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Identity HelpStrange crystals with voids

19th May 2017 10:37 UTCGiuliano Bettini

07341080016029693636087.jpg
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
01920370015652962793613.jpg



FoV 3mm
02701060015652962793634.jpg

19th May 2017 15:28 UTCPeter Slootweg 🌟

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.

19th May 2017 17:20 UTCDonald B Peck Expert

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.

19th May 2017 17:25 UTCRui Nunes 🌟 Expert

Apatite crystals is my guess

19th May 2017 21:13 UTCErin Delventhal Manager

I have seen specimens of quartz do this, for what that's worth.

20th May 2017 04:45 UTCGiuliano Bettini

01754060016029693642367.jpg
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.

20th May 2017 06:33 UTCDana Slaughter 🌟 Expert

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?

20th May 2017 06:54 UTCGiuliano Bettini

03324380016029693649139.jpg
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
03591950015652962799932.jpg





FoV 2 cm
04586680015652962795206.jpg

20th May 2017 07:32 UTCGiuliano Bettini

Hmmm...

it seems like this one (but different matrix)

http://www.quartzpage.de/gro_text.html#honeycomb
 
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