What’s this rock? August 8
I got this email from a lady recently who is trying to identify a rock she found. She gave me permission to post the photos and her email in case anyone has a definitive answer.
I don’t know who else to write to I am writing anyone or organization that comes up under the search of blue agate.A couple of months ago I found a very unique stone, which no one I have shown has ever seen anything like it. The stone is dark purple with deep swirls of periwinkle blue waving horizontally across. What is most unusual is it’s bright vibrant unique colors. The stone also has fossil imprints and fossil’s that still may remain on the stone. It is quite large approx. 6″ X 7″ and in it’s raw form. I found it in upper westchester NY above a cave/cliff area. It definitely is not a stone native to the area.A lapidary, a few jewlers and a gemologist all looked at it and they all said they never saw anything like it. All they told me is that it is not Sapphire, Amethest or Diamonds (Dah!). I was hoping SOMEONE could give me a little more insight alought a picture in this case is not worth a thousand words. I would appreciate any help from anybody, even if you have to foward this message on. The curiosity is killing me.Thank you very kindly,Tam
My guess is a rock fulgurite. Here are some examples of rock fulgurites that are similar in look generally, though the color is different:
http://geology.about.com/od/rocks/ig/fulgurites/fulgrock.htm
http://www.minresco.com/fulgurites/caca.htm
http://205.243.100.155/frames/longarc.htm <– that one is sort of manmade (almost at bottom of page) but shows what lightning can do and the different colors it can show)
http://www.notjustrocks.com/wst_page6.html shows finding rock fulgurites
Do you have any ideas? If you do, just put them here in the comments and I’ll make sure Tam gets them.
Samuel Trommler Jr. Aug 9
Hi!
I am the owner of notjustrocks.com and an avid fulgurite collector with thousand of specimens in my collection. For what it’s worth, I’m pretty sure it’s NOT a rock fulgurite, or even a fulgurite of any kind. I have dozens of rock fulgurite specimens in my collection and they are mostly characterized by splatter and glaze on the surface of host rocks. The swirl pattern DOES resemble a traditional large size fulgurite, but is lacking the tubular or cylindrical shape which is typical of almost all fulgurites. The glassy part is also a color I have never seen in fulgurite before (fulgurites are typically black, grey, green, white and sometimes red or brown depending on impurities present in the host material). I would recommend contacting Sharon Cisneros of minresco.com directly and possibly sending her a sliver or chip for further composition analysis. She has been very helpful in the past with such matters. Good luck!
~Samuel Trommler Jr. (President, Not Just Rocks Inc.)
robyn Aug 9
Hi Samuel, Thanks for your info! I was basing that on some New York fulgurites I’ve seen, but with photos, I can only guess. I’ll pass this on to Tam. Robyn
Kat Aug 15
I can’t tell from the photo if the blue has any chatoyancy. If it does, it might be Labradorite. Since that stone is found in glacial deposits, that could explain why it was found so far from “home”.
Whatever it turns out to be, please let us all know… Cats are curious creatures!
The StarThrower Aug 24
I passed this pic on to my favorite (in-house) geologist/gemologist and this was his response:
This appears to be opal, but could be chalcedony — it could even be slag glass, no more than one can tell from a picture. However, I would place a bet on one of these three. The latter is very likely as I think I see some very round bubbles, but the image is not good enough to resolve them for sure. The color also seems a bit bright and glassy for opal or chalcedony. So my best guess is that it is a slag glass chunk with a small outside chance that it is chacedony. — DKH
hong hong Nov 13
I think this is a agate rock, agate rock are striped like that.
hong hong Nov 13
It could be blue amber, blue obsidian rocks, or just beach pebble glass rock. who knows.