In this month’s newsletter we will talk about the rare and valuable element Caesium (Cs) which has been gaining interest in the minerals industry. Pioneer Resources recently reported a resource estimate of 10,500 tonnes of caesium ore at their Sinclair deposit in Western Australia. This deposit contains a grade of 17.1 % caesium oxide (Cs2O) in the form of pollucite.
Pollucite is a rare caesium-rich zeolite mineral (Cs,Na)2Al2Si4O12 · 2H2O) and forms in extremely differentiated zones of rare lithium-caesium-tantalum pegmatite systems. Caesium is most commonly used as a lubricant for oil and gas drilling. In addition to the Sinclair deposit, it is also found in economic concentrations at the Tanco Mine in Canada and Bikita Mine in Zimbabwe.
A combination of portable X-Ray fluorescence (pXRF; Fig. 1) and near infrared (NIR) spectroscopy can be used to detect elevated Cs and pollucite, respectively. Most pXRF units report Cs and a Cs calibration can be developed on the Bruker Titan to provide more robust results. Pollucite produces a diagnostic spectrum in the near infrared (NIR) region (Fig. 2) and can be detected using portable devices such as the TerraSpec ASD.
Figure 1 A portable XRF spectrum of a Caesium-rich sample (red). X-ray emission lines for Caesium are indicated in blue.
Figure 2 – NIR Spectrum of pollucite with a number of diagnostic absorption features, particularly at lower wavelengths (~960 and 1150nm).