It’s commonly stated that there is more gold waiting to be discovered than what has been unearthed so far. That’s probably true. What’s undoubtedly truer is that gold will be microscopic, invisible gold, beyond the reach of the small scale miner.
Today’s commercial operators can profitably recover gold the size of a red blood cell, something like 5 microns in diameter. To give you an idea of scale, a human hair might be 75 microns across.
Drew Barkoff told me last year that the reason it took until the 1980s to discover the tremendous gold deposits in north-central Nevada was that none of it was visible, even in samples containing nearly ounces per ton. The riches of this so called Carlin-type material became evident only through geochemical analyses.
Gold prospecting is now done at the parts per billion level, mineable grade now around 8.5 ppm. But you don’t need a dedicated gold mine to profit from it. Gold and other precious metals can make economic or add to the revenue of a copper mine or even a sand and gravel operation.
ASARCO’s Mission Mine in Sahuarita, Arizona is a large open pit copper mine. They recover precious metals as these tend to follow copper through flotation recovery and eventual smelting. In 2016 the Mission Mine produced 1.3 million ounces of silver.
Teichert Construction is the biggest road building company in California with sand and gravel operations throughout the state. They have, for example, produced aggregate in Sacramento County for decades from an old channel of the American River.
Unlike ASARCO, Teichert is a privately held corporation under no regulation to make figures public. Independent consultants working with Teichert on streamlining recovery sometimes speak off-the-record. They estimate Teichert at Sacramento recovers enough gold to pay for all the aggregate they produce.
The small scale miner is mostly confined to the world of visible gold, say, down to 10X magnification. It remains to be seen how much visible gold is still recoverable within the limited economic power of the small scale miner. But the power of their ingenuity is also immeasurable and we should not underestimate their ability to surprise us in the coming years.
The best way to keep up with the small scale miner and independent prospector is by subscribing to the ICMJ’s Prospecting and Mining Journal. I just call it The Journal:
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