AN ULTRASONIC PROBE FOR THE EXTRACTION OF MICROSCOPIC QUANTITIES OF MINERALS FOR X-RAY WORK

The instrumentation and procedure is described for the extraction of v ery small and pure samples from polished mounts and thin sections of m inerals, for X-ray analysis and other micro-analytical techniques. It uses a stand-mounted, tunable ultrasonic probe (400 W/15-50 kHz) incli ned at 45 degrees to a microscope stage. The tip of the probe, usually a steel needle, is located on the desired mineral and an appropriate ultrasonic frequency is selected. Very fine powders are produced from grains as small as 0.01-0.005 mm. A distinct advantage of this techniq ue is that, as different minerals powder at different rates and differ ent frequencies, it is possible to separate a single mineral from an i ntergrowth of two or more minerals.