Diffraction methods in the characterization of new mineral species

Data from publications describing new minerals in the periods 2001-2005 and 2016-2020 have been analysed to evaluate the contributions of diffraction methods to the new mineral characterisations. The two periods were chosen to be on either side of a sudden increase in new mineral descriptions from ~50 to 120 per year and coincidentally correspond to the changeover from the majority (60%) of the new descriptions using photographic film cameras to record the powder diffraction patterns of the minerals, to using modern diffractometers. During both periods, diffraction data obtained using laboratory-based single-crystal diffractometers accounted for almost three-quarters of the crystallographic studies. Modern diffractometers can now routinely be used to collect high-quality data on crystals down to a few mu m in size, once the province of synchrotrons. Large facility-based diffraction centres like synchrotrons and scientific nuclear reactors account for less than 10% of the new mineral publications. The review focuses on diffraction methods for the characterisation of fine-grained minerals, with sub-mu m sized crystals. Transmission electron microscopy/electron diffraction methods are important for these cases, with an exponential increase in 3D ED methods during the last 15 years and increased usage of electron back-scattered diffraction methods for micro-inclusion minerals, especially in meteorites.

Automated summary

The analysis of data from publications describing new minerals in the periods 2001-2005 and 2016-2020 shows the significant contributions of diffraction methods to new mineral characterizations. The use of modern diffractometers has increased, allowing for high-quality data collection on small crystals, which was once only possible at synchrotrons.