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I agree with what Bruce has said. Some of these inclusions look very similar to synthetic fluid inclusions (in quartz) that Bob Bodnar has made here at Virginia Tech.  And some of the inclusions also definitely look like quartz.  You should also consider that the brown ones, however, could be very thin plates of ilmenite. These occur in pyroxenes, although most commonly as subsolidus exsolution lamellae in magmatic Ti-rich opx and cpx rather than in metamorphic minerals.  In any case, these thin plates in pyroxene are translucent and brown, very much like yours look.

I also concur with Eric's earlier comments that you should definitely examine these with SEM (or BSE on a microprobe) with EDS available for mineral identification.  The appearance on a surface will likely eliminate textural ambiguity introduced by multi-level very small inclusions within the thickness of the section.

Bob T.

Bruce Yardley wrote:
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Dear Fatemeh

 

Nice photographs! I think that this is probably not a symplectite texture, because that term is normally used to imply an intergrowth. Instead, these look like fine grained inclusions. The most likely possibilities are quartz, possibly with some graphite and/or ilmenite, but some of them look very like fluid inclusions. You should study them at high magnification and with crossed polars to see if you can tell how they are modifying the birefringence of the staurolite host. If you find it difficult to tell, because the inclusions are much thinner than the section, then you might try to get the section ground thinner so that any birefringence differences between inclusions are made clearer. Small solid inclusions like this almost certainly arise due to the porphyroblast beginning to grow when the rock matrix was very fine grained. For example, if inclusions are of quartz each one will have a different extinction position as it is a different original grain. It looks like the matrix of the rock is now very coarse grained and rich in muscovite. Sometimes pelitic rocks are graphitic and fine grained during their early metamorphic history, but the graphite is gradually burned off, and once it is gone it is easier for the matrix to recrystallise to a much coarser grain size. You can find a wide range of staurolite textures in the literature, but I am not sure if I can recall any exactly like this. Start with the textbooks of texture such as Vernon or Barker and look at examples of staurolites in my “Atlas of Metamorphic Rocks”.

 

Good luck

Bruce Yardley

 

 

Professor Bruce Yardley

School of Earth and Environment - Earth Sciences

University of Leeds

Leeds LS2 9JT

UK

Tel. +44 (0)113 3435227

 

 

-----Original Message-----
From: Metamorphic Studies Group [mailto:[log in to unmask]] On Behalf Of fatemeh fadavi
Sent: 08 December 2008 10:46
To: [log in to unmask]
Subject: Fwd: Staurolite

 

 

---------- Forwarded message ----------
From: FATEMEH ERFANI <[log in to unmask]>
Date: Mon, Dec 8, 2008 at 2:12 PM
Subject: Fwd: Staurolite
To: [log in to unmask]



---------- Forwarded message ----------
From: FATEMEH ERFANI <[log in to unmask]>
Date: Sun, Dec 7, 2008 at 9:06 AM
Subject: Staurolite
To: [log in to unmask]

Dear sir

 

It is Fatemeh Fadavi new member of your beneficial comunity MSG.

I am master of petrology who has worked on metapellitic rocks.

Resently i has seen a sympelectite texture on Staurolite in a Garnet Staurolite Silimanite schist.

Do you minde if you follow me how can i find apporpriate contents about it or where can i download suitable papers.

 

Thanks for your attention

Sinserely yours

F.Fadavi

 

 


--
Robert J

Dr. Robert J. Tracy

Professor of Geosciences

Department of Geosciences

5064 Derring Hall, Virginia Tech

Blacksburg VA 24061-0420

 

Office Phone:  540-231-5980

Fax: 540-231-3386

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