Two thin sections of local rocks

[The QCC]

It's July the 4th and these rock thin sections will not light up the sky with fireworks.
They did provide some exciting moments watching spinning disks and flying rocks.

Click the photo to view the thin section photos.

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[Rodney]

How thin were you able to go with your rock sections? I worked with some amber sections but a lot softer material, even though a lot of time with primitive means.

Rodney

[The QCC]

The rock thin sections, including the epoxy mountant, are 80-90 microns thick.
I made a thin section of sulphur

Sulphur thin section

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as an experiment. The slice started out about 20mm thick and ended up approx. 110mm on the slide.
With soft material I finish them off by hand on 1200-1500 grit wet/dry emery paper.
I put a velcro dot on the slide and use a rubber finger to move the slide around on the emery paper.

Slide with velcro holder

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Finger pressure for soft rocks

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[Rodney]

Oh ok good work with hard rock samples, I think as far as I ever took it was 1000 grit automotive wet sand paper working with amber, other than my rock crusher working with rock particles.

Rodney

[The QCC]

If you can crush rocks fine enough to pass through a 100 mesh screen, then you can cement the crushed rock to a glass slide. The process is called comminution.
The slide can be viewed with a polarizing microscope.
McCrone mineral set

[Rodney]

I have a rock section I would like you to look at. I think I had it cut with a diamond blade, then I sanded one flat section down and then I used a fine knife sharpening rock with a circular motion of the sample for several hours. While polishing this out I used dish washing liquid in water. I think the rock is actually a fossil of bone. If I can obtain a good picture I may post it in a new topic later for any ones identification or thoughts.

Rodney

[The QCC]

Rodney:

A slice of rock should be at least 100 microns thin in order to transmit light. Add the thickness of the mount and the minimum thickness for transparency is approx. 125 microns.
The 100 microns is hard to achieve without first polishing one side and then mounting it.
Once mounted you can grind/polish it down. If you hold the mounted specimen up to a light and you can see light through the rock, you are close to transparency.

[Rodney]

No qcc it want be anywhere close to 100 microns thin. The purpose of a picture would be just to look at this section with a top light and how unique the patterns look. May take a long time to get this one thin enough for transmitted light.

Rodney