X-ray diffraction of soil samples taken from a crime scene. The soil is contained within the capillary sample holder (centre). X-rays are passed through the soil samples to produce a diffraction pattern. The pattern produced depends on the crystal structure of the mineral present. This method is used to produce a detailed analysis of the minerals present within the soil. The results can be compared and matched to a geographical map of soil types and assist as evidence towards a crime investigation. Photographed at the Macaulay Institute, Aberdeen, UK.