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Strange crystals with voids

Posted by Giuliano Bettini  
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Giuliano Bettini May 19, 2017 10:37AM
Strange crystals with voids
On pegmatite, Catri, Sant'Ilario in Campo, Campo nell'Elba, Elba Island, Livorno Province, Tuscany, Italy.
I wonder what these crystals are with these holes, and why are these holes here?
Thanks.

FoV 6 cm


Area 6x8 mm


FoV 3mm

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Peter Slootweg May 19, 2017 03:28PM
The crystals might very well be beryl. The reason for the holes can differ. Or they are the result of dissolution, what i think has happened here. Or the crystals may have been intergrown with other minerals that have dissolved, leaving the holes behind. Another mechanism for creating crystals with holes is skeletal growth but that is not the case here.
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Donald B Peck May 19, 2017 05:20PM
I agree with Peter, and lean toward the dissolution hypothesis. There are two crystals just below and slightly left of the circle on your first photograph that are distinctly different minerals, and interesting (I don't know what they are). In the third photo, the crystal seems to be foliated (shown along the top of the hexagonal or pseudohexagonal image. Could it be muscovite? There is a similar small crystal in the second photo, right of center.
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Rui Nunes May 19, 2017 05:25PM
Apatite crystals is my guess
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Erin Delventhal May 19, 2017 09:13PM
I have seen specimens of quartz do this, for what that's worth.
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Giuliano Bettini May 20, 2017 04:45AM
Thanks to all.
Erin, that's interesting. In fact it may seem like quartz. Do you have any examples, or some references?
One more photo, area 3x4 mm.

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Dana Slaughter May 20, 2017 06:33AM
Such quartz crystals are known from AZ. Kunz mentioned them (along with drawings) in the American Journal of Science and Arts, 1887, page 479. I once had a specimen from the Arthur L. Flagg (1883-1961) collection of Phoenix, AZ from a different location to the west.

I can't tell if your crystals are quartz---are any striations visible on the crystal faces?
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Giuliano Bettini May 20, 2017 06:54AM
Thanks. I remembered to have see a similar crystal, in another sample of the same locality (Catri).
So I took some photos, and I show them.




FoV 3 mm




FoV 3.5 mm




FoV 2 cm




Edited 1 time(s). Last edit at 05/20/2017 09:13AM by Giuliano Bettini.
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Giuliano Bettini May 20, 2017 07:32AM
Hmmm...
it seems like this one (but different matrix)
http://www.quartzpage.de/gro_text.html#honeycomb
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