The Duthie mine is located on the south west slope of Hudson’s Bay Mountain, 13 kilometres west of Smithers.

The Duthie mine country rock consists of Lower-Middle Jurassic Hazelton Group volcanics comprised mainly of spherulitic flow-banded rhyolite and massive lapilli tuff which is cut by numerous diabasic and dioritic dikes. The flow-banded rhyolite outcrops along the southern part of Hudson Bay Mountain and is overlain to the north, east and west by massive lapilli tuff. The contact dips 20 degrees north at about 1220 metres in elevation on the Henderson vein. In the vicinity of the veins the host rock is highly altered and bleached.

A Middle-Late Cretaceous Bulkley Intrusions stock intrudes the core of Hudson Bay Mountain and is comprised of porphyritic granodiorite and quartz monzonite with associated quartz veining.

The mineral deposits of the Duthie mine occupy four main fault zones, originally known as the Ashman, Henderson, Fault Plane and Dome. The mineralized fault zones or "vein-lodes" strike northeast and dip between 50 degrees southeast to 70 degrees northwest. They range from a few centimetres to 2.4 metres in width and from 213 to in excess of 1067 metres in length. The vein lodes are sliced, sheared and brecciated and host sulphide veins or infillings with vein quartz and carbonate gangue. The main ore minerals are galena, sphalerite, tetrahedrite, pyrargyrite, pyrite, arsenopyrite, gold, chalcopyrite, silver and freibergite. Ore from the Henderson-Ashman lode also contains pyrrhotite and marcasite. All the ore contains gold and rare visible gold is associated with the arsenopyrite. The ore is associated with minor quartz and carbonate gangue and is crosscut by younger chalcedony veins up to 5 centimetres in width.

There is a progressive change in the mineralization in a northeast direction along the Henderson-Ashman vein lode as the deposit approaches the granodioritic stock which forms the core of the mountain. The galena-sphalerite-tetrahedrite ore changes to arsenopyrite-sphalerite ore that contains more gold and zinc but less galena and silver.

The Henderson vein lode is marked by intense faulting and more brecciation than the other veins and has proved to be the most productive. It outcrops between 1082 to 1280 metres elevation for about 610 metres and then joins the Ashman vein lode. The combined veins have been traced to the northeast for 460 metres at 1360 metres elevation. The Henderson vein strikes 065 degrees and dips between 50 degrees southeast to 80 degrees northwest. The Ashman vein is traceable for 520 metres southwest of its junction with the Henderson.

At 1090 metres elevation, the Henderson vein joins the Fault Plane vein lode and the two veins plunge at a low angle southwest. The Henderson vein has a near vertical dip, whereas the Fault Plane striking nearly parallel, dips 55 to 60 degrees southeast.

The fourth vein, the Dome (093L 089), lies 400 metres southeast of the Henderson and strikes 065 degrees and dips 75 to 85 degrees northwest. The Dome vein is well-defined for 215 metres.

The Duthie mine was first discovered in 1922 and mining from the ‘front end’ continued until 1930. From 1946 until 1954, the ‘back end’ or Breccia zone was worked by Sil-Van Consolidated Mining and Milling Company. At this time, a 136-tonne-per-day mill was operated with lead and zinc concentrates being shipped to Trail. Over 72200 tonnes of ore was milled during this time.

In the mid 1980s, the Duthie property was owned by Consolidated Silver Standard Mines Limited and operated by Duthie Mines Limited. From 1984 through 1988, more than 3 600 metres of horizontal adit development of three levels was completed. A mill capable of producing 45 tonnes per day of flotation concentrates was in operation from 1984 until 1986. In 1988, proven and probable reserves were 24 500 tonnes at 2.74 grams per tone gold, 655.1 grams per tonne silver, 4.4 per cent lead and 5.5 per cent zinc; with a further 72 500 to 90 600 tonnes of inferred reserves (Property File Rimfire Cummer, 1989).

Measured geological reserves at Duthie are 19,700 tonnes grading 207 grams per tonne silver, 2.55 grams per tonne gold, 5 per cent lead and 7.5 per cent zinc (Map 58).