Lion Copper and Gold Corp., a Canadian based mine development company, and its wholly owned U.S. subsidiary, Singatse Peak Services, LLC, are focused on the development of their Yerington Copper Project.
On March 18, 2022, the Lion Copper and Gold entered into an Option to Earn-in Agreement with Rio Tinto to advance studies and exploration at Yerington. Under the agreement, Rio Tinto has the exclusive option to earn a 65% interest.
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Summary:
The Mineral Resources considered for the Yerington Copper Project PEA encompass the Yerington Deposit, W-3 stockpile, Vat Leach Tails (VLT) stockpile and MacArthur Deposit.
Deposit Types
The Yerington Deposit represents a partially mined porphyry copper deposit hosted in porphyry dikes that formed in stocks of the upper Yerington Batholith. The Yerington porphyry system has been tilted westerly so that the plan view of the deposit is a cross sectional exposure. Mining has revealed an alteration geometry displaying the original pyrite-rich cap (present-day leached sericite-limonite on the west end of the Yerington pit) grading downward easterly to quartz-sericite-pyrite alteration and to potassic alteration in the central portion of the pit, and then continuing to a soda-flooded root zone at the eastern end.
Geological Setting and Mineralization
The Yerington Property (the Property) includes both the Yerington Deposit and a portion of the Bear Deposit which represent two of three known porphyry copper deposits in the Yerington district. Like the Mason copper-molybdenum property located 2.5 miles to the west, the Yerington and Bear Deposits are hosted in Middle Jurassic intrusive rocks of the Yerington Batholith.
Copper mineralization on the Property occurs in all three phases of the Yerington Batholith. Intrusive phases, from oldest to youngest, are known as the McLeod Hill Quartz Monzodiorite (field name granodiorite), the Bear Quartz Monzonite, and the Luhr Hill Granite, the source of quartz monzonitic (i.e. granite) porphyry dikes related to copper mineralization.
Following uplift and erosion, a thick Tertiary volcanic section was deposited, circa 18-17 Ma. This entire rock package was then extended along northerly striking, down-to-the-east normal faults that flatten at depth, creating an estimated 2.5 miles of west to east dilation-displacement (Proffett and Dilles, 1984). The extension rotated the section such that the near vertically emplaced batholiths were tilted 60° to 90° westerly. Pre-tilt, flat-lying Tertiary volcanics now crop out as steeply west dipping units in the Singatse Range west of the Property. The easterly extension thus created a present-day surface such that a plan map view represents a cross-section of the geology. Yerington Porphyry Copper Deposit.
The Yerington Mine produced approximately 162 million tons of ore grading 0.54% Cu, of which oxide copper ores amenable to leaching accounted for approximately 104 million tons. A 1971 snapshot of head grades shows oxide mill head grade averaging 0.53% Cu and sulfide grades ranging from 0.45% to 0.75% Cu (D. Heatwole, personal communication).
Mineralization
Yerington Porphyry Copper Deposit
The general geometry of copper mineralization below the Yerington pit is an elongate body extending 6,600 feet along a strike of S62ºE. The modeled mineralization has an average width of 2,000 feet and has been defined by drilling to an average depth of 400-500 feet below the pit bottom at the 3,500-foot elevation.
The copper mineralization and alteration throughout the Yerington district and at the Yerington Property are unusual for porphyry copper camps in that the mineralization is “stripey”, occurring in WNW striking bands or stripes between materials of lesser grade. Clearly, much of this geometry is influenced by the strong, district-wide WNW structural grain observed in fault, fracture and, especially, porphyry dike orientations. Altered, mineralized bands range in width from tens of feet to 200-foot-wide mineralized porphyry dikes mined in the Yerington pit by Anaconda.
Oxide copper occurred throughout the extent of the Yerington pit, attracting the early prospectors who sank the Nevada-Empire shaft on copper showings located over the present-day south-central portion of the pit. To extract the copper oxides, Anaconda produced sulfuric acid on site, utilizing native sulfur mined and trucked from Anaconda’s Leviathan Mine located approximately 70 miles west of Yerington.
Greenish, greenish blue chrysocolla (CuSiO3.2H20) was the dominant copper oxide mineral, occurring as fracture coatings and fillings, easily amenable to an acid leach solution. Historic Anaconda drill logs note lesser neotocite, aka black copper wad (Cu, Fe, Mn), SiO2 and rare tenorite (CuO) and cuprite (Cu2O). Oxide copper also occurs in iron oxide/limonite fracture coatings and selvages.
Chalcopyrite (CuFeS2) was the dominant copper sulfide mineral occurring with minor bornite (Cu5FeS4) primarily hosted in A-type quartz veins in the older porphyry dikes and in quartz monzonite and granodiorite, as well as disseminated between veins in host rock at lesser grade. The unmined mineralized material below the current pit bottom is primarily of chalcopyrite mineralization.
MacArthur Deposit
The MacArthur Deposit is a large copper mineralized system containing near-surface acid soluble copper and the potential for a significant primary sulfide resource that remains underexplored (IMC, 2022). The Deposit is one of several copper deposits and prospects located near the town of Yerington that collectively comprise the Yerington Mining District. The Deposit is underlain by Middle Jurassic granodiorite and quartz monzonite intruded by west-northwesterly-trending, moderate to steeply northdipping quartz porphyry dike swarms.
The MacArthur Deposit consists of a 50 to 150-ft thick, tabular zone of secondary copper (oxides and/or chalcocite) covering an area of approximately two square miles. This mineralized zone has yet to be fully delineated. Limited drilling has also intersected underlying primary copper mineralization open to the north, but only partially tested to the west and east.
Oxide copper mineralization is most abundant and particularly well exposed in the walls of the legacy MacArthur pit. The most common copper mineral is chrysocolla; also present is black copper wad (neotocite) and trace cuprite and tenorite. The flat-lying zones of oxide copper mirror topography, exhibit strong fracture control and range in thickness from 50 to 100 feet. Secondary chalcocite mineralization forms a blanket up to 50 feet or more in thickness that is mixed with and underlies the oxide copper. Primary chalcopyrite mineralization has been intersected in several locations mixed with and below the chalcocite. The extent of the primary copper is unknown as many of the holes bottomed at 400 feet or less.
The MacArthur Deposit is part of a large, partially defined porphyry copper system that has experienced complex faulting and post-mineral tilting. Events leading to the current geometry and distribution of known mineralization include: 1) Middle Jurassic emplacement of primary porphyry copper mineralization by quartz monzonite dikes intruding the Yerington batholith; 2) Late Tertiary westward tilting of the porphyry deposit from 60° to 90° through Basin and Range extensional faulting; 3) secondary (supergene) enrichment resulting in the formation of a widespread, tabular zone of secondary chalcocite mineralization below outcrops of oxidized rocks called leached cap; 4) oxidation of outcropping and nearsurface parts of this chalcocite blanket, as well as oxidation of the primary porphyry sulfide system.