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Cross Polarized Light Microscopy The greatest challenge is getting the sample to a uniform correct thickness. the tendency is to round down the edges. This causes it to be thick in the middle and worn to nothing on the edges. A good target thickness for a finished thin section is 30 microns, but that is 30 microns of sample that has not been destroyed by sub-surface damage due to shattering of the mineral grains with rough grit. To help accomplish this, the sample is again coated in epoxy and allowed to set. It is then ground on diamond laps to a thickness of approximately 200 microns, recoated with epoxy and finally taken down to the final thickness using various lapping compounds and finished on a cloth lap with a diamond slurry. There is equipment that is designed specifically for each of these tasks. I have an older Struers setup. It consists of a Discoplan to trim and rough grind the slide after the sample is attached, A polisher on which to grind/polish the sample and a PdM-Force head to hold the samples at the appropriate pressure against the grinding medium while keeping them flat. It's no wonder why bargain thin sections are often disappointing and good thin sections are never cheep. Even if the sample material was free, they are costly to produce. Speaking of sample material, the minimum amount used  in the production of a standard thin section is approximately 1g, So keep that in mind when you  are eyeing those exotic thins. Whether or not you are interested in taking photomicrographs, viewing meteorites in Xpol (cross polarized light) is something that every meteorite collector should experience.