[Jewelry making - Article 00122] - Re: [Orchid] Blue Quartz/Blue Agate

[Beth Rosengard]

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    Hi Carrie, Agate, a type of chalcedony, is a member of the quartz
    family (chemically, silicon dioxide).  The difference is that all the
    varieties of chalcedony (agate, jasper, etc.) are microcrystalline or
    cryptocrystalline.  In other words, they are composed of microscopic
    crystals of silicon dioxide as opposed to what we call quartz, whose
    well-formed, definitely non-microscopic crystals we're all familiar
    with. 

    Agate is distinguished by its banded appearance and usually includes
    translucent material; jasper is massive, dense and opaque. 
    Microcrystalline quartz which is translucent but not necessarily
    banded is called simply chalcedony (like the recently very popular
    blue chalcedony). 

    Assuming the material you've described is actually natural quartz
    (as opposed to a simulant, like glass) and if it is even slightly
    translucent rather than opaque (which I suspect), I would be tempted
    to call it chalcedony.  It's difficult to nail down without seeing
    the rough material it came from. 

    On the other hand, if in the rough it formed a band between other
    colors of quartz minerals, then it might properly be called agate. 
    Either way, you can't really go wrong calling it quartz which is the
    umbrella term for the whole family of minerals. 

    I've not seen this material, by the way, but I am not aware of the
    availability of large quantities of a dark blue quartz.  My guess is
    that it's dyed or otherwise color-enhanced. 

Beth   


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