Some rocks, which are composed of several different minerals and organic derivatives (for example coal) are water bearing. How they store and lose water is important in some geological fields as this can give clues about how and why earthquakes happen, and about structural changes within the rocks relative to temperature.
At the University of Rome Tre, Giancarlo Della Ventura and his colleagues are using the Linkam FTIR600 stage to look the loss of water in leucite, a common silicate mineral found in lavas. Using the FTIR600 stage the scientists have demonstrated the ability to monitor the process across samples a few µm thick, and obtain time/dehydration curves.
This loss of water can be very fast. In order to study this dynamic reaction in-situ under non-ambient conditions it is necessary to capture high resolution images quickly. This can be achieved by using the Linksys32-DV software that also controls the stage temperature. Non-equilibrium processes of geological interest and dehydration processes in other minerals can also be studied using the FTIR600 stage and the Linksys32-DV software.
In one experiment a small crystal fragment was heated constantly at 5°Cmin-1, dehydrating smoothly until at 400°C it is almost anhydrous. Images are taken at 1°C intervals, using a 15x objective, illuminating ~170x170µm2 areas to enhance the contrast of the water band at the edge of the crystal.
In a second experiment, a crystal was heated quickly at 50°Cmin-1 up to 300°C, where it had lost approximately 50% of its water. The sample was held at 300°C and images were taken at intervals to show the continued dehydration of the sample. After 150min the sample was nearly anhydrous.
Giancarlo Della Ventura commented the greatest benefit of using a Linkam stage is the “possibility to do experiments in situ, i.e. during the thermal treatment.”
We like to think Linkam stages are being used for earth-shattering science and our equipment certainly has a part to play investigating earthquakes.
By Caroline Feltham