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Please ID - Havent the fainest idea! Am baffled!!!

Posted by claire Brimson  
claire Brimson April 22, 2012 06:19PM

Found this again in Oulujoki riverbed under the ice, was digging ice! Finland. It absolutly stinks of Arsenic! The black stuff on top cannot be marked with a penknife only a pegmatite leaves a scratch and there is a streak of grey/black to it. The rest of the rock leaves a streak of black also and is much softer - easy to scratch with penknife! I have not as yet tried to hit it to see if garlic is realesed. It is also heavy. Some of the black stuff had different colours in it as well. I left it in the sun to see if it would go sticky but it was rock solid as it were.

Any ideas???

Many thanks once again.

open | download - 017.JPG (144.9 KB)
open | download - 015.JPG (164.1 KB)
open | download - 005.JPG (151.9 KB)
José Zendrera April 24, 2012 10:11AM
I can not see any crystalized form on the black / hard part but rounded shapes.
Just a guess: Perhaps a silex nodule in calcareous rock?


Edited 1 time(s). Last edit at 04/24/2012 08:31PM by Jose Zendrera.
claire Brimson April 24, 2012 03:29PM
Jose - I have attached another photo - does this help? Why does it smell Arsenicy?

Many thanks

open | download - 006.JPG (94 KB)
José Zendrera April 24, 2012 08:53PM
Sorry Claire, I have not more ideas, to me, could be a silex nodule, do not looks as crystalized. Also could be something syntetic.
Anyway, if it smells like arsenic, you must take care with it!

claire Brimson April 25, 2012 02:35PM
Thanks Jose, for your help. I am as baffled as you probably are as well.


Sam Cordero, Jr. April 25, 2012 04:33PM
Looks like you have some greenish blue minerals. Those could be the common malachite/chryscola combos. The brown could just be sandstone, and the creamy colored mineral barite. This specimen reminds me of material I found in an old barite locality. Just a hunch. You should perform some basic tests to narrow it down. Good luck.
claire Brimson April 26, 2012 05:45PM
Hi Sam

Many thanks also. Which sort of tests should I try please?

Pekka Ruoho May 18, 2012 06:01PM
Hi Claire,
do you think it could be Arsenopyrite or Löllingite?
try to clean the surface (brush or knife) somewhere.
see this small piece of löllingite from kaatiala after som cleaning
regards PekkaR
open | download - kaatiala.jpg (226.8 KB)
claire Brimson May 18, 2012 06:33PM
Hei Pekka

No, it wasnt that, But.... I do have some of that as well!

Very many thanks for turning up here - tis great to have Finnish guy on here as wel who is local l :-)

Anonymous User May 18, 2012 06:34PM
Clair the last pic seems to show a tar like material? and in the second last can i see vecicals?
Jolyon & Katya Ralph May 18, 2012 06:40PM
Looks like classic gossan material to me - formed after breakdown/leaching of primary sulphide minerals, so if there was any arsenides in that mix the arsenic smell is not surprising.
Paul Brandes May 18, 2012 06:52PM
There is a lot of the same looking material in the Magdalena Mountains of central New Mexico USA from the weathering of iron sulphide rocks near the Graphic and Nitt mines; this material is gossan, just as I suspect yours is as well Claire. The arsenic/sulphide odour you describe is a common indicator of the breakdown of sulphide minerals. The Nitt mine I mentioned earlier has a very pronounced sulphur odour associated with it; you can "smell" the mine long before you see it through the forest.
claire Brimson May 18, 2012 06:58PM
Very many thanks to you guys :-)

I put it on the railroad here as it just stank and was unsafe in smell (arsenic), so now the railroad smells :-D

Thank you very much for your help with this one and with all my queryries on rocks. I learn from you all.


Anonymous User May 21, 2012 09:19PM
Claire the first three pics seem to show what could be fossil sea life ie coral or crynoid stems?
claire Brimson May 22, 2012 05:58PM
Hiya Heath

Many thanks... when I first glanced at it, I thought similar but then a closer inspection showed the black stuff with almost irredence in it and the smell of arsenic was a wee bit overpowering! So that kinda put a halt on my sea theory. I have since found out there is some sort of factory up river..... dont know if that has anything to do with it, but I have since also found other bits similar in the river bed as well...

By the way, I went to the Geological museum to try and find out about your rocks... I spent most of the day there (easiily done - rocks :) ) but could not really find anything that looked similar apart from mica and graphite! I know of graphite mine in Derbyshire/Pennines..... but......????

Will try again when I have time....

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