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210 Views 3 Replies Last post: Jul 9, 2014 4:35 PM by MikeHardman RSS
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Jul 9, 2014 2:57 PM

assistance with Rock I.D Please

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Message was edited by: Rockstar

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    Jul 9, 2014 3:01 PM (in response to Rockstar)
    Re: assistance with Rock I.D Please

    Quartz.

    The rather asymmetrical nature of the crystal is typical.

     

    Mike

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        Jul 9, 2014 4:35 PM (in response to Rockstar)
        Re: assistance with Rock I.D Please

        I thoguht your original question was a little terse!

         

        Nice twinning.

         

        I am not familiar with your test equipment, but in general:

        - such things are only as good as their operator (if that)

        - most mineral species are variable to some extent, which increases the chances for misidentification.

         

        My feeling is still quartz; spinel tends to be more regular in its crystal faces (different crystal systems).

        ...And as you rightly say, a nice clear specimen like this would be rather rare if spinel.

         

        Spinel and quartz have several technical similarities, but one easy one you can use to discriminate is density.

        Spinel is ~3.6-4.1g/ml; quartz is 2.65g/ml.

        You have a nice solid specimen (without cavities and disinclined to absorb water), so you will be able to measure its volume accurately using the water displacement method. Then, once weighed (more accurately than 'about 45g'), you can calculate its density.

        Let us know!

         

         

        For ref:

        - spinel - http://www.mindat.org/min-3729.html

        - quartz - http://www.mindat.org/min-3337.html

         

        Welcome to NaturePlus!

         

        Mike

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