The Griswold copper occurrence is located on an unnamed south flowing tributary of the Bridge River, approximately 11.3 kilometres northwest of the junction of Nichol Creek and the Bridge River.
The showing occurs within a quartz diorite to granite intrusion of the Jurassic to Tertiary Coast Plutonic Complex, later intruded by leucocratic quartz porphyry and partially covered at higher elevations by basalt of the Pleistocene Garibaldi Group.
Mineralization consists of disseminated chalcopyrite, bornite and pyrite with trace molybdenite within a breccia zone. Secondary minerals include malachite and azurite. Wallrock alteration associated with fractures and the breccia comprises chlorite, sericite and some potassium feldspar.
A 25-metre channel sample taken across this zone in the vicinity of an old adit developed in the breccia, contained 0.80 per cent copper with only trace molybdenum and precious metal values (Assessment Report 3320).
In 2005, a chip sample from the adit yielded 1.84 per cent copper, 0.012 per cent molybdenum, 9.6 grams per tonne silver and 0.25 gram per tonne gold over 1.5 metres (sample 164661; Assessment Report 28271).
In 2011, drillhole RS11-06 yielded 0.043 per cent copper over 189 metres, including 0.103 per cent copper over 18 metres from the southern extension of the breccia zone (Assessment Report 33319).
The area was originally explored by Cominco in the 1930’s. An adit, 62.5 metres long and located at an elevation of 1500 metres, was completed during this time. In 1971, Cerro Minerals completed a program of geological mapping and soil sampling on the area as the Mel and Russnor claims. During 2005 through 2012, programs of prospecting, geochemical sampling, trenching, an induced polarization survey and 2031.5 metres of diamond drilling in nine holes were completed on the area as the Copper 1-25 claims.