High grade copper ore was mined periodically from an open pit and underground workings at the Cambrian Chieftain occurrence, located 5.5 kilometres northeast of the head of Pender Harbour, 2.5 kilometres southeast of Sakinaw Lake on Sechelt Peninsula.
The earliest record of exploration in the Chalice prospect area was in 1913, when R. Durnsford Jr. drove the Stein tunnel (092GNW061). In 1937, two exploration adits were driven on the Cambrian Chieftain occurrence by Sheep Creek Gold Mines Ltd. In 1940, Alaska-Pacific Mining Co. Ltd. optioned the Cambrian Chieftain and advanced an adit 64 metres, 150 metres southwest of the Upper Sheep Creek adit. Four diamond-drill holes totalling 367 metres were also completed. Caron Mining Ltd. optioned the property in 1949 and continued development of the Sheep Creek adits. Ore was mined and shipped to a Tacoma smelter from the underground workings in 1949 and 1950. Silurian Chieftain Mining Co. Ltd. optioned the property in 1953 and a zinc showing was trenched. In 1961, Colonial Mines optioned the property and continued open pit mining ore from the Sheep Creek underground workings. Ore shipments were made to Britannia (092GNW003) and to a Tacoma smelter. A soil geochemical survey was carried out by Cone Mountain Mines Ltd. in 1972. Further exploration work was contracted to Weymark Engineering by MHB Resources in 1980. Sierra Nevada Gold Ltd. completed a magnetic geophysical survey on the Silver Lee claim in 1981. The Cambrian Chieftain claim group lapsed and the Ham 1-6 claims were staked on the ground covering the Upper and Lower Sheep Creek adits and open pit. B. Sauer staked the Cambrian Chieftain II in 1988. The Cu 1 and 2 claims were added in 1989 and 1990 respectively.
The former Cambrian Chieftain mine is hosted at the north end of a roof pendant of intermediate to mafic flows and tuffs, limestone, dolomite and chert of the Upper Triassic Karmutsen Formation, Vancouver Group. The roof pendant is surrounded by diorite and quartz diorite along the southwestern margin of the Jurassic to Cretaceous Coast Plutonic Complex. The volcanics are variably metamorphosed to greenstone and metadiorite while the calcareous sediments are locally altered to skarn. Bedding strikes north and dips vertical to steeply to the east. These units are cut by numerous narrow andesitic (greenstone) dikes striking northwest and dipping vertical to steeply southwest.
A zone of discontinuous garnet and epidote-rich skarn alteration, possibly related to shearing, strikes north-northeast for 550 metres and dips 65 to 85 degrees east, within thinly bedded limestone, chert and massive greenstone. The zone varies up to 30 metres in width. Chalcopyrite, pyrite, magnetite, and sphalerite occur along fractures and as disseminations in the actinolite- chlorite-garnet-epidote skarn. Copper mineralization is most intense in the northern 150 metres of the zone, where chalcopyrite forms massive bands and pods up to 0.9 metre thick accompanied by minor pyrite, sphalerite and magnetite. Two chip samples of this mineralization assayed as follows (Minister of Mines Annual Report 1950, page 172, Samples 13 and 22):
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Sample Width Gold Silver Copper Zinc
(m) (g/t) (g/t) (%) (%)
13 1.52 Trace 106 9.4 0.5
22 0.70 0.69 445.6 30.6 <0.3
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Two samples of skarn were taken from an old trench in 1991. Sample JZ-9101 yielded 17.41 per cent zinc, 0.33 per cent copper and 6.9 grams per tonne silver (Assessment Report 22195). The rock sample contained 3 to 5 per cent magnetite, 25 to 30 per cent sphalerite, 3 to 5 per cent pyrite and 2 to 3 per cent chalcopyrite in a fine grained skarn matrix of actinolite, chlorite, garnet and carbonate. Sample JZ-9102 yielded 4.00 per cent zinc, 0.05 per cent copper and 3.5 grams per tonne silver from a similar mineralogy.
An area of greater zinc mineralization occurs near the south end of the zone, 420 metres south-southwest of the main workings. Massive veins of pyrite, pyrrhotite, sphalerite, chalcopyrite magnetite and hematite are developed in a light coloured, epidote- bearing hostrock. A chip sample taken across a width of 4.6 metres assayed 5.8 grams per tonne silver, 0.19 per cent copper and 13.5 per cent zinc (Assessment Report 3757, Map 2, Sample 2).
A total of 1421 tonnes were mined intermittently between 1949 and 1963 by various operators. A shipment of 241 tonnes in 1949 averaged 1.93 grams per tonne gold, 261.9 grams per tonne silver and 13.96 per cent copper (Minister of Mines Annual Report 1949, page 217).
