Crystal coated cave pearls

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Cadbun

New member
My first post here, I'm just after a trip into a cave in the beautiful Burren in County Clare where we found some amazing cave pearls that are covered in outward radiating calcite crystals. There are plenty of them occurring in a series of pools along a section of oxbow passage about 1m above stream level. The largest is about 3cm in diameter and they are not fixed in place.
Any other cave pearls I have seen are smooth on the outside - which I believe is the norm?
But a quick internet search showed up some photos of something that might be similar in Ogof Rhyd Sych in Wales.
So is this an unusual form of cave pearl?
Where else have they been seen?
How do they form a crystal coating but remain unattached?
 
C

Cadbun

New member
A couple of photos...
 

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mikem

Well-known member
Cauliflower like formations are indicative of pools that dry out, leaving the calcite to precipitate wherever it can
 
C

Cadbun

New member
Thanks Mikem, but they do not have a 'cauliflower' form, which I would associate with moon milk.
Each pearl is roughly spherical but the outer surface is like a hedgehog with individual outward pointing crystal growths. I could see inwards for about 5mm between each growth point. To me crystal tips like this must indicate growth in a saturated water solution, but then why are they not cemented in place?
 
Pitlamp

Pitlamp

Well-known member
It's an interesting question.

Do you know anyone who is into macro photopgraphy who might be able to obtain a good close up view?
 
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mikem

Well-known member
What I'm talking about is nothing to do with moonmilk, but the coating of supersaturated pools due to the water evaporating off (although pearls are apparently also supersaturated). Yours maybe dogtooth? Which forms in very still pools or:
caves.org

Triangles

Triangular forms in caves are found in two different typs of situations. They may be monocrystals on the surface of flowstone, distinct from the usual crystal structure which is parallel…
caves.org caves.org
 
C

Cadbun

New member
Given the lack of any definite answers as to their formation and after a bit of soul searching I have removed 2 of these for analysis. A photo attached with a 1 cent coin for scale.
I hope to get one cut in half and there is a possibility of dating if suitable.
cave pearl hedgehog.jpg
 
Pitlamp

Pitlamp

Well-known member
Didn't Art Palmer produce a definitive book about cave minerals of the world several years ago?
If you haven't already, it might be worth leafing through that for any relevant information?

Nice picture by the way. (y)
 
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