These systems were first discovered near Carlin, Nevada in the mid 1960's using geochemical techniques. The gold is locked up in sulfides and is therefore not visible, thus they were never found by the older prospectors. To recover this gold, you need to roast the material. Roasting is very expensive and energy intensive, but Northern Nevada has a network of processing facilities anxious to purchase this material. If the ore is oxidized then the gold can be simply recovered by heap leaching which is very inexpensive.
Although the recognition of this ore type is growing globally, nowhere in the world approaches the size of the districts in Nevada. The Carlin, Getchell and Cortez Districts have multiple mines any one of which might be a contender for a world class deposit.
Carlin type gold production currently dwarfs production from other deposit types in Nevada. Please note the history of gold production in the USA is in the graph show below (Figure 2). Nevada was a minor contributor until the 1980's. Early production from 1849 is attributed to the California Gold Rush with production from orogenic type gold. From the 1890's until 1940 and the start of World War II, major production was from the Homestake Mine in South Dakota with continued production from mainly orogenic systems in California and the Carolinas in the eastern U.S.
The paradigm shift and the ability to explore for a new type of deposit with large endowment has created tremendous wealth for Nevada and the USA.
The most significant discovery outside of the established districts was the new Pequop Gold District in northeast Nevada. No exploration efforts were focused in this area because geologic models concluded these were the wrong rock type. Australian geologists came to Nevada to look for areas ignored by main stream exploration efforts, and using stream sediment chemistry discovered the Pequop District. In the last down turn, the company responsible for the Pequop discovery was divested due to the lack of material drill results. AuEx Ventures bought the company, reinterpreted the geology and generated the first round of material drilling at Long Canyon in 2005. AuEx was sold with enormous premiums to share holders in 2010; the spinout with the same staff and board became Renaissance Gold. Renaissance Gold has several projects of the Carlin type in eastern Nevada. Most importantly, the Wood Hills South Project, a possible extension of the Pequop Trend, is in an earn-in agreement with Newmont Mining, the owner of Long Canyon which is being developed for an anticipated 2017 production startup.