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How Crystalline Gold Shapes Form


GeoJack

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GeoJack, that's a good question I would be interested to hear about how certain types of crystalline gold develop or are made. I am sure there are many theories....and some probably do take the shape of the host rock, but some as far as I understand are grown. I once researched trigon gold..and they mentioned gold molecules formed the shape, little etchings of pyramid shape. There is no obvious " Mold" that it took form from in the host quartz or seam it had developed in. Hopefully someone more knowledgeable than me can answer this question. Chris Ralph?

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Gold crystallizes in the isometric system. The conditions under which the crystals form (heat, pressure, solution strength, time) and traces of other elements each influence which of the isometric forms develop.

Scroll down this page and try out the different potential 3D crystal forms by clicking on the little icons to the right of the 3D model.

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Clay, nice link, plenty of info there and nice graphics. I was more interested in the conditions / association with other elements that directly influence the shape / form. I am familiar with the California Mother Lode arborescent and Rye Patch Nevada gold and wondered what elements are different in these areas to create the different forms. I understand the form is dictated by the crystalline structure of the atoms themselves, but what drives the structure?

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From what I've read gold always forms in a crystalline structure when originally coming out of solution while being deposited in veins, but a lot of gold that has already formed gets reintroduced back into solution by being exposed to extremely hot thermo fluids around 4000 degrees during tectonic events and reforms after the solution cools down into the form we are used to finding on the surface, although what we find has also most often been exposed to water action at some point, almost all gold found at depth in veins has a crystalline structure, especially "pocket gold".

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J, It seems that the concentration of gold in the supercritical/ hydrothermal waters, and chemical makeup, influences the crystals growth.

But it gets deap thinking why one crystal, in the same pocket decided to be a cube, and one a octahedron or dodecahedron...

That really is a question for none other than the Grand Architect Himself.

Chris Ralph has a good wite up on crystal growth, found in his book fists full of gold. Page 170

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Thanks Wes, I'll dig that book out and look at it again. I'm really interested in getting some AU from the Rye Patch area, very beautiful and would like to have some for my specimen collection.

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  • 2 weeks later...

Yeah, some of the borax is still on the button. I boiled it in sulfuric acid but didn't have enough to finish the job. What I was referring to was the texture of the surface of the gold. All the lines. Will remelt.

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Being a Science kind of a guy, my Hypothesis is that depending on what the Gold is Doped with. It may take one crystal Structure being doped with silver, copper or Boron. More pure gold seems to take on the Diamond shape.

Gold here in New Mexico seem to have silver, copper and some Boron in the mix. I've found wire gold that had the continuous Diamond structures.

Edited by homefire
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Rim, new graphite cup, just purchased it from the Gold Summit. Same for the borax mix, fresh bag. When I busted it out of the borax, it had that design on it.

Homefire, mother lode gold tested 92% AU, 6% Silver. Was smallest pieces from acid wash of crystalline gold, no placer. We've got the "arborescence" gold here.

Nobody else have buttons with this on them or do they normally come out smooth?

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Well El D put up a picture of a button up top and his is smooth...He can probably help you. I'm learning too.

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After seeing the last post of "Amazing Specimen" I wonder what causes the crystalline gold to form in the shapes it does. I thought it was the cracks and fissures of the host rock but I am sure I am wrong. Would be a great article for the ICMJ.

You're not wrong, by injecting into cracks is how many minerals are deposited.

Everything has a temp at which it melts, and temps at which it solidifies.

Concider water, it has a very low melting point and a very low freezing point.

Gold too has it's melting point and it's "feezing" point.

When and how it solidifies or melts depends on the conditions.

Injection deposition seems to be most common.

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