The La Verde deposit represents the upper portions of a copper porphyry deposit.

The intrusive complex at La Verde is dominated by quartz-diorite, which is exposed along an east-west-trending arcuate mountain range roughly 5.5 km long, 1 km wide and up to 290 m above the surrounding blanket of Quaternary sediments. The range is known as the Sierra del Marqués and is divided into the Cerro La Laguna (West Hill) and Cerro Mina La Verde (East Hill) by a topographic low known as La Puerta located roughly in the centre of the arc.

The West Hill deposit has a north-northeast-trending elliptical outline, approximately 300 to 500 m wide by 800 m in length. Mineralization on the West Hill deposit occurs in veins within phyllicpropylitic alteration envelopes and the mineralization outcrops in a number of locations, commonly marked by the appearance of limonite-malachite stained waste piles and / or sparse vegetation “kill” zones.

The West Hill consists of steeply-dipping to vertical bands of epidote-sericite-quartz-calcitealtered quartzdiorite and quartz-gabbro porphyry containing veinlets, veins and disseminations of pyrite-chalcopyrite pyrrhotite-arsenopyrite.

Phyllic-propylitic alteration veins strike east-northeast within the quartz-gabbro porphyry stock, east-southeast within surrounding quartz-diorite, and east-west common to both. Historic mapping indicates linear east-trending zones of quartz sericite alteration that can be traced for up to 900 m on surface.

In drill core, mineralized veins vary from a few centimetres to several metres in width. Zones of mineralization often consist of groups or swarms of mineralized veins with increased alteration intensity correlating with increased vein density.

A low vein density usually corresponds with weakly mineralized zones, with sulphides generally restricted to veins. Wall-rock alteration occurs as discrete envelopes around the veins. Surrounding host rocks are generally unaltered.

Where there is high vein density, alteration in vein selvages coalesces and sulphides commonly occur as disseminations in the vein selvages. The altered and/or mineralized host rock is characteristically lighter in colour, non-magnetic and visually distinct from unaltered quartzdiorite / quartz-gabbro host rock.

Localized high grade mineralization has been observed in drill core. As an example, drillhole C11-04-02 intersected massive chalcopyrite veins of greater than 2 m core-width. The non-truewidth sample assayed 13.88% Cu over 3.99 m. Underground mapping indicates that these wider zones of high grade mineralization pinch and swell over the width of the drift and plunge either steeply east or steeply west.

East Hill.
The #1 Zone (Breccia) is exposed at surface between sections 812300 to 812600 m E as a roughly easttrending series of malachite-stained quartz-diorite breccia outcrops. Weathering and copperoxide mineralization is generally restricted to within 20 m of surface.

Mineralization occurs principally as disseminations and blebs of bornite-chalcopyrite± arsenopyrite-molybdenite throughout the matrix and within fragments of brecciated quartzdiorite. Some mineralization also occurs as planar fracture veinlets and joint coatings within large quartz-diorite blocks and unbrecciated quartz-diorite wall-rock. The breccias are generally weakly to moderately altered to an assemblage of chlorite-sericite-calcite±quartz. Zones of patchy pink alteration have been interpreted to be potassically altered (potassium feldsparchloritesericite±quartz-epidote-calcite) fragments and are almost always associated with higher grade bornite molybdenite-arsenopyrite mineralization within the #1 Zone.

The #1 Zone forms a well-defined, fairly consistently mineralized body at a cut-off grade of 0.3% Cu. It has rough dimensions of 150 to 220 m wide, 100 to 150 m deep and 200 m long. The western boundary of the zone is quite sharp as it passes into sporadically mineralized breccia. The zone thins into two separate mineralized bodies to the east in section 812450 m E, before it apparently pinches out in section 812500 m E. This area is poorly delineated, but the IP chargeability inversion data indicates that there is potential for undiscovered mineralization at depth or along strike.

The lower contact of the #1 Zone dips gently to the north between 20° to 30° and roughly parallels the breccia / quartz-diorite footwall contact, but extends into unbrecciated footwall up to 90 m in section 812350 m E. Mineralization within the footwall differs in that it occurs principally as veinlets and disseminations associated with a mix of alteration assemblages including quartz-potassium feldspar-sericite-chlorite.

Copper mineralization within the #2 Zone generally does not begin until 50 to 150 m below surface. However, the western extension between lines 812300 m E to 812350 m E comes within 5 to 10 m of surface and is clearly visible as a chargeability inversion anomaly. The upper 100 to 200 m of this zone is hosted within a rootless, unbrecciated, quartz-feldspar porphyry which shows little alteration outside of the mineralized veinlets. Below the porphyry, mineralization continues down into quartz-diorite and quartz-diorite breccia.

The #2 Zone trends east-southeast and at a cut-off grade of 0.3% Cu forms a well-defined, consistently mineralized, vertically dipping tabular body between 50 to 150 m wide, up to 250 to 300 m in strike length, and with a dip extent of 350 m that is open at depth. The bottom of the mineralizing system has yet to be defined for most of its strike length and there is potential to add significant tonnage to this zone at depth.

The #3 Zone is intermittently exposed on surface for roughly 400 m between sections 812325 to 812725 m E as a southeast trending zone of malachite-stained breccias of quartz-feldspar porphyry in the northwest and quartz-diorite breccia extending from the centre to the southeast. Mixed breccias of quartz-feldspar porphyry and quartz-diorite occur within the contact areas between the two main rock types. Weathering and copper oxide mineralization is generally restricted to within 20 m of surface except in zones of faulting where surface waters have percolated to greater depths.

Mineralization within the #3 Zone occurs as blebs, disseminations and veins of chalcopyritebornite within sericite/kaolinite-chlorite-quartz±calcite-potassium feldspar altered framework supported breccias of quartz-feldspar porphyry, quartz-diorite and mixed varieties of the two. Quartz-feldspar porphyry breccias tend to be more tightly packed with less rotational movement than brecciated quartz-diorite, and in several cases brecciated dykes of quartz-feldspar porphyry are observable in drillcore.

Copper mineralization within the #4 Zone does not outcrop and generally does not begin until 100 to 300 m below surface. Historic mapping indicates that it is manifested at surface as a 60 to 90 m wide northwest trending band of weakly to non-mineralized green sericitized crackle breccia between sections 811925 to 812250 m E. Near its eastern boundary in section 812225 m E, the #4 Zone approaches within 20 to 30 m of surface where it appears to merge with the #2 Zone.

Mineralization within the zone is characterized by blebby to disseminated chalcopyritepyrite bornite-arsenopyrite occurring principally within the matrix to a hydrothermal “crackle” breccia cemented by a combination of quartz-calcite-tourmaline-chlorite gangue. Brecciated host rocks are dominantly quartz-diorite, but several intervals of brecciated quartz-feldspar porphyry indicate the area was intruded by several felsic dykes prior to, and possibly coincidental with brecciation.

The Las Minitas prospect occurs 2 km east-southeast of the East Hill. The prospect is characterized by an area, roughly 100 by 50 m, of exposed malachite chips and a few shallow historic trenches.

The La Verde project lends itself to a conventional truck and shovel open pit mining method.

The conceptual mining schedule calls for ex-pit mining rates of Ktonne/day during Year 1, 264 Ktonne/day from Year 2 to 4, and an average of 296 Ktonne/day from Year 5 to 18.

For this size of mining operation and the selectivity required in this type of deposit, large size mining equipment is proposed. Both productivities and costs have been estimated on the following operational scheme:
• Drilling and Blasting on 15 m benches.
• Primary loading with rope and hydraulic shovels.
• Use of 225 tonnes haul trucks.
Use of electric equipment (primary drills and rope shovels) is considered.

The open pits were scheduled using the Milawa algorithm which is part of the Whittle Four-X package. Highlights of the selected mining schedule are:
• The selected schedule calls for 21 years of mining activity; in Year -1, 65 million tonnes are pre-stripped, open pit mining occurs between Year 1 and Year 19, and stockpile reclaiming in Years 20 and 21.
• Metal prices and mill recoveries are the same as those used for NSR calculation and pit optimization. [2018-TR p.123]

Crushing equipment is based on the AMC database for similar size base metal projects. Two gyratory crushers of 60” x 89” are proposed.

From this AMC has determined that two 22 MW SAG mills (12.2 m x 6.7 m with wraparound gearless motors) and two 15 MW ball mills are required. A single regrind mill of 2.15 MW capacity is also indicated.

The ball mills are in closed circuit with cyclones.

The proposed flowsheet is a conventional copper concentrator flowsheet comprising crushing, grinding (SAG, Ball mill pebble crusher – SABC), and flotation with concentrate regrind and three stages of cleaning. There will be two trains of grinding and two rougher flotation banks followed by a common regrind and cleaner circuit.

“Fixing” the arsenic as a stable waste product is also a vital part of the process and this will be achieved at La Verde by wet scrubbing of the roaster exhaust gases to capture the arsenic (as water soluble arsenic trioxide) and the oxidized particulate (mainly iron oxide). The iron oxide will dissolve in the acid scrub liquor to provide the necessary iron (minimum 4:1 Fe:As stoichiometric ratio), along with limestone to neutralize the liquor and air oxidation, to stabilize the arsenic as hydrated ferric arsenate (FeAsO4.2H2O; artificial scorodite). This is environmentally stable over a much wider range of pH and oxidation potential than a calcium ars ........