The Retsch XRD-McCrone Mill is used for the preparation of samples for subsequent X-ray diffraction (XRD). A grain size of < 10 µm is required for a good quality (quantitative) X-ray diffraction. To avoid amorphisation of the sample during grinding, (wet) milling is done in a McCrone Micronizing mill. The crystal lattice is almost entirely preserved during grinding operation. The grinding vessel consists of a 125 ml capacity polypropylene jar fitted with a screw capped gasketless polyethylene closure. The jar is filled with an ordered array of 48 identical cylindrical corundum grinding elements. The grinding time for optimum micronization is between 3 and 30 minutes. A typical sample volume is between 2 and 4 ml. The material feed size cannot 0.5 exceed 0.5 mm. Particles larger than 0.5 mm should be crushed in the mortar prior to milling with the McCrone mill.