rocks in the area are a sequence of lower greenschist–grade metamorphosed sedimentary and volcanic rocks correlated based on lithological similarities to rocks of the Asitka Group found elsewhere (Geological Survey of Canada Open File 483). Fossil evidence from later regional mapping dates at least part of the sequence as Mississippian (Geological Survey of Canada Paper 80-1B, pages 207-211). A tentative Devonian to Permian age is assigned to these rocks. Five stratigraphic units have been recognized and are, from oldest to youngest: feldspathic chlorite schist; phyllite, sericite and calcareous sericite schist; massive rhyolite, chert and sericite schist; carbonate; and upper feldspathic chlorite schist. The rocks are complexly folded and have undergone at least two phases of deformation. They are predominantly calc-alkaline with minor alkaline members. The sequence is similar in many respects to rocks of the Kutcho Formation in the southeastern corner of the Cry Lake map area. To the south of the Stikine River, Lower Jurassic Toodoggone Formation (Hazelton Group) volcanic rocks and Upper Cretaceous sedimentary rocks of the Sustut Group dominate. Small zones and pendants of Upper Triassic Takla (Stuhini) Group are found to the east and north of the Toodoggone Formation rocks. The Asitka and Takla Group rocks have been intruded by Late Triassic and Early Jurassic quartz monzonitic rocks and Middle Jurassic granodioritic rocks.

Locally, skarn zones have been developed near the contact between interbedded limestones, limey shales, argillaceous sediments and volcanics (plagioclase porphyry and plagioclase porphyritic flows) of the Takla (Stuhini) Group and a multi-phase intrusive composed of diorite, monzonite, quartz monzonite and aplite. The volcanics have been hornfelsed, silicified and propylitically (chlorite-epidote) altered, whereas the limestone and limey shales have been converted to actinolite-tremolite-epidote-chlorite skarn zones hosting magnetite with minor pyrite and pyrrhotite. Minor facture filling pyrite and chalcopyrite with limonite alteration are also reported in the altered volcanics, whereas the intrusive contains alteration envelopes comprised of potassium feldspar, chlorite and epidote with pyrite along fractures. Molybdenite mineralization is also reported along fracture planes and in quartz veinlets in diorite, granite and lamprophyre dikes in the area. All units are intruded by narrow andesite or diabase dikes.

In 1982, samples of pyrite-rich volcanics yielded up to 0.2 gram per tonne gold (Sample 18807; Assessment Report 11152).

In 1991, two float grab samples (3915 and 3926) of pyritic feldspar porphyry assayed 0.17 and 1.20 grams per tonne gold, and two unconsolidated sediment samples yielded 1900 and 5800 parts per billion gold (Property File - P. Reynolds [1994-10-26]: Summary Report on the Mountain Mineral Claim).

In 1997, diamond drilling yielded intercepts up to 0.09 gram per tonne gold and 0.05 per cent copper over 6.71 metres in hole 97-1 (Assessment Report 25535).

In 2018, a float sample (PB088B) of massive magnetite, taken from an east-facing slope to the northeast, assayed 45.06 per cent iron and 0.065 per cent molybdenum (Assessment Report 36516).

Work History

In 1967 and 1968, Cordilleran Engineering Ltd., on the behalf of Quebec Cartier Mining Company, completed a program of regional prospecting, geological mapping and geochemical sampling on the area. This work identified minor molybdenite mineralization at a location referred to as site No. 53.

During 1980 through 1983, SEREM Ltd carried out several seasons of exploration on the area as the Mountain group of claims. Exploration programs included prospecting and rock, silt and soil sampling with initial geochemical sampling identifying two distinct, northeast-trending, copper-gold geochemical anomalies. In 1985, SEREM carried out VLF-EM and VLF-EM(R) surveys and detailed mapping on the area. They concluded that the gold geochemical anomalies coincided with a ‘pyritic feldspar porphyry unit’ and the claims were allowed to lapse.

During 1991 through 1995, the area was prospected, and rock sampled on the behalf of Joh Mirko. In 1996, Waymar Resources Ltd completed a program of prospecting, rock sampling and ground magnetic and electromagnetic (VLF) surveys on the area. The following year, a single diamond drill hole, totalling 233.78 metres, was drilled on the Mountain claim geochemical/geophysical anomaly. The drillhole is reported to have intersected poorly mineralized, silicified metasedimentary rock containing minor pyrite and pyrrhotite and cut by infrequent, thin, basic dikes.

In 2007, Arcus Development Group and Rimfire Minerals Corporation completed a program of geological mapping and rock, silt and soil sampling on the surrounding area as the Williams property.

In 2015, Running Dog Resources Ltd. completed a program of geological mapping and rock, silt and soil sampling on the area as the Castle property. Later in the year, a lineament analysis program was conducted.

In 2016, a further program of prospecting, geological mapping and rock and soil sampling was completed on the area as the Park My Bills property.

In 2018, Running Dog Resources Ltd., and Attunga Holdings Inc. completed a geochemical survey on the Abbey property, located 4 kilometres northeast of the castle occurrence. Highlighted results included the rock float sample B097822, which graded 10.3 grams per tonne silver and 0.972 percent copper (ARIS 38332).