The mineral deposits along the Carlin Trend form a suite of deposits known as Carlin-type. Carlin deposits comprise stratabound disseminated gold mineralization hosted by Silurian-Devonian carbonate rocks that have been metamorphosed to varying extents. The deposits are hydrothermal in origin and are usually structurally controlled. The carbonate host rocks are part of an autochthonous miogeoclinal carbonate sequence exposed as tectonic windows beneath the Roberts Mountains allochthon. The allochthonous rocks are a sequence of lower Paleozoic dominantly siliciclastic eugeoclinal rocks that were displaced eastward along the Roberts Mountains Thrust over younger units during the Upper Paleozoic Antler Orogeny. The Carlin Trend is the largest concentration of gold deposits in North America. NGM and other companies have discovered over 40 deposits along the 64 kilometre long, north–northwest-oriented Carlin Trend. Gold deposits are generally hosted in a variable stratigraphic package of Ordovician through Lower Mississippian rocks. The preferential host rocks are autochthonous carbonate assemblage rocks that are now preserved in uplifted tectonic windows. All Carlin Trend gold deposits that have been discovered to date are either within the Bootstrap, Lynn, Carlin, and Rain tectonic windows, or proximal to them. Within specific deposits, Cretaceous and Tertiary dike swarms and a Jurassic-aged granodiorite stock (Goldstrike stock) may constitute as much as 15% of the mineralized material.

Host rocks are most commonly thinly-bedded silty or argillaceous carbonaceous limestone or dolomite, commonly with carbonaceous shale. Although less mineralized, non-carbonate siliciclastic and rare metavolcanic rocks can locally host gold that reaches economic grades. Felsic plutons and dikes may also be mineralized at some deposits. Deposits typically have a tabular shape and are stratabound, localized at contacts between contrasting lithologies but can also be discordant or breccia-related.

Mineralization consists primarily of micron-sized gold and sulfide grains disseminated in zones of siliciclastic and decarbonated calcareous rocks and are commonly associated jasperoids. Major ore minerals include native gold, pyrite, arsenopyrite, stibnite, realgar, orpiment, cinnabar, fluorite, barite, and rare thallium minerals. Gangue minerals typically comprise fine-grained quartz, barite, clay minerals, carbonaceous matter, and late-stage calcite veins.

Goldstrike - Betze-Post
The Betze-Post deposit, the largest on the Carlin Trend, is divided into sub-deposits which, from east to west, are the Deep Post, Post, Betze, West Betze, and Screamer. Other zones within the pit are North Betze, West Barrel, and North Screamer.

Five generations of pyrite mineralization have been recognized at the Betze-Post open pit. Early stages of diagenetic pyrite, and coarse-grained pyrite in the metamorphic aureole of the Goldstrike diorite, are barren. Early hydrothermal, very fine-grained pyrite and marcasite grains of the third generation are coated by a 25 µm thick rind and cut by micro-veinlets of arsenic and gold bearing pyrite of the fourth generation. Barren, late hydrothermal coarse-grained pyrite and marcasite is accompanied by barite and stibnite. Sulphides make up approximately 2% by weight of the ore, locally up to 20%.

Mineralization may be predominantly oxides, sulphides, or refractory or carbonaceous sulphides. Weathering alteration extends up to 200 metres in depth resulting in oxide mineralization, which overlies the refractory sulphides. Alteration has liberated gold by the destruction of pyrite and resulted in the formation of oxide and secondary sulphate minerals, which include goethite, hematite, jarosite, scorodite, alunite, and gypsum. The alteration is deepest in the Post deposit due to extensive fracturing and high pyrite content.

Goldstrike - underground mines
Gold mineralization in the underground mine is subdivided into East Banshee, West Banshee, Meikle, South Meikle, (East) Griffin, Extension, West Griffin, Rodeo, Barrel, West Rodeo, and North Post deposits and sub-deposits. The sulphide mineralization is associated with silicification and argillization, and there is little or no oxide mineralization. In sulphide mineralization, the gold is intimately associated with very fine-grained pyrite and marcasite. Associated sulphide minerals include arsenopyrite, realgar, orpiment, and stibnite. Gangue minerals include quartz, calcite, and barite. Realgar and orpiment are generally low in abundance; however, these minerals are locally common in stockwork veinlets, fracture fillings, and breccia matrices.

Gold Quarry
The mineralization of Gold Quarry is generally bounded on the northwest by the northeast-striking Chukar-Alunite Fault zone, and on the southeast by the north–northeast-striking Deep Sulfide Feeder Fault zone. Mineralization is preferentially located in the hanging wall of the Chukar-Alunite Fault Zone and in the footwall of the Good Hope Fault. Gold mineralization is disseminated, with higher gold grades concentrated adjacent to structures.

Tri-Star (Silverstar and Goldstar)
The gold deposits at the Tri-Star complex (formerly Genesis) are developed along the Tuscarora, Turquoise, and Ridge anticlines within the Lynn Window. They occur over an area of about 3.2 kilometres long by 1.9 kilometres wide. The Silverstar deposit occurs in the hinge of the Tuscarora anticline whereas the Bluestar Point, Bobstar, Goldstar, and Payraise deposits occur on the more western anticlines. The anticlines are intruded in the north by the 158 Ma Goldstrike intrusion, a thick composite diorite–granodiorite sill complex.

Mineralization is preferentially developed in laminated silty limestone and bioclastic debris flows of the Popovich and Roberts Mountains Formations, but locally can also occur in contact metamorphosed calc-silicate hornfels, Rodeo Creek Formation siliceous mudstone, siltstone and calcarenite, Vinini Formation mudstone/quartz hornfels, and fractured Goldstrike intrusive margins. Gold deposits generally occur where mineralizing fluids exploited thrust faults, conjugate northwestand northeast-striking normal faults, and anticline hinge zones. The deposits have dimensions that range from about 183 to 457 metres by 61 to 183 metres. Mineralization can be stratabound locally but is typically discordant to the formations along faults with thicknesses ranging from 15 metres to 91 metres.

Emigrant
Gold mineralization at the Emigrant deposit is located along the flanks of the Emigrant antiform with the majority of the mineralization being concentrated on the western limb in a shallow, southwestdipping tabular orebody located at the contact between siltstones of the Mississippian Webb Formation and limestones of the Devonian Devils Gate Formation.

Leeville (West Leeville, Turf, Four Corners Deposits)
Gold deposits of the Leeville underground Complex are hosted by lower Paleozoic carbonates of the Devonian Rodeo Creek Formation (Drc), Devonian Popovich Formation (Dp), and Siluro-Devonian Roberts Mountains Formations (SDrm), and a series of highly altered, undifferentiated dikes cross cutting stratigraphy. Gold mineralization is controlled by a combination of lithology and structure. Intrusive rocks occur as dikes and sills, and locally host mineralization. Lithologic hosts include Rodeo Creek, Popovich, and Roberts Mountains Formations that vary between sub-horizontal to moderately folded. Mineralized material consists of 60 – 90% quartz, 5 - 20% kaolinite, 1 - 17% carbonate, and 3 – 7% pyrite. Gold mineralization in the Leeville complex is wholly refractory.

The Carlin Complex has three major open pit operations including Goldstrike, Gold Quarry and Goldstar (part of the Genesis/Tri-Star Complex). All three are truck and shovel operations. Blasting is required and blast patterns are laid out according to material type using rock type designations of hard, average, soft, or a combination of the three. The pit design varies between 6.1 metre to 12.2 metre (20 to 40 ft) benches and, where possible, up to 18.3 metre (60 ft) benches in the ore, though mined in 6.1 metre (20 ft) cuts. Slopes vary based on location.

The Carlin Complex has three major operating underground mines including Goldstrike underground, Leeville and the Portal Mines (including Pete Bajo and Exodus/Northwest Exodus, El Niño, Rita K). All mines utilize drift and fill and/or long-hole stoping and are accessed by shaft or portals.

Ground conditions vary greatly in the different mining areas. Poor conditions in some areas are due to increased brecciation and/or alteration of original structures. Oxidation affects rock strengths in some areas and requires corrosion-resistant ground support. Generally low-strength rock conditions are the key factor in the mine design and mining method selection.

Leeville has three shafts; the No. 1 shaft has two 7-cubic yard (~10 ton) skips for transporting aggregate for CRF underground and one station on the 4675 Level; the No. 2 shaft has two 7-cubic yard (~10 ton) skips for transporting ore to surface, a two-deck service cage for personnel and supplies transport, a six person chippy cage for personnel transport, and stations at the 4450 and 4315 Levels; and the No. 3 shaft has two stations, at the 4100 Level and at 4000.

Goldstrike has two shafts and three portals: including the Meikle and Rodeo Shafts, and the North Post, Betze No. 1 and No. 2 portals. The Meikle shaft is approximately 548.6 m (1,800 ft) deep, extending to the 1,128 m (3,700 ft) level, while the Rodeo shaft is 396 m (1,300 ft) deep and extends to the 1,250 m (4,100 ft) level. Hoist operation in both shafts is automated with human oversight provided. There are ventilation shafts and boreholes for ventilation in both the Meikle and Rodeo mines. The three portals all are accessed from the Goldstrike open pit.

The underground mines utilize three forms of backfill including cemented rock fill (CRF), uncemented run of mine waste, and paste fill.

Goldstrike underground operations use two mining methods for extraction: long hole open stoping and underhand drift & fill, both of which rely on cemented backfill for support.

Goldstrike underground mine consists of 11 separate production areas stretching over a length of 12,000 ft, and a vertical distance from approximately 600 ft to 2,000 ft below surface. At the southern end of the underground zones, the pit workings cut the underground zones.

In relatively good to fair ground conditions, where longhole stoping methods are used, the wall and back instability is reduced by mining smaller, longhole sections and filling before mining the next section. In poor ground, the underhand drift and fill method provides a backfill roof for subsequent lifts in the mining cycle.

The underhand drift and fill method is utilized in areas of fair to poor ground conditions regardless of the width of the zone. The underhand drifts are nominally designed as 4.6 metres (15 ft) wide by 4.6 metres (15 ft) high. The minimum width is 4.6 metres (15 ft) (one drift). The primary drift is driven with increased ground support to hold the ground open, then backfilled with a high strength cemented rock fill at the Meikle mine, paste fill at the Rodeo and North Post mine. Where the ore width exceeds the nominal drift width, subsequent drifts are developed (parallel or at oblique angles to the primary drift) and then backfilled. This process continues until the entire ore shape at a given elevation has been excavated and filled. Successive lifts are taken beneath the primary workings, utilizing the backfill as an engineered back. This method can provide a consistent production rate from a mining area given a sufficient number of headings to complete the full mining cycle.

Transverse longhole stopes are designed at various heights ranging from 10.7 m (35 ft) to 30.5 m (100 ft), based on the existing and planned sill development levels used in the active mining areas. Stope widths are designed at 6.1 to 7.6 metres (20 ft to 25 ft), based on the ground conditions. In secondary stopes, the width is dictated by the actual dimensions of the adjacent primary stopes. Development of the secondary sills may be reduced to 4.0 metres (13 ft) leaving a rock “skin” to account for poor quality backfill in the adjacent stopes. The overall stope length is based on the transverse dimension of the ore; however, individual stopes can be limited to 13.7 metres (45 ft). Transverse longhole stopes are designed with at least 60° hanging walls and with subvertical footwalls.

Mill 5 - Crushing and grinding where ore is ground to the appropriate particle size, usually about 65% -200 mesh.

Mill 6 - Crushing and dry grinding. The Mill 6 facility receives crushed refractory ore and processes it in a dry grinding circuit that includes a double rotator ball mill as well as static and dynamic separators ahead of a baghouse and fine ore bin. The ground material is then sent to the roaster prior to leaching and gold recovery.

The processing operations contained in the Carlin Complex are:
• Mill 5 (flotation and cyanide leaching), was commissioned at Gold Quarry in 1988, capacity - 5 mtpa;
• Mill 6 (Roaster), was commissioned at Gold Quarry in 1994, capacity - 3.2 mtpa;
• South Area Leach;
• North Area Leach;
• Emigrant Area Leach;
• Goldstrike Autoclave, capacity - 5 mtpa;
• Goldstrike Roaster, capacity - 6 mtpa.

Goldstrike process facilities provide the capability to treat single refractory ore (sulphidic) and double refractory ore (sulphidic and carbonaceous) through roasting or pressure oxidation. The roaster circuit accommodates Goldstrike open-pit and underground ore as well as other ore from NGM assets including but not limited to Cortez Hills Open Pit, Cortez Hills Underground, Leeville underground and Pete Bajo underground. A blended feed to the roaster is required to control the circuit heat balance. Pressure oxidation also receives a blended feed from ........