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975 Views 1 Reply Last post: Oct 20, 2013 12:24 PM by MikeHardman RSS
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Oct 20, 2013 9:55 AM


Portobello edinburgh sumarian?neolithic?alien?

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    Oct 20, 2013 12:24 PM (in response to nowayusa2013)
    Re: p

    I don't think it is anything so exciting, certainly not alien.


    It is a pebble of concretionary nature.


    That is, many rocks contain veins, of one arrangement or another. Where the veins are particularly concentrated and arranged, it may be a concretion of the sort called a septarian concretion or nodule. (There are other concretions that do not have the veining.)


    If I am understanding your photos correctly, your particular pebble crosses the contact between two somewhat different fine-grained rock types, probably sedimentary. I suspect the blue side looks bluer in the photo than it really is (?). Veins with a pale blue colour are not common in sedimentary rocks (in metamorphic rocks there are several candidate minerals, such as kyanite). If I had to guess, I would choose celestine.

    See also



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