The area of the Minera Florida Mine is underlain by upper cretaceous volcanic and intrusive rocks. The volcanic rocks comprise porphyritic andesite, brecciated andesite, lithic and crystal tuff, and brecciated tuff. The bulk of these rocks are also affected by a sequence of hydrothermal alteration. The intrusive rocks comprise mainly granodiorites and monzodiorites.

Gold mineralization in the Minera Florida Mine area occurs as native gold and electrum associated with sulphide minerals, such as pyrite, chalcopyrite, sphalerite and galena, as well as magnetite. Mineralization is commonly associated with hydrothermal alteration including quartz, adularia, epidote, chlorite, and actinolite. Quartz occurs in four types; as grey siliceous zones, green quartz, translucent quartz, and white quartz. Some veins exhibit metal zoning, with a zinc-rich silver-rich zone in the upper part of the vein, a goldrich zone in the central part, and a zinc-rich zone in the lower part of the vein.

In general, mineralized structures include an inner quartz vein (core) consisting of material exhibiting quartz flooding or massive quartz, surrounded by stockwork of quartz veinlets and/or hydrothermal breccia, both of which are mineralized. Gold mineralization in the Minera Florida Mine area has been identified in four types of rocks, in places adjacent to each other, as follows: (1) silicified crystal tuff; (2) lithic to crystal tuff; (3) brecciated tuff; and (4) porphyritic andesite.

There are at least nineteen mineralized veins discovered and partially developed in the Minera Florida Mine area. These veins range from 0.8 metres to 30 metres in thickness, and the average grade ranges from 1.5 grams per tonne of gold to 12 grams per tonne of gold, 6 grams per tonne of silver to 100 grams per tonne of silver, and 0.1% Zn to 1.81% Zn. Many of the mineralized veins at the Minera Florida Mine area do not have a surface expression, but are associated with structures identified by underground diamond drilling.

Minera Florida is an underground gold mine located south of Santiago in central Chile. The underground workings are developed by adits driven from surface and is accessed at several elevations via multiple portals. An internal ramp system provides access to the stopes. Sublevels are driven in the veins and mining sequence advances from the top down, with pillars left at regular intervals. Underground mining operations are mechanized, utilizing: articulated haul trucks; electronic hydraulic development and production jumbos; load-haul dumpers; and a number of ground support and service equipment. Ore is hauled using 25-tonne trucks from the mine to a transfer point and 40-tonne trucks haul the ore from the transfer point to the process plant. Waste is transported by 25-tonne trucks. The primary mining method is sublevel open stoping. Thickened (paste) tailings from the processing facility are deposited in a TSF that consists of a downstream compacted fill embankment constructed in 2 phases. The embankment has a maximum height of 16 m with a high density polyethylene liner on its upstream face. The Minera Florida operation consists of several underground mines that are accessed via six adits. Mining at Minera Florida is conducted using various underground variations on SLS, either traditional SLS or longitudinal retreat. The different mining zones are accessed via ramps that provide flexibility and access to the ore at different elevations. Traditional SLS is used for veins thicker than 3.5 m. This method considers an upper level for production drilling, which is carried out in a descending pattern for benching or in an ascending one when undercutting the back. For veins thinner than 3.5 m, a longitudinal retreat method is applied. This method considers the development of a single lower gallery which is used for uphole drilling and subsequent (after the ore is blasted) ore extraction using remotely operated equipment to access the stope. In both cases, pillars are left in place to control dilution and to provide ground support. Where required, stopes that have been completely mined can be backfilled with development waste to reduce waste haulage distances and save on waste dump capacity. Underground operations are carried out by Minera Florida Ltda with the support of contractors that are responsible for hauling ore from the mine to the processing plant, transportation of materials and personnel. Underground mining operations are mechanized, utilizing: articulated haul trucks; electronic hydraulic development and production jumbos; load-haul dumpers; and a number of ground support and service equipment.

The crushing plant is operated on a two 12-hour shifts per day, seven day per week schedule. The trucks deliver the ore (<635 mm) to a dump hopper. The undersize is crushed to -100 mm by a 112 kW primary jaw crusher and then placed either in one of three 80-tonne storage bins or alternatively on a stockpile. The ore is then further crushed by a 224 kW HP300 standard secondary cone crusher and a 224 kW HP300 short head tertiary crusher. The final crushed product is 100% passing 10 mm and is delivered to one of two 600-tonne storage silos ahead of the grinding circuit. Additional storage is provided by stockpiling adjacent to the silos.

The crushed ore is fed to one of two 3.7 m x 4.3 m Dominion Engineering ball mills where it is ground to a 65% passing 75 µm in closed circuit with a cyclone cluster.

The cyclone overflow is delivered to the flotation circuit that consists of eight 20 m3 flotation cells arranged in a rougher, scavenger, cleaner, and recleaner configuration. The bulk sulphide concentrate produced contains 22% Zn, approximately 105 g/t Au, and some silver (silver content varies with the head grade).

The flotation bulk concentrate is thickened to 50% solids and leached with NaCN (sodium cyanide) solution in a series of ten 50 m3 leach tanks providing 72 hours of residence time. The products of the leaching circuit are a pregnant solution containing approximately 30 g/m3 Au and a thickened pulp containing the zinc sulphides. The leaching circuit recovers approximately 97% of the gold and 81% of the silver.

The pregnant solution is clarified, heated, and then pumped to four electrowinning (EW) cells where gold and silver sludge is deposited on the cathodes. The sludge is periodically washed off, filtered, and dried prior to being smelted into doré ........