Procedure for preparing the small amounts of the XRD samples:

1. Small amounts of the fine powder sample are pressed into the indentation of an acrylic glass sample holder.

2. Very small sample amounts (micro gram or less) of powdered specimen are loaded into thin walled glass capillaries. Use Mark tubes of 1.0 or 0.3 mm diameter and 0.01 mm wallthickness. The capillary tubes are stuck with beeswax into brass hulls. The hulls can be stuck into metal pegs and screwed directly on the XYZ-stage.

3. To reduce the background scattering from the glass wall, powdered samples are also dusted on thin foils and fixed by a light touch of hair spray. Use 15 µm sheets of Hostaphan or 6 µm sheets of Polypropylen or 3 µm sheets of Mylar. The foil is held by Vaseline on the sample holder, and is also suitable for fixation to goniometer heads as well as on metal pegs.

4. Individual, tiny particles are placed under microscopic control with the help of a very fine needle on a strip of 3 µm Mylar, which has been previously coated with a fine trace of hair spray. The Mylar sheet is mounted on a goniometer head with a stretching device.

5. Side-Drifted (plastic) These Plexiglas mounts have a 1 x 2 cm specimen well 1 mm deep machined from one edge of the mount. Samples are loaded by clamping a microscope slide to the top of the mount with a pair of small binder clips then dropping the powder into the cavity formed by the well in the mount and the glass slide. When the well is filled, the clips are removed and the glass slide carefully taken off leaving the side-drifted specimen level with the top of the mount surface.

6. Top-mount (plastic) These Plexiglas mounts have small wells machined into the top surface of the mount to hold a powdered specimen. The wells vary somewhat in depth (from a fraction of a mm to about 2 mm) and dimension (from 1 x 1.5 cm to almost the full size of the mount) to accommodate different volumes of powder. These are loaded by dropping powder into the well and “leveling” it with a glass slide or other flat-edged tool. The small-well mounts are best to use for low-volume specimens that are not susceptible to preferred orientation. Because of the way these mounts are loaded and leveled, preferred orientation will be strong in materials that are susceptible to it.

7. Glass Slides (for slurry mounts made with water, alcohol or acetone) 27 x 34 mm glass microscope slides are available for use as sample mounts in the lab. A slurry mount is made by mixing a quantity of powdered sample with liquid (typically water, alcohol or acetone) in a glass vial, agitating it to produce a suspension, dropping the suspension on a glass slide with an eyedropper and allowing it to dry. The resultant specimen is a thin layer of material that will show strong preferred orientation in materials susceptible to it. This is the preferred method for mounting clay samples where preferred orientation is used as a tool for sample characterization.

8. Double-stick tape mounts (on glass slide or Plexiglas mount) Double-stick cellophane tape is placed in the center of a glass slide or the back (flat) side of Plexiglas mount and a small amount of fine powder is “dusted” onto the tape. Unlike other methods, the analyzed specimen is not recoverable and the analyzed volume of sample is small and particle statistics will not be very good. The sticky character of tape can reduce preferred orientation in some materials, but this is very dependent on the powder geometry and not quantifiable. In spite of the limitations, this type of mount is extremely quick to prepare and is useful for quick scans for phase identification.

9. Zero-background mounts (off-axis quartz plate) Single-crystal flat machined quartz plates cut with the c-axis at large non-vertical angle to the machined surface should (theoretically) produce no background in a diffractometer. We have several of these (home-made and not perfect) plates available in the lab that may be used for slurry mounts and one with a small (~ 1 x 5 mm) machined groove cut in the center that can be used for a small amount of powder. We expect to acquire more of both varieties from the Gem Dugout (http://www.gemdugout.com).

10. Thin Film Mounts (plastic or aluminum with clay) These mounts are deep (5-10 mm) U-shaped rectangular wells that are used in combination with Plasticine clay to mount thin-films for analysis that are too small to be placed directly in the sample holder. A small cylinder of clay is formed, placed in the bottom of the mount extending above the top edges then a thin film sample is placed on top and pressed down until the top surface is level with the top edges of the mount. Large thin-film plates (that are not too wide) may be mounted directly in the spring-mount of the diffractometer.