The majority of the gold produced in Goldfield has come from ores that are close enough to the surface to be oxidized by the air. This oxidized ore is normally a soft, shattered, earthy material usually stained yellow to brown by oxides of iron.

The excitement over IOCG deposits began with the discovery of a monster deposit at Olympic Dam in Australia in 1976. The discovery was accidental as the operator was searching for strata-bound copper deposits.

Because the forces of erosion and gravity tend to carry lighter materials like quartz away more easily, the heavy minerals like gold or silver will tend to be concentrated in the general area around the vein outcrop. These concentrations are what make residual placers so attractive.

For approximately 30 years, the mines produced good ore, some so rich it was simply sent straight to bagging, bypassing milling and loaded directly on the rail cars.

Gold, on the other hand, is super rare, and is one of the rarest elements in the earth’s crust. It averages only 0.000004 percent of the earth’s surface. That is four parts in a billion.