Florida Canyon is a large, relatively young epithermal gold deposit adjacent to an active geothermal system. The close spatial association with the geothermal system has led to a general belief that Florida Canyon is a hot spring-style, epithermal gold deposit. Hydrothermal alteration assemblages and the mineralogy of both oxidized and unoxidized gold mineralization at Florida Canyon have been described and interpreted by Fifarek et al. (2011) as having formed in a low-sulfidation, epithermal environment. Age dates on adularia from quartz-adularia-sulfide±gold veins in the deposit indicate gold mineralization occurred episodically at about 5 Ma, 4.6 Ma, and between 4.6 and 2.2 Ma along and in the footwall of the N-S, range-bounding fault at the west margin of the Humboldt Range; this mineralization was overprinted by steam-heated alteration and oxidation at various times between 2.2 Ma and 0.9 Ma Fifarek et al., 2011). There are no known volcanic or intrusive rocks of similar age nearby, and the deposit has been considered to be of the amagmatic subtype of the low-sulfidation epithermal classification.

Rock units that are more favorable hosts to mineralization include silty argillite, hornfelsed contact zones with mafic sills, karsted limestone, and platy, silty limestone with interbeds of calcareous shale. Local factors that influence the occurrence and geometry of mineralized bodies include variations in folds, foliation, and bedding in favorable units, intersecting structural fabrics, and proximity to lowangle structures (Taylor 2001). Hypogene mineralization at Florida Canyon consists of native gold and electrum associated with quartz, iron oxides, pyrite, marcasite, and arsenopyrite (Hastings et al., 1987). Quartz is the major gangue mineral. Secondary minerals identified in the Florida Canyon deposits to date include gypsum (likely remobilized from the Grass Valley Formation), alunite, barite, native sulfur, calcite, dolomite, fluorite, anhydrite, pyrargyrite, pyrrhotite, and stibnite. There are two types of hydrothermal, epithermal quartz veins at Florida Canyon (Hastings et al., 1987). The most important are vein swarms and stockworks that contain most of the gold mineralization. These veins are often randomly oriented, though generally follow a north-northeast trend (Hastings et al., 1987) and are characterized by colorless, euhedral to subhedral quartz, or banded chalcedonic white to colorless quartz that contains limonite after pyrite (Taylor, 2001).

The second type of hydrothermal quartz veining occurs as large, through-going, banded fissure veins that follow the original north-northeast structural fabric (Hastings et al., 1987). These veins are interpreted to represent a late hydrothermal event that overprinted the earlier episode of gold-bearing quartz veining and stockworks. These veins are characterized by bands of coarse, prismatic quartz alternating with bands of cherty chalcedony and only occasionally contain economic gold grades. Milky white bull-quartz veins, considered to be metamorphic in origin, may also be present in the mineralized zones, but they are not gold bearing (Taylor, 2001). Locally, pervasive silicification is generally associated with areas of high-density quartz veining and/or intense hydrothermal brecciation (Taylor, 2001). Sericite, adularia, clay, and chlorite occur locally in quartz veins, breccia matrix, and on fracture surfaces. There is extensive argillization and bleaching throughout the deposit area, with pervasive hematization that is largely confined to silty units marginal to the bleached areas (Hastings et al., 1987).

A different style of mineralization has been recognized in the more recently discovered deposits east of the original Florida Canyon Main, Madre (Brown Derby), and Northeast Extension (Central) ore bodies (Larsen, 2009 internal memos). At Radio Tower East (aka Switchback) and Cone, karsted surfaces in Natchez Pass Limestone are replaced by cryptocrystalline silica forming jasperoid and hornfelsed contact zones between mafic sill and limestone are strongly quartz-veined and pyritized.

The Florida Canyon Mine consists of a series of connected open pits, Phase 4 Main Pit, Phase 5 Brown Derby Pit and Phase 6 Central Pit and three adjacent smaller pits, Radio Tower West Pit, Jasperiod Hill Pit and the Switch Back Pit. The pits have a surface foot print of approximately 404.8 acres.

Ore and waste materials will be mined by a fleet of 993- and 992-Cat loaders, 785-Cat trucks, and 777-Cat trucks.

The early mining in this pit has access issues in the upper benches. Due to limited bench working space and bench access, the upper benches will need to be mined by dozing material off the bench and into an existing pit. Once the dozing has been completed this material can be utilized for road construction as required. The existing pit conditions and geotechnical data should be gathered to confirm pit slope assumptions prior to mining. It may be that remote controlled dozing may be recommended; however this option should be considered when investigating the site in detail.

Annual ore grade material production is scheduled to be 7.2 million tons, while total ore grade material and waste production is limited to 53,000 tpd.

The Florida Canyon Mine uses conventional cyanide heap leach technology for the recovery of gold and silver.

The following is a summary of recovery methods:

• Material to be crushed will be delivered from the open pit mine to a crusher stockpile located adjacent to the primary crusher.
• During regular operations (~1100 tph), a loader will feed a hopper. An apron feeder will draw the material from the hopper to a primary jaw crusher. The primary jaw crusher will reduce the material to 80% passing 5in. The material will report to a conveyor which will deliver the crusher material to a vibrationg screen.
• The vibrating screen will size the material. The undersize will report directly to a conveyor to be conveyed to a a blender wheel agglomerator. The over size (>5in) will report to a twostage cone crusher to be reduced to 100% passing 1½in. The crushed material will report to the conveyor to be delivered to the agglomerator.
• Cyanide and lime will be added to a blender wheel agglomerator. The agglomorate will be transfered to a conveyor to be delivered to the radial stacker.
• The agglomerate will be stacked at the end of the radial stacker. After a curing period, the material will be loaded into haul trucks and dumped on the leach pad. A dozer will be used to flatten the leach pad material.
• A dilute process solution containing cyanide (~0.2 lbs/ton) will be applied in a counter current application using a drip irrigation system.
• The resultant pregnant solution will flow through a collection system and be stored in pregnant solution ponds.
• The pregnant solution will be pumped to an absorption-desorption-recovery (“ADR”) plant for gold recovery. The gold will be absorbed onto activated carbon granules, then periodically stripped from the carbon using a Zadra type desorption process.
• The gold will then be plated unto wool cathodes in (2) electrowinning cells. The gold and silver doré will be removed by pressure washing, filtering, dried and then smelted to produce a gold-silver doré bullion.

Based on a design throughput of 7.2 million tons per year and an overall recovery of 71.1% for gold, approximately 65,000 to 70,000 ounces of gold will be produced per year.

The newly installed second CIC plant will nearly double the processing capacity with throughput increasing from 18,000 solution tons per day to 30,000 solution tons per day. The additional flow will allow for more square footage to come under leach and increase gold production. The additional CIC capacity will be operational in early Q1 of 2018.