Overview

Mine Type	Open Pit & Underground
Status	Inactive / Suspended
Commodities	Tungsten Copper
Mining Method	Truck & Shovel / Loader Longhole stoping Cut & Fill
Mine Life	...
Snapshot	November 19, 2015 - The Cantung Mine has been abandoned by North American Tungsten Corporation Limited through an orderly process under the CCAA proceedings. The Government of the Northwest Territories (GNWT) has acquired the leasehold interests for both the Northwest Territories and Yukon mineral rights to North American Tungsten Company Limited’s (NATCL) Mactung property.

Deposit type

• Skarn

Summary:

Cantung is a typical skarn-type deposit, albeit of an unusually large size for a tungsten bearing skarn. As with most skarns, the mineralization is related to a granitic intrusion and its associated intrusive dykes. These intrusive units are believed to have given off reactive fluids that have then come in contact with the overlying reactive Ore Limestone and Swiss Cheese Limestone units.

The two main historic scheelite skarn ore bodies, the Open Pit and E-Zone, are spatially located within the Ore Limestone unit on the upper and lower limbs, respectively, of a recumbent anticline on the west side of the Flat River Syncline.

The major scheelite ore body mined from underground at Cantung historically was the EZone ore body. Since reopening in 2010, the mine has expanded the known extent of the scheelite ore horizon down dip along the lower limb of the recumbent anticline to the south and to the west as well as along the upper limb to the west.

These expanded areas include the West Extension, the Amber zone and Below 3700 elevation level along the lower limb of the fold and the Upper West Extension along the upper limb of the fold. The underground ore zones extend 4,360 ft. along strike, 1,200 ft. down-dip along the lower limb, with some interruption from intrusive sills and dikes, and 200 ft. up dip from the fold hinge along the upper limb.

Throughout most of the underground deposit, three main ore lenses are present: one lens occurs within the Swiss Cheese Limestone, the second lens occurs at the upper contact of the Ore Limestone with the Swiss Cheese Limestone, and the third lens occurs at the lower contact of the Ore Limestone with the Younger Argillite or the granodiorite unit. Intermediate lenses also occur within the Ore Limestone but they tend to be less continuous than either the second or third aforementioned lenses.

The scheelite mineralization in the West Extension and Amber zone is usually fine to medium grained (locally coarse grained), finely to coarsely disseminated and sometimes concentrated in bands, especially within the Swiss Cheese Limestone. These banded concentrations are also observed in the Open Pit Swiss Cheese Limestone ore. Scheelite is usually present in a massive to semi-massive pyrrhotite skarn or a calc-silicate skarn containing abundant pyroxene, garnet and minor pyrrhotite. Both skarn types generally contain chalcopyrite, with some black sphalerite locally. Skarn development in the Ore Limestone and Swiss Cheese Limestone underground is limited by general proximity to the granodiorite intrusive as well as an abundance of fluid transporting fractures and structures. The scheelite mineralization in the Open Pit has been genetically linked by previous researchers to an aplitic dyke and/or quartz vein stockwork that intruded up towards the Open Pit, bringing ore bearing fluids from depth.

Mining Methods

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Comminution

Crushers and Mills

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Processing

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Production

Operational metrics