The Bonthorne mine is a skarn deposit hosted in a roof pendant within granodiorite of the Early-Middle Jurassic Island Plutonic Suite. Host rocks are north-striking, steeply east-dipping limestone and volcanics of the Upper Triassic Vancouver Group. The limestone stratigraphically overlies the volcanics. Intricate small-scale folds are recognizable in the limestone where it has not been destroyed by skarning. The volcanic rocks exhibit low grade metamorphism.

Several major northwest trending step faults, dipping steeply to the northeast, and smaller faults with a northeast trend, are recognized. Skarn mineralogy consists of garnet, epidote and actinolite. The alteration is most intense near fault zones and where limestone is in direct contact with the intrusive rocks. Skarn zones are limited to a 60-metre vertical distance from the pluton.

Mineralization consists of masses and disseminations of magnetite, bornite, chalcopyrite and pyrite. Higher copper grades occur in the fault zones and near the intrusive-limestone contacts. Magnetite occurs throughout the skarn and was reported to be of sufficient quantity to be recovered (Minister of Mines Annual Report 1920, page 20A), although production records do not show this. Production, between 1904 and 1938 was intermittent.

Combined (possible and potential ore) are 1,900,000 tonnes grading 1.5 per cent copper, 0.31 gram per tonne gold and 23.20 grams per tonne silver (Assessment Report 462, page 13).

See also Prince (092E 032).

The showings were staked by prospectors Jones and Laidlaw in 1897 and optioned to Barclay Bonthrone, of Vancouver, who drove a 76-foot adit in 1898. In 1899 ex-Governor Dewdney, of Victoria, purchased the property for the Dewdney Canadian Syndicate, Limited, of London, Ebgland. In 1902, 5 claims, the Victor (Lot 571), Tinnicanum (Lot 580), Scotlet, Leschi, and Victor No. 1 Fraction (Lots 582-584) were Crown-Ganted to the Syndicste. Exploration and development work was continued into 1904. No further activity was reported until the Vancouver Island Copper Company optioned the property in 1907. The workings were reopened and an aerial tramway installed. In 1908 the option was sold to The Tyee Copper Company, Limited, and operations continued thoughout the year. The option lapsed in 1909 and the property reverted to the owners, Dewbey and Springett, of Victoria.

In 1916 the property was optioned by Messrs. Eden and Tanner, of Seattle, and subsequently sold to the Tidewater Copper Company. Additional claims were staked and a 100 ton per day concentrator was put into operation in December 1917. Extensive underground exploration and development work was carried out and a mineralized zone estimated at 250,000 tons was developed from No. 2 adit. Mi11 capacity was increased to 300 tons per day by 1920. Operations were suspended in 1921, due to the low price of copper, and resumed in March 1922. Further exploration and development work was carried out until November 1923 when the mine closed and the ccmpany was placed in the hands of a receiver; the assets were subsequently acquired by the debenture holders.

Pacific Tidewater Mines Limited optioned the property in 1928 and carried out diamond drilling; the option was given up the following year. Japanese interests, through Sidney Inlet Mining Cmpany, Limited, reopened the mine in 1938. Further development work was done in Nos. 2 and 3 adits and the mill operated for a short period, mainly from the old pillars and the dump. Development work to that time totalled over 910 metres of drifts and-crosscuts, and some 76 metres of raises and winzes in about 12 adits.

In 1956 the 16 Crown-granted claims were owned by X.Y.Z. Hetals, Limited, and H.E. Dendoff. Bewkirk Mining Corporation Limited optioned the property in 1956 and 8 diamond drill holes were put dovan on the Tinnicanum and Scotlet claims; the option was subsequently dropped. Paco Resources Ltd. reported a geophysical survey on the property in 1962.

London Pride Silver Mines Ltd. held an option on the property in 1963. Diamond drilling totalling 549 metres was done in 7 underground holes and 3 surface holes on the Prince property.

Reserves were reported (1967) at 1,234,500 tonnes averaging 1.5 per cent copper (B.C. Dept. of Mines, Published Reserves, p. 32).

Texada Mines Ltd. optioned the property from the Estate of Hubert E. Dendoff in 1973. Work during the year included geological mapping on surface and underground, a magnetometer survey over 19.8 line-kilometres, and a geochemical soil survey (673 sample) over 19.3 line-kilometres.