Micro-raman spectroscopy of selected macerals of the huminite group: An example from the szczerców lignite deposit (central Poland)

Lignite (ulminite reflectance Rr = 0.27%) from the Szczerców deposit (Central Poland) is dominated by huminite group macerals, containing a high proportion of attrinite and densinite. Densinite and ulminite are more abundant in small aromatic units than attrinite, which may result from their stronger gelification. The differences in Raman spectral characteristics between attrinite and ulminite are more pronounced than between attrinite and densinite. Fusinite, in comparison with the huminite group macerals, is composed of larger, more varied aromatic systems. The D4 (1190–1200 cm⁻¹) and D5 bands (1280–1290 cm⁻¹), most likely, correspond to different chemical structures, and their origin should be further investigated.