XIV
h
International Conference on Molecular Spectroscopy, Białka Tatrzańska 2017
291
T5: P–11
Raman spectroscopy as a method for evaluation of fossil resins
maturation grade
Beata Naglik
1
, Lucyna Natkaniec-Nowak
1
, Paweł Stach
1
,
Przemysław Drzewicz
2
, and Maksym Bogdasarov
3
1
Faculty of Geology, Geophysics and Environmental Protection, AGH University of Science and
Technology, 30 Mickiewicza av., 30-059 Krakow, Poland, e-mail: beata.naglik@op.pl
2
Polish Geological Institute-National Research Institute,4 Rakowiecka Str.,00-975 Warsaw, Poland
3
Brest State University named after A.S. Pushkin, Brest, Republic of Belarus
Fossil resins are a products of trees defense mechanisms formed millions years ago. Their
preservation to this time was possible due to the diagenetic and/or catagenetic alterations of their
chemical constituents: mono-, di-, tri- and sesquiterpenoids. Although fossilization processes are
not fully understood yet, the maturation grade of fossil resins is believed to be strictly related to
their age. Therefore, many of the fossil resins features are interpreted in relation to their age, i.e.
Raman spectroscopic characteristic [1]. It is believed that the 1640/1440 cm
–1
intensity ratio
could be used as relative age dating of fossil resins; although shape of their Raman spectra may
be affected by thermal events during their fossilization [1]. In this study it was assumed that
fossil resins maturation grade depends primarily on the pT conditions of their
diagenetic/catagenetic alterations. Therefore comparative Raman spectroscopic studies were
performed on fossil resins originating from miocene deposits of Dominican Republic and
Sumatra Island and additionaly on specimens of eocene age from Russia (Sachalin). Dominican
and Sumatran resins are characterized by different Raman spectra despite their the same age.
The 1640/1440 cm
–1
ratio is higher for Sumatran samples indicating more matured resins. It
could be explained by the diastrophic events occurred during their evolution (volcanic activity
marked by the presence of magmatic rocks in amber-bearing formation). Russian eocene
samples show Raman spectra similar to early cretaceous resins with very low intensity ratio of
1640/1440 cm
–1
. This remarkable observation could be interpreted only when taking into
consideration geological background of the studied resins. They are associated with terrigenous
rocks interbedded with tufs subjected to thermal alterations characteristic for medium
catagenesis [2]. On the basis of presented results it could be clearly stated that Raman
spectroscopy could be quite good method to asses the degree of fossil resins maturation, but
more attention should be given to the geological factors controlling their alteration processes,
not their aging itself. This statement should be confirmed on the basis of further, systematic
studies of fossil resins originating from different age and geological environments.
Keywords: fossil resins; Raman spectroscopy; maturation grade; fossilization
Acknowledgment
This work was supported by AGH-University of Science and Technology project No. 11.11.140.319.
Analysis were carried out by Tusnovics Instruments Sp. z o.o., Krakow, Poland.
References
[1] W. Winkler, E.Ch. Kirchner, A.Asenbaum, M.Musso, J. Raman Spectrosc. 32(1) (2001) 59.
[2] M.A. Bogdasarow, БрГУ им. А.С. Пушкина, Брест (2010) 263 (in Russian).
XIV
h
International Conference on Molecular Spectroscopy, Białka Tatrzańska 2017
292
T5: P–12
Blue or green? Raman spectroscopy in study of turquoise from the
Carico Lake Mine area, Lander County, Nevada (USA)
Aleksandra Wesełucha-Birczyńska
1
, Lucyna Natkaniec-Nowak
2
,
Beata Naglik
2
, and Katarzyna Kulmaczewska
2
1
Faculty of Chemistry, Jagiellonian University, Ingardena 3, Krakow, Poland;
2
Department of Mineralogy Petrography and Geochemistry, AGH-University of Science and
Technology, 30 Mickiewicz Av. 30, 30-059 Krakow, e-mail: beata.naglik@op.pl
Turquoise – hydrated aluminum and copper phosphate CuAl
6
[(OH)
2
|PO
4
]
4
·4H
2
O – is a rare
mineral in nature. It usually occurs in the form of massive, cryptocrystalline aggregates, very
rare single prismatic crystals. There are two varieties of turquoise, blue and green. Very often
within their range are different forms of black and brown Mn and/or Fe oxides concentration.
This mineral is a product of weathering processes of rocks rich in Al
2
O
3
and phosphates
(apatite). In that zone it coexists with goethite, chalcedony and kaolinite. On the Lander Country
in Nevada (USA) two rock complex, i.e. Valmy and Slaven Chert Formations, include veins and
thin turquoise toppings of blue and green varieties of that material [1]. The samples tested come
from an owner of the Carico Lake Turquoise Mine, where turquoise occurs within quartzites.
Based on the study [2–4], the color of turquoise is associated with the content of Cu and Fe in
the structure of this phosphate. Typically, the blue color is associated with a higher Cu / Fe
quantitative ratio, whereas green with opposite relationships.
These findings were verified after examining minerals using Raman microspectroscopy. A
Renishaw inVia Raman micro-spectrometer working in confocal mode, connected to a Leica
microscope, was used for the measurements of the Raman spectra. The 514.5 nm and 442 nm
laser beam line were focused on a samples by 100 magnifying, a high numerical aperture (NA
= 0.9) Leica objective.
It is expected that the phosphate group will form a distinct set of vibrations, the prominent
band in the spectrum of studied minerals is symmetric stretching mode (ν
1
) [5]. The green
variety is characterized by the most intense band of about 1043 cm
–1
, while the blue has a
variable position of this mode in the range 1047–1024 cm
–1
. A shift to a lower wavenumbers
may be assigned to structural changeability and to the replacement of Al atom by Fe in the
structure [5]. In the range of 900 to 100 cm
–1
, the Raman spectra are quite complex, with bands
varying in the positions and intensity. The phosphate ν
2
bending mode, the most intensive
component, is observed at about 420 cm
–1
and 424 cm
–1
for green and blue variety, respectively.
Green turquoise is very sensitive to operation of laser light, even quite low laser power of
about 1–3 mW, and also longer than 30 s exposure time leads to modification of the sample.
Inclusions filled with organic/carbonaceous matter were observed in both samples.
Keywords: turquoise, Raman microspectroscopy, Lander County, Nevada, USA
Acknowledgment
This work is supported by AGH-University of Science and Technology project no. 11.11.140.319.
References
[1] B.J. Francka, Thesis in Geosciences, Master of Science. Texas Tech. University, 35–36 (1980) 42.
[2] C.O.Clark, C.P.Poole, A.Farach, American Mineralogist 64 (1979) 449.
[3] Z. Huifen, L. Chuanyi, M. Zhongwei, Geochemistry, 3, 4, (1984) 322.
[4] E. Crespo-Feo, J. Garcia-Guinea, V.Cirrecher, P. Prado-Herrero, Radiat. Meas. 45 (2010) 749.
[5] R.L. Frost, B.J. Reddy, W.N. Martens, M. Weier, J. Mol. Struct. 788 (2006) 224.
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