Mathematician Prof Dr Ralf Hielscher has been developing the open source software MTEX with an international team for more than 15 years. MTEX utilises the latest methods of image processing and harmonic analysis for the mathematical description of polycrystalline materials and their properties. MTEX is used both at TU Freiberg and worldwide in industry and research to analyse electron microscopy images. Applications range from minerals and rocks in geology to highly specialised steel, titanium or magnesium alloys in materials science and biological objects such as mussel shells or teeth.