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Could this be epidote?

Posted by Mathias Stålek  
Could this be epidote?
February 19, 2012 06:39PM
Hi!

This is probably a rather basic question.
Could this green mineral be epidote?

There is not much sign of cleavage but it could be because it rather fine grained.
Hardness 6-7
Density 2.96 g/cm3 but this is average and some parts are quartz and feldspar so the green mineral is heavier.
The origin is a metamorphic iron ore.

Thanks.

Regards, Mathias


Re: Could this be epidote?
February 19, 2012 07:15PM
    
It could be epidote, or it could be a mineral in the chlorite group. A teacher of mine consequently called these "shitandpowderite", because it's difficult to tell what it is and they're kind of ugly looking.
avatar Re: Could this be epidote?
February 19, 2012 07:30PM
Mathias,

Your specimen looks like a piece of basalt that has been "epidotised" during burial metamorphism. The hardness fits, as does the specific gravity. It is not derived from the metamorphism of iron ore.

Curiously, where was this found??
Re: Could this be epidote?
February 19, 2012 08:06PM
    
Yes, most probably epidote.
Re: Could this be epidote?
February 20, 2012 06:47AM
Thanks!

It was found on the mine dump of a closed iron mine in Idkerberget. It's a small town in Dalarna province in Sweden. I can't find the locality on Mindat. I don't know much much more of the geological settings.

I guess it's derived for metamorphism of feldspar.
avatar Re: Could this be epidote?
February 20, 2012 07:56AM
    
I know such specimen under the name pistazite which is a variety of epidote.
avatar Re: Could this be epidote?
February 20, 2012 11:28AM
    
Mathias,

I agree with the others that your specimen looks most likely to be massive epidote.

However, regarding your observation that " . . . I can't find the locality on Mindat . . .". There are many known mineral localities not listed on Mindat. It would not be reasonable to attempt to list every known spot where massive material of very abundant rock-forming minerals such as quartz, calcite, epidote, the common feldspars, pyroxenes, micas, garnets, clay minerals, etc can be found. That would involve listing every outcrop - every mountain crag, coastal rock, stream bed, gravel pit, road cutting etc in the world!

For very common minerals, it has to be a matter of judgement regarding such features as unusual crystallisation (e.g. exceptional crystal size, colour, or rare habit), an unusual paragenesis, economic importance, etc. as to whether a particular occurrence is of sufficient interest to be worth registering as a Mindat locality.

Having said all that, my view is that any mine site is worth registering, since that would qualify the locality in terms of being an "economically important deposit"!

Pete N.
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