Little Crystal

[yakker]

Before the snow covered everything up, I spotted this little guy on the river wash. I'm so looking forward to being able to kayak up river to investigate the possible sources!
(and for anyone with a keen eye, yes that is a table-top my father made of old hockey sticks... )



and still wondering what kind of rock/mineral this might be (from an earlier post). Deep blue green and although the pic is blurry, you can see the cross-hatching of 'grain'. The piece held to light is the same as the one at @ 2 o'clock in the basket. Central Virginia Blue Ridge foothills. Thanks for looking!

 

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[BurntBear]

The first photo looks like a terminated Quartz crystal.

The other two really look like Blue Quartz. I have many specimens just like this from North Carolina:



Blue Quartz is almost always caused my tiny, needle inclusions of other minerals (Tourmaline, magnesio-riebeckite and dumortierite).

http://www.quartzpage.de/blue.html

 

[yakker]

Thanks BB! Yeah- I knew about the little crystal- which would have been x2 terminated had it not been bashed on one end The other- I don't think it's blue quartz. I find a lot of that and where I am it's very opaque, but blue- like yours. This has some clarity to it- and the criss-cross grain isn't rutile- though I have seen rutile in other specimens of other things. This is a deep greenish blue. I've tried scratching it to see if it's soapstone, but it isn't and doesn't scratch w/ copper or nail. I had seen somewhere a sub-category of serpentine called serpentinite, but haven't seen that word anywhere else, and don't even know if it's a real mineral or what. I posted a bunch of pieces maybe a week ago. Not great pics, but at least they show glassy face, where one is broken and the association w/ other rocks, plus the texture and 'grain'. I'd read somewhere that sometimes this serpentine would be associated w/ asbestos, and I'm not certain whether I see it or not. There seems to be a silver almost fabric-like fibrous area on one piece. Take a look if you get a chance and see what you think. If you can't figure it from the (not great) pics, I'll bring them down to the rock shop in town and see what that guy thinks. Thought maybe you'd come across stuff like this in your Appalachian adventures...

 

[BurntBear]

I think you're right. It may be part of the Serpentine Group.

Some Serpentine related specimens:

http://www.mindat.org/photo-121303.html

http://www.mindat.org/photo-155034.html

 

[thehunter123]

Nice crystal yakker! There's more where that one came from I can guarantee you that...the big deposits always start with that first small one. Kayaking sounds like a blast! Good luck with your search.

 

[yakker]

Thanks Hunter123! Yeah, hence my 'name'. Yakking has revealed any number of otherwise inaccessible places to me, and I'm always frustrated when I have to rely on my feet alone. I've found 4 of those little puppies so far. All of them river-worn, but crystals none the less. Def. looking forward to spring. BTW, I LOVE what you're pulling out of that pocket! Just stunning

 

[DDancer]

Neat stuff and a good score on the crystal. I would not think there were serpentine's like that~ have to read up on them a bit more. Hrm... seems like a good prospect.

 

[Eu_citzen]

I'd investigate towards flourite, try scratch it with a knife. The lines could be signs of cleavage,

 

[yakker]

Hey EU-- I tried scratching it w/ a knife, and it doesn't. I'm not convinced it's serpentine. But I considered that it might be in the family, so to speak. I'd never read anything about serpentinite- which was the closest thing I could find that was found in association w/ epidote. I'd looked up epidote and knew that it was present in that area- and went looking for it. When I found those deep green rocks w/ translucence, I tried to figure out what was found in association w/ epidote. 'Serpentinite' came up. I'll have to keep investigating this. I know there's more up there too. Just have to wait for the snow to melt now... Had never considered flourite. Thank you. The VA Blue Ridge is an interesting place. And I'm a wet-behind-ears amateur

 

[DDancer]

Fluorite would have scratched with a knife but EU did point out a good thought on the apparent striations in the stone. Any thoughts to it having a relation to feldspar?

 

[Eu_citzen]

I'd like a better picture, please. Will a quartz scratch it?

As for serpentine, it will also get scratched by a knife. So you can get that one out of the equation.
Serpentinite is a rock containing serpentine.

Serpentinite outcrop:


Close-up:


I think your "association" is a bit to... Close up? Epidote alone doesn't make out much reliable information for an association, IMHO.
The rocks it occurs in can tell you so much more.

 

[yakker]

Hi Eu- Thanks for that. I can't get a pic today- missed the light (and don't have proper indoor lighting). Quartz does scratch it. It is mixed in with quartz. Tried grinding a piece last night. The green translucent grinds, the quartz (obviously) doesn't on my table-top grinder- which, BTW is not made for grinding stone... Just thought I'd give it a go to see what happened. I could get a face on the green, but not if there was any quartz where I was grinding. Could it be talc?

 

[Eu_citzen]

Talc is about the softest mineral you can find - so no. I'd go with DD and guess feldspar or even cordierite. Do you see colour variations depending on angles?

 

[yakker]

Talc is about the softest mineral you can find - so no. I'd go with DD and guess feldspar or even cordierite. Do you see colour variations depending on angles?

Duh...I knew that. Queen of stupidity here. Feldspar- meaning what's often called amazonite? It's a little dark (I think) for that. As for color variations at different angles, I *think* I see variations, but I'm not certain if it's the mineral or where quartz has a presence. Dim light today, and I just can't capture the color. The best I can say is deep blue-green- or green-blue. Like the color of some algae- but not at all yellowish. I think I'll have to pay a visit to my local rocks and gems guys and see what he says. Also joined the local chapter of rocks and miners club, so that'll help too. Thank you for all you efforts. My pics just don't help...

 

[Eu_citzen]

Let's just call it feldspar for the sake of ease. Although the colour for amazonite can vary greatly.