[Rockhounds] Blue Schist

[Lawrence Rush]

Teri: I know little about either blueschist or lapidary! So, I'll let 
someone else answer this...it does seem to me that schist, in general, would 
not be a good candidate for cutting cabs, as it usually has several minerals 
of varying hardness as  constituents, including mica.

Larry




----- Original Message ----- 
From: "teresa jetter" <territoones1 at ameritech.net>
To: "Rockhounds at drizzle.com: A mailing list for rock and gem collectors" 
<rockhounds at lists.drizzle.com>
Sent: Monday, July 23, 2007 11:01 AM
Subject: Re: [Rockhounds] Blue Schist


> Hi Larry
> could you tell me what the hardness of the Blueschist
> usually is?  It seems from the reading that it can be
> formed from a few different specimens.  Would it be
> good or bad, for cutting cab's?
> Thanks
> Teri J
> --- Pmodreski at aol.com wrote:
>
>>
>> Hi Larry,
>>
>> I'll give an answer.  Blueschist (it's usually
>> written as one word)  actually
>> refers to a particular kind of metamorphic rock,
>> glaucophane  schist.  This
>> contains the mineral glaucophane, which is actually
>> kind of a  bluish-purple.
>> It's found in areas such as coastal northern
>> California--the  Franciscan
>> Formation.  Someone who lives in the S.F. Bay area
>> and  knows about local geologic
>> sites would probably know how to obtain a  specimen.
>>
>>
>> It's not really noted for good crystals, just a
>> somewhat unusual
>> grayish-bluish-purplish rock that is of interest to
>> geologists.   Glaucophane schist
>> occurs in metamorphic rocks that form in a somewhat
>> unusual  environment of high
>> pressures and relatively low temperatures; in zones
>> of plate  collision and
>> subduction (e.g., California!).
>>
>> Pete Modreski
>>
>>
>>
>> In a message dated 7/17/2007 8:06:19 AM Mountain
>> Daylight Time,
>> larryrush at worldnet.att.net writes:
>>
>> List: I  received this from a student in Fla. I
>> don't know of any "blue
>> schist", the  only thing that comes to mind is
>> possibly a finely divided kyanite
>> schist. Can  anyone help her?
>>
>> Larry Rush
>>
>>
>>
>>
>>
>>
>>
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