 |  Property Description and Location
The Cantung Mine is located in the western Northwest Territories, Canada, approximately 300 km northeast of Watson Lake, Yukon, close to the Yukon border. The mine is a primary producer of tungsten concentrate from open pit and underground mines. It was opened in 1962.
Land Tenure
NATC has leases from DIAND covering the mine and associated service areas. The current leases are listed in the table below. Scott Wilson RPA has relied on NATC data for this information and has not independently confirmed the status of the claims and leases.
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NTS Area: 105 H/16
Latitude/Longitude: 61.9717°N, 128.2683°W
Ore Type: oxide
Mining Method: underground
Access: 306 km, all weather road from Watson Lake, YT
Project Status: Producing Tungsten Mine.
History
Prospectors discovered the Cantung Mine tungsten deposit in 1954, while looking for copper. In 1959, the Canada Tungsten Mining Corporation Ltd. was formed to acquire and develop the property. The Cantung Mine commenced production in 1962 from an open pit at the rate of 300 tons per day (stpd), with suspensions in 1963 due to low tungsten prices and in 1966 due to the destruction of the mill by fire. The construction of a new 350 stpd mill was completed in 1967 and, in 1969, the capacity was increased to 450 stpd.
In 1971, deep drilling discovered the "E Zone". This zone was accessed through an adit collared at the valley bottom, close to the town site. The mill began to process the underground ore in 1974. In 1975, the mill was further expanded to 500 stpd. A major mill expansion in 1979 increased the mill capacity to 1,000 stpd. In 1986, the mine ceased operations due to low tungsten prices.
In 1985, Amax Inc consolidated ownership of the Cantung Mine and transferred all tungsten assets, including the Mactung Project at Macmillan Pass, to Canada Tungsten Mining Corporation, retaining majority control. Aur Resources Inc. optioned the properties in 1995 and Canada Tungsten and Aur merged in 1996.
In 1997, NATC purchased the Cantung mine, together with the related assets of the former Canada Tungsten Inc., from Aur.
After an improvement in tungsten prices commencing in 2000, NATC reopened the Cantung mine in December 2001. Underground production and milling resumed at this time. In December 2003, NATC was placed under the protection of the Companies Creditors Arrangement Act (CCAA), and the mine was closed. In November 2004, NATC successfully completed a plan of arrangement to deal with creditors, allowing planning for reopening to commence. Preparatory work for the reopening began in July 2005, and production resumed in late September 2005.
Bedrock and Mineral Deposit Geology
CanTung deposit is a member of a group of tungsten skarn deposits located along the eastern margin of the Selwyn Basin. The Selwyn Basin extends into the Yukon. The Tungsten area is underlain by a series of Cambrian sediments, including limestones, intruded by Cretaceous granites. Tungsten mineralization is found within scheelite-bearing skarn associated with the granitic intrusions.
The Cambrian sediments are folded into a northwest-trending syncline with small, tight folds on the overturned southwest limb. A quartz monzonite stock known as the Mine Stock intrudes the sedimentary sequence, altering the limestones to skarn. Two limestone units host ore-bearing skarn, these are the Swiss Cheese Limestone and the Ore Limestone. The older Swiss Cheese Limestone is a dolomitic siltstone containing pods of impure limestone, and hosts 'chert ore'. The Ore Limestone is a finely laminated blue-grey recrystallised limestone or marble, and hosts 'skarn ore'.
The Pit Zone orebody was mined by open pit from 1962 to 1973. Total production from the pit during this period was 1.69 million tonnes grading 1.75% WO3. The orebody is hosted in both limestone units and consists of diopside-hedenbergite-garnet skarn with quartz, calcite, scheelite, microcline and local pyrrhotite. The northerly dipping Pit Zone is cut by a fault on its southern side and pinches out to the north. The main zone of the orebody, hosted in the Ore Limestone, was originally 200 by 90 by 20 metres in size and contained 1.2 million tonnes grading 2.47% WO3. The chert zone, located beneath the main zone in Swiss Cheese Limestone, was originally defined as 3.56 million tonnes grading 0.65% WO3. Part of the chert ore was not mined.
The E Zone is located closer to the quartz monzonite stock and has undergone more intense metasomatism. Mineralization occurs within an east-trending lens in the Ore Limestone of approximate dimensions 820 by 150 by 12 metres. The lens dips to the south at 20º. The zone contains less pyroxene-garnet skarn than the Pit Zone but contains abundant pyrrhotite. Biotite and amphibole are also present in the lower part of the zone.
Reserves
The CanTung mine has a NI43-101 probable reserve of 1 million tons at 1.17% WO3 (1.1 million MTU'S); indicated resource of approximately 3 million tons at 1.21% WO3 (3.2 million MTU'S); and an inferred resource of 734,000 tons at 0.74% WO3 (493,000 MTU's). These reserves were calculated as of September 2006.
Production
The mine is expected to produce 400,000 metric tonne units of concentrate a year.
Geology
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Southeastern Yukon and southwestern Northwest Territories are underlain by a thick sequence of late Precambrian and lower Paleozoic sedimentary strata, which are intruded by several Cretaceous granitic plutons. Basement rocks comprise upwards of 3,000 m of fine-grained Proterozoic clastic sediments, predominantly slate and phyllite, referred to as the Grit Unit. In the mine workings, the lowest stratigraphic unit exposed is argillite of the Proterozoic Grit Unit, referred to as the Older or Lower Argillite. The overlying Swiss Cheese Limestone, or Chert Unit as it is referred to at the mine, is in the order of 40 m to 50 m thick. The Ore Limestone is approximately 30 m thick in the Open Pit, thickening to approximately 100 m in the underground E Zone. The stratigraphically overlying argillite and interbanded quartzite, which averages approximately 150 m in thickness, is referred to at the mine as the Younger or Upper Argillite. At the top of the local stratigraphic sequence is a light buff dolomite with interbedded quartzite, which has a maximum thickness of approximately 600 m, however, this is not seen in the mine workings.
The Open Pit and E Zone orebodies lie on the west limb of the Flat River Syncline. This limb is steeply dipping and overturned in the west, but becomes flat to the east, where in the area around the two mined deposits it forms a recumbent anticlinal fold that trends east to west. The Open Pit lies on the flat lying upper limb of this fold and the E Zone on the lower limb.
Two of the deposits at Cantung have been mined. These are the original Open Pit orebody, which was mined from 1962 to 1973, and the E Zone, which was mined between 1973 and 1986, again between January 2002 and December 2003, and is currently in production. Both deposits are in calc-silicate skarn zones that replace the Ore Limestone.
Mineralization at the Cantung mine comprises skarn replacements within the Ore Limestone. At the Open Pit, mineralization is also present as lower grade replacements in the underlying Chert Unit. The Open Pit skarn ore is comprised of scheelite and minor chalcopyrite disseminated in a gangue of pyrrhotite, diopside, garnet, and actinolite. The E Zone ore differs in several respects from Open Pit ore. It typically contains massive to semi-massive pyrrhotite and, in addition to pyroxene and garnet, contains abundant hydrated calc-silicates actinolite and biotite.
Exploration
The mine property has been covered nearly completely by ground and airborne magnetic and electromagnetic surveys, and by geochemical stream sediment and soil sampling. No obvious targets were discovered by these surveys, with the exception of the geochemical anomalies in the upper reaches of Rifle Range Creek. The following exploration targets are in order of priority.
West Extension - The continuation of the West Extension on strike to the northwest, and down dip of the underground workings is, in the opinion of the mine personnel, the best exploration target in the mine, as the mineralization is open in both directions. Ore widths in general are not high, however, grades are generally good (About 2%).
E-Zone: Pillar Recovery - There is potential to add pillars to the Life of Mine Plan, should positive results be obtained in currently planned pillar recovery areas.
E Zone: Local East Extension - A similar, though less well defined, target to the West Extension exists on strike to the east of the E Zone.
Rifle Range Creek - The target area at Rifle Range Creek lies under a small ice field in a cirque on the northeast side of Tungsten Mountain where anomalous concentrations of tungsten were discovered in stream sediments and till during sampling programmes of the late 1970's. Follow-up soil sampling in 2003 and 2004 extended the area of anomalous tungsten southwestward towards the edge of the ice field. Rifle Range Creek has the highest rating of all exploration projects outside the established mining areas.
Other targets exist as well.
Mineral Resource and Mineral Reserve Estimates
Mineral Resources for the Cantung Mine, as of September 1, 2006, are listed below in Table 1-4. These Mineral Resources encompass both audited resources in the underground mine, as well as those recently updated for the Open Pit and PUG (Pit deposit, Underground ore) Zones. Mineral Resources are inclusive of Mineral Reserves; excess resources may at some time in the future become reserves, however, at present they cannot be included in the estimate of Mineral Reserves. The Mineral Reserves include material for which there is a mining plan, and at least a conceptual design. Mineral Reserves for the Cantung Mine, as of September 1, 2006, are summarized in Table 1-5 below.
Table 1-4 Cantung Inferred and Indicated Mineral Resources
North American Tungsten Corporation Ltd. - Cantung Mine
| Zone |
Tons |
Grade (WO3 %) |
STU'S |
| INDICATED RESOURCES |
| West Extension | 321,000 | 2.03 | 652,000 |
| E-Zone | 231,000 | 1.71 | 395,000 |
| Shop Zone | 75,000 | 1.22 | 92,000 |
| Main Zone Pillars | 457,000 | 1.63 | 745,000 |
| South Flats | 190,000 | 1.86 | 353,000 |
| Subtotal Underground | 1,274,000 | 1.76 | 2,236,000 |
| Open Pit / PUG Zone | 1,660,000 | 0.80 | 1,328,000 |
| TOTAL Indicated Resources | 2,934,000 | 1.21 | 3,564,000 |
| INFERRED RESOURCES |
| Open Pit / PUG Zone | 734,000 | 0.74 | 543,000 |
| Zone |
Tons |
Grade (WO3 %) |
STU'S |
| CANTUNG PROBABLE RESERVES |
| Zone | Tons | Grade (WO3 %) | STU'S |
| West Extension | 233,000 | 1.21 | 282,000 |
| E-Zone | 72,000 | 1.45 | 113,000 |
| Shop Zone | 60,000 | 0.98 | 59,000 |
| Main Zone Pillars | 422,000 | 1.12 | 468,000 |
| South Flats | 219,000 | 1.20 | 263,000 |
| Stockpile | 25,000 | 1.05 | 26,000 |
| TOTAL Probable Reserves | 1,031,000 | 1.17 | 1,211,000 |
The following table summarizes the production history of the operation from the restart of operations in 2005.
Table 6-1 2005 - 2006 Production Statistics
North American Tungsten Corp. Ltd. - Cantung Mine
| Period | Tons Milled | % WO3 | Recovery |
|---|
| October 2005 | 24,991 | 0.80 | 61.14% |
| November 2005 | 29,805 | 1.15 | 72.46% |
| December 2005 | 28,907 | 0.94 | 59.12% |
| January 2006 | 29,027 | 1.04 | 69.04% |
| February 2006 | 26,612 | 1.04 | 67.58% |
| March 2006 | 30,447 | 1.15 | 75.05% |
| April 2006 | 31,286 | 1.04 | 71.14% |
| May 2006 | 28,564 | 0.95 | 69.84% |
| June 2006 | 32,573 | 1.32 | 74.2% |
| July 2006 | 31,493 | 1.20 | 76.66% |
| August 2006 | 18,027 | 1.30 | 74.98% |
| September 2006 | 28,011 | 1.13 | 71.75% |
| Total | 339,743 | 1.09 | 70.89% |
| Period |
Tons Milled |
% WO3 |
Recovery |
| October-06 | 32,585 | 1.14 | 71.94% |
| November-06 | 27,969 | 0.97 | 67.34% |
| December-06 | 31,787 | 1.00 | 68.63% |
| January-07 | 33,173 | 0.98 | 68.04% |
| February-07 | 23,712 | 1.54 | 73.87% |
| March-07 | 25,674 | 1.50 | 72.3% |
| April-07 | 32,352 | 1.35 | 77.67% |
| May-07 | 32,182 | 1.17 | 77.74% |
| June-07 | 30,841 | 1.07 | 76.57% |
| July-07 | 33,394 | 1.36 | 75.91% |
| August-07 | 33,118 | 0.94 | 77.73% |
| September-07 | 31,152 | 0.99 | 76.24% |
| Total |
367,939 |
1.16 |
74.11% |
| MTU's |
286,031 |
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