Joint unmixing of SWIR and TIR reflectance spectra for mineral composition

The HyLogger-3 System produces large amounts of hyperspectral data, and software to interpret these data automatically is essential. The jCLST unmixing algorithm, included in The Spectral Geologist software package, uses the HyLogger thermal infrared spectra, with the shortwave infrared spectra, to provide an estimate of modal mineralogy. This paper describes how the latest version of jCLST operates and demonstrates its performance on a set of carefully analysed samples. Errors are typically ±7–15 vol% and are similar to those obtained with much wider bandwidth emissivity measurements in the mid-infrared. The rationale for hyperspectral unmixing of TIR spectra to mineral composition is discussed. The jCLST unmixing algorithm is described, and its performance on a set of carefully analysed samples is presented. Errors are typically ±7–15 vol% and are similar to those obtained with emissivity measurements in the mid-infrared.