Earthy, finely crystalline, weathering, and condensation products sometimes occur at the surface and subsurface of waste dumps or burning coal dumps which remain after coal mining. Surface crusts at the burning dumps of bituminous coal at Hemanice (Silesia, Czech Republic) were investigated using a lightweight portable Raman spectrometer.
The compact instrument, with 785-nm diode excitation, allowed for the recording of good quality Raman spectra, and for the identification of a series of more-or-less complex sulfates (mascagnite, letovicite, sabieite, pyracmonite) as well as common sal ammoniac and sulfur. The great complexity of the mineral associations is demonstrated in aggregates of efremovite, godovikovite, boussingaultite, and sabieite.
In this case, the handheld instrumentation does not allow for ideal detection and discrimination of finely crystalline minerals in complex mixtures.