Is this Azurite from Sierra Rica, Chihuahua, Mexico?

A few weekends ago I picked up a specimen at a rock show identified as "Melanite / Chihuahua, Mexico." In looking at it, it doesn't seem to be Melanite at all. The sample is about 1.25 in long, and contains blue and black-ish (probably why the seller thought Melanite) crystals:

entire sample

Not the greatest closeups, but the first is of the predominately black-ish area (field of view of about 5mm), and the other of an area with more blue crystals (field of view of about 4 mm):

black-ish area
blue crystals

Assuming the location is correct, Mindat has a couple examples of Azurite and Quartz like these:

http://www.mindat.org/photo-221152.html
http://www.mindat.org/photo-221153.html

which look similar. Is it likely that the sample that I have is really Azurite from Sierra Rica?

Thanks!

C.

Yes, that's all azurite and there also appears to be a little massive cuprite present in the matrix.

However, your locality attribution is a little enthusiastic, to say the least. You can't seriously attribute a specimen to a locality by visual comparison, and even lesser so when it is a common mineral such as azurite and there are literally hundreds of possible locations in Mexico. Also, considering that the identification provided by the dealer was entirely wrong, can you really be sure about the locality ? What if two labels were mixed up and there is still a melanite from Mexico - now labelled as azurite from XYZ - in the dealer's stock ?

The situation is somewhat different for rare minerals, unique habits or particular mineral associations that only are known from a very limited number of occurrences. In those cases and with some research, a specimen can be attributed to a locality with a certain probability, but even then, a question mark has to be put on the label.

Peter Haas Wrote:
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> Yes, that's all azurite and there also appears to
> be a little massive cuprite present in the
> matrix.

Thanks for the confirmation.

>
> However, your locality attribution is a little
> enthusiastic, to say the least. You can't
> seriously attribute a specimen to a locality by
> visual comparison...

While I agree on principle, three times alone in the last week I have uploaded images to Mindat where I have received reviewer comments indicating that the location I specified was not specific enough (though was all I had based on the sample ID tags), and the location given to me by them that I should change it to before image approval - apparently others can make the determination just by visual comparison. One was even like this, with a dealer-misidentified sample that listed a particular city as a location which is really an entirely different mineral type from a specific mine, but at that same city. I was just making an attempt to do the same at identification.

C.

Charles,

You have done nothing wrong - if the label with your specimen only gives a general locality you do NOT need to make up a more specific locality for your specimen.

In this case the guidance given to you by the reviewer was incorrect - and we will be reviewing our guidance on these issues.

Jolyon

Hi,

I just posted this specimen from Sierra Rica to my Mindat page. Azurite on pale amethyst quartz, 5cm by 7cm. Acquired in 1978.


Best wishes,

Joe

Jolyon Ralph Wrote:
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> You have done nothing wrong - if the label with
> your specimen only gives a general locality you do
> NOT need to make up a more specific locality for
> your specimen.

Thanks for the clarification - I appreciate it! I expect it needs to be evaluated on a case-by-case basis, but for the various submissions, should I restore the locations to what my sample ID tags read, or leave them with the reviewer-provided locations?

C.

Joseph Polityka Wrote:
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> I just posted this specimen from Sierra Rica to my
> Mindat page. Azurite on pale amethyst quartz, 5cm
> by 7cm. Acquired in 1978.

Thanks for the image - that's a nice example. I do see similarities with my sample - the matrix in particular - but hard to tell if it really is from that locality, too.

C.

Charles - if there is expert opinion that your sample comes from a particular mine or deposit, then re-labelling here is fine. If there is doubt, best to stay with the more generic locality on the label.

Jolyon