Summary:
The mineral resource areas within Project Fenix are classified as low to intermediate-sulphidation epithermal precious metals deposits. The Project Fenix deposits can be silver-dominant (El Gallo Silver) or gold-dominant (El Gallo Gold). Although the mineral resource areas have differing mineralogy and morphology, all deposits in the Project have quartz stockwork and quartz breccia as the main mineralization hosts.
El Gallo Silver
A low to medium sulphidation silver-dominant epithermal precious metal deposit. Silver mineralization is associated with minor gold as well as anomalous lead and zinc. Certain features of the El Gallo Silver deposit distinguish it from many other typical Mexican epithermal deposits. For example, mineralization is not hosted in through-going fault veins instead it is hosted in breccias and quartz stockwork zones associated with hypabyssal intrusions and pre-existing breccia zones.
Mineralization is hosted in siliceous breccia zones and quartz stockwork zones. These zones often occur at lithologic contacts, particularly contacts of the porphyry intrusions (ANDP, QFP). Contacts are usually brecciated and often have adjacent multi-lithic breccia zones. This brecciation is thought to be pre-, syn- and post-mineral with mineralizing hydrothermal fluids using these zones as a conduit and host. At least one other brecciation event occurred after mineralization as evidenced by many of the breccias containing mineralized clasts. Zones of quartz stockwork veining usually occur adjacent to these breccias.
Mineral zones commonly have tabular geometry oriented sub-horizontally or gently dipping (20 to 30°) both to the north and to the south and often occur in multiple stacked zones. Often, these zones reflect control by sill-like contacts of ANDP or QFP or other lithological contacts but may also reflect shallow dipping structures. Tabular zones vary in width up to about 165 ft (50 m) thick but average about 50 ft (15 m). Their lateral extent in a north-south sense (across strike) is also variable but is often on the order of 650 ft (200 m). An at- or near-surface sub-horizontal mineralized zone averaging about 50 ft (15 m) thick is dominant in many portions of the mineral resource. This near-surface mineralization constitutes a significant portion of the mineral resource. In the central part of the mineral resource, this near-surface mineralization is continuous for up to 1300 ft (400 m) north-south.
El Gallo Gold
El Gallo Gold consists of low- to intermediate-sulphidation epithermal gold and silver mineralization. The majority of the El Gallo Gold deposits are gold-dominant and locally contain strongly anomalous base metals. Mineralized zones at El Gallo Gold occur as tabular veins or quartz stockwork zones, sometimes occurring as parallel sets.
Gold mineralization within the El Gallo Gold Mine area occurs in five deposits along two distinct structural trends. A north-west trending structure hosts the San Rafael and Samaniego deposits. The second structural trend is northeast-striking and includes the Sagrado Corazón, Lupita and Central deposits. These structural trends are characterized by one or more individual structural zones of sheared and brecciated rock resulting from faulting of generally limited displacement. Within these structures the mineralization occurs as pods that pinch and swell both along strike and down dip. These pods may reach a strike length of up to 330 ft (100 m) and widths of up to 100 ft (30 m). Contacts between mineralized material and barren rocks are typically sharp and well defined, and they often correspond with faults that show minor post-mineral movement. These structures have been shown to flatten at depth in some instances, as is the case with the La Prieta vein at the southern (down dip) extension of the Samaniego deposit.
San Rafael
Gold mineralization occurs along the same structural system as Samaniego and is best developed on an east-west main structure dipping 45° to the south. This mineralization has largely been mined out. The main zone tended to occur at or near contact between underlying andesite flows and tuffs (footwall volcanics) and overlying andesitic agglomerate (hanging wall volcanics) that dip at a moderate angle to the south-west. The San Rafael deposit was about 400 m (1,300 ft) along strike and gradually horsetails and weakens to the east beyond the intersection with the southeast-striking Las Vacas zone. The San Rafael zone extended approximately 250 m (820 ft) down dip where, below an elevation of 325 m (1,070 ft), it was no longer significantly mineralized. The mined-out portion of the deposit ranged from a few meters to several tens of meters in thickness.
Samaniego
Samaniego consists of a complex north- to northwest-trending structural system that dips about 50° to the south-west and has a strike extent of about 600 m (1,970 ft). Samaniego mineralization is continuous for up to nearly 400 m (1,300 ft) down dip. Four main mineralized vein zones, Upper Samaniego Hill, La Prieta, Lower Samaniego Hill, and High Angle occur within the Samaniego deposit. The deposit appears to be connected structurally to the south to the San Rafael deposits, though mineralization is weakly developed in the area between the two pits. The mineralized structures tend to occur at or above the contact between underlying andesite flows and tuffs and overlying agglomeratic andesite. Individual zones can merge with each other or eventually pinch out laterally. The veins range from a few meters to a few tens of meters in thickness. To the north-west, the Samaniego structural trend is truncated by an east-west fault, with the possible structural offset of the Samaniego trend occurring to the east. Along the down dip extent of the La Prieta vein within the Samaniego deposit, the structure flattens and swells to roughly 30 m (100 ft) thick. Gold grades in this pod, which has an aerial extent of approximately 50 by 100 m (160 x 330 ft), average roughly 0.1 oz/t (3g/t) gold, higher than average for the El Gallo Gold deposits.
Sagrado Corazón-Central-Lupita
Sagrado Corazón-Central-Lupita is a northeast-striking mineralized trend on the south end of the El Gallo Gold Mine area. This structural zone is laterally continuous over a distance in excess of 1,800 m (5,900 ft), from Sagrado Corazón in the south-west through Central to Lupita in the north-east. This zone dips steeply to the southeast at 60-85°. The structural trend occurs at or near the irregular contact between intrusive rocks (predominantly diorite) to the north-west and volcanic rocks (andesitic flows and agglomerate) to the south-east. Locally along the trend, the mineralized zone splits into one or two subparallel zones. Mineralization gradually weakens to the south-west and north-east along the trend. To the north-east it appears to be truncated by a north-south fault, which places a down-dropped block of probably post-mineral tuffs to the northeast. On the south-west end of the trend (Sagrado Corazón), the steeply dipping mineralized zone is generally a few tens of meters thick and extends down dip in excess of 125 m (410 ft) where it weakens. In the Central part of the trend, mineralization at surface is weak and generally is 1 m (3 ft) to 10 m (33 ft) thick. It extends down dip in excess of 100 m (330 ft), where it weakens but is not completely drilled off in some locations. On the north-east (Lupita) part of the trend, the steeply dipping mineralization is more complex, consisting of one to three subparallel zones, with a combined thickness generally of a few tens of meters. Mineralization extends down dip in excess of 100 m (330 ft), where it appears to be closed off.