The Marquis of Lorne prospect is located 2.4 kilometres east of the Similkameen River and 18.5 kilometres south of Princeton.
The area is underlain by the eastern facies of the Upper Triassic Nicola Group, comprising mafic augite and hornblende porphyritic pyroclastics and flows. These rocks are intruded by diorite and monzonite, locally pyroxenite and gabbro, of the Early Jurassic Copper Mountain and Lost Horse intrusions.
Mineralization is hosted in shear zones in andesitic and cherty tuff, with minor volcanic siltstone and sandstone, formerly included in the Wolf Creek Formation (Geological Survey of Canada Memoir 171). Most of the shear zones lie within 50 metres of the Copper Mountain stock (Copper Mountain Intrusions).
One prominent shear zone occurs in andesitic tuff, 40 metres south of the stock. The zone strikes 175 degrees and is vertical. The tuff is highly fractured and altered, with extensive limonite, jarosite and malachite staining. A grab sample contained 1.97 per cent copper and 10.7 grams per tonne silver (Assessment Report 15854, Appendix C, sample CME 81). A chip sample taken over 5 metres on the north side of a shaft contained 0.563 per cent copper, 0.012 gram per tonne gold and 3.6 grams per tonne silver (Assessment Report 11617, Figure 4).
A second parallel shear zone lies 60 metres southwest, in cherty tuff, 50 metres south of the stock. The zone exhibits epidote, chlorite and malachite, and traces of pyrite. A grab sample contained 1.53 per cent copper and 17.1 grams per tonne silver (Assessment Report 15854, Appendix C, sample CME 83). A chip sample returned 0.115 per cent copper, 0.002 gram per tonne gold and 2.4 grams per tonne silver over 5 metres (Assessment Report 11617, Figure 4).
Traces of malachite and chalcopyrite occur in two northeast- striking shear zones up to 1.5 metres wide and 15 metres long, about two hundred metres west-southwest of the previous shear zone. Pale greenish grey albite (?) alteration is associated with these two zones.
This prospect was mapped by Newmont Mining Corporation of Canada Ltd. in 1970 and 1971, and sampled in detail by Kidd Creek Mines Ltd. in 1983 and Targa Resources Inc. in 1986. Various other operators have conducted geophysical and geochemical surveys over this deposit between 1968 and 1975.
