The Pipestem mine is situated approximately 2 kilometres east of Spider Peak near the headwaters of Siwash Creek and was located in 1920.
The mine area is underlain by grey to black, locally organic-rich, pyritic, slaty argillite intercalated with well-bedded siltstone, all assigned to the Lower and Middle Jurassic Ladner Group. A number of northwest- striking bands of medium to very coarse-grained, tuffaceous, fossiliferous wacke also occur within the sequence. The bands vary from 5 to 45 metres thick and are the principal host to gold mineralization.
The sedimentary rocks have been intruded by narrow sills and dikes up to 4 metres thick. Several porphyritic felsic sills, similar to those associated with gold occurrences in the Siwash Creek area (MINFILE 092HNW004, 005, 015-017), host thin quartz veins with pyrite.
The Ladner Group sediments have all undergone a complex history of structural deformation characterized by folding and several north to northwest striking faults. The wacke bands are also cut locally by a pronounced fracture cleavage.
Precious metals at the Pipestem mine occur in sulphide-bearing quartz veins and stringers in wacke exposed in surface trenches and with quartz-sulphide mineralization preferentially concentrated either along fault contacts between wacke and argillite beds or along fracture-related shatter zones cutting wacke. The veins have hydrothermally altered the host rocks at the surface and have chloritized the sediments where exposed underground. Pyrite cubes up to 1.25 centimetres on each side, arsenopyrite and sericite occur in association with this alteration. Rare visible gold has also been reported.
Discrete but fragmented quartz veins up to 0.4 metres wide, quartz stringer swarms and quartz breccia zones up to 1.5 metres wide were also encountered in underground workings. The quartz is white and massive to vuggy in character. The breccia zones comprise sharply angular, silicified, sulphide-bearing fragments of chloritized Ladner Group sediments supported by quartz.
The highest gold values were reported to have been concentrated in narrow, sulphide-rich wallrock alteration envelopes that surrounded poorly mineralized to barren, vuggy quartz veins, stringers and breccia zones within the wacke bands. The sulphides include coarse-grained pyrite with variable arsenopyrite, minor pyrrhotite and trace amounts of chalcopyrite.
Development at the Pipestem mine included a 10-metre deep shaft, open cuts and four adits totalling over 300 metres. Production is recorded for the years 1935, 1936 and 1937, when a total of 8460 grams of gold, 1151 grams of silver and 55 kilograms of copper were recovered from 1498 tonnes of ore.
Surface diamond drilling carried out at the mine in 1982 defined a narrow gold-bearing zone plunging to the south from the surface showing. The best intersection was encountered in hole LCN 82-39, where a 5-metre interval graded 4.46 grams per tonne gold (Assessment Report 11158). The best intersection from 10 underground holes graded 3.05 grams per tonne gold across 5 metres; while another drill hole (UP82-10) yielded 0.855 gram per tonne gold over 40.68 metres. One grab sample from the old stope on the No. 4 level graded 40.46 grams per tonne gold (Assessment Report 11158).
During 1976 through 1978, Longbar Minerals completed programs of soil sampling and 9.0 line-kilometres of ground geophysical surveys. In 1980 and 1984, Aquarius Resources completed programs of soil and rock sampling on the area. In 1982, Carolin Mines completed a program of geological mapping, rock and soil sampling, trenching and 29 underground and surface diamond drill holes, totalling 2360.37 metres. During 1994 through 1996, Athabaska Gold Resources completed programs of geological mapping, geochemical sampling and trenching on the area. In 2012, New Carolin Gold completed airborne magnetic and radiometric surveys, totalling 759 line-kilometres, on the area.
