[meteorite-list] what is the world standards for petrographical preparations(polarization microscopy)

[Paul H]

E. L. Jones jonee at epix.net wrote:

>I am also interested in the use of "quartz" 
>as index markers.  This isn't in any of my 
>reference books.  Are they attached to the 
>specimen and ground at the same time as the 
>thin section?

No. The person grinding the thin section uses 
the bifringence of whatever minerals are 
present to judge the thickness of the thin 
section. Quartz is used as an index marker 
simply because, it is so common as to be 
present in most sedimentary, igneous, and
metamorphic rocks. When it isn't present, 
a person uses whatever mineral happens to
be in the thin section as an index.

Some web pages are:

Making Petrographic Thin Sections
http://www.union.edu/PUBLIC/GEODEPT/COURSES/petrology/thinsections.htm
http://almandine.geol.wwu.edu/~dave/other/thinsections/
http://www.lpl.arizona.edu/~rhill/fossil/thnsect.html

Making Petrographic Thin Sections
http://www.uni-wuerzburg.de/mineralogie/links/tools/making.html

Rock-Forming Minerals in Thin Section
http://www.uwgb.edu/dutchs/petrolgy/thinsect.htm

Atlas of Rocks and Minerals Under the Microscope
http://www.geologynet.com/thins.htm

Igneous rocks in thin section
http://www.union.edu/PUBLIC/GEODEPT/COURSES/petrology/ig_minerals.htm

Minerals in thin sections
http://www.uni-wuerzburg.de/mineralogie/links/petrology/thinsection.html

>Another question I have.  Is there a house 
>that specializes in preparation? Kinda of 
>like the $2 a carat faceting deals one can 
>get in Thailand?
 
There are many places that specialize in making
thin sections. Typically, a person gets what
they pay for. A quick search using Google will
find a number petrographic labs that make thin 
sections. If you are going to pay 5 to 50 dollars
a gram for a meteorite, paying 15.00 dollars for
a high quality thin section is the least of 
your costs.

The people that use to make the thin sections for 
my research (and search for more shocked quartz) 
from samples in the Brushy Creek Carter is:

National Petrographic Service, Inc.
5933 Bellaire Blvd., Suite 108
Houston, TX 77081
http://www.nationalpetrographic.com/

Their price list is at:
http://www.nationalpetrographic.com/thin_sections.htm

Their price are average for what thin sections cost.

Elton

>Roman Davidov wrote:
>>Dear list members. Hello.
>>My question is: What is the world standards for 
>>petrographical preparations. If I'm not mistaken 
>>in English it sounds like "THIN SECTIONS".

Yes, as noted above, the term is "thin section".

>To be more concrete I mean: form and sizes of 
>object glass (width,height,thickness); 

The glass slide of the standard thin section is 
27 x 46mm (1" x 1 7/8"). Larger slides are produced,
but size might vary according to the lab that 
prepares them. For example, National Petrographic
has 38 x 75mm (1.5" x 3") and 50 x 75mm (2" x 3")
size glass slides for larger size thin sections.

>type of optical glue (we are using composition
>named "Canadian Balsam");

Hillquist A-B is used to glue slabs to slides.
However, Canadium Balsam is the standard for 
attaching the coverslip. If you want to do any
microprobe, etxching, or similar work, i.e. for
identifying shocked quartz, the thin section needs
to be finished by polishing and the coverslip 
left off.

>linear sizes of object (I'm sure that thickness 
>is one to all of the world - 0.003 millimeters); 
>form and sizes of cover glass. 

The only requirement for the size of the object
is that it is a few mm smaller than the size of 
the glass slide being used. The coverslip is
larger than the specimen and smaller than 
the slide. 

The coverslips come in sizes, thicknesses, and 
optical character that are standardized for use  
in making thin sections. A person needs to talk 
with the people supplying the coverslips and 
get the technical specifications of what they
are selling to see if they are suitable for 
thin sections.

...text deleted...

Yours,

Paul
Baton Rouge, LA





	
		
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