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Possible Fake: Blue Hemimorphite from Ojuela
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Ibrahim Jameel




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PostPosted: Sep 30, 2020 23:07    Post subject: Re: Possible Fake: Blue Hemimorphite from Ojuela  

James Bennet, I have been to Mapimi, and down to the water table at Ojuela with one of the many teams of miners working the mine. Just to clarify about the situation there: there is no single mine owner. It is a 500+ year old mine that was previously worked by a single entity, but today it provides a livelihood for scores of local specimen miners (or "risqueros" as they are called.) As far as I am aware, there is also one small enterprise that still employs miners to mine ore in areas that were not previously tapped out. The rest of these specimen mining teams work independently, though most sell to a few larger sellers in Mapimi, if they do not have their own foreign contacts.

The major American dealers of Ojuela material (such as TopGem) have long-established relationships with some of these mining teams and local distributors-- in fact, TopGem, citing their local sources and decades of experience, were among the first to raise concerns about the possible counterfeit nature of these specimens. My understanding is that based on concerns raised by them and a few others, Mr. Trinchillo was kind enough to undertake the expense of actually verifying the claims that these specimens were fake, to the benefit of the entire community.

For that reason, boycotting Mapimi as a whole is entirely unfair, both to the US dealers who take the time to verify their material, as well as to many of the honest locals. This is still a world-class locality, with many things to offer. However, the problem over the last couple years seems to be that particular influential, local parties have made alliances with some shady figures and conspired to pull off these deceptions. Based on what I heard in Mapimi, these are probably the same individuals responsible for the kobyashevite. Again, it is mostly hearsay, but.... in a small town like Mapimi, where everyone knows everyone's business, it is at the very least worth considering.

Based on this I would offer 2 main takeaways: 1) echoing an old-time US dealer of Ojuela material: if it is a cheap, common Ojuela mineral and it suddenly appears vividly blue or green, and not obviously colored by aurichalcite or rosasite inclusions, be wary. More often than not, this is either a result of post-mining, or just an outright fake. In the past it was copper sulphate (as I mistakenly guessed), but this has shown they are using new compounds. To further expand on his observations, perhaps next time it will be red or yellow... just be wary of new, brightly colored items from there with little precedent 2) when the local Mapimi dealers or old-time wholesalers sound the alarm, it might be worth considering their opinions, over foreign experts, and *do not trust your eyes* when it comes to in situ videos. These videos seemed to settle the debate for many on social media. As values increase, so will the intricacy of the lies. I am reminded of stories from gem dealers, of mud-covered children emerging from gem pits with "freshly mined" corundum, which upon closer examination, are later found to have been heat treated......

Of course, it is probably just a matter of time until the next attempt... I hope it is caught equally quickly!
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PostPosted: Dec 31, 2023 13:23    Post subject: Re: Possible Fake: Blue Hemimorphite from Ojuela  

This thread is already well over 3 years old, but I notice that one question that was raised repeatedly in this thread was never answered, namely why was only the hemimorphite colored blue and not the associated calcite? (This disparity was initially used as evidence that the specimens must be natural and not faked.) The answer is actually quite simple and related to the fundamental difference between a "paint" and a "dye": A paint merely covers the underlying surface, but a dye becomes chemically bonded to its substrate. So dyes can be quite selective about what they will react to or bond with. An organic chemist friend tells me that copper-phthalocyanine bonds to surfaces with hydroxyl. Hemimorphite has (OH), calcite does not.

As we slide into the year 2024, I wish everyone here a very happy, healthy and prosperous New Year, and keep an eye out for future mineral "enhancement" trickery - "Better life through chemistry", as the old DuPont ads used to claim?
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