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Identity Help"Angel wing" calcite... Locality?

3rd Feb 2010 22:54 UTCMichael J. Bainbridge Expert

Anybody know where this might have come from?

It is from the collection of the Canadian Museum of Nature in Ottawa, specimen #35435.

Labeled as: "angel wing" calcite, Locality unknown.

Close-up of re-crystallized surface:

Thanks,

Michael

4th Feb 2010 01:58 UTCAnonymous User

Far too widespread a mineral to risk putting a locality on it, in my opinion.

4th Feb 2010 04:31 UTCMichael J. Bainbridge Expert

Certainly, but the formation is rather unusual - fluid etching of massive calcite with later re-crystallization, it would seem.

Oh yes, I should say that it's BIG too. Small things like this might be fairly common (although I've never seen one), but it might help to know that it's 25cm tall. FOV on the CU is 8.6cm x 5.8.

No, a guess certainly won't do. I just thought that somebody might say, "ah, yes. I remember in 1967 when Tucson was flooded with these things from..." Or something like that. I would never attach a definite location to it (neither, I'm sure, would Michel), but I thought I'd throw it out there in hopes of being able to put a "probably from..." on the photo.

We'll see...

4th Feb 2010 14:43 UTCAnonymous User

Aha! The size changes a lot, the probability of these occurring is greatly decreased. Unfortunately I know not where it could have come from. Neat piece though.

4th Feb 2010 15:29 UTCMichael J. Bainbridge Expert

Oh, and I should say that, based on the catalog #, it would have been acquired sometime in the 50s, or 60s (although, it might have come from an older collection).

4th Feb 2010 16:45 UTCReiner Mielke Expert

A lot of that sort of thing came out of Mexico around that time.

4th Feb 2010 17:41 UTCMichael J. Bainbridge Expert

Excellent, that's a start! Any locations in particular, or was it fairly ubiquitous?

Thanks

4th Feb 2010 19:24 UTCMaggie Wilson Expert

http://www.mindat.org/photo-121890.html

some time to kill this afternoon, so I'm searching the database, Michael... what do you think of the attached? It's also a unique form, though certainly not of the same scale

4th Feb 2010 20:54 UTCMichael J. Bainbridge Expert

Wow, you must have had A LOT of time on your hands to search calcite in the db! Thanks!

I'm inclined to say that that specimen, although visually similar, would have formed differently. Those look like stacked, modified rhombs, similar to the saddle shapes we often see in dolomite. Certainly an unusual form, but it appears to be fairly standard deposition on matrix. ie, the calcite formed that shape as it crystallized.

The museum specimen however, appears to have been etched into that shape (starting from massive calcite and dissolved, roughly along the cleavage planes, into that form). The surface xls then formed over the etched base as the solution cooled. The etched calcite "wing" shape would be analogous to the matrix, and the surface texture the crystal deposition.

At least, that's my uneducated guess.

So, it's actually the unusual form of the 'matrix' which I think might be diagnostic, not the crystals themselves.

25th Feb 2012 23:03 UTCjames jjjj

looks like mexico

5th May 2012 18:23 UTCAnonymous User

A large amount of "angel wing" Calcite was mined in Durango, Mexico during that time period by the Torrecillos family from Durango. This location also produced a lot of cleave Calcite rhombs. I can not say for sure that this specimen is from there.

Dennis

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