Terrestrial Lithium exploration adapted from Raman diagnosis of phyllosilicates for Mars

Analyses using a benchtop Raman instrument at the University of Aberdeen and a prototype instrument for remote deployment on Mars based at the University of Leicester successfully discriminated between four varieties of mica. The mica minerals muscovite, biotite, lepidolite and zinnwaldite can be distinguished using a decision tree based on the peaks measured. The micas were measured in context within granites in Aberdeenshire, where the lithium-bearing micas lepidolite and zinnwaldite confer anomalous enrichments in lithium to the host granites. Deployment of the prototype instrument in field conditions at two different sites successfully identified zinnwaldite and muscovite. Thereby, the technique accomplished the discrimination of lithium-rich rocks. Experiments at a ‘blind’ site in the field, where the mica identification was unknown to the user, were partially successful. The data suggest that a portable instrument could be developed to allow the rapid detection of lithium-bearing species. Raman spectroscopy has the potential to contribute to the exploration of one of the most important elements required in meeting a future green economy.