Brookbank Project

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Mine TypeOpen Pit & Underground
StagePreliminary Economic Assessment
  • Gold
Mining Method
  • Truck & Shovel / Loader
  • Blast Hole Stoping
Backfill type ... Lock
Mine Life... Lock


Metalore Resources Ltd. 26 % Direct
Orion Mine Finance Group 29.6 % Indirect
Equinox Gold  Corp. 44.4 % Indirect
GGM owns 100% of the lease that covers the Brookbank deposit with the remaining portion of the project tenements being subject to two Joint Venture (“JV”) agreements with Metalore Resources Limited (“Metalore”). The first JV is a GGM 74% / Metalore 26% split with the second a GGM 79% / Metalore 21% split.

Greenstone Gold Mines is a 60/40 joint venture company between Equinox Gold and Orion Mine Finance Group.

Deposit type

  • Hydrothermal
  • Breccia pipe / Stockwork
  • Vein / narrow vein


The 6.5 kilometre long Brookbank shear zone hosts the Brookbank, Cherbourg, and Foxear deposits. The deposits occur along lithological contacts between mafic volcanics and metasediments. Other areas of gold mineralization are present in one or more of the localized deformation bands within the hanging wall mafic volcanics, which are generally parallel to the Brookbank main zone within the Brookbank shear zone structure.

The zones of mineralization at Brookbank, Cherbourg, and Foxear occur within one of several bands of intense deformation and hydrothermal alteration at or near the contact between domains of mafic flows and polymictic conglomerate. Hydrothermal alteration in the vicinity of the mineralization consists of silicification, carbonatization, sericitization, chloritization, hematization and sulphidization. This alteration is commonly marginal to quartz-carbonate veins, fractures, and stockworks and may exceed 50 metres in width locally.

Mineralogical studies indicate that the precious metal mineralization consists of goldsilver particles with an approximate gold to silver ratio of 80:20. The gold occurs primarily as late fracture-controlled mineralization. The mineralization forms elongate lenticular particles associated with grain boundaries and possibly crystallographic planes. The gold generally consists of fine grained free gold particles, although there is very little visible gold even in areas of plus 30 g/t Au assays. Gold values are highest in the quartz–carbonate veinlets/stringers.

Sulphide mineralization (pyrite and minor chalcopyrite) is also present within the sheared host and quartz veinlets.

Economic concentrations of gold in the Geraldton area are typical of Archean epigenetic hydrothermal gold deposits normally considered to be mesothermal lode gold deposits. The gold mineralization is primarily located in areas of high strain and deformation with brittle structures providing a pathway and also hosting mineralization as veins or replacement zones with associated alteration. There are also low grade zones that locally have less obvious structural control, less veining, and less intense hydrothermal alteration on a hand specimen scale, but these clearly have strong deposit scale structural controls.

The mineralization on the Brookbank Project occurs within quartz-carbonate veinlets/stringers, fractures and/or stockworks associated with hydrothermal alteration. The latter is generally located within bands of intense deformation at the contacts between domains of mafic flows and polymictic conglomerate.



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Operational metrics

Daily ore mining rate 900 t *
Daily milling rate 900 t *
Annual ore mining rate 328,500 t *
Ore tonnes mined, LOM 2,161,596 t *
* According to 2015 study.

Production Costs

Assumed price Gold USD 1,250 / oz *  USD
* According to 2015 study / presentation.

Project Costs

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Heavy Mobile Equipment


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Mine Management

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