The Carlin Trend in the state of Nevada has a notable gold mining and exploration history, a prosperous present and a rich future.
Few gold districts in the world stir miners’ imaginations like the Carlin Trend in Nevada.
As the largest gold-producing region in the US, the trend hosts some of the best geology for gold mining and processing, along with a safe and mining-friendly jurisdiction in the state of Nevada. For investors interested in gold exploration in the US, the Carlin Trend should be a familiar term that evokes the potential for rich gold mines and returns for those who invest in the right companies.
“Gold in basically every rock”
According to Mercenary Geologist Mickey Fulp, the geology of the Carlin Trend makes for perfect gold-mining territory. “It’s got the right kind of host rocks, it’s got a lot of structure, it’s got anticlines where the gold is concentrated, it’s got a great gold budget,” says Fulp. “There’s gold in basically every rock known there over the proper ages. It’s one of those areas.”
Located in Northeastern Nevada, the Carlin Trend consists of a belt of sedimentary rock-hosted gold deposits that are about 5 miles wide and 40 miles long. Geologists believe the trend was formed when a terrane — a piece of the Earth’s crust — collided with the North American Plate about 350 million years ago. The pressure and temperature associated with the collision produced hot springs along the suture zone, bringing dissolved minerals towards the surface.
These minerals, primarily silver and gold, precipitated along the fissures and faults in the rock. Several episodes of subsurface magmatism occurred before the collision, adding to the mineral deposition.
Geologist Brent Cook, co-publisher of the Exploration Insights newsletter, describes what happened next: about 40 million years ago the western US began pulling apart, stretching the Earth’s surface and forming volcanoes. “As Nevada was pulled and wrenched apart, deep cracks formed in the Earth’s surface. These cracks did two things; they drew the gold-bearing fluids toward them, and provided the conduits to move the fluids toward the surface,” Cook writes about Nevada’s geology.
“Along the way to the surface, chemical, temperature, and pressure changes in the fluid and adjacent favourable rocks resulted in the precipitation of massive amounts of gold. The more important of these cracks are now delineated by the major gold trends of Nevada: Carlin, Cortez, and, to a lesser degree, the Walker Lane,” he explains.
Discoverers Livermore and Coope
Exploration at what is today known as the Carlin Trend began in 1961, when Newmont Mining (NYSE:NEM) geologists John Livermore and Alan Coope arrived in Carlin, Nevada to visit the Blue Star mine and the Gold Quarry prospect.
The story goes that Livermore became interested after hearing a talk by a US Geological Survey geologist about an area in Northern Eureka County that might host gold deposits. Except the deposits were “disseminated,” meaning microscopic and therefore invisible to the human eye.
Livermore and Coope started exploring just south of Blue Star, theorizing that gold would be found below a fault known as the Roberts Mountains Thrust. Drilling started in 1962, and on the third hole they hit a gold intercept of 100 feet averaging 1.03 ounces per ton. The prospect would become the Carlin mine, the first gold mine in the Carlin Trend. It opened in 1964 and by 1968 had produced a million ounces.
The 1980s were a prolific decade for discoveries in the area between Newmont’s Rain and Emigrant deposits in the south end, and Barrick Gold’s (TSX:ABX,NYSE:ABX) Dee and Storm deposits in the north end of the Carlin Trend, as it was named in 1987. The decade kicked off with new finds at Gold Quarry, Rain and Genesis, followed by 16 new deposits or extensions of existing mines.
In the mid-1990s, some of the open-pit gold mines in the Carlin Trend began moving underground, with miners targeting higher-grade sulfide refractory ores vs. the oxide gold-bearing ores found near surface. Deeper deposits have been discovered at Rossi, Dee, Meikle, Gold Bug, Rodeo, Deep Post, Deep Star, Turf, Four Corners, West Leeville, Hardie Footwall, Deep Carlin, Mike, Rain, Tess and Rain Extension.
107 million ounces of reserves
Since its discovery, over 84 million ounces of gold have been pulled from the Carlin Trend. It hosts the second-largest known gold resources in the world, after the Witwatersrand Basin in South Africa, and accounts for over a third of US gold output. While numbers vary depending on which mines are included, the Carlin Trend may contain up to 107 million ounces of proven and probable gold reserves.
The Carlin Trend isn’t only significant for the amount of gold it has produced and hosts — but also for the type of deposit and the method of mining it. “Carlin-type” deposits have become common vernacular among gold explorers. The microscopic gold scattered throughout these deposits is usually very low grade. But what they lack in grade, they make up for in volume. After the value of these deposits became known in the 1980s, geologists around the world starting hunting down Carlin-type deposits.
To extract gold from such low-grade deposits, miners crush tons of rock, which is piled into heaps and irrigated with cyanide. The cyanide percolates through the heap, extracting the gold. Cyanide heap leaching is a technique that was pioneered at the Carlin Trend.
Major producers Newmont and Barrick
Gold production in the Carlin Trend has been and continues to be dominated by two major gold companies: Newmont and Barrick.
While Newmont is credited for discovering the Carlin Trend and operating its first mine, the company has over the years continued to increase its gold output in the trend. Open-pit mines include the Emigrant pit and Gold Quarry pit in the south end, and the Silverstar pit in the north end. Underground operations include Leeville, Chukar, Pete Bajo and Exodus. In all, Newmont’s Carlin operations produced 944,000 ounces in 2016, while reserves as of the end of last year totaled 15 million ounces.
Barrick’s biggest producer in the Carlin Trend is Goldstrike. The company acquired the mine in 1987 from PanCana Minerals and Western State Minerals, which had a 50/50 joint venture on it.
One of the top gold mines in the world, Goldstrike now comprises the Betze-Post open-pit mine, along with the Meikle and Rodeo underground mines. Operations at Goldstrike produced 1.1 million ounces in 2016, and as of December 31, 2016 it had proven and probable gold reserves of 8.1 million ounces.
In 2016, Barrick sold its Bald Mountain mine in the Carlin Trend to Kinross Gold (TSX:K,NYSE:KGC) for $610 million, along with half of its Round Mountain mine, also in Nevada. Bald Mountain produced 130,144 gold equivalent ounces in 2016 and has proven and probable reserves of 2.1 million ounces.
Carlin-type deposits in Nevada’s other notable gold trends
Major companies and juniors are setting their eyes on Nevada’s other promising gold trends — including Independence, Walker Lane and Battle Mountain-Eureka, also known as the Cortez Trend. Barrick has made some significant discoveries of Carlin-type deposits on the Cortez Trend. Its Pipeline and Cortez Hills mines produced over 1 million ounces in 2016 and have produced over 21 million ounces since 1994. The Cortez Camp has provided continued successful exploration results for Barrick, ensuring that it will be a significant gold-producing trend for many years to come.
“While the Carlin Trend has historically been Nevada’s most important trend, it’s an exclusive zip code these days. Most of the best properties are already controlled by Newmont, Barrick and now Kinross,” says Trey Wasser, president and CEO of Ely Gold & Minerals (TSXV:ELY,OTCMKTS:ELYGF). “They dominate because of the expense involved in exploring the deeper targets remaining on the trend.”
Ely Gold currently has a property portfolio of more than 20 exploration projects throughout Nevada available for sale. Other trends like the Walker Lane and Cortez offer less expensive exploration properties with the added upside of having Carlin-type deposits and high-grade epithermal vein targets.
“We have originated over 40 option properties and royalty interests in Nevada in the last two years. We rarely come across viable targets on the Carlin Trend,” notes Wasser. “Most of the companies looking to explore in Nevada are focused in the Walker Lane and Cortez Trend, where exploration is more affordable and where good projects are still available.”
While the Carlin Trend is one of the most heavily explored gold belts in the world, gold continues to be found. Recent developments include the discovery of the Arturo deposit, a joint venture between Barrick and Premier Gold Mines (TSX:PG). First gold was poured there in 2016, with ore processed at Barrick’s Goldstrike Mill 3 miles to the south. There have also been expansions of the Leeville, Turf, Genesis and Gold Quarry deposits, and development at Newmont’s Exodus, Pete Bajo and Emigrant properties.
According to Brent Cook, in a mature exploration belt like the Carlin Trend, “most new exploration targets are blind from the surface and usually quite deep.” That means that exploration necessitates techniques that are quite costly, including diamond drilling. Cook says one way for a junior to overcome this hurdle is to partner with a major gold company that can assist with the financing.
“The advantage of bringing a major mining company into the mix is the depth of experience they provide and the possibility of a buyout should the exploration prove successful. The disadvantage, of course, is shareholder dilution as the data collection process (drilling) advances,” Cook writes.
Another strategy is for the exploration company to accept funding from more cashed-up partners that will allow it to drill test new targets. The advantage of this tactic, says Cooke, is that it minimizes dilution; however, should a discovery be made, shareholders will receive a smaller share of the eventual prize.
“Any speculator in Nevada exploration (or anywhere for that matter) needs to weigh the risk to reward offered by a company’s financing strategy,” he concludes.
Finding that big discovery hole that will interest majors is of course the primary goal of juniors exploring in Nevada. Given its long and exciting history, as well as its its still-ample gold reserves, the state is likely to continue adding to mining lore.
This article was written according to INN editorial standards to educate investors.