FMF - Friends of Minerals Forum, discussion and message board

[Ibrahim Jameel]

I have noticed a number of new posts on social media regarding blue hemimorphite form Ojuela. Before you spend money on this, I wanted to raise some concerns: 1) These hemimorphites are colored by copper sulphate- it is mainly external, it is not an aurichalcite/ rosasite inclusion. This is the 2nd copper sulfate stained/ based mineral from Ojuela in less than a year, (the other being kobyashevite) after decades and decades of none being found. Yes, there is copper in Ojuela, but if this material is so common, why do we have no chalcanthite specimens? Why is the limonite matrix not more red (as with the cuproadamite, from more copper-rich zones?) 2) A Seattle-based chemist grew identical kobyashevites (complete with selenite) in his lab and there were rumors from the miners at Ojuela (related to me first hand) that the Kobyashevites were being manufactured in a garage somewhere nearby. Those too, were accompanied by a grainy in-situ video. 3) A prominent dealer in Tucson with contacts close to the mine reported that these hemimorphites were being faked as well. Think about it: copper sulfate is water soluble and easily obtainable-- you can get 10 lbs on ebay for under $30. 4) Natural copper sulfate bearing solutions are highly acidic and (on the few specimens that had calcite) the calcite was not eaten away. The limonite is not stained, but apparently the copper sulfate can react with the hemimorphite, but be washed out of the limonite. Another miner told me that some are real, and some are fake. There is a chance some of it is real, but also strong circumstantial evidence that much of it is not-- If any are real, determining the difference seems to have something to do with the paragenesis of the calcite. Again, the Tucson dealer with far more experience indicated that his contacts called them fake--Even with the grainy, in situ video. Two copper sulfate minerals built upon cheap, abundant Ojuela material (hemimorphite/ calcite) both within a year, using the same basic ingredients, after decades of none being found seems like a huge coincidence. It would be nice to discuss if you think it is real or not, but all the same: caveat emptor.

[Tomasz Praszkier]

Ibrahim, I am suspicious about this stuff as well, but what I have seen does not look like it is covered with chalcanthite, but more like with inclusions of it. Did you look under a microscope at these pieces? Also if they were "colored" by chalcanthite it would be all over, not only on hemimorphite crystals.
It should be easy to say after examining some specimens under simple magnification I think ...
Kobyashevites - I have seen videos as they are collected in situ in the mine. So for sure some are natural.

[Peter Megaw]

This material is being studied carefully. The blue does not wash off in water or acetone and there is a later stage of well formed calcite crystals to over 1 cm that are not blue..although some have blue zones. The matrix is not stained and blebs of hemimorphite in the matrix are blue. Pieces have been trimmed and found to contain blue crystals. Some are transparent enough to see the hemimorphite within the calcite is blue. The size and sharpness of single rhombic crystals indicate that the calcite is not a post mining product. Heating the specimens to 150C for 15 and 30 minutes and multiday exposure to hot sun have no visible effect on the color. High resolution microscopy does not show inclusions or intergrowths. The hemimorphite shows a glossy corrosion typical of exposure to an acid solution (hemimorphite gelatinizes readily in even slightly acid pH. The associated calcite shows no sign of acid leaching.

These specimens reportedly come from Cumbres or Palomas Oriente (near Cumbres). Cumbres is the best known copper bearing area in the mine and lighter blue hemimorphites have come from there periodically.

Initial Raman and SEM analytical work indicates the blue is not chalcanthite...or any other sulfate. Carbonate and arsenate also appear unlikely.

It is not impossible that some of these are natural and some dyed somehow. However, the videos of the pockets suggest that there is enough material in situ to go around.

Investigation continues on specimens from the batch with calcite overgrowths. Specimens from other batches...especially with no calcite and a range of blue colors would be welcome.

[Peter Megaw]

Sorry...tried to download a video showing miners collecting the blue hemimorphite underground. Too big and the wrong file type.

[Jean Sendero]

Thank you Peter for the clarifications.
Cheers

[Jordi Fabre]

[Jean Sendero]

On Instagram? Would that work?
Let me know and Jean Sendero will post it.

[Jordi Fabre]

[Jesse Fisher]

Hello Jordi,
I have the video from Peter and can post it to YouTube, if you want. Do I then just post the link here in a reply message?

Jesse

[Jesse Fisher]

Here is the link:

[Jordi Fabre]

[Peter Megaw]

Check out the other video Jesse posted on YouTube. It's another perspective...and while you're at it check out the great music he and Joan make and post there!!

[Jesse Fisher]

If anyone is interested, you can find it under the name "borogroves"

[Kevin Schofield]

[Jesse Fisher]