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A Laboratory Manual for X-Ray Powder Diffraction
A split may be taken from each sample to be analyzed by X-ray diffraction and mounted in a optical medium (such as Piccolyte) as a smear slide. These slides are used to check the semiquantitative diffraction techniques, to detect amorphous materials or minerals present in trace amounts, to identify layer-silicate species concentrated in the silt fraction, and to examine the biological debris.
| PREPARATION OF SMEAR SLIDES | |
Materials Required:
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| Label the slide temporarily with the felt marking pen. A pen with water soluble ink is used because the labeling is not soluble in xylene which may be necessary later to clean excess Piccolyte from the slide. Place the hot plate in a fume hood and set it at about 150 C (or about 300 F). Exact setting must be determined by experiment. Too hot and the xylene will boil forming bubbles; too cool and the evaporation of xylene will be slow. The cured mounting medium must no longer be tacky or viscous, but not be yellow or brittle. |  |
| Place a small amount of sample in the center of the slide. |  |
| Add a drop of distilled water and spread the sample into a thin layer with the glass rod. |  |
| Place the slide on the hot plate to dry. When completely dry, place one or two drops of Piccolyte on the center of the sample. |  |
| After the Piccolyte has been allowed to cook for several minutes (exact time depends on the temperature and amount of xylene used as a thinner), place a glass cover slip over the sample. |  |
| Press the cover slip down with a pair of tweezers. The Piccolyte should spread to fill the space beneath the cover glass. |  |
| Remove the slide from the hot plate and allow it to cool. If the slide has too much Piccolyte, it can be cleaned with a single edge razor and by washing with xylene.
Xylene is a hazardous chemical and a known carcinogen. If this chemical is used to clean the slides, work under a fume hood and wear protective gloves. |
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| The slide is then permanently labeled with a glass scriber (diamond or carbide tip). This is not done earlier because glass chips may end up in the sample and may be confused with volcanic glass. |  |
