Lapidaryforum.net
Let's Rock => Identifications of Materials => Topic started by: axllaird on December 04, 2018, 04:59:21 AM
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Recent outing to the coast revealed a green stone that went from dark to light green and silver as you turned it? Google research showed a similarity to Seraphinite although i'm not sure that would be possible from east coast Scotland? The stone won't scratch with a knife...
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Some other rocks found on the day...
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thanks for looking :occasion14:
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Wish I could help with an ID, but for sure you can rule out Seraphinite with a Mohs hardness of between 2-4.
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To me, it resembles the green mix of serpentine and marble found in the Highlands - it has a name, but cannot recall it.
Another possibility would be a feldspar like labradorite, although I haven't seen a pattern like that. The pattern also isn't something I've seen in prehnite, which I also initially thought as a candidate.
Some of those reds look as if they'd cut nice gems, too!
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Hi hummingbirdstones and rocks2dust and thanks for the input. The green stone is a puzzle especially with the hardness...hmmm. I had a look at the Iona marble pictures found around the highlands and came across descriptions of good quality stone as green nephrite or Iona Jade...that would be so cool but my stones still looks a little odd compared to the google pics. The little green nodule stone feels pretty light so i'm hoping its hollow when i cut it.
I have found a beach that is absolutely awash with the red jasper you can see in the pictures, there are also greens and oranges there too but in smaller quantities.
Cheers :occasion14:
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We have a sone here that fits the qualifications , enstatite , but yo0u will not find it on the internet except for the pieces I have posted on this forum. The net shows crystalline enstatite but it also comes in a massive form and is green and extremely chatoyant.
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I knew you'd know what it was, Frank! :icon_sunny:
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Obviously this is just a guess but there are not a lot of massive chatoyant things out there. Having said that I just cut a 65 lb jade we found in situ a few years ago and it was wildly chatoyant. I know for sure that this type of enstatite as well as orthoamphiboles of a different but wild chatoyantcy are found along the coast of Greenland and glaciers could have moved them to Scotland. A few years ago we were startled by a geology paper that was able to trace a rare fossil in quartzite found on my island in Puget Sound to it's source in Alberta changing the way a lot of people think about glacial paths.
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Interesting and it makes perfect sense to me that glaciers could have moved it from Greenland to Scotland.
Sure hope you're going to show a piece of that chatoyant jade for us to drool over!
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Thank you lithicbeads i love this forum. Wow it never crossed my mind the possibility of glaciers and a well travelled stone...just when you think you're getting a handle on this a whole new set of possibilities opens up.
I polished a face on one of the stones and it takes a super polish, it looks so good and so strange i was beginning to think it was manmade. I think i'll have a little 'water of life' to help me contemplate :occasion14:
Thanks again... :hello:
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The color of that green stone matches our massive idocrase ( vesuvianite ) perfectly but I have seen many thousands of pieces and have never seen chatoyantcy.
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It is nigh impossible that stones in Scotland would be glacial erratics originating in Greenland. For one thing, there is no way anything would be carried across an ocean basin and up the other side (much less across the Mid-Atlantic Ridge). The British Isles also were never connected to Greenland in the past (before Pangea split apart). For isolated deposits near harbors, there is always the possibility of ship ballast being dumped, though the likelihood is very slight that any such rock would have come from Greenland (a Viking wreck?). Occam's Razor would have you look for something similar that is closer to home.
The suggestion of vesuvianite is an interesting possibility. There is some metamorphosed vesuvianite in limestone deposits in Aberdeenshire and Skye, though I haven't seen anything as large or similar in appearance as your pieces from there (just small, brown crystals). Worth considering, however.
I'm also wondering whether what you've described is chatoyancy (a shifting inner glow/line caused by inclusions, lamellae, etc.) or pleochroism (a shift of color depending on how the crystal is oriented)?
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Hi rocks2dust, i managed to get some outside pics 2day to try and shine a light so to speak. Some great points from your post especially something closer to home and the chatoyant or pleochroism(new for me)question. I don't have the answer unfortunately and may have to make a video.
I had a look on the internet for some time yesterday trying to compare it to something, but maybe its simply a strange variant of a common green stone?
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I also finished a cabochon for a friend from the red material in the pics. It turned out well so i popped out and filled another rucksack yesterday.
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cheers :occasion14:
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Just to stir the pot- While your piece does not look like nephrite it is known from the Shetland Islands from a body of ultramafic rocks.Fetlar and Balta Islands have reportedly hosted nephrite.That is all the info I could find.
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While being abundantly ignorant, my initial thought was Nephrite. Of course, living on a glacial till I pretty much think I could find almost anything left by the glacier, so I'm assuming similar conditions occur where you are--but, I'm probably wrong.