The property straddles the Piché Group volcanic rocks that separate Pontiac Group metasedimentary rocks to the south from Cadillac Group metasedimentary rocks to the north. In the property area, all lithologies strike east-west and dip steeply south at approximately 85°.

Cadillac Group
The The Cadillac–Larder Lake Fault Zone (CLLFZ) is a major regional crustal break that consists mainly of chlorite-talccarbonate ultramafic schist, and ranges in thickness from 100 to 300 ft (30 to 100 m) in the mine area, and narrows significantly to about 40 ft (12 m) wide to the east of Zone 36 East. Across the property, the fault is subparallel and close to the Piché Group-Cadillac Group contact, but is generally enveloped by Cadillac Group sedimentary rocks (argillites, greywackes and, to a lesser extent, chert).

Piché Group
The veins of the O’Brien Project were mostly injected into the volcanic and sedimentary rocks of the Piché Group. From south to north, the Piché Group stratigraphy is divided into the following units:
• Southern volcanics: tuff and basaltic schists;
• Southern porphyritic andesite;
• Central volcanics: tuff and basaltic schists;
• Sporadically pebbly greywacke and argillite (“Mine Conglomerate”);
• Northern porphyritic andesite;
• Northern volcanics: tuff and mafic schists (with small quantities of argillite, greywacke, chert and massive to variably porphyritic basalt flows).

All the above ........

Due to the narrow vein nature of the orebody, two (2) underground mining methods were considered in the study, modified Avoca and long-hole mining with captive sublevels.

The mineralized material will be transported to surface using a combination of 3.5-cubic-yard to 6-cubic-yard scoop trams and 30-tonne trucks. Waste material will be used to backfill mined out stopes as much as possible or will be brought to surface and stored on a dedicated waste pad.

The current PEA is based on an underground mine with access by decline to a vertical depth of 550 metres in the 36E area and 250 metres in the Kewagama area.

The expected average daily production rate during the production period is estimated in this PEA between 450 and 500 t/day. The overall project mine life is expected to be approximately 6 years, including a two-year pre-production period.

Modified Avoca mining method
The modified Avoca mining method was mostly used in the present study.

The modified Avoca mining method consists of drilling a series of vertical holes downward into mineralization from one level to another. The mineralization is then blasted in vertical slices, and the broken material ends up in the bottom sill and is extracted using LHDs. For every sill and sublevel horizontal slice, a primary slot opened by drop raise method is excavated at each extremity of the level, and blasting of a first stope 18 to 22 metres in length along strike is achiev ........

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