The Patricia showing is located on the west side of Mount Riordan, 1 kilometre southeast of Nickel Plate Lake and about 20 kilometres east of Hedley, British Columbia.
The Patricia showing is located on the eastern edge of the Hedley Mascot and Nickel Plate mining camp. The general area has been extensively prospected. The property was explored in 1973 by Corval Resource Ltd. There is evidence of an old abandoned adit, discovered in 1986 during property exploration by Placer Development Ltd.
Hostrocks of the Patricia occurrence are marble (limestone), quartzite and minor altered andesite tuff of the Triassic Nicola Group. The limestone is probably part of the limestone-rich French Mine Formation of the Nicola Group. The rare marble layers dip flat to gently dipping. Nicola Group rocks are presumably separated from deformed ophiolitic volcanics of the Apex Mountain complex by a fault. These are intruded by fine grained, biotite hornblende granodiorite and microdiorite of the Early to Middle Bromley Batholith and coarse grained, pink granite of the Middle Jurassic Nelson Plutonic Suite. The pink granite appears to be older than the fine-grained granodiorite. Partial skarn overprinting of these intrusive rocks indicates post-skarn mineralization. These are cut by late granite and mafic porphyry dikes.
This is one of several small, discontinuous, irregular skarn zones in the French Mine Formation of the Nicola Group, which forms an elongate mass 900 metres long by 500 metres width. An old adit was discovered driven into one of these skarns. A dump at the portal contained granite and garnet-diopside skarn.
At the Patricia showing, a highly altered skarn zone appreciably different from the Nickel Plate skarn is composed primarily of massive, coarsely crystalline andraditic garnetite, quartz, and epidote with variable amounts of carbonate, hedenbergite, clinopyroxene, actinolite and traces of chlorite and wollastonite. The garnet colour is variable and includes black, red, pink, brown, green and yellow-green in crystals up to 6 centimetres diameter and prominent growth zonations. Some outcrops show sharply defined subparallel colour zonation. Optically, the garnets are birefringent with iron-rich (andraditic) cores and aluminum-rich (grossularitic) edges. This may indicate that the skarn originally may have formed in an oxidizing environment and later evolved to a more reducing environment, that may have coincided with the deposition of gold and sulphides.
Locally, skarn contains small pockets and irregular veinlets and disseminations of magnetite intergrown with variable amounts of pyrite, chalcopyrite, pyrrhotite and trace bornite. Jarosite alteration is present. Visible traces of scheelite are seen over a wide area, both in skarn and as detrital fragments in soils but is best developed near the summit of Mount Riordan. Some scheelite outcrops may also contain minor powellite and axinite, although this has not been positively identified.
Gold values are generally low. In 1986, 4 diamond-drill holes were drilled on several magnetic and/or skarn zones. Drillholes 89-17, 89-18 and 89-19 were drilled in the vicinity of the skarn described above. Drillhole 89-17 intersected garnet-diopside-epidote skarn with minor pyrite, pyrrhotite and chalcopyrite above biotite granodiorite. Drillhole 89-18 intersected siliceous metasediments and fragmental lapilli tuff with narrow granodiorite dikes. Drillhole 89-19 also intersected skarn above granodiorite with chlorite veins and scattered pyrite stringers. Overall, drill core samples yielded insignificant precious and base metal values. The best precious metal intersection was over 3 metres between 71 and 74 metres from drillhole 89-18. The sample yielded 2.06 grams per tonne gold and 15.77 grams per tonne silver (Assessment Report 15244). Further trenching in the area in 1989 exposed sulphides in strongly silicified metasediments, quartz and shear zones. Samples, however, failed to yield anomalous precious and precious metal values (Assessment Report 18940).
