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"Angel wing" calcite... Locality?

Michael J. Bainbridge February 03, 2010 10:54PM
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:

open | download - 35435.jpg (193.3 KB)
open | download - 35435A.jpg (269.8 KB)
Anonymous User February 04, 2010 01:58AM
Far too widespread a mineral to risk putting a locality on it, in my opinion.
Michael J. Bainbridge February 04, 2010 04:31AM
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...
Anonymous User February 04, 2010 02:43PM
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.
Michael J. Bainbridge February 04, 2010 03:29PM
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).
Reiner Mielke February 04, 2010 04:45PM
A lot of that sort of thing came out of Mexico around that time.
Michael J. Bainbridge February 04, 2010 05:41PM
Excellent, that's a start! Any locations in particular, or was it fairly ubiquitous?

Maggie Wilson February 04, 2010 07:24PM

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
Michael J. Bainbridge February 04, 2010 08:54PM
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.

Edited 1 time(s). Last edit at 02/04/2010 09:03PM by Michael Bainbridge.
james jjjj February 25, 2012 11:03PM
looks like mexico
Anonymous User May 05, 2012 05:23PM
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.
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