February 8, 2021

How Do Geologists find gold? - Epithermal Deposits

Gold deposits are getting harder to find.  Since the 1980s, the rate of discovery has decreased dramatically. This means it is less likely geologists looking for new deposits will be able to go out and find outcropping systems.

At Orogen Royalties, geologists use the understanding of mineral systems to predict where gold might occur below the surface if there aren’t any gold bearing outcrops. An example of this would be low sulfidation epithermal systems.  These systems are ancient hot springs or geothermal systems in which hot water ascends through faults and fractures shallow in Earth’s crust.  Where the water begins to boil, gold and silver drop out to form veins and breccias.  Other elements, such as mercury, remain mobile as the water turns to acidic steam.  This mercury-rich steam travels all the way to the surface leaving leached rocks with mercury minerals, such as cinnabar, behind. Geologists looking for gold systems can look for mercury-rich minerals at surface and use them as a proxy for a more gold and silver rich system at depth. These geologic observations can be paired with emerging technologies such as spectral remote sensing, which measures visual and infrared light reflected from rocks on Earth’s surface to map zoning and clay mineralogy that can help us determine where we are in a mineral system.

The team at Orogen used techniques discussed in this video to identify the Silicon property, which is now a developing royalty asset.  Other projects in our portfolio including Elba, Baby Doe, and Kalium Canyon were also identified using this methodology.

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