The Tulsequah Chief and Big Bull deposits are volcanogenic massive sulphide deposits. The ore is found in the hinge zone and limbs of a steeply plunging synclinal fold. The ore minerals consist of sphalerite, chalcopyrite, galena, tennantite-tetrahedrite and native gold. Gangue minerals include pyrite, quartz, sericite, barite and/or gypsum and lithic fragments.

Regionally, The Tulsequah Chief deposit is located in the Paleozoic-aged Mount Eaton group which is a volcanic arc assemblage contained within the Stikine Terrane of northwest BC. The Llewelyn fault separates the Mt Eaton assemblage from older and more deformed tectonostratigraphic blocks to the west. These include the Whitewater Suite (which hosts the nearby Polaris-Taku gold deposit) and the Boundary and Mt. Stapler suites. Tertiary age Sloko volcanics unconformably overlie all of these older blocks.

At Tulsequah Chief the enclosing stratigraphy has been well defined from surface and underground development mapping as well as from information obtained from extensive surface and underground drilling. The deposit occurs at the base of a rhyolite-dominated sequence of volcanic flows and fragmental units. These rocks sit above a thick assemblage of mafic volcanics (basalts and basaltic andesites). In turn the rhyolites are overlain by a mafic dominated sequence of basalt flows, breccias and sills. In the mine area a thick diorite/gabbro sill intrudes the rhyolites above the sulphide deposits. This sill is geochemically identical to the upper mafic volcanic units. Basaltic dykes, interpreted to be feeders to the thick sill, cut through the sequence. Late stage Sloko dykes of Tertiary age are associated with faults cutting all of the mine sequence rocks.

The Tulsequah deposits consist of a number of stacked sulphide lenses developed within the basal stratigraphy of the felsic volcanics. The thickest part of the deposit is located within a synclinal structure termed the H syncline. Thinner portions of the sulphide lenses extend into the limbs of this structure and into the F anticline to the west. Two prominent faults occur within the H syncline and subparallel to the axial plane of the fold. These faults, the 4400E and the 5300E faults, may represent focal points of renewed movement on older basin-bounding growth faults at the time of sulphide deposit deposition. The G lens which occurs in the fold limb east of the 5300E fault is interpreted to be a fault offset of the main H/AB2 lens within the main H syncline structure.






Project development chronology

The Tulsequah project area has had a long and diverse exploration and development history. The chart below displays some of the history of these activities.

In the 1950s Cominco Ltd. extracted 935,536 tonnes of ore, comprised of 575,463 tonnes from the Tulsequah Chief mine and 360,073 tonnes from the Big Bull deposit. The combined grade, production and recovery from both mines, as obtained from production records, is outlined below:

Combined Historical Production from Tulsequah Chief and Big Bull Mines

At Tulsequah Chief this production was achieved through the development of 9 underground levels connected with an internal winze (shaft) and day-lighting through 5 adits on the west side of Mount Eaton (Click here to view photo). The earliest production took place in the “I” zone – a stratigraphically higher sulphide lens on the eastern limb of the H syncline fold. As development proceeded deeper the thicker H/AB 2 lens was discovered and later production concentrated in this area. The 5400 and 5200 levels provided the main haulage levels for the mine. Only the uppermost portion of the main H/AB lens was delineated by Cominco at the time of the mine shutdown in 1957.

Exploration re-commenced in 1987 through a Redfern/Cominco Joint Venture. Successive exploration programs expanded the underground access for drilling deeper holes into the deposit and were successful in delineating a large expansion of the previous resources at the Mine. At the end of 1994 a geological resource was estimated which fed into subsequent feasibility and reserve definition.

Resource Definition, Exploration Potential

The following table sets out the resource calculation for the Tulsequah project pursant to a recently completed resource model completed by Amec Americas Ltd. (AMEC)in February of 2005. This model was estimated in compliance with the standards set out in National Instrument 43-101. It includes measured mineral resources derived from a portion of the 1957 reserves defined from historical production as well as both indicated and inferred mineral resources derived from drilling conducted to define the deposit since 1987. The resource model was interpolated using a combination of inverse distance weighing and ordinary kriging methods on 2 meter composited drill data, weighted by specific gravity. The independent Qualified Person, as defined by NI 43-101, for the estimate is Dr. Stephen Juras, P.Geo.

The deposit remains open at depth and along strike. This is due to the lack of drill holes testing the deposit at depth and to the present underground drill stations being poorly located to test the folded deposit geometry in the vicinity of the F anticline and the western limb extensions.

The favourable mine stratigraphy extends for over 800 meters to the SW where it is interpreted to meet another major synclinal fold structure. Surface outcrops of the rhyolite units in this area are sericitically altered with abundant disseminated pyrite – similar to the alteration observed in the footwall envelope to the known deposits. This portion of the mine stratigraphy remains untested for the possible presence of additional sulphide lenses.

In the Big Bull deposit area Cominco records estimated a 1957 shutdown reserve of 50,000 tonnes. Limited wide-spaced surface drilling by Redfern in 1993 and 1994 located extensions of the sulphide deposits at depth and along strike to the northwest. The Big Bull mineralizing system appears to be plunging towards the northwest beneath Mt. Manville and will likely require new underground access to allow drilling platforms for further exploration of this deposit. Big Bull host stratigraphy appears to be more distal than exhibited at Tulsequah Chief with finer grained volcanics and volcanic-derived sediments. It is noteworthy that historical production at Big Bull yielded ore with lower copper but higher lead and zinc values and higher associated gold and silver values.


2004 Exploration Program Progress Results and Discussion


The resource remains open in several areas, and is currently limited only by the amount of drilling that has been done to define the deposit. Additional drilling is expected to result in an increase to this resource. Due to excellent continuity of the deposit in the down-dip direction, the best potential for adding tonnes is to continue drilling below the resource. The 2004 program included development of additional underground access to provide drill platforms for these long drill holes.

Additional areas of high potential lie along strike to the west of the deposit. This area was explored partially in 2003 and yielded a new massive sulphide lens to the west of the main deposit. This lens remains open to expansion laterally and down-dip.

As a result of the improvement in the global markets for base and precious metals the focus of the 2004 program was to convert the existing inferred resources at Tulsequah to the indicated category through completion of infill drilling. This will increase the amount of the resource available to be utilized in subsequent feasibility updates. AMEC E&C Services Ltd. were contracted as the Qualified Person to complete the re-estimation of the Tulsequah Chief resources at the conclusion of the 2004 program, in compliance with the requirements of National Policy 43-101.

The schematic long-section below presents the location of the previous holes and identified resources for general reference. The company’s PowerPoint presentation also provides information on the current program. Please note that this section is viewed to the South, hence East is on the left side of the drawing and West is on the right. The location of reported drillholes from the current 2004 program are highlighted.

The Tulsequah Camp was opened on April 2, 2004 and preparations begun for underground development and commencement of drilling. Drilling started on April 12 using the drill rig stored on the property from the 2003 program. The underground program commenced with single shifts in mid-April and began double-shifting in late April when tracked equipment was fully available. As of June 18 the underground drifting and the new deep drilling set-up was completed. Two additional drill rigs were mobilized to the site on May 7 and commenced drilling operations on May 10. All three rigs continued through to the completion of the program in early November. Drilling operations were completed on November 6, 2004.

All drilling was conducted from underground stations. A total of 54 holes totalling 30,444 metres were completed in the program. Holes were completed to meet infill drillhole spacing target minimums of 35m in both the H and G zones. Drilling has confirmed much of the earlier interpretation and the structural setting of the dposit. The thickest part of the deposit lies roughly within the axial plane of the H syncline and reaches estimated true thicknesses of up to 31m. Drilling confirmed excellent continuity of high-grade sulphide mineralization and some of the highest grades obtained on the project were obtained in this year's program. Drilling was also conducted on the G zone which is a faulted offset of the H deposit on the east side of the 5300E fault zone. Results to date from the G zone have also provided potential for improvement in grades with numerous intersections containing elevated gold and copper values.

Deep drilling was conducted in eforts to extend the H zone mineralization to depth. This effort ran into problems within an interpreted cross-fault which appears to down-drop stratigraphy. Several drill-holes could not penetrate the fault zone due to sticking rods and were abandoned short of the target. The intersections of the horizon for the holes which were completed obtained intense alteration and suggest that the main deposit bends to the east towards the 5300E fault zone. No drillhole information was obtained on the east side of the 5300E fault at depth. Due to the poor geometry between the fault and the current drill setup locations further development may be required before this target area can be adequately explored for deposit extensions.