The Bosun mine is situated on the east side of Slocan Lake, between Silverton and New Denver at 615 metres elevation above sea level in the Slocan Mining Division. The mine is located on the Boatswain Fraction Crown grant (Lot 3112).
The showings, discovered in 1898 were staked as the Fidelity and Fidelity Fr. claims; the Fidelity (Lot 2411) was Crown-granted to F.L. Byron and associates in 1898. Development work in several adits and a shaft was carried out under the name Fidelity Mining Company. Adjacent showings, staked as the Tyro, Botswain Fr. and Tyro Fr. (Lots 3111-3113, respectively), were Crown-granted to the North-West Mining Syndicate in 1899. The Bosun Mines, Limited, incorporated in England to consolidate the above companies, was registered in B. C. in 1899. The Fidelity Fr., Cracker Jack and Broken Lock (Lots 3748, 3747 and 3735) were Crown-granted to Bosun mines in 1900. Operations continued into 1903 when development work totalled some 1095 metres of drifts, crosscuts and raises in 5 adits and a 23-metre shaft.
Roseberry Surprise Mining Company, Limited was incorporated in November 1917 to acquire the Bosun property and others in the same area. The company owned a mill at Rosebery, about 6.5 kilometres up the lake, and Bosun ore was milled there in 1918-19. Development work continued into 1928 and included the No. 6 (Main) level driven 915 metres from the 1ake shore, and a 43-metre inclined winze sunk at 832 metres from the portal to establish No. 7 level.
The property was purchased by Colin Campbell, of New Denver, in 1928. Lessees continued intermittent operations in various areas of the mine until 1943. Santiago Mines, Limited acquired the property in 1945. Development work in the lower levels included a winze from No. 7 level to establish No. 8 level. New Santiago Mines Limited was incorporated in January 1951 and development work continued from November to mid 1953. Lessees continued to explore and mine ore remnants in various areas of the mine into 1959 and in 1963. In 1970 the company name (New Santiago) was changed to Santico Mining and Exploration Ltd. In 1982 the company amalgamated with Heather Resources Inc. under the latter name.
Regionally, the area lies on the western margin of the Kootenay Arc, in allochthonous rocks of the Quesnel Terrane. In the vicinity of the occurrence, the Quesnel Terrane is dominated by very fine grained clastic sedimentary rocks of the Upper Triassic Slocan Group that include locally weakly metamorphosed argillite, quartzite, limestone and some tuffaceous rocks. These sedimentary rocks are intruded by dikes, sills and stocks of varied composition and origin. Permian and/or Triassic Kaslo Group metamorphosed volcanic rocks occur to the north of the Slocan Group rocks. Middle Jurassic Nelson intrusions are immediately south of the Slocan Group and are inferred to be the source of granitic to pegmatitic sills and dikes found in the area. The Nelson intrusions comprise at least six texturally and compositionally distinct phases ranging from diorite to lamprophyre. The most dominant phase is a medium to coarse grained potassium feldspar porphyritic granite (Paper 1989-5).
The Bosun mine is hosted by impure quartzite, slate and limestone of the Slocan Group that generally strike 115 degrees and dip 45 to 75 degrees southwest. The sedimentary rocks have been folded, fractured, faulted and regionally metamorphosed to greenschist facies. The regional northwest trending asymmetric Slocan syncline is thought to be Middle Jurassic and is the first recognizable deformation in the sequence. Dikes and sills of biotite quartz monzonite, one to 25 metres thick, cut the sedimentary rock and several fault structures are evident and host vein mineralization in the area. Later stage normal and thrust faults and shearing have chopped, deformed and remobilized the veins and mineralization. Horizontal displacement can be several metres to over 90 metres. Drag features are also present.
The occurrence consists of a vein within a fracture striking 060 degrees and dipping 35 to 65 degrees southeast. The vein has been developed by six main adits and several intermediate levels and raises. The No. 6 or main level is about 1130 metres long and explores three separate orebodies known as, from west to east, the West, the Central and the Third orebody. The West orebody plunges at low angles to the west but the Central and Third do not show this trend. Within the workings, the vein is discontinuous, varying from a few centimetres up to 1.5 metres. For the most part, it follows an altered quartz monzonite dike. The ore consists of galena and sphalerite associated with minor pyrite, tetrahedrite, pyrargyrite, native silver and chalcopyrite in a gangue of quartz, siderite and calcite. Minor cassiterite also occurs within the high grade sphalerite ore. The wallrock immediate to the vein contains disseminated pyrite.
As followed northeast along the levels, the vein is offset to the southeast by bedding plane shears that strike 125 degrees. These shears appear to lie along narrow altered sills of quartz monzonite. The structure is further complicated in the vicinity of the Central orebody by a split commencing below the No. 4 level. The ore follows mainly the hangingwall section of this split which has provided most of the production from the mine. The Central or main orebody was mined almost continuously from surface down to the No. 7 level, about 150 metres below surface. The ore was stoped from large blocks about 150 metres long generally bound by bedding plane shears. The fracture hosting the deposit appears to pinch out below the No. 8 level where it contains only siderite and minor sulphide mineralization.
Production from the Bosun mine between 1898 and 1976 yielded about 60 tonnes of silver, 4906 tonnes of lead, 3145 tonnes of zinc, 814 kilograms of cadmium, 37 kilograms of copper and 3 kilograms of gold from 63,222 tonnes mined.
