Visualising mineralogical heterogeneities and texture in a mudstone concretion using hyperspectral imaging

It is often difficult to identify and quantify mineralogical heterogeneities on the centimetre to metre scale by optical means, when these heterogeneities have apparently similar colours. Therefore, a general image processing workflow combined with mineralogical analytical methods is presented by using contact-free hyperspectral imaging techniques on a mudstone concretion. The application of spectral algorithms reveals a distinct texture in a visually homogeneous black rock. The pattern is confirmed by optical and electron microscopy as well as X-ray diffraction, showing a layered texture of varying amounts of siderite and clay minerals. The rapid and contact-free visualisation of rock anisotropies such as mineralogical heterogeneities in overall homogeneous rocks may thus enable a better prediction of mechanical and petrophysical heterogeneities on mm- to 100 m scale.