Identification of spurious X-ray diffraction maxima in clay mineral samples using a biotite plate

A biotite plate cleaved along {001} was used to record the spectral profile from a copper tube using two different Philips diffractometers. The (006) reflection from the biotite as recorded on the older diffractometer was found to exhibit peaks due to radiation arising from tungsten Lα emission lines. In addition to the peaks from the tungsten radiation a peak due to the CuKα₁ satellite reflections was also visible. It is important to be able to recognise the reflections arising from radiation not caused by the primary emission line from the X-ray tube so that the minerals in the sample can be correctly identified.