Gold mineralization at the Black Fox Mine occurs in several different geological environments within the main carbonate alteration zone, which has a strike length of over 1,000 metres and a variable true width ranging from 10 metres to over 100 metres. This mineralized envelope occurs primarily within komatiitic ultramafics and lesser mafic volcanics within the outer boundaries of the PDDZ. The auriferous zones have several modes of occurrence, from concordant zones that follow lithological contacts and have been subsequently deformed, to slightly discordant zones associated with syenitic sills and quartz veins or stockworks.

The Black Fox Mine deposit has an overall first order south-southwest plunge (SSE in mine grid) with a second order westerly internal gold mineralization plunge. The first order plunge is parallel to stretching/intersection lineations and dominant folds, plus the local elongation of units. The second order plunge is at a high angle to the stretching lineation and controlled by stacking of S-SW dipping (to true north) reverse shear vein systems, vein arrays and shear zones which dip more shallowly to the south than the overall dip of the ultramafic host unit and faults that are parallel to it, and are stacked vertically within carbonate-talc-chlorite altered parts of the ultramafic unit (Rhys, 2016). This secondary ore control could be controlled by the north verging drag folds (Chappell, 2018).

Work carried out to date has identified four different styles of mineralization within the mineralized envelope at the Black Fox Mine. These are:

• Free gold associated with east to south east striking (100 to 170 degrees) moderately to steeply dipping (40 to 80 degrees) quartz-carbonate-chlorite shear veins; sigmoidal vein arrays that strike to the west, north-west (290 to 315 degrees) and dip moderately (30 to 60 degrees) to the south. Visible gold is observed along chlorite stylolites, slip surfaces and within the vein matrix itself.
• Gold-bearing pyrite associated with albite-carbonate-sericite altered syenitic and plagioclase porphyry sill-like bodies spatially associated with gold-bearing quartz-carbonate vein systems.
• Gold associated with disseminated fine-grained pyrite within intensely sheared Fecarbonate- sericite-albite altered mafic volcanic rocks adjacent to or within ultramafic rocks. These zones are associated with variably deformed quartz-carbonate veins that can host visible gold as well (Rhys 2016). This type of mineralization is denoted as BMV.
• A much less common form of gold mineralization occurs in carbonate-quartz-talc alteration as disseminated free gold flakes (Figure 14D), seen in the Deep Central Zone in areas of elevated matrix quartz and/or quartz veinlets in the altered ultramafic volcanic rocks matrix (Rhys 2016).

The production rate is based on available stopes as of October 31, 2017 (the time that the assets were transferred from Primero to McEwen Mining Ontario). Consequently, the mine has a variable monthly mining rate, averaging approximately 500 tonnes per day. The average ounces recovered at the mill per day is approximately 140, which is equal to an average of 4,200 ounces per month over the 26 months in the LOM.

LOM development requirements are approximately 4,400 metres total. This development consists of 935m of ramps, and 2,030 metres of lateral development, 1,280 metres of sills and 140 metres of raises.

The mine is accessed by a portal located at a bench at a depth of 87 metres within the Black Fox Pit.

Stopes are typically mined in 15-metre lengths along the strike with widths varying from 5 up to 20 metres.

The mining method is long hole retreat. The stope sequencing has generally been top-down as new ore is found at depth.

Cemented hydraulic backfill is used in almost all stopes. Stopes are mined in alternating sequence using backfilled stopes as pillars for subsequent mining of adjacent stopes.

Ore mined is crushed and hauled to the mill.

At Black Fox, development of the access to the Froome underground deposit has advanced 30%. The plan is to reach the deposit in the second quarter of 2021, complete the necessary development and achieve commercial production in the fourth quarter of 2021. [08/06/2020, PR]

Crushing is currently carried out at the mine site via a contract service (LPL Contracting). McEwen Mining does not own the crushing equipment. The crushed material is trucked to the Black Fox mine where it is processed.

The crushing configuration is comprises a three stage semi-portable circuit. Mineralized rocks are reclaimed into a feed hopper that feeds a vibrating feeder from which rocks enter a jaw crusher. The crushed product is discharged to a secondary cone crusher. The cone crusher product feeds two screens where the undersize material is the final crushed product. Screen oversize is split to feed two tertiary cone crushers. The crushed product is returned to the screens.

The crushed material is conveyed from the fine ore bin to the feed chute of the primary ball mill which is operated in closed circuit with three hydro cyclones. The cyclone underflow is recirculated to the ball mill while the overflow is further ground in one of the two regrind mills. The regrind mills are operated in closed circuit with five secondary cyclones. The overflows from the secondary cyclones flow to a vibrating trash screen. The trash screen undersize falls into the thickener feed pump box. The head sampler removes feed aliquots on 20-minute intervals from the thickener feed line.

Ore from the Black Fox Mine is processed at the Black Fox Mill.

Gravity Circuit
A gravity circuit comprised of a fines riffle and a coarse riffle in series is present in the mill. The gravity circuit was installed as a trial unit and has yet to be commissioned. The riffles are currently not being used without any future commissioning being planned.

There is a #6 Deister shaking table in the grinding section that is currently not in use.

Leaching
The ground slurry is then pumped to a thickener for dewatering. The thickener underflow is pumped to the first of two (2) leach tanks. An alternate head sampler exists on the leach feed line but is currently not in service. The slurry flows by gravity from the first tank to the second. Lime slurry is added to the first leach tank for pH control.

The overflow from this leach tank flows to a series of two (2) additional leach tanks and four (4) CIL tanks, where the gold now in solution is a ........