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There are two techniques for XRD analysis to mount small amount of material depending on the volume of material available.  Separating a vein or other spot can be done by using a hammer, or other spatula or tool, to chisel out only the parts you want.  Small flecks of the other parts of the sample are okay to have mixed in with the material of interest, but do your best to pick these out with tweezers or a brush.

Preparing Mount for Small Amount of Material

Note: Sample mounting on Figure 1 is for backloading sample holder of the Aeris XRD. Similar technique should be used for frontloading sample holder of the Bruker XRD. In case of Bruker XRD, spacer is put first.

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1. Freeze dry the sample prior to analyses (for about 12 h). It helps to collect sample material of interest (e.g., mineral vein in hard rock samples).
2. Use tools to scratch the surface of interest (Figure 2, Step 1) and use mortar and pestle to grind uniformly.
   
3. Place a small amount of sample powder in the center of the zero background silicon disk (Figure 2, Step 2). See XRD Sample Preparation Clay Separations for how to mount the sample holder.
   
4. With a disposable glass or plastic Pasteur pipette or eye-dropper, add 2–3 2-3 drops of acetone, 70 % isopropyl alcohol or distilled water to the sample (Figure 2, Step 3). Note: Isopropyl dries faster than water and is preferred over acetone because of the fumes.
5. Spread the sample to a thin layer using a glass rod, teflon spatula, or the tip of the pipette or eye-dropper. Alternatively, use a glass rod or Teflon spatula. The slurry should be spread evenly across the disk. If there is not enough material to cover the entire disk, concentrate the sample in the middle of the disk where the X-rays will contact the sample (Figure 2, Step 4). You can also use a piece of tape, stick it to the sample holder and sprinkle the ground sample onto it.
6. Place the sample in the dessicator desiccator to dry before running in the XRD (Figure 2, Step 5). See Figure 1, Step 5 left for the final product.

Figure 2. Sample Slurry/Smear Slide mounting

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XRD Sample Preparation for a small amount of material - September 27, 2022