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 Post subject: What is this?
PostPosted: Thu Sep 03, 2009 5:39 pm 
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I found a brown (ugly?) stone not far from where I live. Since I am always looking for weird things to cut I give almost any material a chance... so I cut it and made a quick polish just to get a view of how it would look like and if I could use it in one my jewellery pieces...

Do you have any idea what it could be?

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PostPosted: Thu Sep 03, 2009 6:01 pm 
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Location: San Francisco
Hardness?


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PostPosted: Thu Sep 03, 2009 6:26 pm 
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I would say around 3-4.
Matrix: White
Some veins with darker (green) minerals which should be >3-4 in hardness. Probably Pyrite may be seen in some spots on the back off the stone.
The green spots is black on the brown decomposed surface.


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 Post subject: Re: What is this?
PostPosted: Sat Sep 10, 2011 4:31 am 
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Location: Sweden
As I suppose its a rock found in Sweden I would suggest some kind of calcium based mineral. It looks similar to the mix of marble and diopside found around Sala silvermine, the pyrite specks are also common there.

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 Post subject: Re: What is this?
PostPosted: Thu Sep 15, 2011 3:01 pm 
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If it doesn't scratch glass then it's not a quartz based rock, maybe it's calcite based such as marble.
Calcite reacts to a tiny droplet of white vinegar with effervescence (I suggest trying white vinegar first as this acid acts softly, but you'll need to watch closely to see the effervescence).


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