Carlin is a sediment-hosted disseminated gold deposit.

Ore in the Leeville Project area occurs in two strata-bound zones located in the upper 350 feet of the Roberts Mountains Formation. Ore grade mineralization is located in the footwall of the West Bounding Fault, which trends northeast, dips 60 degrees west, and has approximately 150 feet of apparent normal displacement. The thickest and highest-grade portion of the deposit is located where the northwest-striking Rodeo Creek Fault intersects the footwall of the West Bounding Fault. Ore occurs in grey to black, decalcified (calcite removed) and weakly to moderately silicified rocks composed of 60 to 70 percent quartz, 10 to 30 percent dolomite, 7 to 16 percent kaolinite and illite, and 2 to 4 percent pyrite (Jackson et al. 1997). Mineralized zones of the ore body occur at depths of 1,500 to 2,000 feet below ground surface.

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.

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.