FMF - Friends of Minerals Forum, discussion and message board

[Pete Richards]

I have just seen this thread for the first time. The discussion is good, and I don't disagree with any of it. But I am struck by the comment in the second post that the specimens are very similar. Without knowing how similar, it makes me wonder if these fakes are casts of natural crystals. The form is that of well crystallized gold. If the figure is not of a very tiny crystal fragment , I think it has too coarse crystals to result from crystallization from an amalgam or other quick synthetic processes.

If this is a natural specimen, it should show a single crystal x-ray pattern from small pieces of a specimen. If it is a cast, it will be polycrystalline, and will look like a powder pattern under x-ray.

My good friend John Rakovan did a brilliant analysis of this issue and published it in a recent Rocks & Minerals article (January/February 2009) - it turns out that the idea of the single crystal vs poly-crystal test is a good one, but can be compromised if the surface of a natural crystal has taken a beating, as would happen if it tumbled down a river or stream. The details are too complex to repeat here, but that article might be a great resource for dealing with this question.

[Paul S]

This is my first post on this forum and I'd like to thank you all for the information you have given already. I have done some research myself on this topic, so let me tell you all my story.

I have recently finished my access database system, so now I'm adding my minerals to it. I have in my possession one of those lovely gold crystals from Icabaru and when I was searching the net for some extra information (I wanted to know how common gold-palladium alloys were), I stumbled upon this thread. There are two problems with these crystals, is there palladium present and are they synthetic? According to some of you they might be synthetic; at least there are only traces of palladium present.

I can live with having bought a crystal with less palladium in it then promised. But because I collect minerals and synthetic crystals (I partially make them myself), I want to know to what database I have to add this crystal to.

As I am a little familiar with synthetic crystals, I did some research on the surface of the crystal. I have a 20x-40x magnification stereo microscope and an old 100x magnification school microscope (I made some top lighting on it for mineral viewing). At 100x magnification the crystal seems to have only a few flat surfaces and those are really tiny compared to the faces of the crystal. At some of those surfaces it’s possible to see scratches, but they are not traces of treatment with tools. At some places there is also a very thin plated structure.

My findings are that it is unlikely that they were electrochemically grown. There are almost no round parts to it, there are no ‘bubbles’ and there is no clear direction of growth. Normally those kinds of crystals have a lot of cavities in them, but they are not present in my specimen. Gas-phase growth is out of the question because the faces aren’t smooth enough and the edges aren’t sharp enough. Crystallization out of the melt is possible, but that would probably yield much sharper crystals (I have no experience with making gold crystals from melt though).

The idea of casting such crystals is possible, but I have not found crystals that look the same on the internet (as suggested above) and there are no signs on the crystals of being made by a casting process (mold lines).

So my question now is: can these crystals have formed naturally?

Kind regards,

Paul

[Paul S]

I continue on this subject, because I contacted a gold prospector about my Icabaru gold specimen. I told him the story about it, with our thoughts and analysis of the gold crystals. He thinks that it is highly unlikely that someone would make these crystals on purpose especially if sold for such relatively low prices. He also thinks its very difficult to make large crystals outside of a very controlled environment using the amalgamation process. He has made microscopically small crystals using such a method, but his photo's show very smooth crystal faces.

So I think we can conclude that these crystals were not produced by amalgamation and that they do not contain any palladium.

But my question is still however if there are any other examples out there of crystals that look just like these? Maybe those crystals can help solve this mystery.

[jacobb]

[Paul S]

Sadly I have not found any new information on these crystals. They do not compare well to synthetic, nor natural crystals, but I'm not an expert of course.

If anyone has more information, please share, for I have the feeling that this mistery is not yet solved.

[alfredo]

When the Icabaru gold crystal floaters first appeared on the market years ago, many people (including myself) thought they were cast in molds, ie. artificial. But now that the locality has been visited by several reputable observers, who have published articles on it in Lapis and Mineral Up and elsewhere, and after John Rakovan's brilliant testing, there is no longer any doubt whatsoever that these are natural crystals.

Whether or not they should be called "palladium-rich" is another issue. Since no one has ever defined "rich", it would be better to use "palladium-bearing".

[Paul S]

Thanks for the update Alfredo, I should have checked those sources myself, but you have been very helpfull.

I can finally put this mistery behind me (as I'm not really interested in the possible presence of certain minor impurities like palladium).

[alfredo]

Paul, I should have added that, in native gold, the presence of palladium and absence of significant silver may be an indication of microbial mobilization and deposition at ambient temperatures... Very interesting gold!

[TomBryant]

Many years ago I first encountered gold "crystals" recovered from liquid amalgams. The standard common factors were - highly liquid mercury - very fine placer type gold - fairly long residency time (many of them coming from mercury used for amalgamation and forgotten on a shelf for up to a year or more) - a mercury press (not always but it preserved the crystals) and acid to finish cleaning the gold.
Operators encountering this often commented on first seeing the crystals as needles, hairs or blocky crystals coated in mercury and needing to be cleaned up with acid beore they realized they were dealing with gold needles etc.. Microscopic examination showed all of the above and also some hollow tubular needles. None of them were over a 1.5 cm in length. I first encountered them from examination of gold recovered from mercury used in a commercial amalgamation machine and I was pretty confident that no such shapes had gone into it.
Further research indicated that we were dealing with pseudomorphs from the gold amalgams. Microprobe work showed platinum in some of the samples from Alberta which linked to the natural platinum found with the placer gold. Silver was absent from the "crystals" because the acid treatment had removed it along with base metals leaving a very high purity gold.
Every prospector that I have gotten similar samples from since that time was convinced they had gathered these crystals from their placer concentrates yet examination of the original cons showed no such shapes.
While I cannot comment on the crystals being discussed here it is possible that a similar occurrence is happening in these crystals. The prospectors may not have been aware at first that they were making the crystal shapes by virtue of their processing but if there is a buck to be had you can be sure somebody would figure it out .

[Leza Junnila]

A couple years ago my son and I went looking for a so-called gold crystal location left to me by a friend after his demise. It's west of the Leviathan Mine in the Sierras. We hiked all day up to a area that we scanned using metal detectors,and because of the late hour we dug down into a dry creek bed and collected material above the bedrock, planning to pan it later. The sample bounced around in the back of the vehicle a few days before I panned it, and found nothing, however my son needed the backpack for something and dumped the trace dirt out on his garage floor. The next morning while he was doing laundry he let out a yelp when his bare foot stepped on something sharp. He called me to come over and check out this gold colored crystal that was sharp and pointy,it looks like your specimen and it is Au. Pt and Palladium are also found here in trace amounts.