Nevada: Where Low-grade Gold Deposits Can Still Be World Class
Nevada is home to the famous Carlin trend, one of the top three gold fields in the world. The Carlin and other mines along the trend pioneered the method of open-pit mining with cyanide heap leach recovery that today is used at large low-grade gold mines worldwide. The state is also home to other prolific gold trends, including the Cortez.
By Leia Michele Toovey- Exclusive to Gold Investing News The romance of golden riches has attracted would be gold miners for hundreds of years; unfortunately, very few of the early prospectors were successful in their hunt. When the gold rush hit California most who had good fortune in finding gold out west had previous victories back east. Did pure luck play a part? Perhaps, but experience was paramount. These early prospectors were the first to use science to increase the probability of discovering gold. Over the years, gold exploration has evolved. The early-day prospectors searched for gold with nothing more than a pick axe and perhaps a gold pan. Today, explorers hone in on a gold resource by using a variety of technically advanced geophysical surveys. Modern day explorers, while still concerned with discovering gold, are even more interested in the quality of a potential deposit. In assessing quality, an exploration company will estimate the concentration (grade) of the gold, the total amount of gold, the cost of extracting the gold, and the cost of refining the gold. The balance of all these variables determines the value of a mine. The estimated value of a property indicates whether or not it can be developed into a viable mining operation, a transition that many exploration properties never make. When determining the viability of transitioning an exploration property to a profitable mine, the total picture must be assessed. According to the World Gold Council, larger and better quality underground mines contain around 8 to 10g/t of gold, while marginal underground mines have averages of around 4 to 6g/t. Open pit mines usually have lower grades from 1g/t to 4g/t, but can be highly valuable despite the lower average grade. In all cases, the tonnage contained in the deposit is the last and most important piece of the puzzle.