Summary

Mine Type	Underground
Status	Closing / Closed
Commodities	Gold
Mining Method	Open stoping Cut & Fill
Backfill type	...
Snapshot	The Cosmo Mine ceased production in February 2020. Work commenced on the Cosmo Howley rehabilitation strategy in October 2020, under Kirkland Lake Gold ownership, and Agnico Eagle continued implemention of this closure strategy following the merger. Although reclamation is a legislative requirement, the manner it is executed is determined by the company that owns the property. The work at the site aligns with Agnico Eagle’s regulatory and risk based approach to remediate land in a manner that allows for future land use when possible. Reclamation of a 100-year-old mining camp is underway. Acid generating waste rock was excavated and placed into the Cosmo Pit. This waste was layered with non-acid generating waste rock then submerged under 19 metres of water to inhibit acid rock drainage.

Deposit type

• Vein / narrow vein
• Orogenic

Summary:

A variety of genetic models, ranging from magmatic through hydrothermal to syngenetic, have been postulated in the past for the formation of gold deposits in the Pine Creek Geosyncline. Gold and base metal mineralization in the Pine Creek Geosyncline is commonly associated with granite intrusions and have often been classified as high temperature contact aureole deposits. A secondary host rock control has also been suggested due to the association of gold mineralization with carbonaceous metasedimentary rocks, such as at Cosmo Mine.

Native gold is the main mineralization mineral and is commonly present as micron sized grains; coarse nuggets are rare. Gold is commonly associated with pyrite, arsenopyrite and pyrrhotite and in places with minor base metal sulphides. Quartz, chlorite, sericite and carbonates are the common gangue minerals in the gold-quartz deposits.

All gold deposits in the Northern Territory show some structural control at the regional and deposit scales, with most deposits within the Pine Creek Orogen trending northwest southeast.

Base metal mineralization in the Pine Creek Orogen strike significantly differently than the gold veins, suggesting different discrete mineralizing events. They are syngenetic.

Cosmo gold mineralization is hosted across a stratigraphic sequence (‘Cosmo Mine Sequence”) that lies between a major dolerite sill (‘Zamu’ dolerite unit) and a thick package of high sulfide, graphitic mudstone (‘Pmc’ unit). This sequence is folded across the major Cosmo Howley Anticline with numerous limb parallel faults found to splay and roll inwards across the anticline nose as they migrate northwards down plunge. Also of major significance is the shallow (-40o to -55o) east-west F1 Fault which shows local steps and thrust related jogs and is suggested to be at least partly contemporaneous with limb parallel faults. The majority of gold mined to date comes from within ~200m above or below the F1 Fault so an empirical major control on mineralization is credited to this fault.

Mining Methods

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Comminution

Crushers and Mills

Processing

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Commodity Production

Operational metrics

Personnel

Job Title	Name	Phone	Email	Profile	Ref. Date
.......................	.......................	...........	...........		Oct 6, 2023
.......................	.......................				Apr 15, 2024
.......................	.......................				Apr 15, 2024

Employees	Year
......	2022
......	2021