The principal mineral deposits in the Platosa area are high-temperature epigenetic silverlead-zinc carbonate-replacement deposits (CRD).

The Platosa Property lies in the Sierra Bermejillo, a northwest-trending anticline-syncline pair developed in Mesozoic sedimentary rocks. The Sierra Bermejillo Anticline is a relatively open fold that plunges to the southeast. The Saltillera Syncline is a doubly plunging structure located west of the anticline. The folded sequence is cut by a set of north- to northwest-striking, steeply dipping fractures and faults. Tertiary felsic to intermediate dykes and plutons intrude these structures in the western part of the Sierra Bermejillo.

The principal fault system in the property area is the Platosa Structural Zone (PSZ), a 250 to 1,500 metre-wide northwest-trending zone of fracturing and shearing that traverses the eastern margin of the Sierra Bermejillo. The PSZ includes a series of fault planes that strike north–north westerly and dip steeply east; it has been mapped along strike for five kilometres northwest and southeast of the Platosa Mine. It is characterized by brecciated, crushed, and dolomitized limestone; slickenside fracture surfaces; iron and manganese oxides; travertinefilled breccias; and coarsely crystalline selenite veins, some up to five metres thick. The faulted rocks weather recessively and create a negative topographic expression of the PSZ.

Mineralization
The bulk of mineralization cur ........

The primary mining method has historically been a modified room and pillar, with the top of the manto being accessed first. For steeply dipping mantos, the area is benched down to a maximum height of 20 metres at which point a sill pillar is established. This process is repeated below the sill pillar until the bottom of the manto is reached. Historically, sill pillars were seldom necessary considering the flat-lying nature of the mantos, although these will become necessary where the mineralized body dips more steeply.

In 2019, the Platosa Mine transitioned the mining method from cut and fill/drift and fill to an overhand cut and bench method (“OCB”) to improve the overall mining cycle efficiency.

Primary stope accessesfor the OCB method are driven into the deposit horizontally and subsequent bench cuts are conducted until the sill elevation isreached. A cemented rock fill mat is placed on the sill elevation and the remainder of the stope filled with dry rock fill. The sill pillar above is then long hole drilled and blasted on retreat and mucked with a remote scooptram. It is then filled remotely when the pillar extraction is complete. The sequence has a higher cycle efficiency requiring fewer man-hours to extract the stopes than the previous cut and fill method. Development waste from active headings as well as waste that has been stockpiled underground is used to backfill the stopes.

The completion of a dewatering project has allowed the P ........

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