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Modris Baum February 25, 2012 02:05AM
This looks like eudidymite to me.
But I know that at Mt. Malso you can't tell epidymite from eudidymite without analysis.
Has this been analytically verified as epididymite? Seems surprising to me - but maybe my "rules of thumb" are wrong.
Kelly Nash February 25, 2012 03:26AM
That didn't take long, I just entered it about an hour ago. In fact, I meant to enter it as eudidymite, and just corrected it (and now your link goes to another specimen - mine was photo-447559). Thanks for saving me an email from a manager.

But no, it hasn't been analyzed, by me anyway. Perhaps the fellow I bought it from did, but I think most of these from Mt. Malosa are just going on visual ID (see others).

Edited 2 time(s). Last edit at 02/25/2012 03:31AM by Kelly Nash.
Modris Baum February 25, 2012 03:39AM
Hi Kelly,

Actually, I had two comments on two separate photos (one by someone else). The problem with "talk page" comments (which I realized after the fact) is that if you make comments on more than one photo from a locality is that both threads have the same header. But the links (still) go to different photos.


I just put numbers on the messages. Maybe that will help unconfuse things.

Edited 1 time(s). Last edit at 02/25/2012 03:53AM by Modris Baum.
Reiner Mielke February 25, 2012 03:50PM
Why can't you tell them apart at Mt.Malosa without analysis if they are crystals? One is othorhombic and the other monoclinic should be easy to tell the difference?
Modris Baum February 25, 2012 05:43PM
Well - I think I can tell them apart at MSH - most of the time.

As for Mt. Malosa, I'm just parroting what I've read.

But even albite (triclinic) can look orthorhombic at times - and so on and so on.

However, I'm probably the last person who should comment on morphology.
When I distinguish epidymite from eudidymite (or baryte from calcite etc., etc., ) I'm not thinking "this is orthorhombic", "that's monoclinic".
The fact of the matter is that most of the time I'm not sure. The minerals are almost always twinned and often occur together - sometimes epitactically, sometimes not.
I just "know" that one of thme grows like "this and this and this", whereas the other one grows like "that and that and that".
No doubt what I think I "know" is sometimes wrong. And often enough, I can't tell for sure even with what I "know".

Edited 3 time(s). Last edit at 02/25/2012 07:41PM by Modris Baum.
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