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Identity HelpLocality ID needed for Smithsonite

13th Aug 2014 01:24 UTCDan Costian

Dear friends,

Here is a specimen of smithsonite (with possible descloizite and malachite) for which I would like your help to ID the locality.

Thanks for having a look and give me your educated guess.

Dan

13th Aug 2014 10:11 UTCsteven garza

Dear Dan;

My best guess would be AZ/NM; past that?

14th Aug 2014 15:08 UTCDan Costian

Dear Steve,

Thanks for your suggestions. I checked both AZ and NM on mindat but I couldn't find similarities. I mean neither in orange color nor in crystal shape.

It seems that this specimen is very intriguing. It is neither pink (cobaltian or manganoan) nor cadmian (yellow).

Dan

14th Aug 2014 17:14 UTCDoug Daniels

I'm not convinced that is smithsonite, especially if it's from the southwest (and I said "if"); doesn't tend to form such well-defined crystals there. Plus, the color doesn't fit. Still, it could be. A test for zinc would be helpful, but that would be destructive of a piece, so....

14th Aug 2014 18:02 UTCDonald Peck

I'm with Doug. I am not convinced it is smithsonite, either. A very small fragment, heated strongly in a small test tube will develop a coating that is yellow when hot and turns white when cool. Or better, do you know a high school chemistry teacher? He/she would most likely have some cobalt nitrate. Ask him/her to heat a small piece strongly and while it is hot, drop one drop of cobalt nitrate solution on it. If it contains Zinc, it will turn green,

14th Aug 2014 18:17 UTCReiner Mielke Expert

This is a continuation of this thread http://www.mindat.org/forum.php?read,11,331530,331757#msg-331757 and the testing you did suggests it is calcite. As far as I can remember smithsonite will not react with 5% acetic acid. Also did you powder the sample before testing with acid? that can change the results considerably.

14th Aug 2014 18:28 UTCWilliam W. Besse Expert

Calcite, Cuprite

Bisbee, Cochise County, Arizona, USA

I was wondering if it may be a nailhead or similar calcite like the one below from Bisbee:

Bill

15th Aug 2014 02:24 UTCPaul Brandes 🌟 Manager

I wasn't convinced of smithsonite either when I first looked at it, but didn't know what it could be. Now that Reiner has mentioned calcite and reading the other thread, I could see calcite.

Dan, how did you determine it was smithsonite originally (label, educated guess)?

15th Aug 2014 10:01 UTCsteven garza

Dear Paul & Reiner;

If you checked, there was a label that said it was vanadinite; Dan thought it was because he didn't look at the xls knowing the shapes vanadinite wouldn't be in. He also thinks it might be X-ian smithsonite because it's red & you're taking the color into account, not seeing it's probably coated - not included. Since smithsonite from Cave-In-Rock produces a very weak, & short lived reaction to % vinegar, as well as from 79 mine & several other locales (because it's calcian; I wouldn't dare think that specimen was pure/close to); ANY calcite I've tested (even Mn or petroleum included) has a weak sustained reaction, form longer than a couple seconds. That's what Dan reported. Since calcite is in the calcite group, it can form ANY crystals, no matter how unusual/rare the shape/habit, that calcite can. Looking at the shape, just how common is that shape, even for calcite? I've only seen that shape a few times, in all the yrs. of my collecting & studying museum collections. Where did I see it most? English ore deposits; other than that, less than a handful. If I hadn't looked closely at the terminations, I would have had a hard time even saying it was a calcite group carbonate, which is why I waited until Dan's testing, in both the strong & weak acids, before saying "I BELIEVE those to be smithsonite; ...".

A question I have for you, is, how common is it that calcite (other than the cases stated; even my hot raspberry - pink Fe calcite from KY reacts well) doesn't react well with vinegar? I've several samples, but, even then, it's from only a few localities. Would others test & report?

Your friend, Steve

15th Aug 2014 15:21 UTCDan Costian

The acid tests, suggested and interpreted by Steven are at http://www.mindat.org/mesg-11-331530.html

Best regards,

Dan

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