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.

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.

Major lithologic units recognized in the Emigrant deposit from surface mapping, drill hole logging, and litho-chemistry include; Tertiary Indian Wells (Tiw), Tertiary Elko (Te), Mississippian Chainman (Mc), Mississippian Webb (Mw), Devonian Woodruff (Dw), Devonian Devils Gate (Ddg) Formations, and the Devonian Nevada Group (Dng).

Detailed surface mapping and drill hole interpretation indicates that there are a series of N10ºW to N10ºE structures present at Emigrant (Emigrant Fault system). The Emigrant Fault appears to bound the hanging wall to the deposit and places the Mississippian Webb Formation (east side) against the Pennsylvanian Tonka, Mississippian Chainman and Devonian Woodruff formations (west side). Emigrant demonstrates the typical Carlin Trend deposit geochemical signature in that fine-grained gold mineralization is associated with Au, As, Sb, and Hg. Gold occurs as elemental gold encapsulated in quartz as well as in submicrometer substitutions in arsenian rims over pyrite.

The Carlin Complex consists of several large open pit operation and underground mines. The open pit mines of the Newmont-Contributed Mines are split into the North Carlin Mines (Tri-Star/Genesis and Perry), Gold Quarry and Rain/Emigrant. The numerous underground mining sites of the Newmont-Contributed Mines are referred to as the Leeville and the Portal (Pete Bajo and Exodus) Mines.

The Emigrant pits have haul road effective widths for two-way travel of 85 ft (26 m) for cut-to-fill roads and 100 ft (30.5 m) for external fill roads due to the utilization of smaller CAT 789 trucks. Maximum grade for Emigrant roads is 10%. Minimum pit-bottom width is designed at 120 ft (37 m). Bench heights vary from 20 ft (6 m) to 40 ft (12 m).

The Emigrant open pit ceased mining operations in December 2018 while residual leaching of gold continues. [Newmont Form 10-K 2018. P.40]

Heap leaching is used to treat oxide ores containing low gold grades. Typically, gold grades are in the range of 0.25 g/t Au to 1 g/t Au. Heap leaching involves stacking large volumes of low-grade ore and applying lixiviant to recover the gold. Leaching ceases when the gold recovery drops below a pre-determined threshold. The basic steps in heap leaching are:

• Run-of-mine or crushed ore are placed onto a prepared surface;
• Gold dissolution is promoted by applying a weak sodium cyanide solution as the lixiviant to the surface of the heap;
• Solution is collected in the leach pad drain system and then pumped to activated carbon
columns (CIC) where gold loads onto activated carbon; and
• Gold-laden carbon is reclaimed from the CIC circuit and transported to a centralized carbon stripping system where the gold is stripped from the carbon and recovered by electro-winning. Stripped carbon is recycled and reused.

Gold recovery from heap leaching is ........