Amber on the Romanian market

Since 1989 there was a little call for amber on the Romanian market in comparison with our days. Ironically, the Romanian amber was almost absent, despite that an unique Amber Museum was opened in 1980 at Colţi (Buzău County), in the Eastern Carpathians. After the year 1990 the European amber market is dominated by Russia, Poland and Germany. Samples examinated in this report were pieces of amber-like material from Romania, sold as Romanite, and from Russia, Lithuania, Germany and Poland, sold as Baltic amber or Succinite. All this amber-like material is used in ornamental, gemological and curative purposes.They can be found on the Romanian market. For the present study, Fourier transform infrared spectroscopy (FTIR), X-ray diffractometry (XRD) and optical microscopy are methods of choice in amber-investigations. By now, our measurements demonstrate that all material is amber, ambroid or copal. The infrared transmittance spectra were recorded with a JASCO FT-IR 4100 spectrometer using KBr pellet method, with the main specifications: Peltier detector thermostatted DLATGS as standard, Ge coated KBr beam splitter, spectral resolution 0.9 cm^-1, spectral range 7,800 to 350 cm^-1, Jasco software. For certifying the results we used another Bruker Tensor 27 FT-IR spectrometer, using both ATR accessory with a diamond crystal and KBr pellet method. The main technical specifications are: DTGS detector, KBr beam splitter, spectral range 7,500 to 370 cm^-1, resolution ±1cm^-1, ±2 cm^-1, OPUS software. The FTIR spectra show the bands corresponding to the alkyl stretchings between 3000 and 2800 cm^-1, with a characteristic pattern with a maximum intensity near 2923-2924 cm^-1 for the methyl and methylene groups, and two bands of similar intensities at 2866 cm^-1 for the methyl group and 2847-2848 cm^-1 for the methylene groups.The bands due to the carboxilic acid groups have been observed near 1706-1707 cm^-1. The transmittance range is higher in the case of romanite, meaning that it has more carboxylic groups than succinite, probably because of a stronger oxidized process. Four bands appear near 1734-1735 in all the spectra, due to ester groups. A strong band at 1155-1157 cm^-1 is always observed and is attributed to the C-O simple bond stretching of esters. In the ‘Baltic shoulder’ region situated from 1250 to 1150 cm^-1, the shoulder is very distinct in the case of Lithuanian and Polish amber varieties and doesn’t appear at Romanite. Other bands can be to the alkyl groups: 1448 and 1444 cm^-1 for CH₂ and CH₃ bending, 1374 and 1373 cm^-1 for CH₃ bending. There are also spectra with bands at 1642 cm^-1 attributed to the out-of-plane CH ethylenic bendings. The presence of a clear, intense band near 887 cm^-1 because of the exocyclic methylene is an argument for a copal spectrum. No aromatic bands are observed, indicating
that aromatic structures are absent.
   X-ray powder diffraction analyses was performed on a Bruker D8 Advance automated diffractometer equipped with a graphite-diffracted beam monochromator (CuKα radiation, λ=1.54056 Å), at an operating voltage of 40 kV and a beam current of 40 mA. Baltic ambers exhibit the same XRD pattern comprising of a broad peak centered at 2θ=15º. They are in the amorphous state. The records seem to indicate for Romanite and Lithuanian amber some internal crystallization tendency, confirmed also by microscopically studies. These have been marked up using a PANPHOT microscope transmitted light. On the Romanite thin sections a weak anisotropy with grey-yellowish to light-blue colors was observed, although in literature is mentioned that amber does not present crystallization tendencies. Baltic amber studied with this occasion revealed no anisotropy.