The Duchess occurrence refers to an area of minor copper mineralization located halfway between Elkhart and Siwash lakes, 17 kilometres northeast of the community of Missezula Lake. This area lies 20 kilometres east-southeast of the historical Aspen Grove copper camp, between Merritt and Princeton.

The occurrence is hosted in the Upper Triassic Nicola Group, which regionally consists of alkalic and calc-alkalic volcanics and intrusions of island arc origin, and which is the principal component of the Quesnel terrane in southern British Columbia (Geological Survey of Canada Maps 41-1989, 1713A). This belt has been of major economic interest because of its potential for porphyry copper-gold mineralization.

The area of the occurrence straddles the contact between the Eastern belt or facies of the Nicola Group, which is characterized by submarine volcaniclastic rocks and volcanic flows, and the Osprey Lake Batholith to the east (Bulletin 69; Geological Survey of Canada Map 41-1989). The volcanics generally consist of augite porphyritic andesitic or basaltic flows and lapilli tuffs and are accompanied by diorite and minor argillaceous sedimentary rocks (Assessment Reports 4525, 18041, 20994). The Osprey Lake Batholith is a large, composite, locally megacrystic, Middle Jurassic granite to granodiorite intrusion (Geological Survey of Canada Paper 91-2, page 95).

The Duchess occurrence is on the northwestern margin of the batholith, which in this area consists of hornblende biotite granodiorite with a weak foliation parallel to its margin (Assessment Report 4525). The adjacent andesitic volcanics have been contact metamorphosed and hydrothermally epidotized, with minor secondary carbonate (Assessment Report 4525).

This alteration zone is mineralized with pyrrhotite and minor chalcopyrite, which are disseminated in the volcanics or localized in fractures. Locally pyrrhotite forms aggregates between 2 and 5 centimetres across. The chalcopyrite is erratic in its distribution and is generally weak. Pyrite was not recorded.

Strongly altered fault zones, with gold and silver mineralization, occur immediately north of the Duchess occurrence in the Wart claim group (see Annie Oakley [MINFILE 092HNE029] and Brew [MINFILE 092HNE275]).

A zone of massive sulphide (chalcopyrite-pyrrhotite-hematite) mineralization in a basalt is reported approximately 700 metres southwest of the occurrence near the northeast corner of the Elk 20 claim. This approximate area is later referred to as the Nicola zone of the Elk property which was tested by diamond drilling in 2012 and yielded up to 0.63 gram per tonne gold over 0.3 metre in hole NCD12-178 (Assessment Report 34382). This hole tested a coincidental geochemical and geophysical anomaly not the previously recognized zone of massive sulphide mineralization.

Work History

In 1972, Orequest Explorations Syndicate completed a program of soil sampling and a 38.4 line-kilometre ground magnetic and electromagnetic survey on the area as the Duchess claim. Prior to this minor programs of soil sampling and trenching are reported to have been completed by D. Agur.

In 1989 and 1990, Minnova Inc. completed programs of geological mapping and geochemical (rock, soil and heavy minerals) sampling on the Wart claims.

The areas immediately south, east and west of the occurrence have been explored as part of the Elk (MINFILE 092HNE096) property and a complete regional exploration summary can be found there.