Raman spectroscopic study of amorphous and crystalline hydrocarbons from soils, peats and lignite

FT-Raman spectra were obtained from the natural hydrocarbon mixtures ozokerite and hatchettite as well as from the terpenoid minerals fichtelite (norabietane) and hartite (α-phyllocladane). Some of these hydrocarbons occur in soil and peat environments of Holocene age. However, hartite occurs in lignite, in fossilised Glyptostrobus (Taxodiaceae) trees and in pelosiderites of the Bílina Miocene series (about 20 Ma); it represents the accumulated and crystallised product of diagenetic transformation of precursor biogenic terpenoids. Raman spectra of earth waxes investigated confirm their dominantly aliphatic character and oxidative degradation (related to weathering and/or subaerial alteration in museum cabinets). Vibrational assignments are proposed and differences in Raman spectra of fichtelite and hartite discussed. Some of the individual features can be used for discrimination (e.g., hartite bands at 1480, 1310, 1287, 1041, 729 and 693 cm−1 and fichtelite bands at 1302, 836, 717 and 533 cm−1).