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 Post subject: Unknown mineral.
PostPosted: Sat Dec 31, 2016 6:16 am 
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Morning, my parents found a beach full of this mineral in Scotland, UK.
Any ideas what it is?

Thanks.



Image

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Last edited by ChrisUK on Sat Dec 31, 2016 5:06 pm, edited 1 time in total.

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 Post subject: Re: Unknown mineral.
PostPosted: Sat Dec 31, 2016 1:37 pm 
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Hi Chris.
Looks like a mica schist.
Not uncommon in Scotland.


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 Post subject: Re: Unknown mineral.
PostPosted: Fri Feb 24, 2017 9:34 am 
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Granite, made up of quartz, feldspar, and mica.


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 Post subject: Re: Unknown mineral.
PostPosted: Sat May 13, 2017 1:05 am 
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Looks like cobbles of Lewis Gneiss, common in NW Scotland


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 Post subject: Re: Unknown mineral.
PostPosted: Sat May 13, 2017 1:29 pm 
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When your gneiss people take you for granite. ..

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 Post subject: Re: Unknown mineral.
PostPosted: Sun May 14, 2017 11:03 am 
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I'm still going to vote for schist also very common in Scotland....a pre-gneiss so to speak.


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 Post subject: Re: Unknown mineral.
PostPosted: Wed May 17, 2017 4:16 am 
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Barbra Voltaire wrote:
I'm still going to vote for schist also very common in Scotland....a pre-gneiss so to speak.


agree..

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 Post subject: Re: Unknown mineral.
PostPosted: Wed May 17, 2017 6:31 pm 
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I'm not a metamorphic petrologist, but I would definitely favor gneiss over schist based on the coarseness and arrangement of the crystals and the presence of what appears to be k-spar.

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 Post subject: Re: Unknown mineral.
PostPosted: Wed May 17, 2017 11:59 pm 
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I dunno, Stephen..... I definitely do not think it is an example of Lewis Gneiss.


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 Post subject: Re: Unknown mineral.
PostPosted: Thu May 18, 2017 2:19 am 
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I'm not familiar with the Lewis Gneiss in particular, just gneiss in general.

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 Post subject: Re: Unknown mineral.
PostPosted: Mon May 22, 2017 9:25 am 
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These are rocks, made up of several different minerals: in your specimens you can see quartz (transluscent, colorless to grayish), feldspar (opaque, cream color), and mica (shiny and foliated)

IMO, the rock on the left makes me think of granite (random structure), almost pegmatitic considering the size of grains, while the others look more like gneiss (foliated structure with bands)


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