Chemical and spectroscopic signatures of resins from Sumatra (Sarolangun mine, Jambi Province) and Germany (Bitterfeld, Saxony-Anhalt)

The overview of analytical methods for studying of fossil natural resins

The review presents methods that are used frequently for multi-analytical study of fossil resins. The preliminary characterization relies on physical methods such as microhardness, density and fluorescence in UV light measurements. The spectroscopic methods: infrared spectroscopy, Raman spectroscopy, fluorescence spectroscopy are also presented in the paper. Besides that, the review also contains examples of the application of chromatographic methods: gas chromatography, thin layer chromatography, high-performance liquid chromatography, two-dimensional gas chromatography coupled to time-of-flight mass spectrometry as well as sample preparation methods for chromatographic studies such as pyrolysis. Additionally, thermal methods such as thermogravimetric analysis and differential scanning calorimetry also are covered by the review. Beside the examples of application, a detailed description with development history and perspective for further improvement are presented for each method. Moreover, fit-for-purpose assessment of each method is illustrated based on many examples from literature. The paper also contains examples of the application of multivariate statistical analysis and chemometric methods for comparing multiple properties of different fossil resin specimens for differentiation and classification purposes.

Identification of treated Baltic amber by FTIR and FT-Raman - A feasibility study

Heat-treated succinite modified under air, oxygen or inert gas atmosphere to improve its colour and clarity, was studied with Fourier-Transform Infrared and Raman spectroscopy, and referenced to variously altered untreated samples. For treated amber, the macroscopic observations revealed diagnostic features such as (1) the presence of discoidal " sun sparkles" inside the crumbs; (2) unusual colours (e.g. dark red) for transparent specimens; (3) mottled colour patches in "beeswax" and "dragon's blood" amber; (4) luminescence quenching; and (5) significant reduction of pine-tree resinous smell. On FTIR spectra the heat treatment of succinite is mainly marked by: (1) the intensity decrease of 2932 cm^-1 band (>CH₂ and -CH₃), followed by the intensity increase of line at 1732 cm^-1; (2) the shifts of the band from ν(C = O) towards lower wavenumbers (from 1735 cm^-1 to 1714 cm^-1); (3) the decrease of intensity of the band at 888 cm^-1 ((=CH₂ or -CH = CH-); (4) some slight distortion of "Baltic shoulder" in the region 1100-1300 cm^-1. The Principal Component Analysis applied to FTIR spectra enabled to distinguish not only untreated amber from treated one, but also recognize the modifications made under oxygen conditions from the ones in an inert gas. On RS spectra of the treated Baltic amber, the heat modifications are indicated by: (1) slight value increase of the relative intensity ratio I_1650/1445 compared to untreated succinite; (2) the shift of bands near 1650 (C = C) and 1445 cm^-1 (CH₂, CH₃) towards higher wavenumbers.

The study of Dominican amber-bearing sediments from Siete Cañadas and La Cumbre with a discussion on their origin

The paper presents comprehensive mineralogical and geochemical characteristics of Dominican amber-bearing sediments from Siete Cañadas, Hato Mayor Province of the Eastern Mining District (EMD) in the Cordillera Oriental. The characteristics of rocks collected from the borehole in Siete Cañadas area (EMD) were compared with petrography of coaly shales from La Cumbre in the Northern Mining District (NMD). The mineralogy of the rocks was determined using transmitted and reflected light microscopy, scanning electron microscopy, Powder X-ray diffraction and Fourier Transform Raman Spectroscopy. Biomarker analyses by the gas chromatography–mass spectrometry were used to trace the genetic source and transformation stage of organic matter hosted in the core sediments. In this study, the characteristics of rocks from La Cumbre were supplemented with the petrographic data from our studies reported earlier. Based on the findings, it has been concluded that the basins in the investigated parts of the EMD and NMD regions were likely characterized by different, isolated palaeosettings. Transformation and maturation of terrigenous material were affected by locally occurring physicochemical conditions. In both amber deposits, the sedimentation of clastic and organic material proceeded in the presence of marine conditions. In case of the La Cumbre deposit (NMD area), the sedimentation underwent probably in the conditions of the lagoon environment, a shallow maritime lake or periodically flooded plain that facilitated organic matter decomposition and carbonation from meta-lignite to sub-bituminous coal (random reflectance of coal—R_r^o = 0.39%). In the Siete Cañadas (EMD region), the sedimentation took place in a shallow saltwater basin, where terrigenous material was likely mixed with material found in situ (fauna fossils, carbonate-group minerals) to form the mudstones enriched in bituminous substance of low maturity. The organic matter found in the rocks from both deposits is of mixed terrestrial/marine origin and was deposited in the presence of low oxygen concentration and reducing and/or dysoxic conditions.