Gold Quarry is one of the largest gold deposits in North America. It is comprised of two stacked orebodies: an upper structural stockwork and a lower stratabound replacement. Overall strike of the main (upper) ore zone is N45E. It is bounded on the west by the Gold Quarry Fault and on the east by the Grey/Challenger fault systems. Mineralization is continuous over 6000 feet of strike. The Deep West orebody is a silica replacement zone at the contact of footwall carbonate rocks and hanging wall siliciclastic rocks. It averages 250 feet in thickness, strikes N20E, dips 30-35 SE, and as known strike length of 2500 feet. Gold grade is double that of the Main (upper) ore zone. The Deep West ore zone is the down dip extension of the Maggie Creek South ore zone. Gold Quarry is one example of a Carlin trend gold deposit that exhibits primary northwest structural control. Mineralization is localized where the N45W Good Hope fault intersects the NE-trending Chukar-Alunite faults.

Gold grains range from <0.1 to 10.0 microns in size and usually occur associated with microfractures or disseminated in microcrystalline cherty matrix. Au:Ag ratio ranges from about 2:1 in mill grade ores to 1:3 in leach grade ores.

Gangue Materials: silica, iron oxides, kaolinite, barite, alunite, pyrite, illite, montmorillonite.

Carlin’s integrated mining operations consist of four open pits and four underground mines. The open pits include the Emigrant and the Gold Quarry pits in the South end of the Carlin Trend and the Silverstar and Goldstar pits in the North end of the Carlin Trend. The underground mines include Leeville, which is a shaft mine, along with Chukar, Pete Bajo and Exodus, which are portal mines.

The majority of the underground ore as well as higher-grade surface refractory ores are processed through the roaster (Mill 6), which consists of a grinding circuit, roasting circuit and a conventional carbon-in leach circuit. Mill 6 processed approximately 3.4 million tons of ore in 2016. Higher-grade surface oxide ores are processed by conventional milling and cyanide leaching at Mill 5. Additionally, Mill 5 operates as a flotation mill treating lower grade, non-carbonaceous, sulfidic refractory ore to produce a gold/pyrite concentrate. Mill 5 processed approximately 5 million tons of ore in 2016. Lower-grade surface material with suitable cyanide solubility is treated on one of four heap leach pads.

The circuits at the South Area include Mill 5, Mill 6, and two heap leach pads served by a single plant. Mill 5 is a pyrite floatation plant that processes sulfide and oxide ores that are ground in a sag mill and ball mills. The material is then sent to the floatation circuit where the sulfides are floated and dried for later processing in the autoclave or roaster. The oxide material remaining after floatation is sent to a set of carbon-in-leach (CIL) tanks for gold recovery. Mill 6 consists of a double rotating mill and a roaster; sulfide material is fed to the roaster where the sulfides are volatilized. Material leaving the roaster is sent to a set of CIL tanks at Mill 5 for processing. Tailings from both CIL circuits is combined and sent through a Caro’s Acid cyanide destruction circuit before disposal in the Mill 5/6 TSF. Gold-bearing solution from the SAL (i.e., Property and Non-Property Pads) drains to a series of pregnant ponds. Solutions from the pregnant ponds are pumped via pipeline to carbon-in column (CIC) circuits at South Area plant. Loaded carbon is transferred to the carbon handling facility and refinery for further processing.

The circuits at the North Area include a heap leach pad and plant. The gold-bearing solution from the North Area Leach drains to a series of pregnant ponds. Solutions from the pregnant ponds are pumped via pipeline to CIC circuits at the North Area plant. Loaded carbon is transferred to the carbon handling facility at the South Area and refinery for further processing.