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2,237 questions

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stone found on a beach, revealed green translucent crystal inside, cannot identify plz help

0 votes

I found this stone on a beach in south spain, seems to have some kind of crystal formation sandwiched inside of it. Shine a light through the crack and you can see fan like formations growing inside the crystal. I have limited knowledge on gems or geology in general, any help would be much appreciated in identifying this stone/crystal.alt text

asked Dec 17, 2013 by elholmz (140 points)

3 Answers

0 votes

It looks like those are globular aggregates of radiating crystals. Looks most like Prehnite. Does it have a greenish color? Is there more of this material? Can you identify the rock type in the area?

answered Dec 19, 2013 by hershel (52,800 points)

Thank you for your reply. The stone was found on a beach in Gibraltar, which is mostly limestone. The only mineral deposits of anything that looks like the stone are deposits of malachite in morocco. However would only explain the folded exterior rock as i cant find a malachite specimen photo online where the crystal is transparent. The rock itself has ever so slight blue hue to the green and the crystal is deep green. When a light is shone through the stone, the whole stone lights up a vivid bright green.

0 votes

Gibraltar is all limestone, so that would rule out prehnite (unless it was washed up from a different location - though that is unlikely. Since there are caves in the gibraltar limestone, it is likely this is a calcite/aragonite cave formation that is waterworn and is green from organic ocean substances. If you have any strong acid see if putting it on the stone will cause it to bubble up - that would make its identity almost definitive. Also do you have any additional pictures to post?

answered Dec 26, 2013 by hershel (52,800 points)
0 votes
this stone is worth 123,345,567,789,890

answered Apr 28, 2017 by anonymous