Theories on Gold Nugget Formation (Part 4)
(Gold nugget specimen showing elements of visual "crystalline" structure.)
As researchers, geologists, and other earth scientists probe deeper into the mysteries of natural gold nugget formation new theories are being proposed for the origin and growth of nuggets. We've already looked at two of the main theories on gold nugget formation and now I'll present the third.
The third main theory of natural gold nugget formation is crystallization. Crystallization theory proposes the idea that gold nuggets are formed deep underground in very high temperature and intense pressure environments where gold molecules tend to join or "grow" together in elaborate crystalline structures.
As Australian scientist Dr. Rob Hough says, "Previously it was assumed that gold nuggets formed in place where they were found, either precipitated from fluids or grown from microbial action. But all of the gold nuggets we've studied have a crystalline structure and silver content that shows they formed at high temperatures."
Dr. Hough's research studies also suggest that since very high temperatures and pressures typically don't occur at the surface of the earth's crust, gold nuggets (by virtue of this fact) must have originated deep underground. It's believed that these crystallized ended up near the surface as a result of large-scale geological, erosional, and weathering factors over long periods of time.
A Process, Not a "Look"
If you've been around "Bedrock Dreams" for a while now you've heard me mention the overall beauty and monetary value of crystalline gold specimens. Now I'm going to throw you a curve ball. Nuggets formed via the crystallization theory are not necessarily going to display the visible crystalline specimen characteristics so highly prized by museums and collectors.
In other words, a wide range of nugget types in terms of coarseness and size can be formed by the crystallization process. Many of these will look like the common placer gold nuggets you're familiar with already. We're talking about a birthing and growth process here...not necessarily a "look."
Beautiful "Freak of Nature"
During the Cripple Creek, Colorado gold boom of the early 1890s, miners digging deep beneath the earth tunneled into an immense vug (very similar to a geode) large enough for a man to stand upright in. Lining every square inch of this vug were crystals of pure gold, a sight that those present likened to being inside a fantastic treasure chest from an "Arabian Nights" tale. Unfortunately, this stunningly beautiful "freak of nature" was not documented visually and after their initial amazement, the Cripple Creek miners went about the task of removing every bit of crystalline gold from the vug.
(Large crystal vug on a gem mining claim. Just imagine if these crystals were all natural gold.)
What this somewhat sad little tale should suggest to you is that Dr. Hough is probably onto something with the crystallization theory. The Cripple Creek crystalline gold vug was obviously formed at depth under high heat and intense pressure...there's little doubt about that.
More Than One Path?
What do I think? I believe that the three main theories of gold nugget formation all have merit.
I also believe that some nuggets, as the old timers rightly believed, were formed from residual vein or reef gold. With a natural world as wonderfully complex as ours, why can't there be more than one path to gold nugget formation?
Good luck out there.
If you liked this post, you may want to read: "Theories on Gold Nugget Formation (Part 3)"
(c) Jim Rocha (J.R.) 2012
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