Theories on Gold Nugget Formation (Part 1)
(The old timers knew a lot...but science and research may have proven them wrong.)
Back in the day, the old timers had a single, simple theory about the formation of gold nuggets found in wet or dry placers. This is the same theory that you and I were brought up on as we cut our baby teeth as placer mining novices.
Research Tells the Tale
What was that theory? Simply that gold nuggets resulted from the fracturing and weathering out of gold-bearing vein material that had formed deep within the bowels of the earth at some point in the ancient past.
Later on these veins or gold-bearing "sources" were exposed as outcrops and, over time, further reduced in size and coarseness by hydraulic action or erosional factors (in the case of dry or desert placers). The resulting gold nuggets ranged from large, to medium, to small depending on how far they had traveled or how much they'd been "bunged up" along the way.
Gold Prospecting Books
However, recent research performed in nugget-bearing Australian goldfields has shown that a sampling of nuggets recovered in various locales had little, if any, structural or purity connection to nearby gold-bearing vein outcrops or "reefs." In other words, the nuggets were formed from gold pretty much unlike that found in nearby veins.
Three New Theories?
Over the past decade or so, the research of a new generation of mining engineers, chemists, geologists, and other earth science types has turned the old formation theory on its head to a great degree. In fact, some experts now believe that many gold nuggets are formed some distance away from pre-existing veins and at or very near the earth's surface...a theory that would've left many old timers shaking their heads in disbelief.
(The origin of these beauties may not follow standard theory.)As far as I can determine, there are three relatively new theories being bandied about these days when it comes to gold nugget formation. I've decide to give them my own names or tags: Microbial Action, Precipitation, and Crystallization.
I'll discuss these three theories at length in my next post. Until then, take care out there and best of luck.
If you liked this post, you may want to read: "The Perennial Question: 'Where Can I Find Gold?'"
(c) Jim Rocha (J.R.) 2012
Questions? E-mail me at firstname.lastname@example.org