FMF - Friends of Minerals Forum, discussion and message board

[Cesar M. Salvan]

Recently I analysed a sample of putative "palladium-rich" gold from Icabarú, Venezuela. The sample looks like the specimens in the photos you can find in Mindat under the location Icabarú.

The analysis (EDS) show that sample is composed by >99% gold. The palladium present (if any) are under detection level. Trace analysis show that the main trace is Hg.
I tried unsucessfully to find any published information or analysis. I suspect we have a case of fake or at least incorrect classification.

any suggestions or information??

thanks!

[Cesar M. Salvan]

Well, again I did not found any information about the putative palladian gold from Icabarú.

The precise composition of the sample is 99.95% gold, with traces of Hg, Pd and Ag.

This composition, the lack of information about the deposit, the scarcity and shape of samples (and the stunning similarity of samples of the same lot) together with the low price (around current gold cotization), strongly suggest a fake, so be aware.

I know two mineral dealers who distribute these samples. They maintain that this gold is natural and palladian. At least the last statement is false.

Greets

[Jordi Fabre]

César,

You tried to inform these dealers about the real nature of the Gold that they sell? I don't want to look too "naïf" but maybe they just ignore this fact...

Jordi

[Cesar M. Salvan]

Yes indeed. I think the dealer didn´t act in bad faith but I feel a lack of rigorousness:
The dealer told me that he bought the material in Caracas and a sample was analysed by EDS. He stated that the peak of Pd was found in the sample (did not provide quant information). After that, he sold all the material as (Pd-Au). About the origin, supossedly is a gold mine in Icabarú. But this supossition is based on the word of the original supplier.

[John S. White]

I am not an expert on native elements, including gold, so I forwarded this discussion to my good friend Dr. Robert Cook, who is perhaps more knowledgeable about gold than just about anyone else. Here is his reply:

John, here is a comment on the palladium-rich gold. First, "rich", are you kidding? If we
found crystalline gold attributed to a California or Colorado gold mine
that was 99.95% gold, regardless of whatever else constituted the other
0.05% we would be immediately suspicious. It is simply too pure to be
natural if crystalline. Do we call gold with 1% silver gold-silver
allow, silver-rich gold, argentian gold, etc? Of course not. Likely these
specimens are fakes. Bob Cook

[lluis]

Hi Cesar/List

I got also my share of Palladium rich Gold.

I informed the seller, a good faithed one, and I will try to find more about this.
I can also send you my sample for analysis.

Mine was stated as
-99,4% gold
-0,4% palladium
-0,2% nickel

Bought in september 2007. And was not that unexpensive...... :-( (not bullion gold, indeed, but what would be reasonable for a natural gold at price of collector's gold)

With best wishes

Lluís

[alfredo]

Perhaps electrolytically grown crystals?

[lluis]

Good afternoon, Alfredo/List

I do not rely in a electrolitically grown crystals, but the fact that the only impurity found is mercury, makes me wonder if those where grown decomposing a gold amalgam.
To recover the gold with mercury is still used in some places artesanally in Brazil (why not in Venezuela?), so, if anyone found by accident a crystallized one, then it could motive to make more...
Like the faked silver wires from Imiter and so....(although there, some are legit ones)

I will try to find out how a gold crystal could be made.

Really curious (and placing my piece in the black cabinet; unfortunately, it is growing too quickly :-( )

With best wishes

Lluís

[alfredo]

Lluis, Your own specimen doesn't list mercury, just rather abnormally pure gold with a tiny bit of Pd and NI. I was wondering whether that one is electrolytically grown...

[lluis]

Hi, Alfredo

Yes, you are right

But I placed what I was told, without the sheet of paper with the plot of the XRF (I got those only from Jordi :-) ).
I beleived in my dealer (a good faithed one, and reliable).
For circumstances he had not also the analysis, just the word from people who did the analysis.

But occurs that my gold is like the one of Mr. Salván, and he showed us the analysis.
Then, I rely on the paper, and as i said, if he wants/could I will send him my specimen for an analysis.

For electrolysis: when used for that, they tend to produce cawliflower like growings, not such crystals.
I would think in a Kroll process (or a Kroll/Like process), or such methods that passes from a vapour method to produce a pure cristal in a colder place...

Just surfing the net and my books.....

With best wishes

Lluís

[John S. White]

Irrespective of how these may have been grown, and they are almost certainly not natural, please stop calling them palladium-rich gold. 0.4% is not "rich" by anyone's standards. Palladium-bearing might be a better term to use.

[Jordi Fabre]

I copy here a very interesting text from Pete Modreski also located on an other thread: https://www.mineral-forum.com/message-board/viewtopic.php?p=2633#2633

About supposed palladium-bearing gold, some who are on this list and are also MSA members, may have read the posts on the MSA's listserv by Jacques Jedwab (Brussels), who has web pages dealing with "Unconventional platinum-group minerals and mineraloids". These are a variety of poorly or non-crystalline oxide and other compounds associated with gold or platinum-bearing grains and nuggets, and which he proposes to call "Antonil compounds",

"...in recognition of Padre Antonil, who was the first to describe in print the black auriferous mineral grains found around 1695-1700 in Minas Gerais, Brazil, and known since then as “ouro preto” (Pt was to be discovered 50 years later, and Pd 100 years). "

His main web pages are at,
https://www.ulb.ac.be/sciences/upgm/mguide/
and include a comprehensive list of the reported occurrences of such minerals and mineraloids. His article about this that was published in Canadian Mineralogist in 1998,
https://canmin.geoscienceworld.org/cgi/content/abstract/36/3/887
(I think you will not be able to access the text of this, without a subscription) contains a good and interesting historical review of the discovery and puzzlement over, these various minerals.

I thought some of this might be of interest to some on Jordi's forum.

Pete Modreski

[Pete Modreski]

Thank you for reposting this under this Forum theme, Jordi, I had thought that it might be well to do this.

As I noted, most will not be able to access the text of the historical article, and although the abstract is supposed to appear on the url given, I think it does not; so, here is the abstract of that article by Jedwab and Cassadanne. This all is an interesting example of how some mineral materials found in the natural world, by reason of their poor crystallinity, variable and irregular composition, and small grain size, just do not well fit into our conventional definitions of "minerals".

The Canadian Mineralogist, vol.36, pp. 887-893 (1998)
HISTORICAL OBSERVATIONS ON OXYGEN-BEARING COMPOUNDS OF PLATINUM
AND PALLADIUM, MINAS GERAIS, BRAZIL
JACQUES JEDWAB, Laboratoire de Géochimie et de Minéralogie, CP 160/02, Université Libre de Bruxelles, 50, Avenue F. Roosevelt, B-1050 Bruxelles, Belgique
JACQUES CASSEDANNE, Rua do Russel, 680/41, 22.210 Rio de Janeiro, Brasil
Abstract
Dark brown to black compounds associated with native gold were discovered three hundred years ago in Minas Gerais, Brazil, and have been known since then as ouro preto (black gold). These compounds were correctly determined as oxygen-bearing compounds of platinum - palladium - iron as early as 1833 and 1837, but the oversight of the presence of major iron in their composition led to an erroneous definition of palladinite and to the much-delayed recognition of a group of platinum-group element oxides.

[lluis]

Good evening, List

I just wrote because after reading the last Message of Pete Modresky that addres to this thread I reread it and when I found again the message of Alfredo, suggesting that it could be electrolitically grown.

Well, Alfredo has a very good eye: in a mineral fair a reliable source said me that those golds were sold as electrolitically grown by a dealer in Munich, many years ago.
Unfortunately I got no more data.

I am waiting for some more samples of such gold, but if they do not arrive, I will send also my sample to analyze. If mine shows also no Pd and such purity, well, food for though...

With best wishes

Lluís

[AlMelBonville]

My prospecting friends and I are finding grains that a re half gold and half tin-white in alluvials we are working. The material is very dense, somewhat brittle, especially the purely tin-white grains (similar to osmiridium), does not tarnish, does not give off volatiles when heated in open or closed tube and fuses with difficulty in the blowpipe flame.
It is associated with purplish tabular magnetic grains (these very occasionally contain a tin-white grain) and is in the drainage syste of what we believe to be an eroded volcano which now shows up as a magnetic anomaly and some scattered patches mapped as basaltc (will visit these and make thin sections when we have time). This area is adjacent to a well established eroded volcano whose remnant feeder core (hard to access) yields abundant grains of chromite (I have a few hundred grams collected years ago whch I will examine for the presence of tin-white high density grains tonight)
What do you think? I will scan my microscopic photographs and e-mail them to you.
Alan Melbourne

[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.