The South Swamp–Pylon occurrence is situated at the south end of the North Millsite swamp between Doctors Creek and Doctors Point on the west side of Harrison Lake, approximately 42.5 kilometres northwest of Harrison Hot Springs.
The Doctors Point area is underlain by a northwest-striking, gently (30 degrees) east-dipping sequence of interbedded sediments, volcanics and volcaniclastics assigned to the Early Cretaceous Brokenback Hill Formation, which has been correlated as part of the Fire Lake Group (Journeay and Csontos, 1989; Lynch, 1990). Here, the formation comprises volcanic flows and tuff with minor argillite, volcanic sandstone, siltstone and polymictic conglomerate.
These rocks are intruded by the Tertiary Doctors Point pluton and four smaller (25 to 2000-metre-diameter) diorite to quartz diorite plutons (Nagy, Island, Peninsula and Doctors Bay plutons). Potassium-argon age dates for the Doctors Point pluton are 22 to 24 Ma (Geological Survey of Canada Paper 89-1E, page 186) and 20.4 ± 0.8 Ma (Economic Geology, Volume 86, Table 2, 1991).
The diorite plutons are surrounded by a 100 to 300-metre-wide hornfels aureole characterized by silicification, pyrrhotite (up to 15 per cent), pyrite, magnetite and red biotite flake. Cordierite, andalusite, garnet and coarse, poikiloblastic biotite have also developed in the rocks adjacent to the intrusions. Major faults trend 330 and 360 degrees across the property, with numerous conjugate and en echelon fractures.
Mineralization in the Doctors Point area is believed to be genetically and temporally related to the diorite plutons and probably represents a late hydrothermal phase of this magmatic event. The Nagy and Doctors Bay plutons, and the siliceous hornfels immediately adjacent to their margins, locally contain abundant pyrite and pyrrhotite, although these sulphide-rich pockets are not enriched in gold or silver. The gold-silver mineralization postdates both the intrusion of the plutons and a late suite of mafic dikes. The postulated sequence is (1) emplacement of the diorite plutons with some barren sulphide mineralization, accompanied by low-angle cone sheet fracturing in the hornfels aureole, (2) intrusion of the mafic dikes, (3) minor thrust faulting along the fractures, (4) gold-silver-arsenic mineralization along some of the cone sheet fractures and (5) late subvertical faulting. Veins generally dip toward the pluton cores and are predominantly associated with the Doctors Bay pluton, although a few veins lie within or adjacent to the Doctors Point and Nagy plutons. This suggests that the five diorite bodies in the area are related and probably represent apophyses of a single major body (Fieldwork 1984).
Gold-silver mineralization at Doctors Point is hosted in narrow, gently dipping, vuggy quartz-sulphide veins that show an overall spatial association to the pluton margins in that they appear to have followed pre-existing low-angle cone sheet–type fractures resulting from the emplacement of the diorite intrusions. Veins are found in 12 localities, are hosted by either diorite or hornfelsic rocks and contain variable amounts of potassium feldspar, sericite and carbonate. On surface, they vary from 1 centimetre to more than 1 metre in width. Pyrite and arsenopyrite are the most abundant sulphides, with traces of galena and sphalerite and minor chalcopyrite. Locally, the veins comprise coarse, massive sulphide material in which quartz is subordinate. Surface leaching has resulted in abundant boxwork structures in the quartz veins, and many mineralized outcrops are coated with green scorodite. Petrographic work done in 1983 suggests the native gold occurs along the grain boundaries of pyrite crystals and to a lesser extent with arsenopyrite. Microfracturing of these sulphides are infilled with calcite, pyrite, clay, native bismuth, argentite and lead bismuth sulphosalts. The veins have experienced at least two episodes of precious metal mineralization—one with the introduction of gold and the second with the introduction of silver-bismuth minerals.
The South Swamp–Pylon zone is situated 850 metres north-northwest of the Main zone, between the Main and North zones. It is underlain by volcanic and volcaniclastic rocks. The southern half of the zone is intruded by the Doctors Point pluton, and the major fault trending south from the North zone truncates its eastern boundary. Stockwork-style, less than 1-centimetre-wide quartz-sulphide veins assaying up to 100.09 grams per tonne gold are hosted by the diorite (Assessment Report 18365).
Between 1985 and 1988, Universal Trident Industries discovered the South Swamp–Pylon occurrence during trenching.
In 1985, Rhyolite Resources Inc. and Heritage Petroleums Inc. completed 517.6 metres of drilling in the North Millsite area. Drillcore assays reported up to 4.98 grams per tonne gold and 13.71 grams per tonne silver over 1.83 metres in drillhole 85-NM-5 and identified pyrite and arsenopyrite veining—prospective areas for future drilling (Assessment Report 14625).
In 1988, Universal Trident Industries carried out soil and rock sampling, trenching and geological mapping (Assessment Report 18365). sampling of a network of veins and veinlets located directly under a BC Hydro power pylon yielded values of up to 101.9 grams per tonne gold from a 5-centimetre-wide vein (Lennan, W.B. (2007-10-15): Technical Summary Report on the Doctors Point Gold Property).
In 1994, the property lapsed and was subsequently restaked as the Crystal claim by J. Cuttle. Several undeveloped targets were prospected (Assessment Report 23907).
In 1995, Cuttle continued mapping the Crystal claim (Assessment Report 24488).
In 1998, Homegold Resources Ltd. drilled two holes totalling 63.09 metres (Assessment Report 25955).
In 2006, Academy Ventures Inc. conducted geological mapping and soil and rock-chip sampling. Samples yielded up to 53.2 grams per tonne gold and 190.0 grams per tonne silver (sample BS-170706-N04) from a 0.05 to 0.10 metre wide quartz-pyrite-arsenopyrite vein in diorite adjacent to a BC Hydro pylon tower (Lennan, W.B. (2007-10-15): Technical Summary Report on the Doctors Point Gold Property).
In 2008, Urastar Energy Inc. conducted diamond drilling and an induced polarization survey, largely confirming the results of previous drilling (Academy Ventures Inc., Technical Report, March 13, 2009). Diamond drilling yielded intercepts of up to 8.38 grams per tonne gold over 0.7 metre in hole P-4 (Lennan, W.B. (2009-05-11): Technical Summary Report on the Doctors Point (Trio Ceek) Gold Property).
From 2011 to 2012, Johan Shearer conducted mapping and soil sampling and identified sporadic gold and arsenic anomalies northwest of the occurrence (Assessment Report 33502).
