Deposit Type The mineral deposits at Topia are adularia-sericite-type, silver-rich, polymetallic epithermal veins. Silver-gold-lead-zinc mineralization is found in fissure-filling veins along sub-parallel faults cutting andesitic flows, breccias, and pyroclastic rocks. Deposits are usually characterized by multiple veins in areas measuring 10 to 15km2 with individual veins generally less than 2m in thickness but up to 3-4km in length. The Topia district lies within the Sierra Madre Occidental (SMO), a north-northwest-trending belt of Cenozoic-age rocks extending from the US border southwards to approximately 21°N latitude. The belt measures roughly 1,200 km long by 200 km to 300 km wide. Rocks within the SMO comprise Eocene to Miocene age flows and tuffs of basaltic to rhyolitic composition with related intrusive bodies. The Topia area is underlain by a km thick package of Cretaceous and Tertiary andesite lavas and pyroclastic rocks which are, in turn, overlain by younger rhyolitic flows and pyroclastics. The volcanic sequence is transected by numerous faults, some of which host the mineralized veins in the district. There are two sets of faults: one striking 320° to 340° and dipping northeast and the other striking 50° to 70° and dipping steeply southeast to vertically. The northeast-trending faults are the principal host structures for precious and base metal mineralization. Epithermal systems, as the name suggests, form near surface, usually in association with hot s ........

Topia consists of several mines, which comprise Argentina, 15-22, San Miguel, 9 North, San Juan, Recompensa, Hormiguera, El Rosario, La Prieta, El 80, and Durangueno.

The Topia underground mining operation producing approximately 225tpd (operating) from fourteen (14) mines on 52 separate veins using conventional mining methods, including resuing.

Mining at Topia generally consists of development along very narrow veins. Mining is selective using jacklegs, however, where possible, mechanized cut and fill is deployed. All mines are accessed via adits and ramps, although internal passes are constructed to access the upper and lower ore zones. Rock integrity at the mines at Topia is considered favorable, but on rare occasions roof support, in the form of rock bolting, and occasionally wire mesh, is required.

Mining is conducted by contractors and in-house miners sourced from nearby communities and outside cities, and utilizes equipment owned mostly by the Company. Mine contractors and equipment are alternated between the mines to accommodate the variations in production plans.

For the narrower veins at Topia, mining is conducted by modified cut and fill stoping (resuing) to selectively mine the ore and leave the waste for backfill. In a stope the ore is blasted and extracted first, then the wall rock is blasted as stope fill. Drilling is performed with jackleg drills and ore is hand mucked in the stope and dropped down timber crib muck ........

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