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Chichester, West Sussex, United Kingdom, 2008/06/20 - New research published in the Journal of Near Infrared Spectroscopy reveals a way to identify and classify the carbonate rocks produced if liquefied CO2 is pumped below the earth’s surface as would occur during carbon capture and storage.
Carbon capture and storage, or geosequestration, involves locking the carbon dioxide in the form of minerals such as smithsonite and magnesium carbonate minerals. Near infrared spectroscopy offers a means of identifying such minerals and may be employed remotely.
The carbonate rocks, such as smithsonites, include some of the most highly coloured and prized precious gem stones. “Here at the Queensland University of Technology we set out to understand the basis of the colour changes in carbonate rocks”, project leader Professor Ray Frost said. “We now understand the significance of very small changes in trace elements (some may call them impurities).” Near infrared spectroscopy is a scientific tool which has helped us understand the colours in these minerals and may be employed to study the colour in gems and jewellery.
The present paper, the sixth in a series on carbonate minerals, employed NIR spectroscopy to reveal differences in mineralogy and mineral composition which related to the origins of the samples. Ray Frost, together with his students and collaborators, are developing the technique of infrared spectroscopy for the study and identification of minerals. Such a study also has relevance to the identification of minerals on Mars and other planets and their moons.
Understanding the matter which makes up our solar system has challenged scientists for centuries. “We are now a step closer to being able to identify which minerals occur on Mars and other planets in the solar system,” Professor Frost said.
These latest studies were undertaken in collaboration with visiting scientist Professor B.J. Reddys at the Queensland University of Technology.
“Here on earth we will be now be able to use visible–near infrared spectroscopy in combination with multi-spectral remote sensing to greatly enhanced the accuracy of geological mapping,” Professor Frost said. Such remote sensing can be carried out from the air, or even from space.
In the spectra of smithsonite minerals, the main peaks relate, in addition to the anions of OH– and CO32– to Fe and Cu. The effects of structural cations substitution (Ca2+, Fe2+, Cu2+, Cd2+ and Zn2+) on band shifts in the electronic spectral region of 11,000 to 7500 cm–1 (910 to 1330 nm) and vibrational modes of OH– and CO32– anions in the 7300 to 4000 cm–1 (1370 to 2500 nm) region were used to distinguish between the smithsonites.