11th International GeoRaman Conference

Abstract

GeoRaman is an international conference where researchers gather to discuss the application of Raman spectroscopy in the fields of geological, planetary, and archaeological sciences. Historically, the first GeoRaman conference was held in Paris (France) in 1986, and then continued there for some time. After a stint in France, the conference then moved to Valladolid (Spain) in 1999, and then took a wide international journey to Prague (Czech Republic) in 2002, to Hawaii (USA) in 2004, to Almunecar (Spain) in 2006, to Gent (Belgium) in 2008, to Sydney (Australia) in 2010, and then back to Nancy (France) in 2012. For the first time, this conference was held in the continental United States, in St. Louis, Missouri, from 15 to 19 of June 2014. Researchers from over 18 countries attended. GeoRaman XI in St. Louis focused on two major aspects of Raman spectroscopy: (1) the most advanced technologies and instrumentation, from laboratories to a wide variety of field applications, e.g. industrial and security monitoring, geo-fields, deep ocean, and on other planets and (2) the newest applications in studying inorganic, organic, and bio-genetic materials in Earth Sciences, Planetary Sciences, Environmental Science, Forensic Science, Archaeology and Archaeometry, Gemology, and Astrobiology. This special issue of the Journal of Raman spectroscopy dedicated to the 11th International GeoRaman Conference has 31 papers covering areas such as Planetary Science, Astrobiology, Mineralogy and Petrology, Biomineralization, Fluid Inclusions, Archaeology and Archaeometry, and Environmental Science. Several of the papers in this special issue are related to the application of Raman spectroscopy as an instrument for planetary exploration. Wei et al.1 report the first rover test of a Raman spectrometer specifically developed for mission flights, the Mars Micro-beam Raman Spectrometer in the Atacama Desert (Chile). In this work, they discovered γ-anhydrite, which is typically an unstable mineral, in large quantities in the soils of the Atacama Desert. Lui and Wang2 shed light on the dehydration of Na-jarosite, ferricopiapite, and rhomboclase to understand their formation and presence as ferric sulfates on Mars. This paper can be found here http://onlinelibrary.wiley.com/store/10.1002/jrs.4655/asset/jrs4655.pdf. Uriarte et al.3 work on collecting reference spectra of CaCl2.nH2O (n = 0, 2, 4, 6) to enable the geochemical community to identify these key minerals in important fluid geochemical processes here on Earth and Mars. Wang et al.4 provide the first systematic Raman spectroscopic study of phyllosilicates of planetary science importance for the characterization of such materials on the surface of Mars. Bathgate et al.5 identify by Raman spectroscopy primary and secondary minerals of volcanic rock weathering and alteration as a database for upcoming future exploration of Mars. This special issue contains a number of papers detailing the application of Raman spectroscopy to detect chemical traces of life on Mars. Fernandes et al.6 elucidate the pigment chemistry of three lichens of astrobiological relevance. They report the first identification of parietin in these lichens, which this pigment is effective in protecting the organism from free radicals and ultraviolet radiation. The paper can be found here http://onlinelibrary.wiley.com/store/10.1002/jrs.4626/asset/jrs4626.pdf Hooijschuur et al.7 investigate the effects of photodegradation of carotenoids within bacterial cell membranes and calcite. They report that carotenoids residing in the bacterial membranes were less sensitive to photodegradation than the mineral matrix. Harris et al.8 investigated several terrestrial Mars analogue samples to point out a cautionary tale to the astrobiology community potential for confusion in interpreting Raman spectra acquired from these types of samples. Foucher et al.9 demonstrates the potential of Raman mapping of the distribution and change in intensity ratio of the D and G bands arising from carbonaceous material as a biosignature to help identify potential fossilized microbes here in early Earth rocks and Mars. Several of the papers in this special issue are on the application of Raman spectroscopy to problems in mineralogy and petrology. Korsakov et al.10 undertook Confocal two-dimensional and three-dimensional Raman imaging of the Kokchetav metamorphic diamonds from different rock types which these results showed that those various diamonds had different crystal quality with complex internal morphologies associated with defects. The paper by Bartholomew et al.11 investigates the potential of Raman spectroscopy as the number one instrument for mineral identification in the Geosciences. They quantify the range of Raman intensities that can be expected from natural mineral samples and investigate the incorporation of this information into instrument standards and analytical methodology to design data collection strategies across Geoscience laboratories. Carey et al.12 apply machine learning techniques in order to improve mineral identification obtained by Raman spectroscopy. Golovin et al.13 show that the carbonate mineral zemkorite is not likely stable at the Earth's surface but will transform into the more stable polymorph nyerereite at these P-T conditions. Gomez-Nubla et al.14 characterized impact glass formed by meteorite impacts. They show that a substantial degree of post-impact terrestrial weathering can occur in these materials, which needs to be taken under consideration. Frost et al.15 use vibrational spectroscopy to characterize the mineral tangdanite and show that this mineral contains arsenate and sulfate polyhedra. Jehlicka and Vandenabeele16 evaluate portable Raman instruments to investigate the best excitation wavelength in collection of spectra from zeolite and beryllium containing silicate minerals. This work recommends using the portable NIR 785 nm system for the collection of better quality spectra on these materials. Cathelineau et al.17 use Raman spectroscopy to better understand the crystal structure of the economically important Ni-ore talc-like mineral phases, revealing that Raman spectroscopy can quickly evaluate the Ni content in these important economic minerals. Burlet and Vandrabant18 shed light on the structure of economically important manganese oxide minerals lithiophorite and asbolane that are typically difficult to characterize by traditional X-ray diffraction. Lopez and Frost19 shed light on the mineral responsible for the coloration of black marble from a quarry in Chillagoe, North Queensland, Australia. Petriglieri et al.20 use Raman mapping to identify small-scale changes in serpentine mineralogy to enable a greater understanding of the serpentinization process. Moroz et al.21 delineate the best wavelength of laser excitation to collect fluorescence free spectra on thermally immature carbonaceous materials. They clearly demonstrate that the laser excitation wavelength at 325 nm yields the best quality spectra that can be collected from these materials. This was a new session organized at GeoRaman, and while we only have one paper for the special issue, this field is opening up for the application of Raman spectroscopy and should grow enormously in the near future. Bioapatite, a carbonated, hydroxylated calcium phosphate salt, undergoes phase changes during heating. However, these changes are somewhat unclear; Li et al.22 elucidated these thermal transformations using Raman spectroscopy to study various heated material. They observed that the mineral undergoes de-carbonation and recrystallization at relatively low temperatures. This special issue contains a number of papers on fluid inclusions, which have contributed greatly to our understanding of measuring salinity and gaseous phases. Caumon et al.23 shed light on the role of mineral birefringence and on the polarization properties of the O–H stretching band of liquid water for determining the salinity of aqueous fluid inclusions. Tarantola and Caumon24 revealed that salinity measurements in fluid inclusions were overestimated by 1% per 10–15 MPa of negative pressure, thus allowing a way forward to determine the salinity of metastable fluid inclusions by Raman spectroscopy. Li and Chou25 analyze silicate melt inclusions in quartz from granites within pegmatite deposits by Raman spectroscopy revealing for the first time the occurrence of H2 in the vapor phase of the inclusion. Chou26 calibrated the Raman shifts of cyclohexane with the goal of using this calibration to accurately determine the ν1 CH4 band position to calculate CH4 densities in fluid inclusions. Several papers in this special issue are devoted to Archaeology and Archaeometry. Barone et al.27 obtain Raman spectra using portable instruments on an archaeologically significant jewelry museum collection dated to the 17th–18th centuries in order to verify previous identification of the gems in the collection made by conservators. Cianchetta et al.28 used Raman spectroscopy to investigate the process used in the red and black coloring of Athenian pottery. They showed for the first time that these ancient materials were produced using at least two separate firings. Coccato et al.29 investigate carbon black pigments in works of art to elucidate the various sources and origins of different carbons used as artwork color pigments. Rousaki et al.30 analyzed the pigment composition of hunter-gathered archaeological samples from Northern Patagonia. Their work demonstrates these ancient people used clay-like materials rather than the usual hematite as a pigment agent. Belgodere et al.31 determine diffusion coefficients of dissolved carbon dioxide in varying salinities to predict the transport of dissolved gases in sedimentary sequences for mitigation of green house gas emissions. The 31 papers in this special issue dedicated to the 11th International GeoRaman Conference have expanded our understanding in a diverse range of fields. For example, the interaction of geological fluids and their measurement, elucidation of biological activity in recent and ancient environments here on Earth, astrobiological prospecting for life on Mars, thermal transformation of biologically precipitated minerals, mineral stability at the surface of the Earth, structure of economically important minerals, Raman spectroscopy as major tool for mineral identification, and pigment chemistry used in art and cultural artifacts. Given the enthusiasm and quest for knowledge in the GeoRaman community, together with the development of new Raman techniques, the future GeoRaman conferences should continue to generate exciting new research in the Earth Sciences. I would like to thank all the delegates, presenters, and conference assistants (providing great help in the background), the local organizing committee, the international science advisory committee, and Washington University in St. Louis for a wonderful venue. I am extremely grateful to the following companies and institutions that supported this conference: Washington University in St. Louis, Department of Earth and Planetary Sciences, McDonnell Center for Space Sciences, Universities Space Research Association, Lunar and Planetary Institute, Renishaw, WiTec, ThermoFisher Scientific, Andor, Bruker, BWTEK, GemLab Group, Horiba Scientific, Kaiser Optical System, Inc., Ondax, RPMC, SciAps, and R. H. Minerals. Special thanks to the Editor-in-Chief of the Journal of Raman Spectroscopy, Dr Larry Nafie, for making this special issue possible, and of course, to all the authors and reviewers of the manuscripts for their invaluable contribution. It was a pleasure and honor to serve as the guest editor for this diverse collection of papers, and I am looking forward to seeing you at the next GeoRaman conference in Novosibirsk, Russia in 2016!