Cathodoluminescence imaging is an ideal tool for studying geological samples and getting additional contrast and spectroscopic information down to the resolution of a scanning electron microscope. Our cathodoluminescence solutions SPARC, JOLT and SPARC Compact can be combined with other analytical tools such as SIMS, BSE, EDS, WDS and μCT for microanalysis of rocks and understanding rock properties. Keep reading if you want to learn how cathodoluminescence emission from a rock can give insights into crystal growth, zonation, cementation, replacement, deformation, provenance, trace elements, instrinsic and extrinsic defects.
Sample courtesy of dr. Chen Zhenyu (Chinese Academy of Geological Sciences, Beijing)
Zircon is a robust mineral which can persist for long periods of time in the earth’s crust. During growth, changing conditions lead to zonation in the crystal which can be visualized with cathodoluminescence. Zircons are often rich in heavy metals and as such
Microcharacterization of zircons is frequently performed using an SEM cathodoluminescence system. This mineral is extremely resistant to weathering processes and can be found in a wide variety of rocks. Changes in the chemical composition of rocks over time lead to zonation patterns in zircons, in which different zones of zircon have varying chemical compositions. Comparable to rings in trees, the cathodoluminescence imaging of zircons can open up a breadth of information on historical changes in the rock (to learn more about the application of CL for the study of zircons, see this application note).
Cathodoluminescence spectroscopy is commonly applied to study the properties of sedimentary rocks such as sandstones, carbonates, shales, siltstones, and mudstones. Quartz sandstones, a common example of sedimentary rocks, is one of the main sources of fossil fuels (oil, natural gas, coal), which has a robust emission and intrinsic luminescence.
With panchromatic CL imaging, it is possible to map the quartz composition of the sample which enables, for instance, the rigorous segmentation of granular material and cemented material. By combining these results with other SEM techniques, the geological history, as well as the porosity of the rock, can be studied in great detail (to learn more about studying sedimentary rocks, read this white paper).
Quartz in sandstone imaged using a photomultiplier tube
Sapphires are dominated by extrinsic luminescence, therefore they can also be studied with cathodoluminescence.
Сathodoluminescence allows to assess
Sign up for a demonstration of one of our systems and learn about cathodoluminescence technique which can be used in your geological research.
During the demonstration you will learn: