Fluorescent Yellow Mineral?

littlemac1980

Quick question if anyone could please help.

Forgive my total lack of knowledge.

I've been killing time collecting stones and breaking them to see what's inside.

I found a small piece of what I'm guessing is a piece of metamorphic rock.

When I looked at it under UV - none of it was glowing apart from a small amount of black flaky brittle stuff that is bright yellow under UV - I really only have a tiny bit of it so I think taking a photo would be very difficult. It seems to be a thin layer - probably one tenth a millimetre thick and a few millimetres in diameter - it was a small stone.

Any ideas what it is?

littlemac1980

Actually upon further inspection it seems that I had some white substance still attached to the black stuff and it seems to be the White stuff that's turning yellow.

I can't find the reference I had spotted yesterday online but I think I recall that it's likely to be Calcite that's glowing.

Step23

Put a small bit of vinegar on the fluorescent material, if it fizzes, its calcite.

Stephen

littlemac1980

Right well I submerged one piece of the black material which was had some fluorescent material attached to it in a short glass on vinegar and there was no reaction.

When I removed the flake again with a tweezers and checked it under the UV it's still bright yellow to the same extent.

Step23

littlemac1980 wrote: »

Right well I submerged one piece of the black material which was had some fluorescent material attached to it in a short glass on vinegar and there was no reaction.

When I removed the flake again with a tweezers and checked it under the UV it's still bright yellow to the same extent.

Interesting, I'm not sure what the black material could be, odd that is it fluorescent. Possibly something organic?

I think I need more details or a picture.

Stephen

littlemac1980

I managed to take some photos with my phone, unfortunately the image under uv is a good bit darker that it appears in reality (I.e. The yellow is much richer and brighter than it appears) and it's orientated at 90 degrees difference to the "true" colour image despite taking both pictures at the same orientation, and I can't change the orientation on either my phone or iPad.

So here they are:

That's a ten cent piece in the photo.

The piece between the stone and coin is the one soaked in vinegar.

The White specks in the UV image are just something from the plate underneath.

littlemac1980

And :

littlemac1980

Smaller

littlemac1980

Snip

littlemac1980

You can see where the fluorescent piece is attached to the fragment of stone how the fully intact layer was likely attached before I smashed it.

I don't think the black material is fluorescent at all to be fair.

I've since tried just a drop of vinegar on the larges flake to the right but still no reaction.

Step23

Yes it would have been too odd if the black material was fluorescent.

We can assume as there was no fizzing that the mineral is not calcite.

I'm scratching my head to think what it could be, maybe more info on the where you found it would help, geological setting etc.

littlemac1980

Step23 wrote: »

Yes it would have been too odd if the black material was fluorescent.

We can assume as there was no fizzing that the mineral is not calcite.

I'm scratching my head to think what it could be, maybe more info on the where you found it would help, geological setting etc.

Just among stream gravel at the side of a small brook in North West Cork, Redsandstone Area close to Macroom. Rural, with no recent development nearby. 95 percent of all other stones were sandstone with occasional small pieces of Quartz or probably feldspar (as far as I know). A couple other bits of hard gray smoothish stones (kinda like the consistency of Flint - but not Flint).

BASHIR

Mis read the first post

littlemac1980

BASHIR wrote: »

Mis read the first post

Well my first post is incorrect anyway, in relation to the material being black - it's not, it's the whitish material attached to the black that glows.

Unfortunately there's such a small amount of it that it's hard to see any physical characteristic of the material itself.

Step23

littlemac1980 wrote: »

Well my first post is incorrect anyway, in relation to the material being black - it's not, it's the whitish material attached to the black that glows.

Unfortunately there's such a small amount of it that it's hard to see any physical characteristic of the material itself.

See can the white material scratch glass or not... well take it from there!

littlemac1980

I've found reference to something called Espirite that is supposed to glow bright yellow under UV but then the Wikipedia pic of it shows it having a clearly greenish colour.

littlemac1980

Step23 wrote: »

See can the white material scratch glass or not... well take it from there!

Ok I'll try an check that tomorrow morning so and let you know. Cheers.

Step23

littlemac1980 wrote: »

I've found reference to something called Espirite that is supposed to glow bright yellow under UV but then the Wikipedia pic of it shows it having a clearly greenish colour.

Far too exotic for Ireland! I don't think it's even recorded as being found in Ireland.

littlemac1980

I tried to scratch glass with it and while I failed to do so to be honest I don't think its possible to try properly given the small amount I have as when I applied force to it (using the piece attached to the stone) it eventually just ended up dislodging from the piece of black stuff which it is attached to - perhaps that's sufficient to say it doesn't scratch glass but maybe I'd need a larger amount of it by itself to be sure.

Step23

Sorry for the delay coming back to this.

I'll throw out that it could be feldspar. Feldspar can be fluoresce and won't scratch glass, but without a larger sample it is going to tricky to get an exact ID.

Hope I've been of some help,

Stephen

littlemac1980

Step23 wrote: »

Sorry for the delay coming back to this.

I'll throw out that it could be feldspar. Feldspar can be fluoresce and won't scratch glass, but without a larger sample it is going to tricky to get an exact ID.

Hope I've been of some help,

Stephen

No Problem about the delay.

Thanks for your help.

I agree that I need to find a bigger sample to be able to properly consider what it may or may not be.