The unique geology of North America’s Great Basin can be found in Nevada’s gold trends.
Nevada may be one of the most geologically diverse mining jurisdictions in the world.
Nearly every type of rock known to geologists can be found in the state’s desert landscape. The Silver State contains a wealth of precious metals, and it ranks as the fourth-largest gold producing jurisdiction in the world. Nevada is also an important source of many of the world’s most critical base metals, including copper, zinc and molybdenum.
Nevada owes its unique geology and prolific gold production to the complex tectonic history of the North American Great Basin, which gave rise to its widespread landscape of fault-dominated mountain ranges and valleys. “Nevada is dominated by basin-and-range topography that originates from Miocene tectonic extension. Geologically, igneous rocks in Nevada originate from 450 million-year-old seafloor spreading, more recent collisions of tectonic plates and mantle hot-spot activity,” said Gary Billingsley, professional geoscientist and CEO of Aurex Energy (TSXV:AURX). “Most of the economic mineral deposits in Nevada are related to intrusive igneous activity, which may originate from mantle hot-spots, or, more dominantly, tectonic plate subduction.”
Nevada’s gold deposits are primarily found in three major northwest-trending belts: the Carlin Trend, the Battle Mountain-Eureka-Cortez Trend and the Walker Lane Trend. These three trends have given rise to some of the world’s most important gold mining districts. According to Billingsley, Nevada hosts a variety of deposit types, including porphyry and skarn; however, the majority of the state’s gold production comes from low-sulfidation epithermal gold and sediment-hosted Carlin-type deposits.
It is this geological diversity that has shaped Nevada’s economy from the very beginning: the 1859 discovery of silver and gold at the Comstock Lode eventually drew in enough miners and prospectors to establish the state of Nevada five years later.
Even with more than 160 years of mining history, Nevada’s diverse geological landscape still has plenty of potential for further gold discoveries. Besides this excellent geology, Nevada provides a number of benefits for today’s exploration companies. “Nevada offers the opportunity for year-round exploration, where our exploration dollars go further than in other districts. The state ranks as Fraser Institute’s number one jurisdiction in the world for mining investment. Both the state and local governments are highly supportive of exploration and mining. Systematic greenfield exploration using modern geochemical and geophysical techniques hold the potential for discoveries due to the surficial efforts of past explorers,” said Aurex CEO Billingsley.
Aurex owns two exploration projects in Nevada, including the Cook gold-copper project, located within 50 kilometers of Paramount Gold Nevada’s (NYSE:PZG) past-producing Sleeper mine on the Battle Mountain-Eureka-Cortez trend. A hyperspectral survey at Cook, along with extensive surface sampling, has confirmed the potential for both a gold epithermal system and a porphyry gold-copper system. The Whiskey Flat copper-zinc-silver-cobalt project in Mineral County along the Walker Lane trend hosts the historic Quailey mine and is an example of the diverse, polymetallic nature of Nevada’s unique geology.
Nevada gold found in Carlin-style deposits
Nevada is best known for its Carlin-style deposits, named after the town of Carlin, which also gave its name to the Carlin gold mine first discovered in 1961 by Newmont Goldcorp (TSX:NGT,NYSE:NEM). These are large sedimentary rock-hosted disseminated gold deposits that are highly attractive targets for mining, because they often occur near-surface and in clusters, with one large “elephant” deposit surrounded by a group of smaller satellite deposits with similar geology. Estimated to contain up to 180 million ounces, the Carlin Trend is the second-largest gold resource in the world behind South Africa’s Witwatersrand.
The major players in Nevada’s Carlin Trend are Kinross Gold (TSX:K,NYSE:KGC), Newmont Goldcorp and Barrick Gold (TSX:ABX,NYSE:GOLD). Kinross Gold’s Bald Mountain mine had estimated proven and probable reserves of 1,347,000 gold equivalent ounces at the end of 2018. Like Newmont Goldcorp, Barrick has been a major force in Nevada’s gold story since the mid-twentieth century. Through the Nevada Gold Mines joint venture (JV) formed in mid-2019, Barrick and Newmont Goldcorp now jointly operate the world’s largest mining complex in Nevada. The operation combines Barrick’s Goldstrike, one of the world’s top gold producers, and Newmont’s Carlin operation, which consists of three open pits and four underground mines.
Carlin-type deposits are also found in Nevada’s second-most important gold belt, the Battle Mountain-Eureka-Cortez trend, which hosts SSR Mining’s (TSX:SSRM) Marigold mine and Barrick’s Cortez property. In operation since 1989, Marigold is a large heap leach complex with several open pits and probable reserves of 3.06 million ounces of gold. The Cortez property, now a part of the Nevada Gold Mines JV, includes the Pipeline mine complex and the Cortez Hills mine. The Cortez fault corridor is in the southern portion of the Battle Mountain-Eureka trend and connects the Goldrush, Cortez/Cortez Hills and Pipeline deposits.
One of Nevada’s newest mining operations, McEwen Mining’s (TSX:MUX,NYSE:MUX) Gold Bar mine is 50 miles to the south of Barrick’s Cortez operations. The mine was once part of the past-producing Gold Bar mine complex. The open-pit heap leach operation is expected to produce 30,000 to 33,000 ounces of gold in 2019. For its first full year of production in 2020, McEwen’s production guidance outlines 65,000 to 70,000 ounces of gold.
Nevada’s epithermal gold deposits
Nevada also hosts world-class examples of low-sulfidation epithermal gold deposits. In fact, it was an epithermal type system that kicked off the Nevada gold rush in the mid-1800s with the discovery of the Comstock Lode in what is now known as the Walker Lane gold trend. In addition to Comstock, several well-known deposits are associated with this trend, including Kinross’ producing Round Mountain mine; Hecla Mining Company’s (NYSE:HL) producing Hollister, Fire Creek and Midas mines; and the past-producing Tonopah and Goldfield deposits.
Epithermal vein-type deposits are among the world’s most important precious metals producers. In fact, they are the world’s second-largest source of gold, accounting for about 12 percent of annual gold production. Low-sulfidation epithermal deposits are often high-grade, making them excellent targets for both major and junior explorers. In fact, Hecla’s three Nevada mines are prime examples of low-sulfidation epithermal deposits and are some of the highest-grade gold mines in the world.
Nevada is one of the top gold producing regions in the world, with more to be discovered within North America’s Great Basin. As mining companies continue to explore the region, Nevada’s rich geological endowments and friendly mining policies are expected to continue the state’s solid track record for mining success.
Disclaimer: This INNSpired article was written according to INN editorial standards to educate investors.