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Rugose Coral, Mississippian Period, Sulphur, Indiana.


The QCC

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Although this is the same thin section of Rugose Coral posted earlier, they are substantially different in what has been revealed with further polishing.

The original thin section was approx. 80microns thin. The additional polishing with 1200 and 2000 grit diamond disks has proved to reveal additional and unexpected detail at a thickness of 35 microns.
The new slide photos were taken with a Canon 100D on a Zeiss 305edu microscope.

 

Slide 1 is the cross section as previously posted. Hints of what lay hidden are visible, but the slide is too thick to see detail.

1RogoseCoral-FS60-MLX-2__005_Full.jpg

 

Slide 2 is the thin section after another hour of polishing. There are some disc lines in the slide, but I was at the limit of my set up  and feared polishing the specimen to oblivion.

2RugoseCoral-FS61-LX-20_2170_Full6.jpg

 

Slide 3 is viewed through a Dark Field stop.

3RugoseCoral-FS61-ZZX-10_2243_Full15DF.jpg

 

Slide 4 is a close look at the centre of the coral.

4RugoseCoral-FS61-ZZX-20_2242.jpg

 

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Nice work :wub:

"Absence of evidence is not evidence of absence"_ Carl Sagen

No trees were killed in this posting......however, many innocent electrons were diverted from where they originally intended to go.

" I think, therefore I collect fossils." _ Me

"When you have eliminated the impossible, whatever remains, however improbable, must be the truth."__S. Holmes

"can't we all just get along?" Jack Nicholson from Mars Attacks

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This is really excellent!  Is anyone else cutting thin sections of fossils?  I would very much like to learn the older methods of thin-sectioning with hand tools, as it is unlikely that I will ever be able to have sufficient space for lapidary equipment.  It is essential to have thin sections if one hopes to identify fusulinids or bryozoans, hence my interest.

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Making thin sections by hand using a lapping plate, powdered grit, sheet grit and polishing compound takes almost as much space and more money per slide than a hybrid system.

I started out that way buying my supplies from Lee Valley Tools and quickly became a first name customer at the Lee Valley store.

 

My hybrid system consists of a glass lapping plate, a Hi Tech Diamond 6" flat lap machine and six diamond grit discs. The Hi Tech machine comes with three backing plates, a 180 grit "carving" disc,  600 & 1200 grit polishing discs, a small container of 1 micron diamond paste and polishing disc. I added  100 and 2000 grit  diamond discs. I still do a final 1 micron polish by hand on the lapping plate.

Space wise, a small work bench (30" x 48") is sufficient.

I managed to make about 12 slides using the manual method and over 120 with the hybrid system in much less time and at a lower cost per slide.

The photos show my manual method and the HiTech lap machine. Did I forget to mention the manual method is messy.

 

The lapping plate in a roasting pan with  sheet grit.

IMG_0179.jpg

 

IMG_0176.jpg

 

The slide carrier I made to hold the slide while polishing.

IMG_0208.jpg

 

The Hi Tech Diamond flat lap machine.

P1010711.jpg

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