Andy Wallace, Columbus Gold (U.S.) Corporation, c/o Cordex Exploration Co., 573 E. Second Street, Reno, NV, 89502
The seminal event leading to the late twentieth century boom in Nevada gold exploration was the discovery of the original Carlin deposit in 1961 and 1962, by Livermore and Coope of Newmont. Other Carlin-type deposits, such as Getchell and Standard, had been mined prior to that discovery, but the original Carlin was most impressive due to its size, grade, and metallurgy, and it yielded low-cost gold from the start. A small flurry of unsuccessful exploration followed the Carlin discovery, much of it misdirected toward gold in the Roberts Mountains Thrust Fault proper. Eventually the Cortez deposit was discovered, and placed in production in 1969. Exploration geologists began to recognize that gold in Carlin deposits did not report to the gold pan (and thus was passed over by early prospectors), and that the deposits could be stratiform, good grade, and presented large drill targets. Low gold prices through most of the 1970’s limited gold exploration, but a few deposits of the Carlin-type were discovered nevertheless at Pinson/Preble, Alligator Ridge, Sterling, and Jerritt Canyon.
The major increase in the price of gold in the late 1970’s, combined with the good potential to find minable gold deposits, led to one of the biggest exploration booms in history-in Nevada in the 1980’s. The culmination was the opening of twelve new gold mines in Nevada in the single year of 1987. Exploration and mining technology improved with new developments in recovery methods, drilling techniques, geochemistry, and in geophysics. Exploration on the covered pediments began in earnest, leading to discoveries at Sleeper, Marigold, Rabbit Creek, Stonehouse/Lone Tree, and Pipeline. Deep Carlin-type deposits, minable underground, became viable targets.
Exploration for new deposits in Nevada slowed during the 1990’s due to a stagnant gold price, inflation, and the increasing emphasis and spending on “head-frame” exploration by the producers. The gold price had collapsed by the end of the 1990’s, and exploration dwindled to nothing, except in the immediate vicinity of known deposits.
The improving gold price after 2002 has given new life to Nevada exploration, but it has not nearly reached the levels of the 1980’s. Exploration by the few producers left (post-merger) is still largely inside the mine fences. Currently no mid-sized producers or explorers are working in Nevada. New exploration is mostly left to the junior companies, and the more viable ones are having trouble staying funded long enough to succeed. A dampening factor for junior explorers is the narrow focus of the investment community on “trends” and their stubborn insistence that only multi-million ounce discoveries have any importance. The sudden, and extreme, increase in the real cost of drilling has also had a negative effect on the number of exploratory holes drilled.
In the near term, the head frame exploration programs of the producers will likely draw most of the exploration dollars, and remain successful (e.g. the massive Cortez Hills, and Deep Cortez Hills deposits). Although there is currently little exploration for new deposits, potentially significant Carlin-type mineralization has been drilled by AuEx, at Long Canyon in the Pequop Mountains, and by Cordex at Bolo in the Hot Creek Range. In the future, it seems inevitable that exploration in Nevada will be more difficult and costly as it becomes focused on deeper deposits.