Mindat Logo
bannerbannerbannerbanner
Welcome!

Have the reverse-skeletal Madan galenas been faked?

Posted by Patrick Haynes (2)  
avatar Re: Have the reverse-skeletal Madan galenas been faked?
October 27, 2009 12:22AM
    
I think a way to settle this would be so take one of these specimens and give it a good, thorough wash in a clean ultrasonic cleaner.

Then, pour out the water or whatnot and see what residue is left.

Take the residue and examine it under a microscope and see if we get any micro-abrasive material

I sincerely doubt that they could do this with a blaster and not leave at least a few particles of micro-abrasive.

If none was found at all, it would be interesting.

But the evidence, even if the specimen was previously cleaned, should still come out if cleaned and the residue examined.

Just an idea.
avatar Re: Have the reverse-skeletal Madan galenas been faked?
October 27, 2009 10:14AM
It's an interesting idea Bri, but assumes no-one else has cleaned it in an ultrasonic before. It also doesn't rule out the possibility that they were genuine natural skeletal crystals encased in a hard clay where an abrasive tool was used to clean it out.

The only way I think its to examine the surfaces at high magnification looking for signs of abrasive damage as opposed to either chemical etching or natural growth patterns. They should all be fairly easy to differentiate.

Jolyon
avatar Re: Have the reverse-skeletal Madan galenas been faked?
October 27, 2009 11:09AM
Here are a couple of articles regarding natural skeletal galena from Bulgaria. Note that none of the forms in these articles in any way resemble the hollowed cubes we see in the photos before.

[www.geology.bas.bg]

[www.geology.bas.bg]

As I said in my very first message in this thread, we need to be careful to distinguish between what are clearly genuine galena forms (such as those shown in the PDF) and those hollowed-out cubes we're discussing.

Jolyon
Re: Have the reverse-skeletal Madan galenas been faked?
October 27, 2009 04:50PM
    
Does anyone have access to this paper?
[www3.interscience.wiley.com]
Transition from Isometric to Skeletal Crystal Shapes
V. Tonchev, Prof. Dr. Chr. N. Nanev
Institute of Physical Chemistry Bulgarian Academy of Sciences acad. G. Bonchev, bl. 11 1113 Sofia, Bulgaria

Of all the places the authors could have been from....

EMJ
Re: Have the reverse-skeletal Madan galenas been faked?
October 27, 2009 05:26PM
Let's be clear that these features are etch or erosion features (artificial or not), not skeletal growth. You can't have skeletal growth only on edges, without a center. So the fact that very skeletal galenas exist in Bulgaria is irrelevant to this discussion.
Re: Have the reverse-skeletal Madan galenas been faked?
October 27, 2009 05:43PM
    
I actually meant it somewhat jokingly. Still, a funny coincidence.
As for the differential etching of large versus small crystals, wouldn't that be because it's the surface area that's the relevant feature in determining the rate of etching? So, a big cavity would also tend to etch outward more quickly?
EMJ
Re: Have the reverse-skeletal Madan galenas been faked?
October 27, 2009 07:00PM
Helpful info. or irrelevant? [www.minsocam.org]
avatar Re: Have the reverse-skeletal Madan galenas been faked?
October 27, 2009 08:51PM
dissolution of a hoppered crystal could produce unexpected forms
photos of pristine galena from the same location show some hollows in crystals
[www.mindat.org]
[www.mindat.org]
this sample
[www.mindat.org]
could be some intermediary stage of dissolution. while still manufacturable, the inclusion of the large steps in the hoppered face is more complicated to realise and hints at a certain level of sophistication. The galena on the left looks quite natural.
Stepped faces are found there:
[www.mindat.org]
avatar Re: Have the reverse-skeletal Madan galenas been faked?
November 02, 2009 12:56AM
I've just come back from Munich where I haad an opportunity to look at a lot of specimens close-up, including some of these skeletal galenas and also a lot more pieces of different forms of galena from the same deposit.

I also got to talk to a few people about these unusual shapes to get opinions on whether they could have a natural origin, and between us we were able to postulate some vague yet plausible reason that could explain why small cubes and large cubes both ended up with frameworks of a similar thickness, seemingly impossible. Basically, imagine galena cubes growing, and during final growth phase, chemistry changes a little (maybe a little more/less Ag, or something else). Then conditions change and the galena is etched away, but the final stage which would be a layer of similar thickness on all cubes, is more resistant. If the crystals were hopper crystals to begin with, it could explain very easily how these skeletal cubes came about.

Having spent quite some time on this during the Munich show, I have to say I am changing my view now, and I'm more convinced now that they are genuinely natural phenomena. They are certainly worthy of some decent research however to identify the method of formation, because they're unusual!

I also spoke to one of the main bulgarian dealers who handles these things, who wants to send photos that will help convince people they are natural. I also took some photos myself of galenas at the show, on some of the pieces normal galena shows some of the strange stepped patterns we saw in the skeletal cubes and we thought might be because of abrasion loosening particles along lines of cleavage. On closer examination it looks very much more like a growth feature (or an etching/recrystallization feature) than anything physical.

So... if you were about to throw out your skeletal galenas in disgust, wait a moment, they're probably fine after all!

Jolyon

ps. of course, the story is far from over. More research is needed, they are fascinating things.
avatar Re: Have the reverse-skeletal Madan galenas been faked?
November 02, 2009 02:55AM
    
Jolyon, really good investigative comments,

I didn't want to say too much during the early discussion as I have not had the opportunity to see one in real life - one of the pleasures of living at the ends of the earth, but I am always careful to discredit an occurrence without investigation. Lets accept that one of geological/mineralogical situations do occur, how many minerals are currently found only in one location??

Sadly, we now live in a world where there are many people trying to fraudulently remove money from the pockets of naive "rich" people from economically developed nations. Fakes, being of natural history, cultural, atistic etc are one of the many methods used by occupants in underdeveloped countries to "fleece" the unsuspecting.

The result is that any specimen that has unusual color, habitat, associations etc tends to be immediately viewed as a fake, without extensive research to verify these claims. I always thought that we allowed innocence before proving guilt, appears not in these cases - though one has to admit to a fair bit of previous "form" from these countries.

A am sure that if Tasmania was in an eastern european, asian country, etc, some of the minerals specimens we see from the west of Tasmania would also be questioned...

Lets keep an open mind and do the investigations, otherwise we may miss the pleasure of something very rare or unusual due to our cynicism.

Andrew Tuma
Re: Have the reverse-skeletal Madan galenas been faked?
November 04, 2009 07:28PM
Interesting discussion.
By all respect for Rock Currier I can definitely not agree with his arguments.
It is no argument if somebody claims that he knows somebody who knows somebody who knows somebody with a sandblasting machine and that is the fact that the galenas must be fakes.
I know nobody with a sandblasting machine, but I have several skelettal galenas in my private collection. And most of these specimens consist of several attached skelettal crystals, you can never cast by sandblasting. All the edges of my specimens do not have round faces, but stepped faces, which you also can never cast by sandblasting in my opinion.
And to the end, there are small tiny quartz crstals on some of these edges, which you destroy immediately by sandblasting.
To make a long story short - these facts convince me so far, that at least my skelettal galenas are not man made.
Best regards,

Marcus Grossmann
avatar Re: Have the reverse-skeletal Madan galenas been faked?
November 04, 2009 08:20PM
    
Marcus, Rock actually made one from a Tristate galena, so this is not hearsay. If you were more familar with airblasting, you would know that it can be very accurately directed thus preserving the edges and any quartz xls that might have grown there. Why are there none of these quartz xls on the cavernous parts of the galena? What I find troubling are the cleavage steps that are evident in the photos. If there were other species growing in the cavernous regions then you would have proof that these are not fabricated. As with the stringy Ag wires that can occur naturally or be lab grown, these galenas might be real or air blasted. I think the question hinges on whether the cavernous regions show cleavage steps or xl faces. A good photomicrograph should tell the tale.
avatar Re: Have the reverse-skeletal Madan galenas been faked?
November 04, 2009 09:47PM
Rob.

As you know from my earlier messages I was pretty convinced before I went to Munich that these things must be fakes. But having looked more at samples of these and other specimens, I don't think the stepped effect was caused by cleavage but is a growth pattern. I think these things have had multiple periods of growth, selective dissolution and regrowth, which is why you see some other specimens from this area that look like 'melted' galenas. I saw a small 20 euro specimen of normal crystalline galena at Munich from the bulgarian mines, and on the back was an area that looked like it had been melted and showed the characteristic stepped effect you see in the skeletal crystals. Here's a photo of it



There's no way this piece was sandblasted, so I have to accept the stepped patterns in the galenas are almost certainly natural. And if that is natural, then it makes it far more likely that these skeletal galenas are also natural.

Jolyon



Edited 1 time(s). Last edit at 11/04/2009 09:52PM by Jolyon Ralph.
avatar Re: Have the reverse-skeletal Madan galenas been faked?
November 04, 2009 10:00PM
    
Thanks Jolyon. Not having any examples myself I should probably keep my mouth shut and my mind open. The only melted galena I'm familiar with are the rare Nanasivik pieces, none of which showed the cleavages or growth features. I hope you were able to afford that piece or at least get a photo of it. Until there is found some other mineral overgrowing the caverous regions or a photomicrograph shows xl faces from dissolution, I'll maintain my doubts. There is still the possibilty that some are real and some fabricated. It would be interesting to compare photomicrograghs of what Rock created and a purported real one.
avatar Re: Have the reverse-skeletal Madan galenas been faked?
November 04, 2009 10:06PM
    
Thanks for the photo. You added it while I was typing! You are right, that was not airblasted!!! However the growth lines are more ragged than in the usual cavernous areas. So some may be real and some improved?
avatar Re: Have the reverse-skeletal Madan galenas been faked?
November 04, 2009 11:01PM
    
Hi all,
glad that Jol posted his comment(s) .. and also glad that my old school understanding of precipitation/dissloution etc. in hydrothermal systems doesn´t seem to be that wrong - as i wrote earlier the composition of solutions/saturation/temperature etc may affect already crystallized individues in strange ways ... maybe our thermodynamic cracks here can explain the selective solution of faces and edges more sophisticated. But i am still waiting for Rock´s picture of a hand-crafted specimen of that kind. I would consider this very interesting although i am still convinced (and after Jols comments much more) that these Madan specs are natural. Regarding the sand-blasting: IMHO one could only save quartz etc. with baking soda or dolomite abrasive .. with glass (beads) or quartz it would be very hard to selectively blast such parageneses.

BTW Jol, hope you had a good time and good beer in Munich,

cheers
Roger
avatar Re: Have the reverse-skeletal Madan galenas been faked?
November 07, 2009 02:51PM
    
Jolyon,

I saw in the Munich report, that because there are quartz crystals inside the galena crystals, you are leaning toward the fact that they are real. I am not a deposition expert, but the galenas were deposited secondary to the quartz crystals in the pocket.

With that said, it is really quite easy to remove galena, without damaging the quartz crystals inside. As Rock described in his air abrasion technique, this is quite a simple process.

This is a good discussion thread.

Regards,

Ryan
avatar Re: Have the reverse-skeletal Madan galenas been faked?
November 07, 2009 03:12PM
Ryan.

The quartz crystals are not the reason that I believe they are natural. It is a combination of other factors.

Jolyon
Re: Have the reverse-skeletal Madan galenas been faked?
November 07, 2009 04:41PM
I don't have one of these Madan "reverse-skeletal" form galenas, and they apparently do not exist from any other site in the world. I have only paid attention to pictures of them, but remain unconvinced. Are there any conclusively could not have been "manufactured" via air abrasion? This might include (1) minerals growing on top of the skeletal galena (not underneath the galena, as Ryan noted); (2) very small skeletal galenas that could not be the result of air abrasion techniques (there must be such a size limit); (3) galenas in small cavities where it would be impossible/impractical to air abrade them; or (4) galenas collected in situ in the "reverse skeletal" form. Others have hinted that they might have specimens that could not have been faked. I would be quite interested to see some of these.

Also, regarding the theory that these are partially dissolved hopper-growth crystals: is it not still a stretch to call upon what is described as a growth phenomenon (the "stepped" galena crystal) to explain a morphology which is theorized to be the result of dissolution processes?
Re: Have the reverse-skeletal Madan galenas been faked?
November 07, 2009 05:04PM
    
Hello,

This is another interesting discussion on MINDAT.

I think we should watch out for a continuing supply appearing on the market. If this is a one time find, not many will be coming on the market in the future unless they are being hoarded. Jolyon's photo of a specimen featured at the Munich show, which had quartz crystals growing inside a cavity, is positive evidence that these coud be real. If a specimen comes on the market with a fragile mineral like calcite, barite, etc. growing in a cavity, then that would be absolute proof that they are genuine.

Best,

Joe
Author:

Your Email:


Subject:


Attachments:
  • Valid attachments: jpg, gif, png, pdf
  • No file can be larger than 1000 KB
  • 3 more file(s) can be attached to this message

Spam prevention:
Please, enter the code that you see below in the input field. This is for blocking bots that try to post this form automatically. If the code is hard to read, then just try to guess it right. If you enter the wrong code, a new image is created and you get another chance to enter it right.
CAPTCHA
Message:
Mineral and/or Locality  
Search Google  
Copyright © Jolyon Ralph and Ida Chau 1993-2014. Site Map. Locality, mineral & photograph data are the copyright of the individuals who submitted them. Site hosted & developed by Jolyon Ralph. Mindat.org is an online information resource dedicated to providing free mineralogical information to all. Mindat relies on the contributions of thousands of members and supporters. Mindat does not offer minerals for sale. If you would like to add information to improve the quality of our database, then click here to register.
Current server date and time: October 26, 2014 03:41:41
Mineral and Locality Search
Mineral:
and/or Locality:
Options
Fade toolbar when not in focusFix toolbar to bottom of page
Hide Social Media Links
Slideshow frame delay seconds