Spectroscopy is a tool that detects the absorption or emission of light as a function of wavelength. Airborne and orbital spectrometers can detect, differentiate, and map subtle chemical differences in minerals and other compounds. A digital reflectance spectral library that covers the wavelength range from the ultraviolet to far infrared along with sample documentation has been assembled over many years. The library includes samples of minerals, rocks, soils, physically constructed as well as mathematically computed mixtures, plants, vegetation communities, microorganisms, and man-made materials. The samples and spectra collected were assembled for the purpose of using spectral features for the remote detection of these and similar materials.
We've just released the latest version of the USGS Spectral Library - Version 7!
The previously published version of the USGS spectral library (Clark et al., 2007) is the leading database used by the global scientific community to identify materials by their "spectral fingerprints." The library is fundamental for Mineral Resources Program projects to characterize mineral resources with imaging spectrometer data. We plan to expand the USGS Spectral Library with the addition of new samples and to update the spectra resolution and range of existing library samples.
We have released USGS Spectral Library Version 7, an associated data release, and a new interactive portal for the Spectral Library contents. The Version 7 library includes all spectra from the previous version along with more than 1,000 new spectra. This release includes field spectra of mixed vegetation plots in the coastal wetlands of Louisiana, as well as leaf level and plant level spectra of single species. Spectra of oil emulsions, residues and oil-contaminated marsh plants from the Deepwater Horizon oil spill are included. The spectra of biochemical constituents of plants have been added to a new chapter along with spectra of more than 200 other organic compounds. Spectra of grain size series of minerals have been added in addition to spectra of minerals bearing rare earth elements and Lanthanide series compounds. Spectra of vermiculite insulation from the four main historical sources (Louisa, Virginia; Enoree, South Carolina; Libby, Montana; and Palabora, South Africa) were added. A new collection of powdered paint pigments spanning the range of classical artisanal colors is also included.
We are also using a finer resolution spectrometer/microscope to take new spectral measurements and extend the spectral range of the library into the ultraviolet (UV) wavelength range and collecting spectra of individual mineral grains. These measurements will be made for new entries (critical minerals containing rare earth elements) and for increasing the spectra resolution of existing library samples. New additions will include spectra of minerals as a function of grain size, mineral-deposit specific minerals, organic and inorganic compounds, vegetation and man-made materials. We are upgrading our database and metadata structure to increase usability for our customers.
We maintain the USGS Spectroscopy Laboratory equipment necessary for laboratory and field spectroscopy equipment, which is used by and critical to numerous USGS scientists on many projects.
Mineral maps based on Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) data were used to study late Miocene advanced argillic alteration at Cuprite, Nevada. Distributions of iron-bearing minerals, clays, micas, sulfates, and carbonates were mapped using the Tetracorder spectral-shape matching system. Variations in aluminum content of white mica, alunite composition, and the presence or absence of other minerals provided information on alteration temperatures, help delineate relict hydrothermal conduits, and provide insight on acidic conditions during hydrothermal alteration. Thus, spectral maps provide a synoptic view of the surface mineralogy, and define a previously unrecognized early steam-heated hydrothermal event.
As part of the U.S. Geological Survey and Department of Defense Task Force for Business and Stability Operations natural resources revitalization activities in Afghanistan, permissive areas for mineralization have been identified using airborne imaging spectrometer data. Mineral distributions identified using imaging spectroscopy, also known as hyperspectral remote sensing, may be indicative of past mineralization processes in areas with limited or no previous mineral resource studies. To support economic development, the areas of potential mineralization were selected based on the occurrence of selected mineral assemblages mapped using the HyMap™ data (for example, kaolinite, jarosite, hydrated silica, chlorite, epidote, iron-bearing carbonate, buddingtonite, dickite, and alunite). Approximately 30 sites were initially determined to be candidates for areas of potential mineralization. Additional criteria and material used to refine the selection and prioritization process included existing geologic maps, multispectral satellite data, and published literature, and interpretation of data in the context of the regional geologic and tectonic settings. Field-sampling, mapping, and supporting geochemical analyses are necessary to fully substantiate and verify the specific deposit types in the areas of potential mineralization.
The 2010 British Petroleum Deepwater Horizon Oil Spill in the Gulf of Mexico was the biggest oil spill in U.S. history. To assess the impact of the oil spill on the saltmarsh plant community, Airborne Visible Infrared Imaging Spectrometer (AVIRIS) data were flown over Barataria Bay, Louisiana in September 2010 and August 2011. Oil contamination was mapped using oil absorption features in pixel spectra and used to examine impact of oil along the oiled shorelines. Results showed that vegetation stress was restricted to the tidal zone extending 14 m inland from the shoreline in September 2010. Four indexes of plant stress and three indexes of canopy water content all consistently showed that stress was highest in pixels next to the shoreline and decreased with increasing distance from the shoreline. Index values along the oiled shoreline were significantly lower than those along the oil-free shoreline. Regression of index values with respect to distance from oil showed that in 2011, index values were no longer correlated with proximity to oil suggesting that the marsh was on its way to recovery. Change detection between the two dates showed that areas denuded of vegetation after the oil impact experienced varying degrees of re-vegetation in the following year.
Bishop, J.L., Lane, M.D., Dyar, M.D., King, S.J., Brown, A.J., and Swayze, G.A., 2014, Spectral properties of Ca-sulfates: Gypsum, bassanite, and anhydrite: American Mineralogist, 99(10), p. 2105-2115, doi:10.2138/am-2014-4756.
Clark, R.N., Curchin, J.M., Hoefen, T.M., and Swayze, G.A., 2009, Reflectance spectroscopy of organic compounds: 1. Alkanes: Journal of Geophysical Research, 114, E03001, doi:10.1029/2008JE003150.
Clark, R.N., and Swayze, G.A., 2016, U.S. Geological Survey Digital Spectral Library, in Smith, K.S., Phillips, J.D., McCafferty, A.E., Clark, R.N., eds., Developing Integrated Methods to Address Complex Resource and Environmental Issues: U.S. Geological Survey Circular 1413, p. 15-16, http://dx.doi.org/10.3133/cir1413.
Clark, R.N., Swayze, G.A., Carlson, Robert, Grundy, Will, and Noll, Keith, 2014, Chapter 10: Spectroscopy from space, in Henderson, G.S., Neuville, D.R., and Downs, R.T., eds., Spectroscopic Methods in Mineralogy and Material Sciences: Reviews in Mineralogy and Geochemistry, 78(1), p. 399-446, doi:10.2138/rmg.2014.78.10.
Desborough, G.A., Smith, K.S., Lowers, H.A., Swayze, G.A., Hammarstrom, J.M., Diehl, S.F., Leinz, R.W., and Driscoll, R.L., 2010, Mineralogical and chemical characteristics of some natural jarosites: Geochimica et Cosmochimica Acta, 74(3), p. 1041-1056, doi:10.1016/j.gca.2009.11.006.
Hoefen, T.M., Livo, K.E., Giles, S.A., and Swayze, G.A., 2015, Ultraviolet to near-infrared spectroscopy of REE-bearing materials: International Geoscience and Remote Sensing Symposium 2015 (IGARSS2015), July 26-30, 2015, Milan, Italy, IEEE International, p. 3422-3425, doi:10.1109/IGARSS.2015.7326555.
Khanna, S., Santos, M.J., Ustin, S.L., Koltunov, A., Kokaly, A.F., and Roberts, D.A., 2013, Detection of Salt Marsh Vegetation Stress and Recovery after the Deepwater Horizon Oil Spill in Barataria Bay, Gulf of Mexico Using AVIRIS Data: PLoS ONE 8(11), e78989, doi:10.1371/journal.pone.0078989.
Kokaly, R.F., Clark, R.N., Swayze, G.A., Livo, K.E., Hoefen, T.M., Pearson, N.C., Wise, R.A., Benzel, W.M., Lowers, H.A., Driscoll, R.L., and Klein, A.J., 2017, USGS Spectral Library Version 7: U.S. Geological Survey Data Series 1035, 61 p., https://doi.org/10.3133/ds1035.
Livo, K.E., 2015, Spectral libraries for material mapping: National Geospatial-Intelligence Agency, CGS website, 9 p.
Livo, K.E., Clark, R.N., 2014, The Tetracorder user guide—Version 4.4: U.S. Geological Survey, Open-File Report 2013–1300, 52 p., http://dx.doi.org/10.3133/ofr20131300.
Siers, S.R., Swayze, G.A., and Mackessy, S.P., 2013, Spectral analysis reveals limited potential for enhanced-wavelength detection of invasive snakes: Herpetological Review, 44(1), p. 56-58.
Swayze, G.A., 2016, Spectroscopy Laboratory, in Smith, K.S., Phillips, J.D., McCafferty, A.E., Clark, R.N., eds., Developing Integrated Methods to Address Complex Resource and Environmental Issues: U.S. Geological Survey Circular 1413, p. 4-5, http://dx.doi.org/10.3133/cir1413.
Swayze, G.A., Clark, R.N., Goetz, A.F.H., Livo, K.E., Breit, G.N., Kruse, F.A., Sutley, S.J., Snee, L.W., Lowers, H.A., Post, J.L., Stoffregen, R.E. and Ashley, R.P., 2014, Mapping advanced argillic alteration at Cuprite, Nevada, using imaging spectroscopy: Economic Geology, 109(5), p. 1179-1221, doi:10.2113/econgeo.109.5.1179.
Kokaly, R.F., Clark, R.N., Swayze, G.A., Livo, K.E., Hoefen, T.M., Pearson, N.C., Wise, R.A., Benzel, W.M., Lowers, H.A., Driscoll, R.L., and Klein, A.J., 2017, USGS Spectral Library Version 7 Data: U.S. Geological Survey data release, https://dx.doi.org/10.5066/F7RR1WDJ.
Clark, R.N., Swayze, G.A., Murchie, S.L., Seelos, F.P., Seelos, K.D., Viviano-Beck, C., and Bishop, J.L., 2015, Mars Surface Mineralogic Diversity and Mineral Mixtures Mapping Using CRISM Data and the Tetracorder Spectral Mapping System: American Geophysical Union 2015 Fall Meeting, 14-18 December, 2015, San Francisco, CA. View Clark 2015 AGU abstract.
Kokaly, Raymond, 2015, The USGS spectral library and PRISM: Processing Routines in IDL for Spectroscopic Measurements: invited oral presentation and workshop participant at the NASA EcoSIS Workshop, May 28, 2015, Madison, Wisconsin, USA.
Kokaly, R.F., Swayze, G.A., Hoefen, T.M., and Livo, K.E., 2015, Evaluating Field Spectrometer Performance with Transmission Standards: Examples from the USGS Spectral Library and Research Databases (Invited): American Geophysical Union 2015 Fall Meeting, 14-18 December, 2015, San Francisco, CA. View Kokaly 2015 AGU abstract.
Livo, K.E., 2014, Spectral library databases: National Geospatial-Intelligence Agency Spectroradiometer Working Group, Washington, DC, Oct. 22, 2014.
Swayze, G.A., Kokaly, R.F., Clark, R.N., Livo, K.E., Hoefen, T.M., Benzel, W.F., Lowers, H.A., Pearson, N.C., and Driscoll, R.L., 2016, The U.S. Geological Survey Spectral Library Version 7: Geological Society of America Abstracts with Programs. Vol. 48, No. 7, doi: 10.1130/abs/2016AM-283750. View Swayze 2016 GSA abstract.
Swayze, G.A., Pearson, N., Wilson, S., Benzel, W.M., Clark, R.N., Hoefen, T.M., Van Gosen, B.S., Adams, M., and Reitman, J., 2013, Spectrally distinguishing between REE-bearing minerals based on differences in their crystal field F-F transition absorptions: Geological Society of America Abstracts with Programs, Vol. 45, No. 7, p. 278. View Swayze 2013 GSA abstract.
Crustal Geophysics and Geochemistry Science Center