[meteorite-list] Polarizing microscopes & thin sections on a budget

From: J Sinclair <john_at_meteoritecentral.com>
Date: Sun, 8 Jun 2014 16:51:23 -0400
Message-ID: <CAAeS-uvrwTQJJoFXgLr_t7nR3AgXkWTYm03YgYB1vZO=SkZBrg_at_mail.gmail.com>

Hi List,

I don?t remember when I saw my first meteorite thin section through a
polarizing microscope. I feel certain I must have seen photographs
first.

Many years ago I found a polarizing adaptor that would work on a
stereo gemstone microscope that I owned. I then started buying a few
thin sections from fellow dealers.

On several occasions a meteorite collector and friend, Jeff Hodges
came to my house. On one visit, I showed him a collection of left over
meteorites that had been used for making thin sections. One of these
was the Kapoeta Howardite that I acquired from an auction of
meteorites from the E.A. King collection via Steve Arnold. Jeff had a
fellow making thin sections for him and I agreed to let Jeff get some
thin sections made from my meteorites and we would share the slides.
Jeff was very reluctant to share with me who was making his thin
sections but over time he got me in contact with the man that makes
thin sections that are second to none.

Here are some pictures of Jeff?s Kapoeta from an article in Meteorite
Times written by Tom Phillips:

http://www.meteorite-times.com/Back_Links/2007/October/Micro_Visions.htm

Here are a list of some of Jeff?s 600+ thin sections and some fantastic photos:

http://meteoritethinsectiongallery.com/index.html

There are some other great photographers of thin sections that I
haven?t mentioned. Their photos are true art.

Studying meteorite thin sections opens up a whole different meteorite
world than just studying and enjoying fragments and slices. I think
more collectors would get into the joy of looking at and studying thin
sections if they could do it in a somewhat economical way.

Polarizing microscopes can be very expensive. One with stereo
eyepieces can cost several thousand to tens of thousands of dollars.

Here is a good article on polarization and some microscopes that cost
up to $16,500.00.

http://tinyurl.com/mh7xp92

If you are interested in getting into thin sections and don?t want to
spend thousands of dollars, here is an alternative for you.

The 10x and 30x microscope is $249. And the polarizing adaptor is $89.
This gives you a complete set up for $338. If you want, you can spend
a lot more, but this does a really good job for a fraction of the
cost of some scopes.

GemOro also makes a nice 7x - 45x zoom model

If you already have a microscope with a light in the base, all you
need is the adaptor.

Here is my microscope:

http://tinyurl.com/mr9osv5

Here is the adaptor:

http://www.microscopeworld.com/p-1038-motic-microscope-polarizing-kit.aspx

There are other microscopes that this adaptor will work with. This is
just what I use.

A few months back I found a stereo microscope on ebay for $75 and set
up a second polarizing scope for well under $200.

One thing I have to watch with my microscope is that the bottom
halogen light gets hot and I?ve burned one of the polarizing filters a
couple of times and had to replace that filter. The solution is to
place the adaptor on the frosted glass stage that?s included with the
scope and it doesn?t get hot. It also helps to diffuse the light.

Also keep in mind that the quality of thin sections vary greatly. You
want a thin section that is made to standardized thickness (~30
microns) across the entire surface. It can?t be too thick or thin and
there is only a small tolerance. There are other factors too. I?ve
made a couple of thin sections myself by using a flat lap and
different grinding and polishing discs and a digital micrometer but I
would rather pay an expert to do it.

I take my scope and thin sections to gem shows and meteorite exhibits
that I set up at and the public always enjoy them. They can?t believe
they are seeing a rock from Mars at 30x in vivid color with a
fantastic crystal structure.

Hopefully, the ones of you that are interested in getting into
meteorite thin sections, this will help you get started without
spending a fortune.

John
Received on Sun 08 Jun 2014 04:51:23 PM PDT