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File Created: 24-Jul-85 by BC Geological Survey (BCGS)
Last Edit:  20-Sep-12 by Laura deGroot(LDG)

Summary HelpHelp

NMI 104K12 Zn2
Name TULSEQUAH CHIEF Mining Division Atlin
BCGS Map 104K072
Status Past Producer NTS Map 104K12E, 104K13E
Latitude 58º 44' 09" N UTM 08 (NAD 83)
Longitude 133º 36' 04" W Northing 6511483
Easting 580980
Commodities Zinc, Copper, Lead, Silver, Gold, Cadmium Deposit Types G06 : Noranda/Kuroko massive sulphide Cu-Pb-Zn
Tectonic Belt Intermontane Terrane Stikine, Plutonic Rocks
Capsule Geology

The Tulsequah Chief deposit is located on the east side of the Tulsequah River about 10 kilometres north of its junction with the Taku River.

The Tulsequah Chief was discovered in 1925 but saw limited development during the 1930's. Cominco acquired the mine in 1946. The mine produced base metals from 1951 to 1957 and was mined from the 579 and 121 metre elevations. Since the ore from the Tulsequah Chief mine and the nearby Big Bull mine (104K 008) were combined and processed together at the Polaris Taku mine (104K 003) facilites, it is not possible to give accurate values for the amount of commodities recovered from just Tulsequah Chief ore. Recorded production figures give only the total amount of recovered commodities from the combined ore of the two mines. It is known, however, how much ore was actually mined in a given year and from which mine. A breakdown of these tonnages is given in the Production Report comment field. Over the life of the two mines a total of 580,256 tonnes was mined from Tulsequah Chief and 353,314 tonnes from Big Bull at a combined average grade of 3.77 grams per tonne gold, 126.5 grams per tonne silver, 1.59 per cent copper, 1.54 per cent lead and 7.0 per cent zinc.

The deposit is within volcanic rocks which have been mapped by Nelson and Payne (1984) as Upper Paleozoic Stikine. This date was recently reaffirmed by a uranium/lead date of Lower Mississippian on host rhyodacite (Mortensen, Geol. Surv. of Canada, unpublished data). The hanging wall is composed of dacitic tuffs which contain varying amounts of quartz fragments. Underlying this unit are more massive, often aphanitic dacitic to andesitic flows. These rocks contain much less visible quartz and feldspar. In the area of mineralization, alteration consists primarily of sericite-pyrite and locally, anastomosing zones of silica veins and pervasive silicification. The mineralization sits very high in the sequence of altered volcanic rocks. Paleozoic limestones hosting Rugosa fossils have been mapped north of the mine. It is now thought that the Pennsylvanian-Permian fossilized limestone-chert-clastic sequence lies stratigraphically above the deposit which occurs in a northeasterly striking, west dipping sequence of pre-Permian rocks located on the west limb of a north plunging anticline (Casselman, 1989). All rocks are intruded by Paleozoic diorite and dacite dykes and Tertiary rhyolite plugs, sills and dykes.

The Tulsequah Chief occurrence is a classic Kuroko-type stratiform, volcanogenic massive sulphide deposit. The deposit is located near the base of large lenticular mass of dacite-rhyolite pyroclastics at the transition with an underlying thick sequence of andesitic pyroclastics and flows. The deposit is broken into four blocks by north striking, steeply dipping faults, some of which may have been part of synvolcanic growth faults.

The orebody consists of lenses of massive sulphides which attain a maximum thickness of 10 metres and a maximum length of 170 metres. The lenses pinch out at a depth of 230 metres. The main body strikes northeast and dips steeply west, and is often highly sheared. Seven separate conformable lenses have been identified within an open syncline which strikes northeast. Mineralization consists of massive lenses of pyrite and chalcopyrite and semi-massive sphalerite, galena and pyrite throughout silicified, quartz-carbonate-barite-gypsum gangue. Deformation of these lenses is intense, with at least 3 phases of deformation having effected the area.

In 1987, rehabilitation of the 5400 level by Redfern Resources was underway with the focus on extending the existing reserves along strike and to depth. A new discovery, to the northeast of the main workings, returned several well-mineralized drill intercepts. In 1987, a 6.25 metre intercept from one drill hole assayed 6.5 grams per tonne gold, 222.85 grams per tonne silver, 1.4 per cent copper, 2.8 per cent lead and 8.0 per cent zinc (Northern Miner, July 4, 1988, page 20). In 1988, drilling confirms that mineralization called the E lens continues at least 213 metres down plunge from the lowest mine level. Also, the newly discovered G lens has been intersected in 6 holes over a strike length of 137 metres and a dip length over 137 metres. It appears to be open in all directions (George Cross News Letter October 3, 1988).

Mineralization at present is contained in two lenses, the lower AB lens and the stratigraphically higher H lens. True thicknesses range from 1.5 to 7.6 metres in the AB lens and from 1.5 to 38.4 metres in the H lens. Drilling since 1987 has indicated a preliminary reserve of 7,801,060 tonnes grading 1.6 per cent copper, 1.2 per cent lead, 6.5 per cent zinc, 2.74 grams per tonne gold and 109.69 grams per tonne silver (Northern Miner - October 12, 1992, page 3). About 85 per cent of the reserve is contained in the H lens (Property File - Northwest Mining Conference (Spokane, Washington), Handout, 1991)

The Tulsequah Chief drill indicated geological reserve in all categories totals 8,930,000 tonnes grading 1.31 per cent copper, 1.24 per cent lead, 6.62 per cent zinc, 2.53 grams per tonne gold and 107.56 grams per tonne silver (George Cross News Letter No.105 (June 1), 1995).

In July 1995 Redfern Resources Ltd. reported positive results from a 1.5 million dollar feasibility study conducted by Rescan Engineering Ltd. with contributions by a team of independent consulting engineers. The study is based on an initial mineable reserve of 7.2 million tonnes grading 1.24 per cent copper, 1.18 per cent lead, 6.32 per cent zinc, 2.41 grams per tonne gold and 99.33 grams per tonne silver, which is part of the overall geological reserve of 8.9 million tonnes. At a production rate ranging from 800,000 to 900,000 tonnes per year, the mine life is estimated to be about 8.3 years. Economic analysis is based on the year-round utilization of a 160-kilometre access road to be built from the minesite northwards to the existing road at Atlin, British Columbia. An alternative access option contemplates the seasonal use of barges on the Taku River, from its confluence with the Tulsequah River to its outlet at the ocean near Juneau, Alaska. Revisions to the feasibility study are anticipated, but Redfern hopes to file an application for a Mine Development Certificate before the end of the year (Information Circular 1996-1, page 16).

Redfern Resources Ltd. submitted a revised Project Report for the Tulsequah Chief to the Environmental Assessment office on July 8, 1997. Reserves estimated by the company in 1996 are 7.91 million tonnes grading 6.35 per cent zinc, 1.27 per cent copper, 1.18 per cent lead, 100.91 grams per tonne silver and 2.42 grams per tonne gold, and open to depth and along strike (Information Circular 1998-1, page 20). At full production, milling 900,000 tonnes per year, the mine is forecast to produce 53,200 tonnes of zinc, 10,090 tonnes of copper, 9350 tonnes of lead, 75,270 kilograms of silver and 1742 kilograms of gold annually over a minimum mine life of 9 years. The mine will employ 260 people; the capital cost is estimated at $155 million. Redfern has established a maximum public awareness program, including close contacts with the Taku River Tlingit First Nation Band. The company received approval for the mine in March 1998. Production is planned in early 2000.

Redfern received a second project approval certificate in December 2002.

In 2003, Redfern Resources Ltd., a wholly owned subsidiary of Redcorp Ventures Ltd., conducted a surface and underground drill program to locate extensions of existing resources at the Tulsequah Chief deposit. Two surface diamond-drill holes totaled 1069 metres and 21 underground diamond-drill holes totaled 9040 metres. The deposit is open in several areas. Continuity is excellent in the down-dip direction but drill holes at least 800 metres long are required, therefore Redfern explored a more accessible area west of the deposit for a continuation of ore lenses across the 4400 fault. A new massive sulphide lens, with deposit-average grade that is stratigraphically above the main deposit, was intersected in six holes. Nine holes cut the principal H lens, including an uncommonly thick (37 metre) intercept, and six holes cut the AB lenses. One intersection of uncertain correlation returned exceptional precious metal grades of 16.3 grams per tonne gold, 511 grams per tonne silver, 0.08 per cent copper, 0.7 per cent lead and 1.2 per cent zinc over 7.6 metres (Exploration and Mining in BC 2003, page 6).

In 2004, Redfern conducted a major program of in-fill and step-out drilling to confirm and expand resources at the Tulsequah Chief deposit. Three drills recovered 30,444 meters of core in 54 holes and include some of the highest grades obtained over the life of the project. The 5400 level drift was extended 160 meters and all drilling was conducted from three underground stations. The most important part of the deposit, the H lens, forms a steep pipe, or lens, that is about 100 meters long, up to 31 meters in true thickness and was delineated by the current program to 800 meters below previous mining. At that level, a fault zone was encountered that caused several drill holes to be lost. Holes that were completed through the fault penetrated intense alteration and the company suggests that the H lens bends to the east toward the 5300E fault. Drilling also targeted the G zone, which is a faulted offset of the H deposit on the east side of the 5300E fault.

In 2005, Redfern Resources Ltd updated the resource estimate for the Tulsequah Chief deposit. Measured and Indicated resources total 5.38 million tonnes at a grade of 1.41 per cent copper, 1.32 per cent lead, 6.73 per cent zinc, 2.73 grams per tonne gold and 100.8 grams per tonne silver (Exploration and Mining in BC 2005, page 28). The figures represent an approximate 10 per cent decrease in tonnage and total metal content from the previous estimate. The Inferred resource was nearly halved to 1.54 million tonnes at 1.13 per cent copper, 1.07 per cent lead, 5.44 per cent zinc, 2.23 grams per tonne gold and 85.1 grams per tonne silver (Exploration and Mining in BC 2005, page 28). The previous years drilling program determined that the principal H ore zone is restricted in strike length at depth, and it is also disrupted and/or displaced by the 5300 fault. Redfern began an update of the feasibility study done in 2005 but the work was halted in mid-year when it became apparent that increased capital and operating costs, combined with the downgraded resource estimate, made the project financially unattractive.

Redcorp Ventures Ltd. conducted a drill program in 2006 on Tulsequah Chief and Big Bull (104K 008) deposits. It was focused on upgrading resources for the feasibility study, exploration of geophysical anomolies near mine workings as well as regional scale studies. Combined drilling at these two deposits amounted to 23,350 metres. Near the Tulsequah mine workings a new mineralization zone was encountered (A-zone) wich has a NI 43-101 compliant resource estimate. The Indicated resource was 108.9 thousand tonnes at 1.4 per cent copper, 1.24 per cent lead, 6.41 per cent zinc, 2.67 grams per tonne gold and 98.93 grams per tonne silver. The Inferred resource was 98.3 thousand tonnes at 0.73 per cent copper, 1.59 per cent lead, 5.46 per cent zinc, 2.63 grams per tonne gold and 120.14 grams per tonne silver. The A-zone Extension was intersected by five holes, the best of which yielded 1.69 grams per tonne gold, 177.6 grams per tonne silver, 0.98 per cent copper, 0.85 per cent lead and 5.24 per cent zinc over a core length of 11.85 metres (Exploration and Mining in BC 2006, page 35). Mineralization was also discovered west of the 4400 fault, a structure that formed the western boundary of past mine production.

In 2007, fifteen core holes at Tulsequah Chief explored up-dip of the G-zone and A-zone extension. A total of 12,484 metres was drilled at the Tulsequah Chief and Big Bull (104K 008) where a further 20 core holes were completed. A geotechnical assessment of the plant site and the tailings impoundment, a detailed topographic survey (LIDAR) and several environmental programs were also completed. A new mining support plan for development is based on an air cushion barge that will be towed by an amphibious tug and operate year-round on the Taku River. The shipment of equipment and supplies during construction and operation, and the shipment of concentrate would all be done using this system, via Juneau Alaska.

In December 2008 Redcorp suspended construction activities due to uncertainty related to costs to complete development.

In September 2010 Chieftain Metals Inc. purchased the thirteen mineral claims, twenty-five crown-granted claims and four fee-simple lots comprising the Tulsequah project.

In June 2011 Chieftain released results from a NI43-101 compliant preliminary economic assessment. Included in this was updated mineral resources as follows (Press Release June 14, 2011):
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Category tonnes Au (g/t) Ag (g/t) Zn (%) Cu (%) Pb (%)
Indicated 6,000,000 2.63 96.0 6.44 1.42 1.23
Inferred 1,100,000 1.63 72.0 5.02 0.94 0.93
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